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Abstract

The genus Iris consists of approximately 360 species and is distributed to Eurasia, North Africa, and North America. Belamcanda chinensis was incorporated into the genus Iris by APG III as Iris domestica. Iris species have also been cultivated as ornamentals since ancient times. Many flavonoids are isolated and identified from the flowers, leaves, and rhizomes. So far as we know, 6 anthocyanidins, 13 flavones, 20 flavonols, 20 C-glycosylflavones, 14 flavanones, 11 dihydroflavonols, 6 flavan and proanthocyanidins, and 85 isoflavonoids were reported as aglycones and glycosides. However, chalcones, dihydrochalcones, aurones, biflavonoids, and neoflavonoids are not found in the genus Iris. Fifteen xanthones that are related to flavonoids were also isolated from Iris species. In this review, we describe the flavonoids and xanthones that were isolated and characterized from Iris species. Moreover, their phytochemistry, contribution to the flower colors, relationships with taxonomy, and activities and functions are also discussed.

Keywords

flavonoids xanthones flower colors activities phytochemistry

The genus Iris consists of approximately 360 species and is distributed to Eurasia, North Africa, and North America.¹⁷² Belamcanda chinensis (L.) Leman was incorporated into the genus Iris by APG III as Iris domestica (L.) Goldblatt & Mabberley.¹⁸⁰ As a result, the components of B. chinensis were not cited in a few reviews.^173,174,188 Iris species have been cultivated as ornamentals since ancient times. Moreover, Irises were used as emetic and purgative drugs.⁵⁵ Rhizomes of some Iris species (eg, Iris germanica and Iris pseudacorus) were also used as a diuretic, carminative, and against constipation and stomachache.¹⁷³ Furthermore, Iris species were used in the treatment of cancer, inflammation, and bacterial and viral infections.¹⁷³ Steroids, terpenoids, simple phenolics, quinones, etc., were reported from the genus as secondary metabolites.¹⁷⁴

“Flavonoid” is a general name of the compounds that has a 15-carbon skeleton, which consists of 2 phenyl rings (A and B includingrings) connected by a 3-carbon bridge (C ring). In general, vas-cular plants (ferns, gymnosperms, and angiosperms) and mosses possess the biosynthetic ability of the flavonoids except for a few algae,^175-177 fungi,¹⁷⁸ and a marine coral.¹⁷⁹ The flavonoids are divided into several classes, that is, anthocyanins, flavones, C-glycosylflavones, flavonols, flavanones, dihydrofla-vonols, chalcones, dihydrochalcones, aurones, isoflavonoids, including isoflavones, rotenoids, coumaronochromones, pterocarpans, etc., flavan and proanthocyanidins, biflavonoids, and neoflavonoids.

Many flavonoids are isolated and identified from the flowers, leaves, and rhizomes of Iris species. So far as we know, 6 anthocyanidins, 13 flavones, 20 flavonols, 20 C-glycosylflavones, 14 flavanones, 11 dihydroflavonols, 6 flavan and proanthocyanidins, and 85 isoflavonoids were reported as aglycones and glycosides (Table 1). However, chalcones, dihydrochalcones, aurones, biflavonoids, and neoflavonoids are not found in the genus Iris. On the other hand, the related compound, xanthones, consists of C6-C1-C6 and is widely distributed in fungi and algae in addition to angiosperms, gymnosperms, and ferns.⁵ Fifteen xanthones are isolated and identified from Iris species. Flavonoids of Iris have been reviewed by Iwashiana¹⁸¹ Wang et al,¹⁷³ and Kukla-Koch et al.¹⁷⁴ However, the former 2 were published in 1998 (by Japanese) and 2010, and the latter roughly describes major secondary metabolites, including flavonoids and xanthones, in 2015.

Table 1

Occurrence of Flavonoids and Xanthones in the Genus Iris.

I. adriatica Trinajstić ex Mitić

Isoflavonoid: irigenin, irigenin dihexoside, irigenin hexoside, irigenin S, irilone, irilone hexoside, irisflorentin, iriskumaonin methyl ether, irisolone dihexoside, irisolone feruloylhexoside, irisolone sinapoylhexoside, irisolone trihexoside, iristectorigenin A, iristectorigenin A 7-O-gentiobioside, iristectorigenin A hexoside, iristectorigenin A trihexoside, tectorigenin, tectorigenin hexoside (rz),¹⁶¹ irisolone, irisolone 4′-O-gentiobioside, irisolone 4′-O-glucoside (rz),^161,162 irisolone 3′,5′-dimethyl ether 4′-O-glucoside (rz),¹⁶² Xanthone: irisxanthone, irisxanthone 8-O-hexoside, 7-O-methylisomangiferin O-hexoside, 7-O-methylmangiferin, 7-O-methylmangiferin O-hexoside, mangiferin, neomangiferin (rz)¹⁶¹

I. albertii Regel

Xanthone: isomangiferin, mangiferin (lv)¹

I. albicans Lange

C-Glycosylflavone: isoorientin, isovitexin, swertiajaponin, swertisin, vitexin (lv),⁷¹ Isoflavonoid: irigenin 7-O-glucoside, irilone 4′-O-gentiobioside, irisolidone 7-O-gentiobioside, irisolidone 7-O-glucoside, irisolone 4′-O-gentiobioside, iristectorigenin B 7-O-gentiobioside, tectorigenin 7-O-glucoside (lv),¹¹⁵ Xanthone: isomangiferin, mangiferin (lv),^71,115 irisxanthone, neomangiferin (lv)¹¹⁵

I. aphylla L. (=I. hungarica Waldst. et Kit.)

Isoflavonoid: daidzein, formononetin, genistein, tectorigenin, tectorigenin 7-O-glucoside (rz),¹⁴³ Xanthone: isomangiferin (lv),¹ mangiferin (lv)^1,20,143

I. biflora L.

C-Glycosylflavone: isoorientin, orientin, swertisin (lv),⁷¹ Xanthone: isomangiferin, mangiferin (lv)⁷¹

I. bracteata S.Wats.

Flavonol: kaempferol, myricetin, quercetin (lv)²⁰

I. brevicaulis Raf.

C-Glycosylflavone: swertisin 2″-O-(6″′-p-coumaroylglucoside) (lv)¹²¹

I. bulleyana Dykes

Flavonol: quercetin (lv)²⁰

I. bungei Maxim.

Flavone: apigenin, hispidulin (lv),¹¹⁴ Flavonol: irisflavone A, irisflavone B, irisflavone C, irisflavone D (ug),¹²⁴ irisoid A, irisoid B, irisoid C, irisoid D, irisoid E (ug),¹⁴⁰ Isoflavonoid: ayamenin B, irisbungin (lv),¹¹⁴ irilin A, irilin B, irilin D, tlatlancuayin (ug),¹²⁴ Xanthone: mangiferin (lv)¹¹⁴

I. chrysographes Dykes

Anthocyanin: delphinidin 3-O-(p-coumaroylrutinoside)-5-O-glucoside (fl),³⁰ Flavan and proanthocyanidin: procyanidin, prodelphinidin (lv),¹ Flavonol: myricetin, quercetin (lv)²⁰

I. chrysophylla Howell

Anthocyanin: delphinidin 3-O-(p-coumaroylrutinoside)-5-O-gluoside (fl),³⁰ C-Glycosylflavone: isoorientin, isovitexin, lucenin-2, orientin, vicenin-2, vitexin (lv)¹⁸

I. clarkei Baker

Flavan and proanthocyanidin: procyanidin, prodelphinidin (lv)¹

I. crocea Jacquem. ex R.C. Foster

Dihydroflavonol: alpinone (rz),⁵⁷ Flavanone: 5,2′,3′-trihydroxy-7-methoxyflavanone (rt),¹²⁵ hesperetin (rz),¹⁶⁹ Isoflavonoid: 5,7-dihydroxy-6,2´-dimethoxyisoflavone, 9-methoxyirispurinol (rz),⁵⁷ tectorigenin 4′-O-glucoside (rz),^57,169 tectorigenin (rz, rt),^57,125 tectorigenin 7-O-glucoside (rz, rt),^57,125,169 crocetenone (rt),^125,169 irilin A, iriskashmirianin 4′-O-glucoside, irisolidone, irisolone, irisolone 4′-O-glucoside, tectorigenin 7,4′-di-O-glucoside, tectorigenin 7-O-glucoside-4′-O-gentiobioside (rz)¹⁶⁹

I. delavayi Micheli

Anthocyanin: delphinidin 3-O-(p-coumaroylrutinoside)-5-O-glucoside (fl),³⁰ Flavan and proanthocyanidin: procyanidin, prodelphinidin (lv)¹,

Flavonol: myricetin, quercetin (lv)¹

I. dichotoma Pallas

I. domestica Goldblatt & Mabberley (=Belamcanda chinensis (L.) Leman)

Anthocyanin: cyanidin 3-O-(p-coumaroylrutinoside)-5-O-glucoside, cyanidin 3-O-rutinoside, delphinidin 3-O-(acetyl-p-coumaroylrutinoside)-5-O-glucoside, delphinidin 3-O-(caffeoylrutinoside)-5-O-glucoside, delphinidin 3-O-(p-coumaroylrutinoside), delphinidin 3-O-(E-p-coumaroylrutinoside)-5-O-glucoside, delphinidin 3-O-(Z-p-coumaroylrutinoside)-5-O-glucoside, delphinidin 3-O-(feruloylrutinoside), delphinidin 3-O-(feruloylrutinoside)-5-O-glucoside, delphinidin 3-O-rutinoside, delphinidin 3-O-rutinoside-5-O-glucoside, delphinidin 3-O-(acetylrutinoside)-5-O-glucoside, malvidin 3-O-rutinoside, malvidin 3-O-rutinoside-5-O-glucoside, pelargonidin 3-O-(acetylrutinoside)-5-O-glucoside, pelargonidin 3-O-(caffeoylrutinoside)-5-O-glucoside, pelargonidin 3-O-(Z-p-coumaroylrutinoside), pelargonidin 3-O-(E-p-coumaroylrutinoside), pelargonidin 3-O-(E-p-coumaroylrutinoside)-5-O-glucoside, pelargonidin 3-O-(Z-p-coumaroylrutinoside)-5-O-glucoside, pelargonidin 3-O-(feruloylrutinoside), pelargonidin 3-O-(feruloylrutinoside)-5-O-glucoside, pelargonidin 3-O-rutinoside, pelargonidin 3-O-rutinoside-5-O-glucoside, peonidin 3-O-(p-coumaroylrutinoside)-5-O-glucoside, peonidin 3-O-rutinoside, petunidin 3-O-(p-coumaroylrutinoside)-5-O-glucoside, petunidin 3-O-rutinoside, petunidin 3-O-rutinoside-5-O-glucoside (fl),¹⁴⁴ Flavanone: naringenin (rz), ⁹¹ Flavone: hispidulin 7-O-glucoside, jaceosidin 7-O-glucoside (rz),⁸⁰ hispidulin (rz),^81,91,160 kanzakiflavone 2 (rz),^82,91 apigenin, 5,4′-dihydroxy-3′-methoxy-6,7-methylenedioxyflavone, luteolin (rz),^91,160 Flavonol: kaempferol 3-O-glucoside (rz),^81,91 myricetin 7,3′,4′-trimethyl ether (rz),⁸² rhamnocitrin (rz),^83,84,91 isorhamnetin, rhamnazin (rz),^91,160 quercetin (sd),¹⁸⁵ C-Glycosylflavone: isovitexin, isovitexin 2″-O-rhamnoside, swertisin, swertisin 2″-O-rhamnoside (lv),⁸⁵ Isoflavonoid: iristectorigenin B 7-O-glucoside (rz),^{80,91,163,170} irigenin 7-O-glucoside (rz),^{80,84,88–91,145,159,160,163,170,194} irisflorentin (rz),^{80,84,88–91,145,159,160,170} irilin D (rz),^80,81,88,91 iristectorigenin A 7-O-glucoside (rz),^{80,81,91,145,163,170} irigenin (rz),^{80,81,84,88–91,145,159,160,163,170,194} tectorigenin (rz),^{80,81,84,87–92,145,163,170,194} tectorigenin 7-O-glucoside (rz)^{80,81,84,86–88,91,145,163,170,194} tectorigenin 7-O-glucoside (rz), 8-hydroxyirigenin, 8-hydroxyiristectorigenin A, 8-hydroxytectorigenin (rz),^81,82,91, iristectorigenin B (rz),^{81,82,91,163,170,186} tectorigenin 4′-O-glucoside (rz),^{81,82,91,163,170} isotectorigenin (rz),^{82,91,163,170} irisolone (rz),⁸² isoirigenin, 5,7,4′-trihydroxy-6,3′,5′-trimethoxyisoflavone (rz),^82,91,170 irilin D, junipegenin C (rz),^{81,82,91,163,170} 5,7,3′-trihydroxy-8,4′-dimethoxyisoflavone (rz),^83,91 noririsflorentin (rz),^{83,91,160,170} 2,3-dihydroirigenin (rz, sd),^84,185 irigenin 7-O-(6″′-p-hydroxybenzoylglucoside), irigenin 7-O-(6″-vanilloylglucoside) (rz),^{84,160,163,170} 5,6,7,3′-tetrahydroxy-4′-methoxyisoflavone (rz),^{84,160,163,170} iristectorigenin A (rz),^{83,88–91,145,160,163,170} belamcandin, 7,4′-di-O-methyltectorigenin (rz),^89,91 irisolidone, iristectorigenin B 7,4′-di-O-glucoside (rz),⁹¹ irisolone 3′,5′-dimethyl ether 4′-O-glucoside, iristectorigenin B 4′-O-gentiobioside, tectorigenin 7,4′-di-O-glucoside, tectorigenin 4′-O-gentiobioside (rz),^91,170 iristectorigenin A 7-O-gentiobioside, iristectorigenin B 7-O-gentiobioside, junipegenin B (rz),^91,163 homotectorigenin 7-O-glucoside, irilone, isoirigenin 7-O-glucoside, tectorigenin 7-O-gentiobioside (rz),^91,163,170 dichotomitin (rz),^{91,159,160,163,170} dichotomitin 3′-O-glucoside, irilin D 7-O-glucoside (rz),¹⁶³ irigenin 7-O-gentiobioside (rz),¹⁷⁰ isotectorigenin 7-O-glucoside (rz),^{91,159,160,163} genistein (sd),¹⁸⁵ Xanthone: mangiferin (fl, lv),^{14,85,163,170} isomangiferin, 7-O-methylisomangiferin, 7-O-methylmangiferin, neomangiferin (rz),^163,170 nigricanside (rz)¹⁶³

I. douglasiana Herbert

Flavan and proanthocyanidin: procyanidin (lv),¹ gallocatechin-4β-ol, leucocyanidin (lv),¹⁷ Flavonol: isorhamnetin (lv),¹ kaempferol (lv),^1,20 quercetin (lv),^17,20 myricetin (lv)²⁰

I. ensata Thunb. var. ensata (=I. kaempferi Sieb.)

Anthocyanin: malvidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),^{35,42,74,76,79,117,188} petunidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),^35,42,74,76 delphinidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),^74,75,78 delphinidin 3-O-rutinoside, malvidin 3-O-(p-coumaroylrutinoside), malvidin 3-O-rutinoside, petunidin 3-O-(p-coumaroylrutinoside), petunidin 3-O-rutinoside (fl),⁷⁶ malvidin 3-O-rutinoside-5-O-glucoside, petunidin 3-O-rutinoside-5-O-glucoside (fl),^76,93 cyanidin 3-O-rutinoside-5-O-glucoside, peonidin 3-O-(p-coumaroylrutinoside) (fl),⁷⁷ malvidin 3-O-[(4″′-E-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, malvidin 3-O-[(4″′-Z-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, petunidin 3-O-[(4″′-E-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, petunidin 3-O-[(4″′-Z-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),⁹³ Flavone: 5-hydroxy-2′-methoxyflavone, 5-hydroxy-3′-methoxyflavone, 5-hydroxy-4′-methoxyflavone (cc),⁹⁴ C-Glycosylflavone: embigenin 2″-O-rhamnoside (ap),^19,50 swertisin 2″-O-glucoside, vitexin (fl),^35,39 apigenin 6,8-di-C-hexoside, isovitexin, isovitexin 7-O-glucoside, isovitexin 2″-O-rhamnoside, isovitexin 2″-O-xyloside, velutin 6-C-glycoside, vicenin-2 (fl),³⁹ isoorientin (fl, ap),^39,63 orientin (ap),⁶³ Xanthone: isomangiferin (lv),^1,39 mangiferin (lv, ap)^1,19,20,39

I. ensata Thunb. var. spontanea (Makino) Nakai

Anthocyanin: malvidin 3-O-rutinoside-5-O-glucoside, petunidin 3-O-rutinoside-5-O-glucoside (fl),⁴¹ malvidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, petunidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl)^41,74

I. florentina L.

C-Glycosylflavone: isoswertiajaponin, isoswertisin, swertisin (lv),²⁷ Isoflavonoid: iriflogenin 4′-O-glucoside (rz),⁷ irisolone, iristectorigenin B (rz),^7,56 irigenin 7-O-glucoside (rz),^{7,15,25,66,126} irigenin (rz),^{7,15,25,56,66,126} irisflorentin (rz),^7,15,25,56 irisolone 4′-O-bioside (rz),⁶⁷ irilone 4′-O-glucoside (rz),^67,126 irigenin 7-O-gentiobioside, irigenin 7-O-glucosyl-(1→3)-glucoside, iriskashmirianin 4′-O-glucoside, iriskashmirianin 4′-O-glucosyl-(1→3)-glucoside, irisolone 4′-O-gentiobioside, irisolone 4′-O-glucosyl-(1→3)-glucoside (ug),¹²⁶ Xanthone: irisxanthone (lv, rz),^{5,8,27,28,118,126} isomangiferin (lv, rz),^27,28 7-O-methylisomangiferin, 7-O-methylmangiferin (lv), ^5,27, 1,3,5,6-tetrahydroxyxanthone 2-C-glucoside (lv),^5,28 mangiferin (rz, lv),^8,27,28,118 1-hydroxy-3,5,6-trimethoxyxanthone 2-C-glucoside, neomangiferin (ug)^5,126

