From the ethyl acetate extract of the aerial parts of Baeckea frutescens, a new flavonoid, 6,8-di-C-methylkaempferol (1), and three new flavonoid glycosides, 6,8-di-C-methylkaempferol 3-O-α-L-rhamnopyranoside (2), 6-C-methylquercetin 3-O-α-L-rhamnopyranoside (3), and 6-C-methylquercetin 4′-O-β-D-glucopyranoside (4), along with four known flavonoids were isolated. Their structures were elucidated by extensive spectroscopic methods including 1D and 2D NMR experiments, as well as ESI-MS analysis. All the new compounds were tested for their antioxidant activity in the 1,1-diphenyl-2-pecrylhydrazyl (DPPH) radical scavenging assay system. Compounds 3 and 4 showed potent activity with IC50 values of 12.1 ± 0.5 and 13.5 ± 0.9 (μM), respectively.
QuangTH, KiemPV, MinhCV. (2007) A new triterpene from Baeckea frutescens L. (Myrtaceae). International Workshop on Herbal Medicinal Plants and Traditional Herb Remedies - Book of abstracts, Hanoi, Vietnam, 73–74.
7.
IbewuikeJC, OgundainiAO, OgungbamilaFO, MartinMT, GallardJF, BohlinL, PaisM. (1996) Piliostigmin, a 2-phenoxy-chromone, and C-methylflavonols from Piliostigma thonningii. Phytochemistry, 43, 687–690;
8.
SeckinO, NedimeD, KenjiroT, NorioS, ToshioH. (1998) Acylated kaempferol glycosides from the flowers of Delphinium formosum. Phytochemistry, 49, 241–245.
9.
ZhongXN, OtsukaH, IdeT, HirataE, TakushiA, TakedaY. (1997) Three flavonol glycosides from leaves of Myrsine seguinii. Phytochemistry, 46, 943–946;
10.
AgrawalPK. (1989) Carbon-13 NMR of Flavonoids. Elsevier Science, Amsterdam, 294–364.
11.
FossenT, PedersenAT, AndersenQM. (1998) Flavonoids from red onion (Allium cepa). Phytochemistry, 47, 281–285;
12.
ShenCC, ChangYS, HottLK. (1993) Nuclear magnetic resonance studies of 5,7-dihydroxyflavonoids. Phytochemistry, 34, 843–845.
13.
KadotaS, TakamoriY, NyeinKN, KikuchiT, TanakaK, EkimotoH. (1990) Constituents of the leaves of Woodfordia fruticosa Kurz. I. Isolation, structure, and proton and carbon-13 nuclear magnetic resonance signal assignments of woodfruticosin (woodfordin C), an inhibitor of deoxyribonucleic acid topoisomerase II. Chemical & Pharmaceutical Bulletin, 38, 2687–2697.
14.
LeeJS, KimHJ, ParkH, LeeYS. (2002) New diaryheptanoids from the stem of Carpinus cordata. Journal of Natural Products, 65, 1367–1370.
