Content of resveratrol and glycoside and its contribution to the antioxidative capacity of Polygonum cuspidatum (Itadori) harvested in Kochi.

We quantified trans-resveratrol in each part of fresh Polygonum cuspidatum harvested in Kochi Prefecture. A small amount of trans-resveratrol was detected in the edible stem parts, the content varying with seasonal, geographical, and environmental factors. We also examined the antioxidative activity of each part, suggesting that P. cuspidatum contained many more contributing antioxidants other than resveratrol.