I. forrestii Dykes

Flavonol: myricetin, quercetin (lv)¹

I. fulva Ker Gawl.

C-Glycosylflavone: swertisin 2″-O-(6″′-p-coumaroylglucoside) (lv)¹²¹

I. germanica L.

Anthocyanin: delphinidin (fl),¹⁶ delphinidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),^16,113 Dihydroflavonol: taxifolin 7,3′-dimethyl ether (rz),⁵³ Flavanone: 6-hydroxy-5,7,3′,4′,5′-pentamethoxyflavanone*, selenone* (rz),²⁶ 5,7,2′-trihydroxy-6-methoxyflavanone (rz),¹⁵⁷ Flavonol: kaempferol, quercetin (fl),^16,26 3′-isobutenylquercetin*(rz),²⁶ 5,2′-dihydroxy-3-methoxy-6,7-methylenedioxyflavone (rz),¹⁵⁷ C-Glycosylflavone: embigenin X″-O-dirhamnoside (fl),⁴⁷ isoorientin, isovitexin, luteolin di-C-glycoside, orientin, swertisin, vitexin (lv),⁷¹ swertiajaponin (lv),^71,112 isoschaftoside, schaftoside, swertiajaponin 2″-O-arabinoside, swertisin 2″-O-glucoside (fl),¹¹² swertisin 2″-O-arabinoside (fl),^112,113 Isoflavonoid: 5,7,5′-trihydroxy-3′,4′-dimethoxyisoflavone 7-O-glucoside, dichotomitin (rz),^2,123 irisolidone 7-O-glucoside (rz),^{2,123,148,169} irisolidone (rz),^{2,53,123,130,132,148,151,152} irigenin (rz),^{2,17,29,53,123,132,148–150,152,169} irigenin 7-O-glucoside (rz),^{2,29,119,123,150,152,169} irilone (rz),^{23,53,123,131,132,139,148,152} irisolone (rz),^{24,26,53,123,130–132,139,149,151,161} 2-hydroxyirigenin* (rz),26 homotectorigenin 7-O-glucoside, tectorigenin 7-O-glucoside (rz),⁴⁹ tectorigenin (rz),^53,71,139 iristectorigenin B (rz),^53,139 iristectorigenin A (rz),^{53,132,139,150} irisflorentin (rz),^53,123,132 iriskumaonin methyl ether (rz),^{53,123,131,132} irisolone 4′-O-glucoside (rz),^119,131,138 iriskashmirianin 4′-O-glucoside (rz),^119,123,131 irilone 4′-O-glucoside (rz),^{119,123,131,152,169} iriflogenin 4′-O-gentiobioside, irilone 4′-O-gentiobioside, iristectorigenin A 7-O-gentiobioside, 7-O-methyltectorigenin 4′-O-gentiobioside (rz),¹²³ iristectorigenin A 7-O-glucoside (rz),^123,150 irisolone 4′-O-gentiobioside (rz),^123,138 iriflogenin 4′-O-glucoside (rz),^123,131 iriflogenin (rz),^{123,131,132,148} iriskashmirianin A, 5,3′,4′-trihydroxy-6,7-methylenedioxyisoflavone 4′-O-glucoside (rz),¹³¹ iriskashmirianin (rz),^132,148 6-hydroxygenistein 7-O-gentiobioside, irigenin 7-O-gentiobioside, irisolone 4′-O-glucosyl-(1→2)-[rhamnosyl-(1→6)-glucoside] (rz),¹³⁸ 5-hydroxy-4′-methoxy-6,7-methylenedioxyisoflavone, isoirigenin (rz),¹³⁹ junipegenin C 7-O-glucoside (rz),¹⁴⁷ irigenin S (rz),¹⁵² irilin A, irilin B (rz),¹⁵⁷ tectorigenin 4′-O-glucoside (rz),¹⁶⁹ Xanthone: isomangiferin (lv),^1,71 mangiferin O-glycoside (lv),¹ mangiferin (lv, fl),^{1,16,17,20,71,112,113,169,172} 6-dehydrojacareubin*(rz)²⁶

I. gracilipes A.Gray

Anthocyanin: delphinidin glycoside, malvidin 3-O-(feruloylrhamnosylglucoside)-5-O-glucoside, petunidin glycoside (fl),³⁷ C -Glycosylflavone: apigenin 7,4′-dimethyl ether 6-C-[(4″′-acetylrhamnosyl)-(1→2)-xyloside], apigenin 7,4′-dimethyl ether 6-C-rhamnosyl-(1→2)-xyloside, swertiajaponin, swertisin (fl, lv)⁹⁵

I. graminea L. var. graminea

Flavan and proanthocyanidin: procyanidin (lv),¹ Flavonol: myricetin, quercetin (lv)¹

I. graminea L. var. pseudocyperus (Schur.) Beck.

Flavan and proanthocyanidin: procyanidin (lv)¹

I. humilis Georgi

Flavonol: quercetin (lv),1 Xanthone: mangiferin (lv)¹

I. histrioides (G.F. Wilson) S. Arnott

Xanthone: isomangiferin, mangiferin (lv)¹

I. hollandica Hort. ex Todd.

Anthocyanin: delphinidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),¹¹⁰ C-Glycosylflavone: swertisin X″-O-glycoside (fl),¹¹⁰ swertiajaponin (fl),^110,111 diosmetin 6-C-glucoside, isoorientin, isoorientin 2″-O-rhamnoside, isovitexin, isovitexin 4′-O-glucoside, isovitexin 2″-O-(4″′-acetylrhamnoside), isovitexin 2″-O-(4″′-acetylrhamnoside)-4′-O-glucoside, orientin, scoparin, swertiajaponin 2″-O-rhamnoside, swertisin, swertisin 4′-O-glucoside, swertisin 2″-O-(4″′-acetylrhamnoside), swertisin 2″-O-(4″′-acetylrhamnoside)-4′-O-glucoside, vicenin-2, vitexin (fl)¹¹¹

I. hoogiana Dykes

Xanthone: isomangiferin, mangiferin, mangiferin-O-glycoside (lv)¹

I. hookeriana Foster

Isoflavonoid: irigenin, irigenin 7-O-glucoside, irisflorentin, junipegenin A (rz⁶⁰

I. imbricata Lindl.

Xanthone: mangiferin (lv)²⁰

I. innominata Henderson

Flavonol: kaempferol, myricetin (lv),²⁰ quercetin (lv)^1,20

I. japonica Thunb.

Anthocyanin: delphinidin 3-O-(p-coumaroylrutinoside)-5-O-glucoside, delphinidin 3-O-rutinoside-5-O-glucoside, malvidin glycoside, petunidin 3-O-(p-coumaroylrutinoside)-5-O-glucoside, petunidin 3-O-rutinoside-5-O-glucoside (fl),⁴¹ C-Glycosylflavone: embigenin 2″-O-rhamnoside, swertisin (fl),^12,96 Isoflavonoid: irigenin 7-O-glucoside, iristectorigenin A 7-O-glucoside, iristectorigenin B 7-O-glucoside, tectorigenin 7-O-deoxyalloside, tectorigenin 7-O-fucoside, tectorigenin 7-O-gentiobioside, tectorigenin 7-O-glucosyl-(1→3)-glucoside, tectorigenin 7-O-glucoside, tectorigenin 7-O-quinovoside (wp),⁹⁶ iriskumaonin methyl ether, irisjaponin A, irisjaponin B, irisolidone, irisolone methyl ether, iristectorigenin A, junipegenin B, 7-O-methylorobol, tectorigenin (wp)⁹⁷

I. kashmiriana Baker

Isoflavonoid: irisolidone (rz),^22,168 iriskashmirianin, irilone, irisolone, irisolone methyl ether, isoiriskashmirianin (rz),⁴⁵ isocladrastin, kashmigenin, junipegenin (rz),¹⁶⁴ isoirisolidone, isonigricin (rz),¹⁶⁸

I. kumaonensis Wall. ex D. Don

Isoflavonoid: iriskumaonin (rz),^4,46 irigenin 7-O-glucoside (rz, wp),^4,24,46 irisflorentin, iriskumaonin methyl ether, junipegenin A (rz),⁴ irigenin (rz, wp)^4,24

I. lactea Palas var. chinensis (Fisch.) Koidz.

Flavan and proanthocyanidin: procyanidin B1, procyanidin B3, prodelphinidin B3 (sd),¹³⁴ C-Glycosylflavone: embigenin 2″-O-(2″′,3″′-diacetylrhamnoside), isocytisoside 7-O-(2″″,4″″-diacetylrhamnoside)-2″-O-(6″′-acetylglucoside) (lv),¹²² embigenin 2″-O-(4″′-acetylrhamnoside), embigenin 2″-O-(2″′,4″′-diacetylrhamnoside), embigenin 2″-O-(3″′,4″′-diacetylrhamnoside), isocytisoside 7-O-(4″″-acetylrhamnoside)-2″-O-(6″′-acetylglucoside) (lv)¹⁴⁶

I. lactea Palas var. lactea

C-Glycosylflavone: embigenin 2″-O-(2″′-acetylrhamnoside), embigenin 2″-O-(2″′-acetylrhamnoside)-X″-acetate (ap),⁶² swertiajaponin (ap),⁶⁴ Xanthone: isomangiferin, mangiferin (lv)¹

I. laevigata Fisch.

Anthocyanin: delphinidin 3-O-rutinoside-5-O-glucoside (fl),⁴¹ malvidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, malvidin 3-O-rutinoside-5-O-glucoside, petunidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, petunidin 3-O-rutinoside-5-O-glucoside (fl),^41,73 C-Glycosylflavone: apigenin 6,8-di-C-glycoside, isoorientin, isoscoparin, isovitexin, isovitexin X″-O-galactoside, isovitexin 4′-O-galactoside, isovitexin 4′-O-glucoside, isovitexin X″-O-glucoside (acylated), isovitexin 2″-O-rhamnoside, scoparin 7-O-glucoside, swertisin, swertisin X″-O-galactoside, swertisin X″-O-rhamnoside, vicenin-2, vitexin (fl)³⁸

I. lazica Albov

Xanthone: isomangiferin, mangiferin (lv)¹

I. loczyi Kanitz (=I. tenuifolia Pall.)

Dihydroflavonol: 3,5,2′,3′-tetrahydroxy-7-methoxyflavanone, 3,5,3′-trihydroxy-7,2′-dimethoxyflavanone (rz, rt),⁵¹ Flavan and proanthocyanidin: 3′-hydroxy-5,7-dimethoxy-4-O-2′-cycloflavan, 3′-hydroxy-5-methoxy-6,7-methylenedioxy-4-O-2′-cycloflavan (rt),¹¹⁶ Flavanone: 5,3′-dihydroxy-7,2′-dimethoxyflavanone (rz, rt),⁵¹ 5,2′-dihydroxy-6,7-methylenedioxyflavanone, 5,2′,3′-trihydroxy-6,7-methylenedioxyflavanone, 5,2′,3′-trihydroxy-7-methoxyflavanone (rz, rt),^51,116 5,2′,3′-trihydroxy-6,7-dimethoxyflavanone (rt)¹¹⁶

I. lutescens Lam.

Anthocyanin: delphinidin 3-O-[(acetyl-E-caffeoylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, delphinidin 3-O-[(acetyl-Z-caffeoylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, delphinidin 3-O-[(4″′-caffeoylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, delphinidin 3-O-[(acetyl-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, delphinidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, delphinidin 3-O-[(diacetyl(or butyryl)-E-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, delphinidin 3-O-[(diacetyl(or butyryl)-Z-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),¹⁶⁶ C-Glycosylflavone: isoorientin, luteolin di-C-glycoside, swertisin (lv),⁷¹ Isoflavonoid: tectorigenin (lv),⁷¹ Xanthone: isomangiferin, mangiferin (lv)⁷¹

I. macrosiphon Torrey

Flavonol: myricetin, quercetin (lv)¹

I. marsica Ricci & Colasante

C-Glycosylflavone: isoorientin, swertisin (lv),⁷¹ Isoflavonoid: iriflogenin, irigenin, irigenin 7-O-glucoside, irigenin S, irilone 4′-O-glucoside, irisolidone, irisolidone 7-O-glucoside, irisolone, irisolone 4′-O-glucoside, tectorigenin 7-O-glucoside (rt),¹⁶⁵ Xanthone: isomangiferin, mangiferin (lv)⁷¹

I. milesii M.Foster

Flavanone: sakuranetin (rz),³ Flavonol: quercetin 3-methyl ether (rz),³ Isoflavonoid: irigenin, irigenin 7-O-glucoside, iristectorigenin A 7-O-glucoside, prunetin, tectorigenin, tectorigenin 7-O-glucoside, 5,6,7,4′-tetrahydroxy-8-methoxyisoflavone (rz),³ 5,6,7,4′-tetrahydroxy-3′-methoxyisoflavone (rz)⁴

I. minutoaurea Makino

Flavone: acacetin 7-O-glucoside (ap),¹²⁷ Xanthone: 1,6-dihydroxy-3,5-dimethoxyxanthone 6-O-glucoside (ap)¹²⁷

I. missouriensis Nutt.

Isoflavonoid: 5,7-dihydroxy-6,2′-dimethoxyisoflavone, irisone A, irisone B (rz)⁷²

I. monnieri DC.

Flavan and proanthocyanidin: procyanidin (lv)¹

I. nepalensis D.Don

Isoflavonoid: irisolone (rz),^17,33 irigenin (rz),³⁴ irisolidone (rz)⁵²

I. nigricans Dinsmore

Flavan and proanthocyanidin: procyanidin (fl),¹⁴¹ Isoflavonoid: dichotomitin, irilone, iriskashmirianin, irisolone (rz),⁶ iristectorigenin A (lv),¹⁴¹ Xanthone: mangiferin (rz, lv, fl),^141,155 bellidifolin, desmethylbellidifolin, 1,6-dihydroxy-3,7-dimethoxyxanthone,7-O-methylmangiferin, nigricanside, norathriol (rz)¹⁵⁵

I. orientalis Miller

Flavan and proanthocyanidin: procyanidin (lv)¹

I. pallida Lam. subsp. cengialtii (Ambr.) Foster (=I. cengialtii Ambr.)

Xanthone: isomangiferin, mangiferin (lv)^1,70

I. pallida Lam. subsp. pallida

C-Glycosylflavone: embigenin 2″-O-rhamnoside, isoorientin, isovitexin, swertisin 2″-O-rhamnoside (lv),⁷¹ Isoflavonoid: 2,3-dihydroirigenin, 8-hydroxyirigenin, irigenin, irilone, iriflogenin, irisflorentin, iriskashmirianin, iriskumaonin methyl ether, irisolone, iristectorigenin A (rz),¹³² Xanthone: isomangiferin, mangiferin (lv)⁷¹

I. persica L.

C-Glycosylflavone: isovitexin (fl),¹²⁸ embigenin 2″-O-rhamnoside (fl, lv),¹²⁸ Isoflavonoid: tectorigenin (bl)¹²⁸

I. potaninii Mazim.

Dihydroflavonol: 3,5,3′-trihydroxy-7,4′-dimethoxyflavanone (ug),¹²⁰ Isoflavonoid: dichotomitin, iriflogenin, irisflorentin, iriskumaonin, irisolone, 6,8,3′,5′-tetrahydroxy-7,4′-dimethoxyisoflavone 6-O-glucoside, 7,8,5′-trihydroxy-6,3′,4′-trimethoxyisoflavone (ug)¹²⁰

I. prismatica Pursh

Flavonol: kaempferol (lv)²⁰

I. pseudacorus L.

Dihydroflavonol: aromadendrin 7-methyl ether** (lv),³² alpinone** (lv, ap, rt),^32,99,100 E-3-hydroxy-5,7-dimethoxyflavanone (ap),^99,100 Flavan and proanthocyanidin: gallocatechin-4β-ol (lv),^1,17 Flavanone: 5,7,2′-trihydroxyflavanone** (lv),³² Flavone: apigenin**, hispidulin** (lv),³² Flavonol: 5,7-dihydroxy-3,6-dimethoxyflavone (cc, rt),^98,100 isorhamnetin, kaempferol (pl),¹⁰¹ Isoflavonoid: ayamenin C**, ayamenin D**, genistein**, irisone B**, iristectorigenin B**, isogenistein**, lupinalbin A**, 3′-O-methylorobol**, pratensein** (lv),³¹ ayamenin A**, ayamenin B**, iriline B** (lv, rt),^31,91,100 iristectorigenin A** (lv, rt),^31,98,100 tectorigenin** (lv, rt),^31,98,100 ayamenin E** (lv),³² tectorigenin 7-O-glucoside (cc),⁹⁸ biochanin A** (lv, ap, rt),^31,99,100 5,7-dihydroxy-6,2′-dimethoxyisoflavone (ap, rt),^99,100 5,7-dihydroxy-6,2′-methoxyisoflavone 7-O-glucoside, irilone (rt),¹⁰⁰ 5,6-dihydroxy-7,8,3′,5′-tetramethoxyisoflavone (rz),¹⁰² Xanthone: mangiferin (lv, fl),^1,14,17,20 isomangiferin, mangiferin O-glycoside (lv)¹

