5-[(1E)-2-[4-(Phenylmethoxy)phenyl]ethenyl]-1,3-benzenediol is the impurity D of Resveratrol (R150000); a minor constituent of wine, correlated with serum lipid reduction and inhibition of platelet aggregation. Resveratrol is a specific inhibitor of COX-1 and also inhibits the hydroperoxidase activity of COX-1. It has been shown to inhibit events associated with tumor initiation, promotion and progression. Molecular Formula: C21H18O3 Molecular Weight: 318.37