A novel adduct of ECG fused to piceid and four new dimeric stilbene glycosides from Polygonum cuspidatum

Polyflavanostilbene B (1), an unusual adduct of epicatechin-3-O-gallate fused to piceid through a carbon–carbon bond, four new dimeric stilbene glycosides (2–5), and four new compounds (6–9), were isolated from the rhizome of Polygonum cuspidatum.