I. pseudopumila Tineo

Flavone: apigenin, chrysoeriol (lv),⁷¹ Flavonol: kaempferol 3-O-glucoside, kaempferol 3-O-rutinoside (rz),^136,158 C-Glycosylflavone: luteolin di-C-glycoside (lv),⁷¹ isocytisoside, isoscutellarein 6-C-glucoside (rz),¹³⁶ isoorientin, isovitexin (rz, fl), isoorientin 6″-O-glucoside, isovitexin 6″-O-glucoside (fl),^136,158 Isoflavonoid: tectorigenin (lv),⁷¹ irigenin, tectorigenin 4′-O-glucoside (rz),¹³⁶ irigenin 7-O-glucoside, irilone, irilone 4′-O-gentiobioside, irilone 4′-O-glucoside, irisolidone, irisolone 4′-O-gentiobioside, irisolone 4′-O-glucoside, 7-O-methyltectorigenin 4′-O-gentiobioside (rz),^136,158 7-O-methyltectorigenin 4′-O-glucoside (rz),¹⁵⁸ Xanthone: mangiferin (lv),^1,71 isomangiferin (lv)⁷¹

I. pumila L.

Xanthone: mangiferin (lv)^1,70

I. reichenbachii Heuffel

Flavone: acacetin, apigenin, chrysoeriol (lv),⁷¹ C-Glycosylflavone: isoorientin, luteolin di-C-glycoside (lv),⁷¹ Xanthone: isomangiferin, mangiferin (lv)^1,71

I. reticulata M.Beib.

Xanthone: isomangiferin, mangiferin (lv)¹

I. revoluta Colasante

C-Glycosylflavone: isoorientin, swertisin, vitexin (lv),⁷¹ Isoflavonoid: tectorigenin (lv),⁷¹ Xanthone: isomangiferin, mangiferin (lv)⁷¹

I. rossii Baker

Anthocyanin:delphinidin glycoside (fl),³⁶ delphinidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),¹⁰³ C-Glycosylflavone: swertisin (fl), vitexin (lv), swertiajaponin (fl), apigenin 6,8-di-C-arabinoside, isoschaftoside, schaftoside (lv), isoorientin, isovitexin (fl, lv),^36,103 Xanthone: mangiferin (fl, lv),^36,103 mangiferin X″-acetate (lv)¹⁰³

I. sambuchina L.

Xanthone: isomangiferin, mangiferin, mangiferin O-glycoside (lv)¹

I. sanguinea Hornem. ex Donn f. albiflora (Makino) Makino (= I. nertshinskia Lodd. f. albiflora Honda)

C-Glycosylflavone: swertiajaponin, swertiajaponin 2″-O-glucoside, swertisin (fl),⁴³ swertisin 2″-O-glucoside (fl)^43,48

I. sanguinea Hornem. ex Donn var. sanguinea

Anthocyanin: delphinidin 3-O-rutinoside-5-O-glucoside, malvidin glycoside, petunidin 3-O-rutinoside-5-O-glucoside (fl),⁴¹ delphinidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, petunidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),^41,104 Flavonol: myricetin, quercetin (lv),¹ myricetin 3-O-rhamnoside, quercetin 3-O-rhamnoside (lv),¹⁰⁴ C-Glycosylflavone: embigenin 2″-O-rhamnoside (fl),¹⁰⁵ swertisin (fl, lv)^104,105, isoorientin, isovitexin, isovitexin 2″-O-glucoside, swertiajaponin X″-O-hexoside, vicenin-2 (fl),¹⁰⁴ isoorientin 2″-O-glucoside, swertisin 2″-O-acetylglucoside, swertisin X″-acetate (lv),¹⁰⁴ swertisin 2″-O-glucoside, swertiajaponin (fl, lv)¹⁰⁴

I. sanguinea Hornem. ex Donn var. tobataensis S. Akiyama & Iwashina

Anthocyanin: delphinidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, petunidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),¹⁰⁴ Flavonol: myricetin 3-O-rhamnoside, quercetin 3-O-rhamnoside (lv),¹⁰⁴ C-Glycosylflavone: isoorientin, isovitexin, isovitexin 2″-O-glucoside, swertiajaponin X″-O-hexoside, vicenin-2 (fl), isoorientin 2″-O-glucoside, swertisin 2″-O-acetylglucoside, swertisin X″-acetate (lv), swertisin, swertisin 2″-O-glucoside, swertiajaponin (fl, lv)¹⁰⁴

I. sari Schott et Baker

Xanthone: mangiferin (lv)^17,20

I. setina Colasante

C-Glycosylflavone: isoorientin, luteolin di-C-glycoside, swertisin (lv),⁷¹ Xanthone: isomangiferin, mangiferin (lv)⁷¹

I. setosa Pall. ex Link var. canadensis (M.Foster) Hulten

C-Glycosylflavone: isoorientin, luteolin 6,8-di-C-glycoside, vicenin-2 (lv),⁴⁰ Xanthone: isomangiferin, mangiferin (lv)^1,40

I. setosa Pall. ex Link var. nasuensis Hara

Anthocyanin: malvidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, malvidin glycoside, petunidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),⁶⁹ C-Glycosylflavone: isoswertiajaponin, isoswertiajaponin X″-O-rhamnoside, isoswertisin, luteolin 6,8-di-C-glycoside, swertiajaponin, swertisin X″-O-rhamnoside (lv),⁶⁹ isovitexin 4′-O-galactoside, isovitexin X″-O-glucoside, swertisin 2″-O-glucoside, vitexin 4′-O-galactoside (fl),⁶⁹ isoorientin, isovitexin, isovitexin 4′-O-glucoside, orientin, swertisin, vicenin-2, vitexin (fl, lv),⁶⁹ Xanthone: mangiferin (lv)⁶⁹

I. setosa Pall. ex Link var. hondoensis Honda

Anthocyanin: malvidin3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside, malvidin glycoside, petunidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),⁶⁹ C-Glycosylflavone: luteolin 6,8-di-C-glycoside (lv),⁶⁹ isovitexin 4′-O-galactoside, vitexin 4′-O-galactoside (fl),⁶⁹ isoorientin, isovitexin, isovitexin 4′-O-glucoside, orientin, vicenin-2, vitexin (fl, lv),⁶⁹ Xanthone: mangiferin (lv)⁶⁹

I. setosa Pall. ex Link var. setosa

Anthocyanin: delphinidin hexoside, malvidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),⁶⁸ malvidin glycoside, petunidin 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside (fl),^38,69 C-Glycosylflavone: luteolin 6,8-di-C-glycoside (lv),⁶⁹ isovitexin X″-O-glucoside (fl),⁶⁹ isoorientin, isovitexin, orientin, vitexin (fl, lv),⁶⁹ vicenin-2 (fl, lv),^38,69 Xanthone: isomangiferin (lv),¹ mangiferin (lv, fl)^1,38,69

I. sibirica L.

Flavan and proanthocyanidin: gallocatechin-4β-ol, leucocyanidin (lv),¹⁷ Flavonol: myricetin, quercetin (lv)^1,17,20

I. sintenesii Janka

Flavonol: quercetin (lv)¹

I. sisyrinchium L. (=Moraea sisyrinchium (L.) Ker Gawl.)

Flavone: apigenin, apigenin 7-O-glucoside, luteolin 7-O-glucoside (ap),¹⁹² C-Glycosylflavone: isoorientin, isovitexin, isovitexin 7-O-glucoside, orientin (ap),192 Xanthone: mangiferin (lv)²⁰

I. sofarana Fost.

Isoflavonoid: 5-hydroxy-4′-methoxy-6,7-methylenedioxyisoflavone, irigenin, irilone, irisolone, iriskashmirianin, iriskumaonin methyl ether, soforanin A, soforanin B (rz)¹²⁹

I. songarica Schrenk

Dihydroflavonol: songaricol (rz),¹³⁷ Flavonol: irisflavone A, irisoid A (rz),¹³⁷ Isoflavonoid: ayamenin A, 5,7-dihydroxy-6,2′-dimethoxyisoflavone, 5,3′-dihydroxy-7,8,2′-trimethoxyisoflavone, irilin B (rz)¹³⁷

I. spuria Zeal var. carthaliniae (Fomin) B. Mathew (=I. carthaliniae Fomin)

Flavone: pectolinarigenin 7-O-glucoside (rz),¹⁵⁶ Isoflavonoid: irisolidone 7-O-glucoside, iristectorigenin B 4′-O-gentiobioside, tectorigenin 4′-O-gentiobioside, tectorigenin 7-O-glucoside, tectorigenin 4′-O-glucoside (rz)¹⁵⁶

I. spuria Zeal var. spuria

Flavanone: 5,8,2′-trihydroxy-7-methoxyflavanone (rz),^58,169 5,7,3′-trihydroxy-6,4′-dimethoxyflavanone(rz),¹³⁵ C-Glycosylflavone: isoscutellarein 6-C-glucoside (rz),¹³⁵ Isoflavonoid: 5,2′-dihydroxy-7,8-dimethoxyisoflavone (rz),⁵⁸ irispurinol (rz),^59,169 iristectorigenin A 7-O-glucoside (rz),⁶¹ 5,7-dihydroxy-6,2′-dimethoxyisoflavone, iristectorigenin A (rz),^61,135 tectorigenin 4′-O-gentiobioside (rz),^135,154 tectorigenin, tectorigenin 4′-O-glucoside, tectorigenin 7-O-glucoside (rz),^{135,142,154,169} tectorigenin 7-O-gentiobioside, 1,11-dihydroxy-9,10-methylenedioxy-12a-dehydrorotenoid (rz),¹⁴² iristectorigenin B 4′-O-gentiobioside (rz),¹⁵⁴ genistein 7-O-glucoside, tectorigenin 7,4′-di-O-glucoside, tectorigenin 7-O-glucoside-4′-O-gentiobioside (rz),^154,169 iristectorigenin B 7-O-glucoside, iristectorigenin B 4′-O-diglucoside, tectorigenin 7-O-diglucoside (rz)¹⁶⁹

I. subbiflora Brot.

Xanthone: isomangiferin, mangiferin (lv)¹

I. suaveolens Boiss. & Reut. (=I. mellita Janka)

Xanthone: isomangiferin (lv),¹ mangiferin (lv)^1,70

I. tectorum Maxim.

Anthocyanin: delphinidin 3-O-(p-coumaroylrutinoside)-5-O-glucoside, delphinidin 3-O-rutinoside-5-O-glucoside (fl),⁴¹ Dihydroflavonol: aromadendrin 4′-methyl ether (rz),^106,163 taxifolin 7,3′-dimethyl ether 5-O-rhamnoside (rz),¹⁰⁷ aromadendrin 7-O-glucoside (rz),¹⁶³ Flavanone: hesperetin, 5,7,3′-trihydroxy-6,4′-dimethoxyflavanone (rz),¹⁰⁶ Flavonol: rhamnocitrin (rz),^106,163 rhamnazin 3-O-glucoside (rz),¹⁰⁷ C-Glycosylflavone: embigenin 2″-O-rhamnoside (fl, lv),^44,108 embigenin 2″-O-(2″′-acetylrhamnoside), embigenin 2″-O-(3″′-acetylrhamnoside), embigenin, swertiajaponin, swertisin (lv),¹⁰⁸ Isoflavonoid: tectorigenin (lv),^{17,106,109,163} tectorigenin 7-O-glucoside (rz),^{11,55,65,106,107,109,163} iristectorigenin B 7-O-glucoside (rz),^54,106,163, iristectorigenin A 7-O-glucoside (rz),^{54,55,106,109,163} iristectorigenin B (rz),^106,163 tectorigenin 7,4′-di-O-glucoside (rz),^106,163 genistein (rz),^106,109 irigenin, iristectorigenin A, irigenin 7-O-glucoside (rz),^106,109,163 tectorigenin 7-O-fucoside (rz),¹⁰⁷ irisolidone (rz),¹⁰⁹ genistein 7-O-glucoside, homotectorigenin 7-O-glucoside, irilin D 7-O-glucoside, isotectorigenin, isotectorigenin 7-O-glucoside, orobol 7-O-glucoside, tectorigenin 7-O-gentiobioside, tectorigenin 4′-O-gentiobioside, tectorigenin 4′-O-glucoside (rz)¹⁶³

I. tenax Douflas ex Lindley

Flavonol: kaempferol, quercetin (lv),²⁰ C-Glycosylflavone: isoorientin, isovitexin, isovitexin glycoside (lv)¹⁸

I. tingitana Boiss. & Reut.

Anthocyanin: delphinidin 3-O-(p-coumaroylrutinoside)-5-O-glucoside (fl),¹³ C-Glycosylflavone: isoorientin, swertiajaponin, swertisin, swertisin X″-O-xyloside, vitexin (fl),¹³ Isoflavonoid: irigenin, irisflorentin, iriskumaonin, iriskumaonin methyl ether, irisolidone, irisolone methyl ether (rz),²¹ betavulgarin, 5-O-methylgenistein, 5-O-methylgenistein 7-O-glucoside (bl)¹⁵³

I. trojana Kerner ex Stapf.

Xanthone: isomangiferin, mangiferin (lv)¹

I. unguicularis Poir.

Flavone: kanzakiflavone 1 (rz),⁹ kanzakiflavone 2 (rz),¹⁰ Isoflavonoid: irigenin, iristectorigenin A (rz),⁹ irigenin 7-O-glucoside (rz),¹⁰ Xanthone: isomangiferin (lv, rz),^1,10 mangiferin (lv, rz)^{1,10,17,20,70}

I. variegata L. (=I. flavescens DC.)

C-Glycosylflavone: isoorientin (lv),⁷¹ Isoflavonoid: tectorigenin (lv),⁷¹ Xanthone: isomangiferin (lv),^1,71 mangiferin (lv),^1,20,70 mangiferin O-glycoside (lv)¹

I. versicolor L. var. kermesina Barr

Xanthone: isomangiferin, mangiferin (lv)¹

I. versicolor L. var. verscolor

Xanthone: mangiferin (lv)²⁰

I. virginica L. var. shrevei (Small) Anders

Xanthone: isomangiferin, mangiferin (lv)¹

ap = aerial parts, bl = bulbs, cc = callus tissue, fl = flowers, lv = leaves, rz = rhizomes, sd = seeds, ug = underground parts, wp = whole plants. “*” Indicates the compounds found in anoxically treated rhizomes. “**” Indicates the compounds found in the leaves treated with cupric chloride.

In this review, we describe the flavonoids and xanthones which were isolated and characterized from Iris species. Moreover, their phytochemistry, contribution to the flower colors, relationships with taxonomy, and function and activities are also discussed.

Phytochemistry of Flavonoids and Xanthones in Iris Species

Ninety-one Iris taxa have fully or fragmentarily been surveyed for flavonoids and xanthones (Table 1). Their compounds were isolated from the flowers, leaves, rhizomes, and sometimes roots, underground parts, and seeds.

Anthocyanins

Six anthocyanidins, pelargonidin (4), cyanidin (2), delphinidin (1), peonidin (6), petunidin (3), and malvidin (5), which are popular pigments in plants, especially in flowers and fruits, were isolated from the flowers of Iris species as glycosides (anthocyanins) (Table 2, Figure 1). 3-Deoxyanthocyanins such as apigeninidin and luteolinidin are not found in Iris species until now. Of their anthocyanidins, 1, 3, and 5 were frequently detected as a glycoside, 3-O-(p-coumaroylrutinoside)-5-O-glucoside.^36,37,68,144 This was completely identified as 3-O-[(4″′-E-p-coumaroyl-α-l-rhamnopyranosyl)-(1→6)-β-d-gl ucopyranoside]-5-O-β-d-glucopyranoside and 3-O-[(4″′-Z-p-co umaroyl-α-l-rhamnopyranosyl)-(1→6)-β-d-glucopyranoside]-5-O-β-d-glucopyranoside.⁹³ Although 3-O-(p-coumaroylrutino side)-5-O-glucoside of 1 was also found in Iris chrysographes, Iris chrysophylla, Iris delavayi,³⁰ Iris japonica,⁴¹ etc., it may be 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glucoside. In Iris ensata, non-acylated anthocyanins, 3-O-rutinoside-5-O-glucosides of 3 and 5 were accompanied.^76,92 3-O-Rutinosides and 3-O-(p-coumaroylrutinosides) of 1, 3, and 5 were also reported from I. ensata flowers as minor pigments.⁷⁶ Compounds 1, 3, and 5 were detected from each 17, 8, and 8 Iris taxa, respectively, as major anthocyanidins (Table 2). On the other hand, cyanidin (2), which is the most common antho-cyanidin in nature, pelargonidin (4), and peonidin (6) were found in some cultivars of Iris dichotoma and Iris domestica as major pigments.¹⁴⁴ Although 2 and 6 were also found in the flowersof 7cultivarsof I.ensataas3-O-rutinoside-5-O-glucosides, they rarely occur in I. ensata cultivars.⁷⁷ Anthocyanins are not reported in the leaves and rhizomes of Iris species.

Table 2

Anthocyanidins from Iris Species.

