Two orphan flavonoids containing an oxepin structure in ring A and named as Primcortusin (1) and 3’-OH-Primcortusin (2) were isolated from leaf exudates of Primula cortusoides, while P. glutinosa exudates yielded two dihydrochalcone derivatives (3,4). These novel structures have not been detected in other species of Primula so far. Chemical structures were elucidated by 2D NMR and mass spectrometry. The nature of compounds 1 and 2 is discussed, and ideas about their possible origin and that of unsubstituted flavone and other irregular substituted Primula flavones are presented.
(a) Valant-VetscheraK.M., BhutiaT.D., WollenweberE. (2009) Exudate flavonoids of Primula spp.: structural and biogenetic chemodiversity. Natural Product Communications, 4, 365–370;(b) Bhutia TD, Valant-Vetschera KM. (2012) Diversification of exudate flavonoid profiles in further Primula spp. Natural Product Communications, 7, 587–589.
2.
(a) RichardsJ. (2003) Primula.Timber Press, Inc.USA; (b) Blasdale WC. (1945) The composition of the solid secretion produced by Primula denticulata. Journal of the American Chemical Society, 67, 491–493; (c) Wollenweber E, Schnepf E. (1970) Vergleichende Untersuchungen über die flavonoiden Exkrete von “Mehl”- und “Öl″-Drüsen bei Primeln und die Feinstruktur der Drüsenzellen. Zeitschrift für Pflanzenphysiologie, 62, 216–227; (d) Müller H. (1915) The occurrence of flavones as the farina of the Primula. Journal of the Chemical Society, 107, 872–878.
3.
BrunswikH. (1922) Die Mikrochemie der Flavonexkrete bei den Primulinae. Sitzungsberichte der Akademie der Wissenschaften mathematisch-naturwissenschaftlich Klasse, 131, 221–232.
4.
(a) WollenweberE., MannK., IinumaM., TanakaT., MizunoM. (1988) 2’,5’-Dihydroxyflavone and its 5’-acetate-novel compounds from the farinose exudate of Primula. Zeitschrift für Naturforschung, 43, 305–307;(b) Wollenweber E, Mann K, Iinuma M, Tanaka T, Mizuno M. (1988) 8,2’-Dihydroxyflavone from Primula pulverulenta. Phytochemistry, 27, 1483–1486; (c) Wollenweber E, Iinuma M, Tanaka T, Mizuno M. (1990) 5-Hydroxy-6,2’-dimethoxyflavone from Primula denticulata. Phytochemistry, 29, 633–637.
(a) WollenweberE. (1989) Exkret-Flavonoide bei Blütenpflanzen und Farnen. Naturwissenschaften, 76, 458–463; (b) Robien W. (2009) Do high-quality 13C-NMR spectral data really come from journals with high Impact Factors? Trends Analytical Chemistry, 28, 914-922.
7.
KuiM., ShileiZ., SongtaoH., PingL., MeiJ., FeiX., GuangshunL., HaoyiZ., LirongS., WenhuD., WeiW. (2008) (S)-Pyrrolidine sulfonamide catalyzed asymmetric direct aldol reactions of aryl methyl ketones with aryl aldehydes. Tetrahedron Letters, 49, 2681–2684.
8.
McCormickS., RobsonK., BohmB. (1986) Flavonoids of Wyethia angustifolia and W. helenioides. Phytochemistry, 25, 1723–1726.
9.
(a) Valant-VetscheraK.M., BhutiaT.D., WollenweberE. (2010) Chemodiversity of exudate flavonoids in Dionysia (Primulaceae): A comparative study. Phytochemistry, 71, 937–947;(b) Bhutia TD, Valant-Vetschera KM, Lorbeer E, Brecker L. (2011) Unusual compounds from exudates of Dionysia diapensifolia and D. gaubae var. megalantha (Primulaceae). Natural Product Communications, 6, 621–624.
10.
WagnerG.J. (1991) Secreting glandular trichomes: more than just hairs. Plant Physiology, 96, 675–679.
11.
(a) SinghS.B., JonesE.T., GoetzM.A., BillsG.F., Nallin-OmsteadM., JenkinsR.G., LinghamR.B., SilvermanK.C., GibbsJ.B. (1994) Fusidienol: A novel inhibitor of ras farnesyl-protein transferase from Fusidium griseum. Tetrahedron Letters, 35, 4693–4696;(b) Singh SB, Ball RG, Zink DL, Monaghan RL, Polishook JD, Sanchez M, Pelaez F, Silverman KC, Lingham RB. (1997) Fusidienol A: A novel ras farnesyl-protein transferase inhibitor from Phoma sp. Journal of Organic Chemistry, 62, 7485–7488.
