A-type proanthocyanidins from lychee seeds and their antioxidant and antiviral activities.
Two new A-type trimeric proanthocyanidins with two doubly bonded interflavanoid linkages, litchitannin A1 [epicatechin-(2β→O→7,4β→6)-epicatechin-(2β→O→7,4β→8)-catechin] (1) and litchitannin A2 [epicatechin-(2β→O→7,4β→6)-epicatechin-(2β→O→7,4β→6)-epicatechin] (2), were isolated from lychee (Litchi chinensis Sonn. cv. Heiye) seeds together with aesculitannin A (3), epicatechin-(2β→O→7,4β→8)-epiafzelechin-(4α→8)-epicatechin (4), proanthocyanidin A1 (5), proanthocyanidin A2 (6), proanthocyanidin A6 (7), epicatechin-(7,8-bc)-4β-(4-hydroxyphenyl)-dihydro-2(3H)-pyranone (8), and epicatechin (9). Their structures were elucidated on the basis of spectroscopic and chemical evidence. It is the first time that compounds 1-4, 7, and 8 have been reported in this species. Compounds 1-9 showed more potent antioxidant activity than L-ascorbic acid with ferric reducing antioxidant power (FRAP) values of 3.71-24.18 mmol/g and IC50 values of 5.25-20.07 μM toward DPPH radicals. Moreover, litchitannin A2 (2) was found to exhibit in vitro antiviral activity against coxsackie virus B3 (CVB3) and compounds 3 and 6 displayed antiherpes simplex virus 1 (HSV-1) activity.
Xu
Xinya
X
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, PR China.
Xie
Haihui
H
Wang
Yifei
Y
Wei
Xiaoyi
X
D000975:Antioxidants / Q000737:chemistry* / Q000494:pharmacology; D000998:Antiviral Agents / Q000737:chemistry* / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D032125:Litchi / Q000737:chemistry*; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry* / Q000494:pharmacology; D044945:Proanthocyanidins / Q000737:chemistry* / Q000494:pharmacology; D012639:Seeds / Q000737:chemistry; D014780:Viruses / Q000187:drug effects
D000975:Antioxidants; D000998:Antiviral Agents; D010936:Plant Extracts; D044945:Proanthocyanidins