Names (trivial names)	Origins	References
3,5,7,3′,4′,5′-Hexahydroxyflavylium (Delphinidin, 1)	I. chrysographes, I. chrysophylla, I. delavayi, I. dichotoma, domestica, I. ensata var. ensata, I. germanica, I. gracilipes, I. hollandica, I. japonica, I. laevigata, I. lutescens, I. rossii, I. sanguinea var. sanguinea, I. sanguinea var. tobataensis, I. setosa var. setosa, I. tectorum, I. tingitana	^{13,16,30,36,37,41,68,74-76,78,103,104,110,113,144,166}
3,5,7,3′,4′-Pentahydroxyflavylium (cyanidin, 2)	I. dichotoma, I. domestica, I. ensata var. ensata	^77,144
3,5,7,4′,5′-Pentahydroxy-3′-methoxyflavylium (petunidin, 3)	I. dichotoma, I. domestica, I. ensata var. ensata, I. ensata var. spontanea, I. gracilipes, I. japonica, I. laevigata, I. sanguinea var. sanguinea, I. sanguinea var. tobataensis, setosa var. hondoensis, I. setosa var. nasuensis, I. setosa var. setosa	^{35-38,41,42,68,69,73,74,76,93,104,144}
3,5,7,4′-Tetrahydroxyflavyium (pelargonidin, 4)	I. dichotoma, I. domestica	¹⁴⁴
3,5,7,4′-Tetrahydroxy-3′,5′-dimethoxyflavylium (malvidin, 5)	I. dichotoma, I. domestica, I. ensata var. ensata, I. ensata var. spontanea, I. gracilipes, I. japonica, I. laevigata, I. sanguinea var. sanguinea, I. setosa var. nasuensis, I. setosa var. hondoensis, I. setosa var. setosa	^{35,37,38,41,42,68,69,74,76,79,93,117,144}
3,5,7,4′-Tetrahydroxy-3′-methoxyflavylium (peonidin, 6)	I. dichotoma, I. domestica, I. ensata var. ensata	^77,144

Figure 1

Chemical structures of anthocyanidins from Iris species.

Flavones

Thirteen flavones were reported from 9 Iris species as agly-cones and glycosides (Table 3, Figure 2). They were isolated from the leaves, and sometimes from rhizomes as minor com-pounds. In many cases, they were found as aglycones, for example, apigenin (16), acacetin (8), and chrysoeriol (19) are isolated from the leaves of Iris reichenbachii⁷¹; luteolin (15) and hispidulin (18) from the rhizomes of I. dichotoma^91,160; and 16 and 18 from the leaves of Iris bungei.¹⁴ On the other hand, a few flavones were isolated as O-glycosides, that is, 7-O-glucosides of 7 (Iris spuria var. carthaliniae),¹⁵⁶ 8 (Iris minu-toaurea),¹²⁷ and jaceosidin (17) and 18 (Iris domestica).⁸⁰ In Iris species, flavones occurred as C-glycosylflavones, which are described later, and not as O-glycosides in most cases. Two rare methylenedioxylated flavones were isolated from the rhi-zomes of Iris unguicularis, identified as 5,8-dihydroxy-4′-metho xy-6,7-methylenedioxyflavone (9) and 5,4′-dihydroxy-6,7-methylenedioxyflavone (11), and named as kanzakiflavones 1 and 2.^9,10 The latter flavone was also obtained from the rhi-zomes of I. domestica,⁸² together with another rare 5,4′-dihydroxy-3′-methoxy-6,7-methylenedioxyflavone (10).¹⁶⁰ Three rare simple flavones, 5-hydroxy-2′-methoxyflavone (12), 5-hydroxy-3′-methoxyflavone (13), and 5-hydroxy-4′-methoxyflavone (14), were isolated from the callus tissue of I. ensata.⁹⁴ Authors describe that the occurrence of their fla-vones is due to the conditions favoring the formation of lipo-philic flavones in auxin-dependent callus tissue, which can be considered as stress factors.⁹⁴

Table 3

Flavone Aglycones from Iris Species.

Names (trivial names)	Origins	References
5,7-Dihydroxy-6,4′-dimethoxyflavone (pectolinarigenin, 7)	I. spuria var. carthaliniae	¹⁵⁶
5,7-Dihydroxy-4′-methoxyflavone (acacetin, 8)	I. minutoaurea, I. reichenbachii	^71,127
5,8-Dihydroxy-4′-methoxy-6,7-methylenedioxyflavone (kanzakiflavone 1, 9)	I. unguicularis	⁹
5,4′-Dihydroxy-3′-methoxy-6,7-methylenedioxyflavone (10)	I. domestica	^91,146,160
5,4′-Dihydroxy-6,7-methylenedioxyflavone (kanzakiflavone 2, 11)	I. domestica, I. unguicularis	^10,82,91
5-Hydroxy-2′-methoxyflavone (12)	I. ensata var. ensata	⁹⁴
5-Hydroxy-3′-methoxyflavone (13)	I. ensata var. ensata	⁹⁴
5-Hydroxy-4′-methoxyflavone (14)	I. ensata var. ensata	⁹⁴
5,7,3′,4′-Tetrahydroxyflavone (luteolin, 15)	I. domestica	⁹¹
5,7,4′-Trihydroxyflavone (apigenin, 16)	I. bungei, I. domestica, I. pseudacorus, I. pseudopumila, reichenbachii	^32,71,91,114
5,7,4′-Trihydroxy-6,3′-dimethoxyflavone (jaceosidin, 17)	I. domestica	⁸⁰
5,7,4′-Trihydroxy-6-methoxyflavone (hispidulin, 18)	I. bungei, I. domestica, I. pseudacorus	^{32,80,81,91,114,146,160}
5,7,4′-Trihydroxy-3′-methoxyflavone (chrysoeriol, 19)	I. pseudopumila, I. reichenbachii	⁷¹

Figure 2

Chemical structures of flavone aglycones from Iris species.

Flavonols

Although flavonols were found in 23 Iris species, they occur as minor flavonoids in most cases. Twenty flavonols were isolated and characterized as aglycones and glycosides (Table 4, Figure 3). Methoxylated flavonols, rhamnazin (33) and rhamnocitrin (35), were found in the rhizomes of I. domestica^83,84,91,160 and Iris tecto-rum.^106,163 In I. domestica, comparatively rare myricetin 7,3′,4′-trimethyl ether (38) was accompanied.⁸² Another methox-ylated flavonol, quercetin 3-methyl ether (31) was detected in the rhizomes of Iris milesii.³ Rhamnazin (33) was isolated as 3-O-glucoside in I. tectorum.¹⁰⁷ Two rare flavonols, 5,2′-dihydroxy-3-methoxy-6,7-methylenedioxyflavone (23)¹⁵⁷ and 3′-isobuteny-lquercetin (29),²⁶ were found in the rhizomes of I. germanica. However, the latter compound was found in the plants which were treated anoxically and subsequently return to air as long-lived free radicals.²⁶ Comparatively simple 5,7-dihydroxy-3,6-dim ethoxyflavone (20) was obtained from the roots of I. pseuda-corus.¹⁰⁰ This compound was also isolated from callus cultures of the leaves of the same species.⁹⁸ Four rare 2′-substituted flavonols were isolated from the underground parts (rhizomes?) of I. bungei.¹²⁴ They were identified as 5,7,2′-trihydroxy-3,6-dimethoxyflavone (34), 5,2′-dihydroxy-3,6,7-trimethoxyflavone (25), 5,2′,6′-trihydroxy-3,6,7-trimethoxyflavone (39), and 3,5,3′-tri-hydroxy-7,2′-dimethoxyflavone (32) and named as irisflavones A-D, respectively.¹²⁴ Moreover, 5 peltogynoids which may be derived from flavonols were found in the same species and named as irisoids A-E (36, 21, 22, 24, and 37, respectively).¹⁴⁰ Compounds 34 and 36 were also detected in the rhizomes of Iris songarica.¹³⁷ Common flavonols, kaempferol (28), quercetin (27), and myrice-tin (26), were reported from some Iris species, for example, Iris bracteata, Iris douglasiana, and Iris innominata.^1,20 However, they were found in hydrolysates of crude extracts of the leaves and are roughly characterized. As a glycosides, 3-O-glucoside and 3-O-rutinoside of 28 were reported from the rhizomes of Iris pseudopumila,^136,158 and the former glycoside was found in I. domestica.^81,91 3-O-Rhamnosides of 26and 27 were isolated from the leaves of Iris sanguinea and its variety, var. tobataensis.¹⁰⁴

Table 4

Flavonol Aglycones from Iris Species.

Names (trivial names)	Origins	References
5,7-Dihydroxy-3,6-dimethoxyflavone (20)	I. pseudacorus	^98,100
1,8-Dihydroxy-9,10-dimethoxypeltogynoid (irisoid B, 21)	I. bungei	¹⁴⁰
1,10-Dihydroxy-8,9-dimethoxypeltogynoid (irisoid C, 22)	I. bungei	¹⁴⁰
5,2′-Dihydroxy-3-methoxy-6,7-methylenedioxyflavone (23)	I. germanica	¹⁵⁷
1,8-Dihydroxy-9,10-methylenedioxypeltogynoid (irisolid D, 24)	I. bungei	¹⁴⁰
5,2′-Dihydroxy-3,6,7-trimethoxyflavone (irisflavone B, 25)	I. bungei	¹²⁴
3,5,7,3′,4′,5′-Hexahydroxyflavone (myricetin, 26)	I. bracteata, I. chrysographes, I. delavayi, I. douglasiana, forrestii, I. graminea, I. innominata, I. macrosiphon, I. sanguinea var. sanguinea, I. sanguinea var. tobataensis, I. sibirica	^1,17,20,104
3,5,7,3′,4′-Pentahydroxyflavone (quercetin, 27)	I. bracteata, I. bulleyana, I. chrysographes, I. delavayi, I. domestica, I. douglasiana, I. forrestii, I. germanica, I. graminea, I. fumilis, I. innominata, I. macrosiphon, sanguinea var. sanguinea, I. sanguinea var. tobataensis, I. sibirica, I. sintenesii, I. tenax	^{1,16,17,20,26,104,185}
3,5,7,4′-Tetrahydroxyflavone (kaempferol, 28)	I. bracteata, I. domestica, I. douglasiana, I. germanica, innominata, I. prismatica, I. pseudacorus, I. pseudopumila, I. tenax	^{1,16,20,26,81,91,101,136,158}
3,5,7,4′-Tetrahydroxy-3′-isobutenylflavone (3′-isobutenylquercetin, 29)	I. germanica	²⁶
3,5,7,4′-Tetrahydroxy-3′-methoxyflavone (isorhamnetin, 30)	I. domestica, I. douglasiana, I. pseudacorus	^{1,91,101,146,160}
5,7,3′,4′-Tetrahydroxy-3-methoxyflavone (quercetin 3-methyl ether, 31)	I. milesii	³
3,5,3′-Trihydroxy-7,2′-dimethoxyflavone (irisflavone D, 32)	I. bungei	¹²⁴
3,5,4′-Trihydroxy-7,3′-dimethoxyflavone (rhamnazin, 33)	I. dichotoma, I. domestica, I. tectorum	^{91,107,146,160,167}
5,7,2′-Trihydroxy-3,6-dimethoxyflavone (irisflavone A, 34)	I. bungei, I. songarica	^124,137
3,5,4′-Trihydroxy-7-methoxyflavone (rhamnocitrin, 35)	I. domestica, I. tectorum	^{83,84,91,106,163}
1,8,10-Trihydroxy-9-methoxypeltogynoid (irisoid A, 36)	I. bungei, I. songarica	^137,140
1,8,11-Trihydroxy-9,10-methylenedioxypeltogynoid (irisoid E, 37)	I. bungei	¹⁴⁰
3,5,5′-Trihydroxy-7,3′,4′-trimethoxyflavone (myricetin 7,3′,4′-trimethyl ether, 38)	I. domestica	⁸²
5,2′,6′-Trihydroxy-3,6,7-trimethoxyflavone (irisflavone C, 39)	I. bungei	¹²⁴

Figure 3

Chemical structures of flavonol aglycones from Iris species.

C-Glycosylflavones

As described in the section Flavones, flavone O-glycosides were the minor compounds in Iris species. On the other hand, C-glycosylflavones were found in the flowers and leaves of many Iris species as major compounds. Twenty C-glycosylflavones were reported from 36 Iris taxa (Table 5, Figure 4). Common C-glycosylflavones, isovitexin (52), vitexin (54), isoorientin (47), orientin (48), and vicenin-2 (49) were isolated from the flowers and leaves of some Iris spe-cies such as I. chrysophylla,¹⁸ I. ensata,^39,63 I. laevigata,³⁸ and I. setosa.⁶⁹ Comparatively, common methoxylated C-glycosylflavones, swertisin (41), swertiajaponin (58), and embigenin (43), were also found in some Iris species, for example, I. albicans,⁷¹ I. ensata,³⁹ I. hollandica,¹¹¹ I. lactea,^62,146 and I. sanguinea.¹⁰⁴ Of their C-glycosylflavones, 52 was pres-ent in I. ensata flowers as 7-O-glucoside, 2″-O-rhamnoside and 2″-O-xyloside.³⁹ Compounds 52 and 41 were found in I. hollandica flowers as acylated O-glycosides, 2″-O-(4-acetylrhamnosides) and 2″-O-(4″′-acetylrhamnoside)-4′-O -glucosides, together with 4′-O-glucosides.¹¹¹ Embigenin was isolated from I. lactea var. chinensis leaves as 2″-O-(2″′,3″′-diacetylrhamnoside), 2″-O-(4″′-acetylrhamnoside), 2″-O-(2″′,4″′-diacetylrhamnoside) and 2″-O-(3″′,4″′-diacetyl-rhamnoside).^122,146 In this species, rarely acylated C-glycosylflavone O-glycosides, isocytisoside (40) 7-O-(2″″,4 ″″-diacetylrhamnoside)-2″-O-(6″′-acetylglucoside), and 7-O-(4″″-acetylrhamnoside)-2″-O-(6″′-acetylglucoside), were reported.^122,146 Isocytisoside (40) was also detected in the rhizomes of I. pseudopumila, together with isoscutellarein 6-C-glucoside (45).¹³⁶ 2″-O-(2″′-Acetylrhamnoside) and 2″-O-(3″′-acetylrhamnoside) were isolated from I. tectorum leaves as other O-glycoside of 43.¹⁰⁸ As rare C-glycosylflavones, apigenin 7,4′-dimethyl ether 6-C-xyloside was isolated from the flowers and leaves of I. gracilipes as (4″′-acetylrhamnosyl)-(1→2)-xyloside and rhamnosyl-(1→2)-xyloside.⁹⁵ Isoscutellarein 6-C-glucoside (45) was also found in the rhizomes of I. pseudopumila¹³⁶ and I. spuria.¹³⁵ As C-arabinosylflavone, apigenin 6,8-di-C-arabinoside (51) was reported from the flowers and leaves of I. rossii, together with other C-arabinosylflavones, schaftoside (53) and isoschaftoside (50).¹⁰³ Most of the C-glycosylflavones were isolated from the flowers and leaves except for the rhizomes of I. dichotoma (47 and 48),¹⁶³ I. pseudopumila (45, 47, and 52),¹³⁶ and I. spuria (45).¹³⁵ Although the presence of C-glycosylflavones were shown in the leaves of many Iris spe-cies, they were not characterized.¹ Some C-glycosylflavones from the flowers contribute to the expression of flower color, especially purple to blue, which is discussed later.

Table 5

C-Glycosylflavones from Iris Species.