12.
RayneS., SasakiR., WanP. (2005) Photochemical rearrangement of dibenzo[1,4]dioxins proceeds through reactive spirocyclohexadienone and biphenylquinone intermediates. Photochemical and Photobiological Science, 4, 876–886.
13.
KrohnK., KouamS.F., KuigouaG.M., HussainH., Cludius-BrandtS., FloerkeU., KurtanT., PescitelliG., Di BariL., DraegerS., SchulzB. (2009) Xanthones and oxepino[2,3-b]chromones from three endophytic fungi. Chemistry - A European Journal, 15, 12121–12132.
14.
BoydD.R., SharmaN.D., HarrisonJ.S., MaloneJ.F., McRobertsW.C., HamiltonJ.T.G., HarperD.B. (2008) Enzyme-catalysed synthesis and reactions of benzene oxide/oxepine derivatives of methyl benzoates. Organic and Biomolecular Chemistry, 6, 1251–1259.
15.
(a) RaoJ.R., CooperJ.E. (1994) Rhizobia catabolize nod gene-inducing flavonoids via C-ring fission mechanisms. Journal of Bacteriology, 176, 5409–5413; (b) Schneider H, Blaut M. (2000) Anaerobic degradation of flavonoids by Eubacterium ramulus. Archives of Microbiology, 173, 71-75.
16.
HanJ., KimS.Y., JungJ., LimY., AhnJ.H., KimS.I., HurH.G. (2005) Epoxide formation on the aromatic B ring of flavanone by biphenyl dioxygenase of Pseudomonas pesudoalcaligenes KF707. Applied and Environmental Microbiology, 5354–5361.
17.
FowlerZ.L., BaronC.M., PanepintoJ.C., KoffasM.A.G. (2011) Melanization of flavonoids by fungal and bacterial laccases. Yeast, 28, 181–188.
18.
(a) SeyringM. (1998) Nachweis und Identifizierung von bakteriellen Endophyten bei in vitro Kulturen von Primula vulgaris Huds. Gartenbauwissenschaft, 63, 27–33;(b) Nagarathman D, Cushman M. (1991) A practical synthesis of flavones from methyl salicylate. Tetrahedron, 47, 5071–5076; (c) Yu D, Xu F, Zeng J, Zhan J. (2012) Type III polyketide synthases in natural product biosynthesis. IUBMB Life, 64, 285–295.
19.
(a) SchöpkerH., KneiselM., BeerhuesL., RobenekH., WiermannR. (1995) Phenylalanine ammonia-lyase and chalcone synthase in glands of Primula kewensis (W. Wats): immunofluorescence and immunogold localization. Planta, 196, 712–719;(b) Ahmed MA, El-Mawla A, Beerhues L. (2002) Benzoic acid biosynthesis in cell cultures of Hypericum androsaemum. Planta, 214, 727–733; (c) Boatright J, Negre F, Chen X, Kish CM, Wood B, Peel G, Orlova I, Gang D, Rhodes D, Dudareva N. (2004) Understanding in vivo benzenoid metabolism in petunia petal tissue. Plant Physiology, 135, 1993–2011; (d) Nan P, Peng S, Zhang Y, Zhong Y. (2002) Composition of volatile oil of Primula obconica in central China. Natural Product Letters, 16, 249–253; (e) Javidnia K, Miri R, Soltani M, Khosravi AR. (2010) Volatile oil of Dionysia diapensifolia Boiss. (Primulaceae) as a rich source of (E)-chalcone. Journal of Essential Oil Research, 22, 386–388.
20.
MooreB., HertweckC., HopkeJ.N., IzumikawaM., KalaitzisJ.A., NilsenG., O'HareT., PielJ., ShipleyP.R., XiangL., AustinM.B., NoelJ.P. (2002) Plantlike biosynthetic pathways in bacteria: From benzoic acid to chalcone. Journal of Natural Products, 65, 1956–1962.
21.
WinkM. (2008) Plant secondary metabolism: Diversity, function and its evolution. Natural Product Communications, 3, 1205–1216.
