Dimeric Stilbene Glycosides fromPolygonum cuspidatum

Two dimeric stilbene glycosides were isolated from an aqueous extract of the root of Polygonum cuspidatum. Their structures were established based on chemical evidence and spectroscopic techniques, including extensive 2D NMR methods. One of these glycosides possesses a novel four-membered ring. Both compounds exhibit strong inhibition of lipid peroxidation, but show no cytotoxic, DNA-cleavage activities and no inhibition of protein tyrosine phosphatase 1B (PTP1B).