Names (trivial names)	Origins	References
5,7-Dihydroxy-4′-methoxyflavone 6-C-glucoside (isocytisoside, 40)	I. lactea var. chinensis, I. pseudopumila	^122,136,146
5,4′-Dihydroxy-7-methoxyflavone 6-C-glucoside (swertisin, 41)	I. albicans, I. biflora, I. brevicaulis, I. domestica, I. ensata, I. florentina, I. fulva, I. germanica, I. gracilipes, I. hollandica, japonica, I. laevigata, I. lutescens, I. marsica, I. pallida, I. revoluta, I. rossii, I. sanguinea f. albiflora, I. sanguinea var. sanguinea, I. sanguinea var. tobataensis, I. setina, I. setosa var. nasuensis, I. tectorum, I. tingitana	^{12,13,27,35,36,38,39,43,48,69,71,85,95,96,103-105,108,110-113,121}
5,4′-Dihydroxy-7-methoxyflavone 8-C-glucoside (isoswertisin, 42)	I. florentina, I. setosa var. nasuensis	^27,69
5-Hydroxy-7,4′-dimethoxyflavone 6-C-glucoside (embigenin, 43)	I. ensata, I. germanica, I. japonica, I. lactea var. chinensis, I. lactea var. lactea, I. pallida, I. persica, I. sanguinea var. sanguinea, I. tectorum	^{12,19,44,47,50,62,71,96,105,108,122,128,146}
5-Hydroxy-7,4′-dimethoxyflavone 6-C-xyloside (apigenin 7,4′-dimethyl ether 6-C-xyloside, 44)	I. gracilipes	⁹⁵
5,7,8,4′-Tetrahydroxyflavone 6-C-glucoside (isoscutellarein 6-C-glucoside, 45)	I. pseudopumila, I. spuria	^135,136
5,7,3′,4′-Tetrahydroxyflavone 6,8-di-C-glucoside (lucenin-2, 46)	I. chrysophylla	¹⁸
5,7,3′,4′-Tetrahydroxyflavone 6-C-glucoside (isoorientin, 47)	I. albicans, I. biflora, I. chrysophylla, I. ensata, I. dichotoma, I. germanica, I. hollandica, I. laevigata, I. lutescens, I. marsica, I. pallida, I. pseudopumila, I. reichenbachii, I. revoluta, I. rossii, sanguinea var. sanguinea, I. sanguinea var. tobataensis, I. setina, I. setosa var. canadensis, I. setosa var. nasuensis, I. setosa var. hondoensis, I. setosa var. setosa, I. tenax, I. tingitana, I. variegata	^{13,18,38-40,63,69,71,103,104,111,136,158,163}
5,7,3′,4′-Tetrahydroxyflavone 8-C-glucoside (orientin, 48)	I. biflora, I. chrysophylla, I. ensata, I. germanica, I. hollandica, setosa var. nasuensis, I. setosa var. hondoensis, I. setosa var. setosa	^{18,63,69,71,111}
5,7,4′-Trihydroxyflavone 6,8-di-C-glucoside (vicenin-2, 49)	I. chrysophylla, I. ensata, I. hollandica, I. laevigata, I. sanguinea var. sanguinea, I. sanguinea var. tobataensis, I. setosa var. canadensis, I. setosa var. nasuensis, I. setosa var. hondoensis, setosa var. setosa	^{18,38-40,69,104,111}
5,7,4′-Trihydroxyflavone 6-C-arabinoside-8-C-glucoside (isoschaftoside, 50)	I. germanica, I. rossii	^103,112
5,7,4′-Trihydroxyflavone 6,8-di-C-arabinoside (apigenin 6,8-di-C-arabinoside, 51)	I. rossii	¹⁰³
5,7,4′-Trihydroxyflavone 6-C-glucoside (isovitexin, 52)	I. albicans, I. chrysophylla, I. dichotoma, I. domestica, I. ensata, germanica, I. hollandica, I. laevigata, I. pallida, I. persica, I. pseudopumila, I. rossii, I. sanguinea var. sanguinea, I. sanguinea var. tobataensis, I. setosa var. nasuensis, I. setosa var. hondoensis, I. setosa var. setosa, I. tenax	^{18,38,39,69,71,85,103,104,111,128,136,158,163}
5,7,4′-Trihydroxyflavone 6-C-glucoside-8-C-arabinoside (schaftoside, 53)	I. germanica, I. rossii	^103,112
5,7,4′-Trihydroxyflavone 8-C-glucoside (vitexin, 54)	I. albicans, I. chrysophylla, I. ensata, I. germanica, I. hollandica, laevigata, I. revoluta, I. rossii, I. setosa var. nasuensis, I. setosa var. hondoensis, I. setosa var. setosa, I. tingitana	^{13,18,35,36,38,39,69,71,111}
5,7,3′-Trihydroxy-4′-methoxyflavone 6-C-glucoside (diosmetin 6-C-glucoside, 55)	I. hollandica	¹¹¹
5,7,4′-Trihydroxy-3′-methoxyflavone 6-C-glucoside (isoscoparin, 56)	I. laevigata	³⁸
5,7,4′-Trihydroxy-3′-methoxyflavone 8-C-glucoside (scoparin, 57)	I. hollandica, I. laevigata	^38,111
5,3′,4′-Trihydroxy-7-methoxyflavone 6-C-glucoside (swertiajaponin, 58)	I. albicans, I. germanica, I. gracilipes, I. hollandica, I. lactea var. lactea, I. rossii, I. sanguinea f. albiflora, I. sanguinea var. sanguinea, I. sanguinea var. tobataensis, I. setosa var. nasuensis, I. tectorum, I. tingitana	^{13,43,64,69,71,95,103,104,108,110-112}
5, 3′,4′-Trihydroxy-7-methoxyflavone 8-C-glucoside (isoswertiajaponin, 59)	I. florentina, I. setosa var. nasuensis	^27,69

Figure 4

Chemical structures of C-glycosylflavones from Iris species.

Flavanones

Fourteen flavanones were reported from 8 Iris species (Table 6, Figure 5). They were all found as free states (aglycones). Common flavanone, naringenin (66) was found in the rhi-zomes of I. domestica.⁹¹ Comparatively, common sakuranetin (62) and hesperetin (70), which are frequently detected in Citrus fruits,¹⁸² were found in the rhizomes of I. milesii,³ I. crocea,¹⁶⁹ and I. tectorum,¹⁰⁶ respectively. In I. crocea, rare 2′-hydroxylated flavanone, 5,2′,3′-trihydroxy-7-methoxyflavanone (72), was accompanied.¹²⁵ 5,7,3′-Trihydroxy-6,4′-dimethoxyflavanone was found in I. tectorum.¹⁰⁶ Five rare 2′-substituted flavanones were isolated from the rhizomes and roots of I. loczyi (=I. tenuifolia) and identified as 5,3′-dihydroxy-7,2′-dimethoxy-flavanone (60), 5,2′-dihydroxy-6,7-methylenedioxyflavanone (63), 5,2′,3′-trihydroxy-6,7-dimethoxyflavanone (68), 5,2′,3′-trihydroxy-6,7-methylenedioxyflavanone (73), and 72.^51,116 Rare methoxylated flavanones, 5,8,2′-trihydroxy-7-methoxyflavanone (71) and 67, were found in I. spuria.^58,135,169 5,7,2′-Trihydroxy-6-methoxyflavanone (69) and polymethoxyl-ated 6-hydroxy-5,7,3′,4′,5′-pentamethoxyflavanone (64) were found in I. germanica.^26,157 Of their compounds, 64 was isolated from the rhizomes which were treated anoxically and subse-quently returned to air as long-lived free radicals, together with a flavonol 29.²⁶ Similarly, another flavanone, 5,7,2′-trihydroxy-flavanone (65) was isolated from the leaves of I. pseudacorus which was treated with cupric chloride, together with rare isoflavonoids and dihydroflavonols.³² Flavanones are not found in the flowers of Iris species.

Table 6

Flavanone Aglycones from Iris Species.

Names (trivial names)	Origins	References
5,3′-Dihydroxy-7,2′-dimethoxyflavanone (60)	I. loczyi	⁵¹
5,7-Dihydroxy-4′-isobutenylflavanone (selenone, 61)	I. germanica	²⁶
5,4′-Dihydroxy-7-methoxyflavanone (sakuranetin, 62)	I. milesii	³
5,2′-Dihydroxy-6,7-methylenedioxyflavanone (63)	I. loczyi	^51,116
6-Hydroxy-5,7,3′,4′,5′-pentamethoxyflavanone (64)	I. germanica	²⁶
5,7,2′-Trihydroxyflavanone (65)	I. pseudacorus	³²
5,7,4′-Trihydroxyflavanone (naringenin, 66)	I. domestica	⁹¹
5,7,3′-Trihydroxy-6,4′-dimethoxyflavanone (67)	I. spuria, I. tectorum	^106,135
5,2′,3′-Trihydroxy-6,7-dimethoxyflavanone (68)	I. loczyi	¹¹⁶
5,7,2′-Trihydroxy-6-methoxyflavanone (69)	I. germanica	¹⁵⁷
5,7,3′-Trihydroxy-4′-methoxyflavanone (hesperetin, 70)	I. crocea, I. tectorum	^106,169
5,8,2′-Trihydroxy-7-methoxyflavanone (71)	I. spuria	^58,169
5,2′,3′-Trihydroxy-7-methoxyflavanone (72)	I. crocea, I. loczyi	^51,116,125
5,2′,3′-Trihydroxy-6,7-methylenedioxyflavanone (73)	I. loczyi	^51,116

Figure 5

Chemical structures of flavanone aglycones from Iris species.

Dihydroflavonols

Eleven dihydroflavonols were reported from 8 Iris species (Table 7, Figure 6). Their compounds were isolated as agly-cones except for taxifolin 7,3′-dimethyl ether (81) (as 5-O-glucoside) from Iris dichotoma¹⁶⁷ and I. tectorum,^106,163 and aromadendrin (76) (as 7-O-glucoside) from I. tectorum.¹⁶³ Dihydroflavonols were found in the rhizomes with related fla-vanones except for I. pseudacorus. Although 3 dihydroflavonols were isolated from I. pseudacorus and identified as aromaden-drin 7-methyl ether (82), alpinone (74), and 3-hydroxy-5, 7-dimethoxyflavanone (75), the former 2 were found in the leaves which were treated with cupric chloride.³² Dihydroflavonols of I. loczyi were 2′-substituted flavanones, 3,5,2′,3′-tetrahydroxy-7-methoxyflavanone (77) and 3,5,3′-trihydroxy-7,2′-dimethoxyflavanone (79).⁵¹ 2′-Hydroxydihydroflavonol was also isolated from the rhi-zomes of I. songarica, identified as 3,5,2′,3′-tetrahydroxy-6,7-methylenedioxyflavanone (78) and named as songaricol.¹³⁷ Aromadendrin (76) and its 4′-methyl ether (84) were found in tectorum,^106,163 and its 5-methyl ether (83) was isolated from I. dichotoma.¹⁶⁷

Table 7

Dihydroflavonol Aglycones from Iris Species.

Names (trivial names)	Origins	References
3,5-Dihydroxy-7-methoxyflavanone (alpinone, 74)	I. crocea, I. pseudacorus	^32,57,99,100
3-Hydroxy-5,7-dimethoxyflavanone (75)	I. pseudacorus	^99,100
3,5,7,4′-Tetrahydroxyflavanone (aromadendrin, 76)	I. tectorum	¹⁶³
3,5,2′,3′-Tetrahydroxy-7-methoxyflavanone (77)	I. loczyi	⁵¹
3,5,2′,3′-Tetrahydroxy-6,7-methylenedioxyflavanone (songaricol, 78)	I. songarica	¹³⁷
3,5,3′-Trihydroxy-7,2′-dimethoxyflavanone (79)	I. loczyi	⁵¹
3,5,3′-Trihydroxy-7,4′-dimethoxyflavanone (80)	I. potaninii	¹²⁰
3,5,4′-Trihydroxy-7,3′-dimethoxyflavanone (taxifolin 7,3′-dimethyl ether, 81)	I. dichotoma, I. germanica, I. tectorum	^53,107,167
3,5,4′-Trihydroxy-7-methoxyflavanone (aromadendrin 7-methyl ether, 82)	I. pseudacorus	³²
3,7,4′-Trihydroxy-5-methoxyflavanone (aromadendrin 5-methyl ether, 83)	I. dichotoma	¹⁶⁷
3,5,7-Trihydroxy-4′-methoxyflavanone (aromadendrin 4′-methyl ether, 84)	I. tectorum	^106,163

Figure 6

>Chemical structures of dihydroflavonol aglycones from Iris species.

Flavan and Proanthocyanidins

Each 3 of flavans and proanthocyanidins were reported from 5 Iris species (Table 8, Figure 7). Of their compounds, proanthocy-anidins were obtained from the seeds of Iris lactea var. chinensis and identified as procyanidins B1 (90) and B3 (89), and prodelphinidin B3 (86).¹³⁴ Two flavans of I. loczyi roots were identified as vary rare 3′-hydroxy-5,7-dimethoxy-4-O-2′-cycloflavan (87) and 3′-hydroxy-5-methoxy-6,7-methylenedioxy-4-O-2′-cycloflavan (88) by single-crystal X-ray diffraction analysis.¹¹⁶ Gallocatechin-4β-ol (= leucodelphinidin, 85) was found in I. douglasiana, I. pseuda-corus, and I. sibirica.^1,17 Although the presence of procyanidins and prodelphinidins was shown in some Iris species, for example, I. chrysographes, I. clarkei, I. delavayi, I. graminea, I. monnieri, and I. orien-talis,¹ their complete identification was not performed.

Table 8

Flavan and Proanthocyanidins from Iris Species.

Names (trivial names)	Origins	References
3,4,5,7,3′,4′,5′-Heptahydroxyflavan (gallocatechin-4β-ol, 85)	I. douglasiana, I. pseudacorus, I. sibirica	^1,17
3,5,7,3′,4′,5′-Hexahydroxyflavan-(4α→8)–3,5,7,3′,4′-hexahydroxyflavan (prodelphinidin B₃, 86)	I. lactea var. chinensis	¹³⁴
3′-Hydroxy-5,7-dimethoxy-4-O-2′-cycloflavan (87)	I. loczyi	¹¹⁶
3′-Hydroxy-5-methoxy-6,7-methylenedioxy-4-O-2′-cycloflavan (88)	I. loczyi	¹¹⁶
3,5,7,3′,4′-Pentahydroxyflavan-(4α→8)-3,5,7,3′,4′-pentahydroxyflavan (procyanidin B3, 89)	I. lactea var. chinensis	¹³⁴
3,5,7,3′,4′-Pentahydroxyflavan-(4β→8)-3,5,7,3′,4′-pentahydroxyflavan (procyanidin B1, 90)	I. lactea var. chinensis	¹³⁴

Figure 7

Chemical structures of flavan and proanthocynidins from Iris species.

Isoflavonoids

Most isoflavonoids have been reported from Leguminoceous plants.¹⁸³ It was also shown that Iridaceae, especially the genus Iris, has many isoflavonoids in the rhizomes or underground parts. Thus, 85 isoflavonoids, including 7 coumaronochro-mones, 4 rotenoids, and 1 isoflavanone, were reported from 32 Iris species as aglycones and glycosides (Table 9, Figure 8). Although daidzein (100) and genistein (158) are the most com-mon isoflavones in nature, they were only found in 1 (Iris aphylla)¹⁴³ and 6 species (I. aphylla,¹⁴³ I. dichotoma,¹⁶³ I. domes-tica,¹⁸⁵ I. pseudacorus,³¹ I. spuria,^154,169 and I. tectorum^106,109,163) of Iris. Genistein (158) was present as glycosides in the rhizomes of I. dichotoma (7-O-gentiobioside), I. spuria, and I. tectorum (7-O-glucoside). In I. pseudacorus, 158 occurred in the leaves which were treated with cupric chloride.³¹ Other common iso-flavones, prunetin (103), formononetin (125), pratensein (162), and biochanin A (102), rarely occurr in the genus Iris and found in I. milesii,³ I. aphylla,¹⁴³ and I. pseudacorus,³¹ respectively. On the other hand, tectorigenin (163) and irigenin (169) were fre-quently reported from many Iris species. Tectorigenin (163) was isolated as aglycone and/or 7-O-glucoside from many species (eg, I. albicans,¹¹⁵ I. aphylla,¹⁴³ I. milesii,³ and I. spuria).^{135,142,154,169} It occurred as 4′-O-glucoside, 7,4′-di-O-glucoside, 4′-O-gentiobioside, 7-O-gentiobioside, 7-O-glucoside-4′-O-gen tiobioside in I. crocea,¹⁶⁹ I. dichotoma,¹⁶³ and I. domestica,^91,172 etc. Rare glycosides of 163, 7-O-deoxyalloside, 7-O-fucoside, 7-O-glucosyl-(1→3)-glucoside, and 7-O-quinovoside were iso-lated from the whole plants of I. japonica.⁹⁶ Although 169 occurred as aglycone and/or 7-O-glucoside in many cases, for example, I. adriatica,¹⁶¹ I. albicans,¹¹⁵ I. hookeriana,⁶⁰ I. unguicularis,^9,10 and I. tingitana,²¹ etc., it was present in I. domes-tica¹⁷⁰ and I. florentina¹²⁶ as 7-O-gentiobioside. In the latter spe-cies, 7-O-glucosyl-(1→3)-glucoside of 169 was also found.¹²⁶ Two acylated glycosides, 7-O-(6″-p-hydroxybenzoylglucoside) and 7-O-(6″-vanilloylglucoside) of 169, were isolated from I. domestica.^{84,160,163,170} Irisolidone (94), irilone (111), irisolone (129), and iristectorigenins A and B (152 and 154) were also found in many Iris species comparatively (Table 9).

Table 9

Isoflavonoid Aglycones from Iris Species.

