Claim: Piceid, a stibenoid glucoside which can produce resveratrol, can be isolated from the Japanese knotweed.
Evidence: Piceid is a stilbenoid glucoside and is a major resveratrol derivative in grape juices. It can also be isolated from Reynoutria japonica (syn. Fallopia japonica), the Japanese knotweed (syn. Polygonum cuspidatum).