The radical scavenging effects of stilbene glucosides from Polygonum multiflorum.

The extract of the root of Polygonum multiflorum exhibited a significant antioxidant activity assessed by the DPPH radical scavenging activity in vitro. The bioassay-guided fractionation of the extract yielded a stilbene glucoside, (E)-2,3,5,4'-tetrahydroxystilbene-2-O-beta-d-glucopyranoside (1) as an active constituent responsible for the antioxidant property. Compound 1 demonstrated a moderate DPPH radical scavenging activity (IC50, 40 microM), while the corresponding deglucosylated stilbene 2 exhibited a much higher activity (IC50, 0.38 microM).