Names (trivial names)	Origins	References
5,7-Dihydroxycoumaronochromone (ayamenin B, 91)	I. bungei, I. pseudacorus	^{31,99,100,114}
5,6-Dihydroxy-7,4′-dimethoxyisoflavone (isoirisolidone, 92)	I. kashmiriana	¹⁶⁸
5,7-Dihydroxy-6,2′-dimethoxyisoflavone (93)	I. crocea, I. missouriensis, I. pseudacorus, I. songarica, I. spuria var. spuria	^{57,61,72,99,100,135,137}
5,7-Dihydroxy-6,4′-dimethoxyisoflavone (irisolidone, 94)	I. albicans, I. crocea, I. domestica, I. germanica, I. japonica, I. kashmiriana, I. marsica, I. nepalensis, I. pseudopumila, I. spuria var. carthaliniae, I. tectorum, I. tingitana	^{2,21,22,52,53,91,97,109,115,123,130,132, 136,148,151,152,156,158,165,168,169}
5,2′-Dihydroxy-6,7-dimethoxyisoflavone (irilin B, 95)	I. bungei, I. germanica, I. pseudacorus, I. songarica	^{31,99,100,124,137,157}
5,2′-Dihydroxy-7,8-dimethoxyisoflavone (96)	I. spuria var. spuria	⁵⁸
5,4′-Dihydroxy-6,7-dimethoxyisoflavone (7-O-methyltectorigenin, 97)	I. germanica, I. pseudopumila	^123,136,158
5,5′-Dihydroxy-3′,4′-dimethoxy-6,7-methylenedioxyisoflavone (dichotomitin, 98)	I. dichotoma, I. domestica, I. germanica, I. nigricans, I. potaninii	^{2,6,91,120,123,133,159,160,163,170}
11,12a-Dihydroxy-9,10-dimethoxyrotenoid (9-methoxyirispurinol, 99)	I. crocea	⁵⁷
7,4′-Dihydroxyisoflavone (daidzein, 100)	I. aphylla	¹⁴³
5,7-Dihydroxy-6-methoxycoumaronochromone (ayamenin A, 101)	I. pseudacorus, I. songarica	^{31,99,100,137}
5,7-Dihydroxy-4′-methoxyisoflavone (biochanin A, 102)	I. pseudacorus	^31,99,100
5,4′-Dihydroxy-7-methoxyisoflavone (prunetin, 103)	I. milesii	³
7,4′-Dihydroxy-5-methoxyisoflavone (5-O-methylgenistein, 104)	I. tingitana	¹⁵³
5,3′-Dihydroxy-4′-methoxy-6,7-methylenedioxyisoflavone (soforanin A, 105)	I. sofarana	¹²⁹
5,4′-Dihydroxy-3′-methoxy-6,7-methylenedioxyisoflavone (iriflogenin, 106)	I. dichotoma, I. florentina, I. germanica, I. marsica, I. pallida, potaninii	^{7,120,123,131,132,148,163,165}
3′,4′-Dihydroxy-5-methoxy-6,7-methylenedioxyisoflavone (iriskashmirianin A, 107)	I. germanica	¹³¹
9,11-Dihydroxy-10-methoxyrotenoid (crocetenone, 108)	I. crocea	^125,169
1,11-Dihydroxy-9,10-methylenedioxy-12a-dehydrorotenoid (109)	I. spuria var. spuria	¹⁴²
5,2′-Dihydroxy-6,7-methylenedioxyisoflavone (irisone B, 110)	I. missouriensis, I. pseudacorus, I. songarica	^31,72,137
5,4′-Dihydroxy-6,7-methylenedioxyisoflavone (irilone, 111)	I. adriatica, I. albicans, I. dichotoma, I. domestica, I. florentina, I. germanica, I. kashmiriana, I. marsica, I. nigricans, I. pallida, I. pseudacorus, I. pseudopumila, I. sofarana	^{6,23,45,53,67,91,100,115,119,123,126,129,131-133,136,139,148,152,158,161,163,165,169,170}
5,7-Dihydroxy-6,2′,3′,4′,5′-pentamethoxyisoflavone (irisjaponin A, 112)	I. japonica	⁹⁷
5,6-Dihydroxy-7,8,3′,5′-Tetramethoxyisoflavone (113)	I. pseudacorus	¹⁰²
5,7-Dihydroxy-6,2′,3′,4′-Tetramethoxyisoflavone (irisjaponin B, 114)	I. japonica	⁹⁷
5,7-Dihydroxy-6,3′,4′,5′-Tetramethoxyisoflavone (junipegenin C, 115)	I. dichotoma, I. domestica, I. germanica	^{82,91,147,163,170}
5,5′-Dihydroxy-6,7,3′,4′-Tetramethoxyisoflavone (irigenin S, 116)	I. adriatica, I. germanica, I. marsica	^152,161,165
5,7-Dihydroxy-6,3′,4′-trimethoxyisoflavone (junipegenin B, 117)	I. dichotoma, I. domestica, I. japonica, I. kashmiriana	^{91,97,163,164}
5,3′-Dihydroxy-7,8,2′-trimethoxyisoflavone (118)	I. songarica	¹³⁷
5,2′-Dimethoxy-6,7-methylenedioxyisoflavone (tlatlancuayin, 119)	I. bungei	¹²⁴
5,4′-Dimethoxy-6,7-methylenedioxyisoflavone (irisolone methyl ether, 120)	I. japonica, I. kashmiriana, I. tingitana	^21,45,97
3′-Hydroxy-5,4′-dimethoxy-6,7-methylenedioxyisoflavone (iriskumaonin, 121)	I. kumaonensis, I. potaninii, I. tingitana	^4,21,46,120
3′-Hydroxy-5,5′-dimethoxy-6,7-methylenedioxyisoflavone (isoiriskashmirianin, 122)	I. kashmiriana	⁴⁵
4′-Hydroxy-3′,5′-dimethoxy-6,7-methylenedioxyisoflavone (kashmigenin, 123)	I. kashmiriana	¹⁶⁴
4′-Hydroxy-5,3′-dimethoxy-6,7-methylenedioxyisoflavone (iriskashmirianin, 124)	I. crocea, I. florentina, I. germanica, I. kashmiriana, I. nigricans, I. pallida, I. sofarana	^{6,45,119,123,126,129,131,132,148,169}
7-Hydroxy-4′-methoxyisoflavone (formononetin, 125)	I. aphylla	¹⁴³
5-Hydroxy-2′-methoxy-6,7-methylenedioxyisoflavone (irisone A, 126)	I. missouriensis	⁷²
Hydroxy-4′-methoxy-6,7-methylenedioxyisoflavone (127)	I. germanica, I. sofarana	^129,139,147
2′-Hydroxy-5-methoxy-6,7-methylenedioxyisoflavone (betavulgarin, 128)	I. tingitana	¹⁵³
4′-Hydroxy-5-methoxy-6,7-methylenedioxyisoflavone (irisolone, 129)	I. adriatica, I. albicans, I. crocea, I. domestica, I. florentina, germanica, I. kashmiriana, I. marsica, I. nepalensis,I. nigricans, I. pallida, I. potaninii, I. pseudopumila, I. sofarana	^{6,7,17,24,26,33,45,53,56,67,82,115,119,120,123,126,129-132,136,138,139,149,151,158,161,162,165,169}
4′-Hydroxy-8-methoxy-6,7-methylenedioxyisoflavone (isonigricin, 130)	I. kashmiriana	¹⁶⁸
5-Hydroxy-6,7,3′,4′-tetramethoxyisoflavone (belamcandin, 131)	I. domestica	^89,91
5-Hydroxy-6,7,4′-trimethoxyisoflavone (7,4′-di-O-methyltectorigenin, 132)	I. domestica	^89,91
3′-Hydroxy-6,7,4′-trimethoxyisoflavone (isocladrastin, 133)	I. kashmiriana	¹⁶⁴
5-Hydroxy-3′,4′,5′-trimethoxy-6,7-methylenedioxyisoflavone (noririsflorentin, 134)	I. domestica	^{83,91,160,170}
4′-Hydroxy-5,3′,5′-trimethoxy-6,7-methylenedioxyisoflavone (irisolone 3′,5′-dimethyl ether, 135)	I. adriatica, I. domestica	^91,162,170
5,7,8,4′-Tetrahydroxy-6,3′-dimethoxyisoflavone (8-hydroxyiristectorigenin A, 136)	I. domestica	^81,82,91
6,8,3′,5′-Tetrahydroxy-7,4′-dimethoxyisoflavone (137)	I. potaninii	¹²⁰
5,6,7,4′-Tetrahydroxyisoflavone (6-hydroxygenistein, 138)	I. germanica	¹³⁸
5,7,3′,4′-Tetrahydroxyisoflavone (orobol, 139)	I. tectorum	¹⁶³
5,6,7,3′-Tetrahydroxy-4′-methoxyisoflavone (140)	I. domestica	^84,90,91,160
5,6,7,4′-Tetrahydroxy-3′-methoxyisoflavone (141)	I. milesii	⁴
5,6,7,4′-Tetrahydroxy-8-methoxyisoflavone (142)	I. milesii	³
5,7,8,4′-Tetrahydroxy-6-methoxyisoflavone (8-hydroxytectorigenin, 143)	I. domestica	^81,82,91
5,7,3′,4′-Tetrahydroxy-6-methoxyisoflavone (irilin D, 144)	I. bungei, I. dichotoma, I. domestica, I. tectorum	^{80-82,88,91,124,163,170}
5,7,3′,5′-Tetrahydroxy-4′-methoxyisoflavone (junipegenin A, 145)	I. hookeriana, I. kashmiriana, I. kumaonensis	^4,60,164
5,3′,4′,5′-Tetrahydroxy-6,7-methylenedioxyisoflavone (irisflorentin, 146)	I. adriatica, I. dichotoma, I. domestica, I. florentina, I. germanica, I. hookeriana, I. kumaonensis, I. pallida, I. potaninii, I. tingitana	^{4,7,15,21,25,53,56,60,80,84,88-91,120,123,132,133,145,159-161,170}
2,5,7,5′-Tetrahydroxy-6,3′,4′-trimethoxyisoflavone (2-hydroxyirigenin, 147)	I. germanica	²⁶
5,7,8,5′-Tetrahydroxy-6,3´,4´-trimethoxyisoflavone (8-hydroxyirigenin, 148)	I. domestica, I. pallida	^81,82,91,132
5,7,3′-Trihydroxycoumaronochromone (ayamenin C, 149)	I. pseudacorus	³¹
5,7,4′-Trihydroxycoumaronochromone (lupinalbin A, 150)	I. pseudacorus	³¹
5,7,5′-Trihydroxycoumaronochromone (irisbungin, 151)	I. bungei	¹¹⁴
5,7,3′-Trihydroxy-6,4′-dimethoxyisoflavone (iristectorigenin A, 152)	I. adriatica I. dichotoma, I. domestica, I. germanica, I. japonica, milesii, I. nigricans, I. pallida, I. pseudacorus, I. spuria var. spuria, I. tectorum, I. unguicularis	^{3,9,31,53-55,61,80,81,83,88-91,96-98,100,106,109,123,132,133,135,139,141,145,150,160,161,163,170}
5,7,3′-Trihydroxy-8,4′-dimethoxyisoflavone (153)	I. domestica	^83,91
5,7,4′-Trihydroxy-6,3′-dimethoxyisoflavone (iristectorigenin B, 154)	I. albicans, I. dichotoma, I. domestica, I. florentina, I. germanica, I. japonica, I. pseudacorus, I. spuria var. carthaliniae, I. spuria var. spuria, I. tectorum	^{7,31,53,54,56,80-82,91,96,106,115,133,139,145,154,156,163,169,170,186}
5,7,4′-Trihydroxy-8,3′-dimethoxyisoflavone (homotectorigenin, 155)	I. dichotoma, I. domestica, I. germanica, I. tectorum	^{49,91,163,170}
5,7,5′-Trihydroxy-3′,4′-dimethoxyisoflavone (156)	I. germanica	^2,123
5,7,2′-Trihydroxyisoflavone (isogenistein, 157)	I. pseudacorus	³¹
5,7,4′-Trihydroxyisoflavone (genistein, 158)	I. aphylla, I. dichotoma, I. domestica, I. pseudacorus, I. spuria var. spuria, I. tectorum	^{31,106,109,143,154,163,169,185}
5,7,3′-Trihydroxy-4′-methoxycoumaronochromone (ayamenin E, 159)	I. pseudacorus	³²
5,7,4′-Trihydroxy-6-methoxycoumaronochromone (ayamenin D, 160)	I. pseudacorus	³¹
5,7,2′-Trihydroxy-6-methoxyisoflavone (irilin A, 161)	I. bungei, I. crocea, I. germanica	^124,157,169
5,7,3′-Trihydroxy-4′-methoxyisoflavone (pratensein, 162)	I. pseudacorus	³¹
5,7,4′-Trihydroxy-6-methoxyisoflavone (tectorigenin, 163)	I. adriatica, I. albicans, I. aphylla, I. crocea, I. dichotoma, I. domestica, I. germanica, I. japonica, I. lutescens, I. marsica, I. milesii, I. persica, I. pseudacorus, I. pseudopumila, I. revoluta, I. spuria var. carthaliniae, I. spuria var. spuria, I. tectorum, I. variegata	^{3,11,17,31,49,53,55,57,65,71,71,80-82,84,86-92,96-100,106,107,109,115,125,128,133,135,136,139,142,143,145,154,156,160,161,163,165,169,170}
5,7,4′-Trihydroxy-8-methoxyisoflavone (isotectorigenin, 164)	I. dichotoma, I. domestica, I. tectorum	^{81,82,91,159,160,163,170}
5,3′,4′-Trihydroxy-7-methoxyisoflavone (7-O-methylorobol, 165)	I. japonica	⁹⁷
5,7,4′-Trihydroxy-3′-methoxyisoflavone (3′-O-methylorobol, 166)	I. pseudacorus	³¹
5,3′,4′-Trihydroxy-6,7-methylenedioxyisoflavone (167)	I. germanica	¹³¹
5,7,5′-Trihydroxy-6,3′,4′-trimethoxyisoflavanone (2,3-dihydroirigenin, 168)	I. domestica, I. pallida	^84,132,185
5,7,5′-Trihydroxy-6,3′,4′-trimethoxyisoflavone (irigenin, 169)	I. adriatica, I. albicans, I. dichotoma, I. domestica, I. florentina, I. germanica, I. hookeriana, I. japonica, I. kumaonensis, I. marsica, I. milesii, I. nepalensis, I. pallida, I. pseudopumila, I. sofarana, I. tectorum, I. tingitana, I. unguicularis	^{2-4,7,9,10,15,17,21,24,25,29,34,46,53,56,60,66,80,81,84,88-91,96,106,109,115,119,123,126,129,132,133,136,138,139,145,148-150,152,153,158-161,163,165,169,170}
5,7,5′-Trihydroxy-8,3′,4′-trimethoxyisoflavone (isoirigenin, 170)	I. dichotoma, I. domestica, I. germanica	^{82,91,139,163,170}
5,7,4′-Trihydroxy-6,3′,5′-trimethoxyisoflavone (171)	I. domestica	^82,91,170
6,4′,5′-Trihydroxy-5,7,3′-trimethoxyisoflavone (soforanin B, 172)	I. sofarana	¹²⁹
7,8,5′-Trihydroxy-6,3′,4′-trimethoxyisoflavone (173)	I. potaninii	¹²⁰
9,11,12a-Trihydroxy-10-methoxyrotenoid (irispurinol, 174)	I. spuria var. spuria	^59,169
5,3′,4′-Trimethoxy-6,7-methylenedioxyisoflavone (iriskumaonin methyl ether, 175)	I. adriatica, I. dichotoma, I. germanica, I. japonica, I. kumaonensis, I. pallida, I. sofarana, I. tingitana	^{4,21,53,97,123,129,131-133,161}

Figure 8

Chemical structures of isoflavonoid aglycones from Iris species.

Rare isoflavones, isoirisolidone (92) and isocladrastin (133), were isolated from I. kashmiriana, together with 6,7-methylenedioxylated isoflavones, irisolone methyl ether (120), isoiriskashmirianin (122), kashmirianin (123), iriskashmirianin (124), and isonigricin (130).^45,164,168 As other rare isoflavones, irisone A (126), 7,8,5′-trihydroxy-6,3′,4′-trimethoxyisoflavone (173), 5-O-methylgenistein (104), and betavulgarin (128) were isolated from I. missouriensis,⁷² I. potaninii,¹²⁰ and I. tingitana,¹⁵³ respectively. 5,6,7,4′-Tetrahydroxy-3′-methoxyisoflavone (141) and 5,6,7,4′-tetrahydroxy-8-methoxyisoflavone (142) were obtained from I. milesii.^3,4 Iris germanica was fully surveyed for isoflavonoids, and many isoflavones were reported.^{49,53,123,138,150} Thus, 5,7,5′-tri-hydroxy-3′,4′-dimethoxyisoflavone (156), homotectorigenin (155),⁴⁹ hydroxygenistein (138),¹³⁸ 7-O-methyltectorigenin (97),¹²³ iri-genin S (116),¹⁵² irilin A (161),¹⁵⁷ and 6,7-methylenedioxy-genated iriskashmirianin A (107),¹³¹ 5,3′,4′,-trihydroxy-6,7-methylenedioxyisoflavone (167),¹³¹ iriskumaonin methyl ether (175)⁵³ etc., as aglycones, and as 7-O-glucosides, 7-O-gentiobiosides, or 4′-O-glucosides. As other 6,7-methylenedioxygenated isofla-vones, dichotomitin (98), iriflogenin (106), and irisflorentin (146) were found in I. dichotoma.^133,163 Soforanin A (105) and 5-hydroxy-4′-methoxy-6,7-methylenedioxyisoflavone (127) were detected in I. sofarana, together with non-methylenedioxygenated isoflavone, soforanin B (172).¹²⁹ Tlatlancuayin (119) and iriskumaonin (121) were obtained from I. bungei¹²⁴ and I. kumaonensis, respectively.^4,46 2′-Substituted isoflavones were present in some Iris species, that is, 5,7-dihydroxy-6,2′-dimethoxyisoflavone (93), irilin B (95), and 5,3′-dihydroxy-7,8,2′-trimethoxyisoflavone (118) from I. songarica,¹³⁷ 5,2′-dihydroxy-7,8-dimethoxyisoflavone (96) from I. spuria,⁵⁸ irisone B (110) from I. missouriensis,⁷² and irisjaponins A and B (112 and 114) from I. japonica.⁹⁷

Iris dichotoma and I. domestica were fully surveyed for isoflavo-noids. Junipegenins B and C (117 and 115), irilin D (144), isotec-torigenin (164), and isoirigenin (170) were found in the former species, together with 98, 106, 111, 146, 152, 154, 155, and 175.^133,163 On the other hand, belamcandin (131), 7,4′-di-O-methyltectorigenin(132),8-hydroxyiristectorigeninA(136),5,6,7,3′-tetrahydroxy-4′-methoxyisoflavone (140), 8-hydroxytectorigenin (143), 8-hydroxyirigenin (148), 5,7,3′-trihydroxy-8,4′-dimethoxy-isoflavone (153), and 5,7,4′-trihydroxy-6,3′,5′-trimethoxyisofla-vone (171) were isolated from the latter species, together with 94, 98, 111, 115, 117, 129, 134, 135, 144, 146, 152, 154, 155, 164, and 170.^{81–84,90,91,160,170} Polymethoxylated isoflavone, 5,6-dihyd-roxy-7,8,3′,5′-tetramethoxyisoflavone (113), was obtained from the rhizomes of I. pseudacorus.¹⁰² In this species, many isoflavo-noids were produced from the leaves which were treated with cupric chloride, together with dihydroflavonols, flavanone, and flavones.^31,32 They were identified as ayamenins A-E (101, 91, 149, 160 and 159), lupinalbin A (150), isogenistein (157), and 3′-O-methylorobol (166), 95, 102, 110, 152, 154, 158, and 162.^31,32 Of their compounds, ayamenins A-E and lupinalbinA were coumaronochromones. As another coumaronochromone, iris-bungin (151) was obtained from the leaves of I. bungei, together with 91.¹¹⁴ Each 2 rotenoids were isolated from I. crocea^57,125,169 and I. spuria.^59,142,169 They were identified as 11,12a-dihydroxy-9,10-dimethoxyrotenoid (99) and 9,11-dihydroxy-10-methoxy-rotenoid (108), and 1,11-dihydroxy-9,10-methylenedioxy-12 dehydrorotenoid (109) and 9,11,12a-trihydroxy-10-methoxyrotenoid (174), respectively. Compounds 99, 108, and 174 were named as 9-methoxyirispurinol, crocetenone, and iris-purinol, respectively. Only 1 isoflavanone was isolated from the rhizomes of I. domestica⁸⁴ and I. pallida¹³² and identified as 5,7,5′-t rihydroxy -6,3′,4′-t rime t hoxy isof lavanone (2,3-dihydroirigenin, 168). Very rare 2-hydroxylated isoflavone, 2-hydroxyirigenin (147) was obtained from I. germanica.²⁶ Other isoflavonoids such as pterocarpans, coumestans, 3-arylcoumarins are not known in the genus Iris until now.

