Anti-HIV activity of flavonoids and proanthocyanidins from Crataegus sinaica.

In addition to quercetin, hyperoside, rutin, vitexin, 2″-O-rhamnosylvitexin, (4″'-O-acetyl)-2″-O-rhamno-sylvitexin, epicatechin, procyanidin B-5, proanthocyanidin A-2, procyanidin B-2 and procyanidin C-1, which were reported before in Crataegus sinaica (Rosaceae), three more flavonoids were isolated from the same plant, i.e. (+)-taxifolin, 3-O-β-arabinopyranosyl-(+)-taxifolin and 3-0-β-xylopyranosyl-(+)-taxifolin. The in vitro anti-HIV activity of some selected flavonoids and proanthocyanidins was evaluated. The dimeric procyanidin B2 and proanthocyanidin A2, and especially the trimeric procyanidin C1 showed some in vitro anti-HIV activity.