Xanthones

Fifteen xanthones were reported from 43 Iris species (Table 10, Figure 9). Of their xanthones, 9 were C-glycosylxanthones. Most popular xanthones were C-glycosylxanthones, man-giferin (184), and isomangiferin (185) which are the common substances in not only Iris but also in the plant kingdom.¹⁸⁴ They were found in 41 and 31 Iris species, respectively. As other xanthones, 1,6-dihydroxy-3,7-dimethoxyxanthone (176), desmethylbellidifolin (180), norathriol (181), nigricanside (183), bellidifolin (187), and 7-O-methylmangiferin (189) were isolated from the rhizomes of Iris nigricans.¹⁵⁵ Nigricanside (183) was also detected from I. dichotoma^133,163 and I. domes-tica.¹⁶³ On the other hand, 189 was obtained from I. adriatica,¹⁶¹ I. domestica,^163,170 and I. florentina,^5,27 together with 7-O-methylisomangiferin (190) and irisxanthone (188). Two xanthone C-glycosides, 1-hydroxy-3,5,6-trimethoxyxanthone 2-C-glucoside (179) and 1,3,5,6-tetrahydroxyxanthone 2-C-glucoside (182), were isolated from the leaves and under-ground parts of I. florentina.^5,28,126 From this species, xanthone glycoside-O-glycoside, neomangiferin (186) was also detected.¹²⁶ Another xanthone O-glycoside was isolated from the aerial parts of I. minutoaurea and identified as 1,6-dihydro-xy-3,5-dimethoxyxanthone 6-O-glucoside (177).¹²⁷ A rare xan-thone was isolated from I. germanica which was treated anoxi-cally and subsequently returned to air as long-lived free radicals and identified as 1,5-dihydroxy-6′,6′-dimethoxypyrano[2′,3′:3,2] xanthone and named as 6-dehydrojacareubin (178).²⁶

Table 10

Xanthones from Iris Species.

Names (trivial names)	Origins	References
1,6-Dihydroxy-3,7-dimethoxyxanthone (176)	I. nigricans	¹⁵⁵
1,6-Dihydroxy-3,5-dimethoxyxanthone 6-O-glucoside (177)	I. minutoaurea	¹²⁷
1,5-Dihydroxy-6′,6′-dimethylpyrano[2′,3′:3,2]xanthone (6-dehydrojacareubin, 178)	I. germanica	²⁶
1-Hydroxy-3,5,6-trimethoxyxanthone 2-C-glucoside (179)	I. florentina	^5,126
1,3,5,8-Tetrahydroxyxanthone (desmethylbellidifolin, 180)	I. nigricans	¹⁵⁵
1,3,6,7-Tetrahydroxyxanthone (norathriol, 181)	I. nigricans	¹⁵⁵
1,3,5,6-Tetrahydroxyxanthone 2-C-glucoside (182)	I. florentina	^5,28
1,3,5,8-Tetrahydroxyxanthone 2-C-glucoside (nigricanside, 183)	I. dichotoma, I. domestica, I. nigricans	^133,155,163
1,3,6,7-Tetrahydroxyxanthone 2-C-glucoside (mangiferin, 184)	I. adriatica, I. albertii, I. albicans, I. aphylla, I. biflora, I. bungei, I. chamaeiris, dichotoma, I. domestica, I. ensata, I. flavescens, I. florentina, I. germanica, I. humilis, I. histrioides, I. hoogiana, I. imbricata, I. lactea, I. lazica, I. lutescens, I. marsica, I. nigricans, I. pallida subsp. cengialtii, I. pallida subsp. pallida, I. pseudacorus, I. pseudopumila, I. pumila, I. reichenbachii, I. reticulata, I. revoluta, I. rossii, I. sambuchina, I. sari, I. setina, I. setosa var. canadensis, I. setosa var. nasuensis, I. setosa var. hondoensis, I. setosa var. setosa, I. subbiflora, I. suaveolens, I. trojana, I. unguicularis, I. variegata, I. versicolor var. kermesina, I. versicolor var. versicolor, I. virginica var. shrevei	^{1,8,10,14,16,17,19,20,27,28,36,38-40,69-71,85,103,112-115,118,133,141, 143,155,161,163,169,170}
1,3,6,7-Tetrahydroxyxanthone 4-C-glucoside (isomangiferin, 185)	I. albertii, I. albicans, I. aphylla, I. biflora, I. dichotoma, I. domestica, I. ensata, florentina, I. germanica, I. histrioides, I. hoogiana, I. lactea, I. lazica, I. lutescens, I. marsica, I. pallida subsp. cengialtii, I. pallida subsp. pallida, I. pseudacorus, I. pseudopumila, I. reichenbachii, I. reticulata, I. revoluta, I. sambuchina, I. setina, I. setosa var. canadensis, I. setosa var. setosa, I. subbiflora, I. suaveolens, I. trojana, I. unguicularis, I. variegata, I. versicolor var. kermesina, I. virginica var. shrevei	^{1,10,27,28,39,40,71,115,163,170}
1,3,6,7-Tetrahydroxyxanthone 4-C-glucoside-7-O-glucoside (neomangiferin, 186)	I. adriatica, I. albicans, I. dichotoma, I. domestica, I. florentina,	^{115,126,133,161,163,170}
1,6,8-Trihydroxy-2-methoxyxanthone (bellidifolin, 187)	I. nigricans	¹⁵⁵
1,3,6-Trihydroxy-5-methoxyxanthone 2-C-glucoside (irisxanthone, 188)	I. adriatica, I. albicans, I. florentina	^{5,8,27,28,115,118,126,161,162}
1,3,6-Trihydroxy-7-methoxyxanthone 2-C-glucoside (7-O-methylmangiferin, 189)	I. adriatica, I. domestica, I. florentina, I. nigricans	^{5,27,155,161,163,170}
1,3,6-Trihydroxy-7-methoxyxanthone 4-C-glucoside (7-O-methylisomangiferin, 190)	I. adriatica, I. domestica, I. florentina	^{5,27,161,163,170}

Figure 9

Chemical structures of xanthones from Iris species.

Contribution to the Flower Colors of Flavonoids

Flower colors of Iris species including cultivars are white, pur-ple to blue, and sometimes red, yellow, and blackish.¹⁸⁹ Of the compounds which were isolated from Iris species, flavones, C-glycosylflavones, flavanones, dihydroflavonols, flavanones, flavan and proanthocyanidins, and isoflavonoids are colorless and flavonols and xanthones are slightly yellow; they do not directly act as flower pigments. Thus, flower colors, especially red and purple to blue, of Iris species are expressed by anthocyanins. Yellow flowers of most of the plants are due to carotenoids and rarely flavonoids, especially chalcones, aurones, and flavonols such as gossypetin and quercetagetin.¹⁸⁷ Practically, 3 carotenoids, β-carotene, lutein, and neoxanthin, were isolated from the yellow flowers of Iris pseudacorus.^190,191 Yellow flavo-noids such as chalcones and aurones are not found in Iris flow-ers until now. On the other hand, red and purple to blue are due to anthocyanins and reported from some Iris flowers (Table 2).

In 1940, anthocyanin was isolated from the dull magenta purple and mulberry purple flowers of Japanese garden iris, I. ensata (=I. kaempferi), named as “ensatin”, and characterized as malvidin (5) 3-O-(p-coumaroyldiglucoside).^42,188 Later in 2014, it was completely identified as 3-O-[(4″′-E-p-coumaroyl-α-l-rhamnopyranosyl)-(1→6)-β-d-glucopyranoside]-5-O-β-d-glucopyranoside and 3-O-[(4″′-Z-p-coumaroyl-α-l-rham-no pyranosyl)-( 1 → 6 ) -β -d-glucopyranoside]-5 -O-β -d-glucopyranoside.⁹³ Corresponding acylated glycosides of del-phinidin (1) and petunidin (3) were reported from I. germanica^16,113 and I. hollandica,¹¹⁰ I. ensata⁹³ and I. laevigata,^41,73 respectively. Thus, purple to blue colors of Iris flowers were shown to be due to acylated glycosides of 1, 3, and 5. On the other hand, it was proved that although C-glycosylflavones themselves were colorless, they are bathochromically shifted the colors of anthocyanins as copigments. Major pigment of Professor Blaauw Iris, a hybrid of I. tingitana, is delphinidin (1) 3-O-(p-coumaroylrutinoside)-5-O-glucoside, and its blue color is expressed by non-metallic copigment complex of the anhy-dro base of anthocyanin and C-glycosylflavones.13 In this experiment, C-glycosylflavones which function as copigments were swertisin (41), its O-xyloside, vitexin (54), isoorientin (47), and swertiajaponin (58).¹³

Flower colors of Japanese Garden Iris (I. ensata) are reddish-purple and purple to blue. Their anthocyanins are qualitatively the same among their flower colors except for a part of reddish-purple cultivars which contain cyanidin (2) and peoni-din (6) glycosides.^76,77 It was shown by in vitro examination that C-glycosylflavone, isovitexin (52), is a copigment sub-stance of I. ensata flowers.⁷⁸ C-Glycosylflavone, swertisin (41) 2″-O-arabinoside, was isolated from the violet-blue flowers of the tall bearded iris cultivar “Victoria Falls”, together with some C-glycosylflavones including a new one and C-glycosylxanthone, mangiferin (184).¹¹² On the other hand, an anthocyanin, 3-O-(p-coumaroylrutinoside)-5-O-glucoside of 1 was found in the flowers as major pigment.¹¹³ More recently, in vitro examination was performed, and the violet blue color expression of this cultivar was shown to be the copigmentation of anthocyanin and swertisin 2″-O-arabinoside.113 In this time, although C-glycosylxanthone 184 was used in copigment exam-ination, it was shown that it slightly contributes to the flower color expression and stability.¹¹³

Dutch iris (=I. hollandica) cultivar “Tiger’s Eye” has grayed violet falls and violet standards. In these flowers, anthocyanin, 3-O-[(4″′-p-coumaroylrhamnosyl)-(1→6)-glucoside]-5-O-glu-coside of 1 and C-glycosylflavone 58 are contained as major flavonoids.¹¹⁰ Moreover, a higher amount of unknown carotenoids were included in the flowers. As a result, it was shown by in vitro examination that anthocyanin, C-glycosylflavone, and carotenoids contribute to the expression of grayed violet falls of cultivar “Tiger’s Eye”. It means that coexistence of the copigmentation and carotenoids is necessary to express their dullish color.¹¹⁰

Iris dicotoma is crossed with I. domestica (formally Belamcanda chinensis). The flower colors of the hybrids derived from these crosses were categorized into 8 groups, violet, brown, orange, red, pink, yellow, and white.¹⁴⁴ Twenty-nine anthocyanins, including glycosides of 1-6, were found in their hybrids. Their anthocyanins were surveyed by high-performance liquid chromatography-diode array detector-electrospray ionization/ mass spectrometry analysis, and it was shown that variation of flower colors of their hybrids is due to qualitative and quanti-tative differentiation of anthocyanins.¹⁴⁴ Although other flavo-noids such as C-glycosylflavones and carotenoids in their flowers were not analyzed, authors presumed that the different quantities of anthocyanins and flavonols, as well as those of carotenoids, are responsible for the diverse flower colors of the individuals examined in this study.¹⁴⁴ Since flower colors of most Iris species are purple to blue, pelargonidin (4) which is scarlet or orange color was not reported. Recently, B. chinensis was transferred to the genus Iris by APG III as I. domestica.¹⁸⁰ Flower colors of I. domestica are orange to red, and compound 4 was found in this species as a major pigment.¹⁴⁴ However, the orange color of this species is may be due to the coexistence of 4 and carotenoids.

Relationships with Flavonoids and Xanthones, and Taxonomy

The genus Iris is divided into 7 subgenera, that is, Iris, Limniris, Nepalensis, Xiphium, Scorpiris, Hemodactyloides, and Pardanthopsis.¹⁷¹ Subgenera Iris and Limniris were subdivided into 6 (Iris, Psammiris, Oncocyclus, Regelia, Hexapogon, and Pseudoregelia) and 2 (Lophiris and Limniris), respectively.¹⁷¹ So far as we know, 79 Iris species were fully and fragmentally sur-veyed for flavonoids and xanthones (Table 1). Of their subgenera and sections, the species of sect. Hexapogon of subgenus Iris (Iris falcifolia Bunge and I. longiscapa Ledeb.) and subgenus Nepalensis (I. barbatula Noltie & K.Y. Guan, I. collettii Hook.f., I. decora Wallich, and I. staintonii Hara) are not analyzed for flavo-noids and xanthones. Mangiferin (184) was found in the leaves of Iris sisyrinchium.²⁰ However, the species was now transferred to another genus Moraea as M. sisyrinchium (L.) Ker Gawl. Three fla-vones, apigenin (16), its 7-O-glucoside, and luteolin (15) 7-O-glucoside, and 4 C-glycosylflavones, isovitexin (52) and its 7-O-glucoside, orientin (48), and isoorientin (47)—were reported from the aerial parts as M. sisyrinchium.¹⁹²

Number of flavonoid classes and xanthones that were iso-lated and characterized by Iris taxa were shown in Table 11. Isoflavonoids were found in 13 species of sect. Iris of subge-nus Iris. Although they were not reported from 10 species, for example, I. albertii, I. chamaeiris, I. imbricata, I. reichenbachii, I. set-ina, and I. trojana, their species were roughly analyzed, and rhi-zomes, in which isoflavonoids are frequently found, were not surveyed. In addition, xanthones were found in most species. C-Glycosylflavones were found in the leaves and/or flowers of some species of sect. Iris.

Table 11

Number of Flavonoids and Xanthones Isolated and Characterized from Iris Species.

	An	Fn	Fl	CG	Fv	Df	Fp	If	Xa
Subgenus Iris
Section Iris
I. adriatica								23	7
I. albertii									2
I. albicans				5				7	4
I. aphylla								5	2
I. chamaeiris									1
I. florentina				3				14	8
I. germanica	2		4	13	2	1		40	4
I. imbricata									1
I. kashmiriana								10
I. lutescens	7			3				1	2
I. marsica				2				10	2
I. nepalensis								3
I. pallida subsp. cengialtii									2
I. pallida subsp. pallida				4				10	2
I. pseudopumila		2	2	7				12	2
I. pumila									1
I. reichenbachii		3		2					2
I. revoluta				3				1	2
I. setica				3					2
I. subbiflora									2
I. suaveolens									2
I. trojana									2
I. variegata				1				1	3
Section Psammiris
I. humilis				1					1
I. potaninii						1		7
Section Oncocyclus
I. nigricans							1	5	7
I. sari									1
I. sofarana								8
Section Regelia
I. hoogiana									3
Section Pseudoregelia
I. hookeriana							4
I. kumaonensis							6
Subgenus Limniris
Section Lophiris
I. dichotoma	29		1	2		2		35	4
I. gracilipes	3			4
I. japonica	5			2				18
I. milesii			1		1			8
I. tectorum	2		2	6	2	3		21
Section Limniris
I. bracteata			3
I. brevicaulis				1
I. bulleyana			1
I. bungei		2	9					6	1
I. chrysographes	1		2				2
I. chrysophylla	1			6
I. clarkei							2
I. crocea					2	1		3
I. delavayi	1		2				2
I. douglasiana			4				3
I. ensata var. ensata	16	3		12					2
I. ensata var. spontanea	4
I. forrestii			2
I. fulva				1
I. graminea var. graminea			2				1
I. graminea var. pseudocyperus							1
I. innominata			3
I. lactea var. chinensis				6			3
I. lactea var. lactea				3					2
I. laevigata	5			15
I. lazica									2
I. loczyi					5	2	2
I. macrosiphon			2
I. minutoaurea			1
I. missouriensis								3
I. monnieri							1
I. orientalis							1
I. prismatica			1
I. pseudacorus		2	3		1	3	1	21	3
I. rossii	2			8					2
I. sanguinea f. albiflora				4
I. sanguiena var. sanguiena	5		4	12
I. sanguiena var. tobataensis	2		2	11
I. setosa var. canadensis				3					2
I. setosa var. hondoensis	3			9					1
I. setosa var. nasuensis	3			17					1
I. setosa var. setosa	4			7					2
I. sibirica			1				2
I. sintenesii			1
I. songarica			2			1		4
I. spuria var. carthaliniae		1						5
I. spuria var. spuria				1	2			18
I. tenax			2	3
I. unguicularis		2						3	2
I. versicolor var. kermesina									2
I. versicolor var. versicolor									1
I. virginica var. shrevei									2
Subgenus Xiphium
I. tingitana	1			5				8
Subgenus Scorpiris
I. persica				2				1
Subgenus Hermodactyloides
I. histrioides									2
I. reticulata									2
Subgenus Pardanthopsis
I. domestica	29	7	5	4	1			44	6
Hybrids
I. hollandica	1			18
I. sambuchina									3

An, anthocyanins; Fn, flavones; Fl, flavonols; CG, C-glycosylflavones; Fv, flavanones; Df, dihydroflavonols; Fp, flavan and proanthocyanidins; If, isoflavonoids; and Xa, xanthones.

Many species belong to sect. Limniris of subgenus Limniris as well as sect. Iris of subgenus Iris. However, of 47 taxa which were surveyed for flavonoids, isoflavonoids and xanthones were only detected in 8 and 14 taxa, respectively. Although anthocyanins which were isolated from the flowers were also found in 17 species, flowers were not analyzed in most species. However, anthocyanins may be present in all Iris species which give red and purple to blue flowers. Flavones, flavonols, flava-nones, and dihydroflavonols are present in the leaves, under-ground parts, rhizomes, flowers, and aerial parts among Iris species as minor compounds. Although the seeds were not analyzed in most species, flavan and proanthocyanidins may be found in the seeds of many species. Practically, 3 proanthocy-anidins 86, 89, and 90 were isolated from the seeds of Iris lactea var. chinensis.¹³⁴

By chemotaxonomic surveys, flavonoids and related com-pounds including xanthones of I. setosa and its 3 varieties, var. nasuensis, var. hondoensis, and var. canadensis, were analyzed.^40,69 Although I. setosa var. setosa is widely distributed to North Hemisphere, the former 2 varieties are endemic to Japan. Of their varieties, var. nasuensis and var. hondoensis are presumed as the hybrids of var. setosa and I. laevigata.²⁰⁰ In the 3 varieties found in Japan, the same anthocyanins and xanthones were present. Although C-glycosylflavones were present in their varieties, their composition was different from each other.⁶⁹ Thus, 4′-O-glycosides and methoxylated flavones which are absent in var. setosa were found in var. nasuensis, and the latter flavonoids were detected from var. hondoensis.⁶⁹ On the other hand, their 4′-O-glycosides and methoxylated flavones were isolated from I. laevigata.³⁸ From their results, var. nasuensis was at least chemotaxonomically presumed to be a hybrid of I. setosa var. setosa and I. laevigata.38 Such fact was proved by a cyto-logical survey of I. setosa var. setosa, var. nasuensis and var. hon-doensis, and I. laevigata.²⁰¹ However, methoxylated flavones are not found in var. hondoensis. The popular isovitexin (52) and vitexin (54), which are present in other varieties as major com-pounds, are not present in the variety var. canadensis. As a result, it was shown that var. canadensis was chemotaxonomically dif-ferent from other varieties.⁴⁴

Iris sanguinea Hornem. var. tobataensis S. Akiyama & Iwashina was newly found as a variety of I. sanguinea in 2009.¹⁹³ This variety has been extinct in the wild and is only propagated in Southern Japan, Kita-Kyushu City. Iris sanguinea var. tobataensis was chemotaxonomically surveyed for flavonoids, together with var. sanguinea.¹⁰⁴ Although flavonoid composition of the flowers and leaves was similar to each other, 1 C-glycosylflavone, acetylated swertisin (41) 2″-O-glucoside, was additionally pres-ent in the leaves of var. tobataensis.¹⁰⁴ Thus, it was presumed that both varieties are closely related but not the same variety. Such fact was also proved by molecular phylogenetic analysis.¹⁰⁴

Activities and Functions of Flavonoids and Xanthones in Iris Species

The flavonoids as medicinal resources have already been reviewed by some authors.^195,196 Relationship between isoflavo-noids and human health was also reviewed.¹⁹⁷ Some functions and activities to plants and other organisms such as oviposition stimulants, feeding attractants, allelopathy, and phytoalexins, etc. were reported by many authors.¹⁹⁸ Activities and functions of flavonoids and xanthones including in Iris species are shown in Table 12. Anthocyanins in Iris flowers surely act as pollinator attractants. Flower color polymorphism and their anthocyanins in Iris lutescens are analyzed for the interaction of plants and insects.¹⁶⁶ Since some insects, especially bee, can discriminate UV-light (UV-A), flavones, flavonols, and C-glycosylflavones in the flowers act as the pollinator attractants.

Table 12

Activities and Functions of Flavonoids and Xanthones from Iris Species.

Flavonoids and xanthones	Activities and function	Origins	References
Flavone
Apigenin (16) 7-O-glucoside	Anti-inflammatory	I. minutoaurea	¹²⁷
Flavonols
Irisoid A (36)	Antioxidant	I. songarica	¹³⁷
Kaempferol (28) 3-O-rutinoside	Antioxidant	I. pseudopumila	¹³⁶
Kaempferol (28) 3-O-glucoside	Antiproliferase	I. pseudopumila	¹⁵⁸
5,2′-Dihydroxy-3-methoxy-6,7-methylene-dioxyflavone (23)	Molluscicidal	I. germanica	¹⁵⁷
C-Glycosylflavone
Embigenin (43) 7-O-neohesperidoside	2,2-Diphenyl-1-picrylhydrazyl radical scavenging, Antitumor	I. persica	¹²⁸
Isovitexin (52)	Antiproliferase	I. pseudopumila	¹⁵⁸
Isoorientin (47) 6″-O-glucoside	Antiproliferase	I. pseudopumila	¹⁵⁸
Swertisin (41)	Hepatoprotective	I. japonica	⁹⁶
Flavanone
5,7,2′-Trihydroxy-6-methoxyflavanone (69)	Molluscicidal	I. germanica	¹⁵⁷
Dihydroflavonol
Songaricol (78)	Antioxidant	I. songarica	¹³⁷
Isoflavonoids
Ayamenin A (101)	Estrogenic	I. songarica	¹³⁷
Daidzein (100)	Antibacterial	I. aphylla	¹⁴³
Formononetin (125)	Antibacterial	I. aphylla	¹⁴³
Genistein (158)	Antibacterial	I. aphylla	¹⁴³
Homotectorigenin (155)	H₂O₂ scavenging	I. dichotoma, I. domestica, I. tectorum	¹⁶³
5-Hydroxy-4′-methoxy-6,7-methylenedioxy-isoflavone (127)	Anti-inflammatory	I. germanica	¹³⁹
Iriflogenin (106)	Cytotoxic	I. germanica	¹³¹
	Radical scavenging	I. germanica	¹⁴⁸
Iriflogenin (106) 4′-O-glucoside	Cytotoxic	I. germanica	¹³¹
Irigenin (169)	Anti-inflammatory	I. germanica	¹⁴⁸
	Cancer chemoprevention	I. germanica	¹³⁹
	Bactericidal, Fungicidal, and Insecticidal	I. germanica	¹⁴⁹
	Antioxidant	I. germanica	¹⁶³
	Antimutagenic, Antioxidant	I. dichotoma, I. domestica, I. tectorum	¹⁹⁴
Irigenin (169) 7-O-glucoside	Antiproliferase	I. pseudopumila	¹⁵⁸
	Antioxidant	I. dichotoma, I. domestica, I. tectorum	¹⁶³
	Antimutagenic, Antioxidant	I. domestica	¹⁹⁴
Irilin B (95)	Antioxidant, Estrogenic	I. songarica	¹³⁷
Irilin D (144)	Cholinesterase inhibitory	I. domestica	¹⁴⁵
	H₂O₂ scavenging	I. dichotoma, I. domestica, I. tectorum	¹⁶³
Irilone (111)	Cytotoxic	I. florentina, I. germanica	^126,131
	Anti-inflammatory	I. germanica	¹³⁹
	Cancer chemoprevention	I. germanica	¹⁴⁸
Irilone (111) 4′-O-glucoside	Antioxidant	I. pseudopumila	¹³⁶
Irisflorentin (146)	Antioxidant	I. dichotoma, I. domestica, I. tectorum	¹⁶³
Iriskashmirianin (124)	Cytotoxic	I. florentina	¹²⁶
	Cancer chemoprevention, Radical scavenging	I. germanica	¹⁴⁸
Iriskashmirianin A (107)	Cytotoxic	I. germanica	¹³¹
Iriskumaonin methyl ether (175)	Cytotoxic	I. germanica	¹³¹
Irisolidone (94)	Antiproliferase	I. pseudopumila	¹⁵⁸
Irisolone (129)	Cytotoxic	I. florentina, I. germanica	^126,131
	Anti-inflammatory	I. germanica	¹³⁹
	Bactericidal, Fungicidal, and Insecticidal	I. germanica	¹⁴⁹
Irisolone (129) 4′-O-glucoside	Cytotoxic	I. germanica	¹³¹
Irisone B (110)	Estrogenic	I. songarica	¹³⁷
Iristectorigenin A (152)	Hepatoprotective	I. spuria	¹³⁵
	Anti-inflammatory	I. germanica	¹³⁹
	Antioxidant	I. dichotoma, I. domestica, I. tectorum	¹⁶³
Iristectorigenin A (152) 7-O-gentiobioside	H₂O₂ scavenging	I. dichotoma, I. domestica, I. tectorum	¹⁶³
Iristectorigenin A (152) 7-O-glucoside	Antioxidant, H₂O₂ scavenging	I. dichotoma, I. domestica, I. tectorum	¹⁶³
Iristectorigenin B (154)	Anti-inflammatory	I. germanica	¹³⁹
	Antimutagenic	I. domestica	¹⁸⁶
Iristectorigenin B (154) 7-O-glucoside	Antioxidant, H₂O₂ scavenging	I. dichotoma, I. domestica, I. tectorum	¹⁶³
Isoirigenin (170)	Anti-inflammatory	I. germanica	¹³⁹
Tectorigenin (163)	Cell proliferation stimulatory	I. domestica	⁸⁰
	Estrogen receptor modulator	I. domestica	⁹²
	Anti-inflammatory	I. germanica	¹³⁹
	Antibacterial	I. aphylla	¹⁴³
	Antimutagenic, Antioxidant	I. domestica	¹⁹⁴
Tectorigenin (163) 7-O-fucoside	Hepatoprotective	I. japonica	⁹⁶
Tectorigenin (163) 7-O-glucoside	Cell proliferation stimulatory	I. domestica	⁸⁰
	Antitumor	I. domestica	⁸⁷
	Modulate inhibitory	I. domestica	⁹²
	Hepatoprotective	I. spuria	¹³⁵
	Antibacterial	I. aphylla	¹⁴³
	Antioxidant	I. dichotoma, I. domestica, I. tectorum	¹⁶³
	Antimutagenic, Antioxidant	I. domestica	¹⁹⁴
Tectorigenin (163) 7-O-glucosyl-(1→3)-glucoside	Hepatoprotective	I. japonica	⁹⁶
5,6,7,3′-Tetrahydroxy-4′-methoxyisoflavone (140)	Antimutagenic, Antioxidant	I. domestica	¹⁹⁴
5,3′,4′-Trihydroxy-6,7-methylenedioxyisoflavone (167) 4′-O-glucoside	Cytotoxic	I. germanica	¹³¹
Xanthone
Mangiferin (184)	Antibacterial	I. aphylla	¹⁴³

Most flavonoids have antioxidant activity. Of the flavonoids in Iris species, 2 flavonols, irisoid A (36) from I. songarica ¹³⁷ and kaempferol (28) 3-O-rutinoside from I. pseudopumila,¹³⁶ were proved as antioxidant substances. Dihydroflavonol, songaricol (78) from I. songarica, show antioxidant activity.¹³⁷ Some isofla-vonoids, irigenin (169) and its 7-O-glucoside,¹⁶³ irilin B (95),¹³⁷ irolone (111) 4′-O-glucoside,¹³⁶ irisflorentin (146),163 iristectori-genin A (152) and its 7-O-glucoside, iristectorigenin B (154) 7-O-glucoside,¹⁶³ 5,6,7,3′-tetrahydroxy-4′-methoxyisoflavone (140),¹⁹⁴ and tectorigenin (163)¹⁹⁴ and its 7-O-glucoside,^163,194 were proved to have antioxidant activity. Similarly, 6 isoflavo-noids, 163 and its 7-O-glucoside, daidzein (100), genistein (158), and formononetin (125) from I. aphylla show antibacterial activity in Gram-positive bacteria and fungi.¹⁴³ Compounds 100, 158, and 125 were found in many plants, especially Leguminosae, and some activities and functions have been reported.¹⁹⁹ Antibacterial activity was also shown by xanthone, mangiferin (184).¹⁴³ Extracts of I. germanica rhizomes which contain 2 isoflavones, 169 and irisolone (129), were shown to have bactericidal, fungicidal, and insecticidal activities.¹⁴⁹ Molluscicidal activity against snail, Biomphalaria alexandrina was recognized in each 1 of the flavanone and flavonol, 5,7,2′-trihydroxy-6-methoxyflavanone (69) and 5,2′-dihydroxy-3-methoxy-6,7-methylenedioxyflavone (23) in I. germanica.¹⁵⁷

The pharmacological function, anti-inflammatory activity, was shown by the flavone, apigenin (16) 7-O-glucoside.127 This activity was also shown by 8 isoflavonoids, 5-hydroxy-4′-methoxy-6,7-methylenedioxyisoflavone (127), 169, 111, 129, 152, 154, isoirigenin (170), and 163 from I. germanica.¹³⁹ Three isoflavonoids, ayamenin A (101), irisone B (110), and 95, were proved to have estrogenic activity in yeast cells expressing human estrogen receptor.137 Estrogen receptor modulator activity was shown in 163 from I. domestica.⁹² As anticancer and antitumor activities, 3 isoflavonoids, 169, 111, and iriskashmirianin (124), have cancer chemoprevention activity.¹⁴⁸ Compound 124 has been recognized to have radical scavenging activity, together with iriflogenin (106).¹⁴⁸ Antitumor activity was shown in C-glycosylflavone, embigenin (43) 7-O-neohesperidoside in I. persica, together with 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity.¹²⁸ Similarly, antimuta-genic activity was known in 169 and its 7-O-glucoside, 154, 140, and 163 and its 7-O-glucoside.^186,194 Common isoflavones in Iris species, 163 and its 7-O-glucoside, were shown to have cell proliferation stimulatory activity against human breast cancer cell lines.⁸⁰ This activity was also recognized in C-glycosylflavone, swertisin (41), and 3 isoflavonoids, 152, and 7-O-glucoside and 7-O-glucosyl-(1→3)-glucoside of 163 from I. japonica and I. spuria.^96,135

Like other activities, antiproliferase activity against mela-notic melanoma cells was reported in flavonol, 3-O-glucoside of 28, 2 C-glycosylflavones, isovitexin (52), isoorientin (47) 6″-O-glucoside, and 2 isoflavones, 7-O-glucoside of 169 and irisolidone (94).¹⁵⁸ Cholinesterase inhibitory and hydrogen peroxide scavenging activities were shown in irilin D (144).^145,163 The latter activity was also reported in 4 isoflavonoids, homo-tectorigenin (155), 7-O-gentiobioside, 7-O-glucoside of 152, and 7-O-glucoside of 154.¹⁶³ Cytotoxic activity was reported in some isoflavonoids, 106 and its 4′-O-glucoside, 111, 124, iriskashmirianin A (107), iriskumaonin methyl ether (175), 129 and its 4′-O-glucoside, and 5,3′,4′-trihydroxy-6,7-methylenedioxyisoflavone (167) 4′-O-glucoside.^126,131

The genus Iris consists of approximately 360 species.¹⁷² Of their species, 90 taxa have fully or fragmentally been surveyed for flavonoids and xanthones (Table 1). Those are approxi-mately 32% of Iris species in the world. One hundred and seventy-five flavonoids, that is, 6 anthocyanidins, 13 flavones, 20 flavonols, 20 C-glycosylflavones, 14 flavanones, 11 dihydro-flavonols, 6 flavan and proanthocyanidins, 85 isoflavonoids, and 15 xanthones are reported from Iris species as aglycones and glycosides. Although their biological and pharmacological activities and functions are unknown in many compounds, they may possess potential abilities. Many flavonoids and xanthones present in Iris species are not known, and further surveys for flavonoids should be done.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Tsukasa Iwashina

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Flavonoids and Xanthones From the Genus Iris : Phytochemistry,Relationships with Flower Colors and Taxonomy,and Activities and Function

Abstract

Keywords

Phytochemistry of Flavonoids and Xanthones in Iris Species

Anthocyanins

Flavones

Flavonols

C-Glycosylflavones

Flavanones

Dihydroflavonols

Flavan and Proanthocyanidins

Isoflavonoids

Xanthones

Contribution to the Flower Colors of Flavonoids

Relationships with Flavonoids and Xanthones, and Taxonomy

Activities and Functions of Flavonoids and Xanthones in Iris Species

Footnotes

Declaration of Conflicting Interests

Funding

ORCID iD

References