(E)-3,5,4'-Tribenzyloxystilbene-d21 is the isotope labelled analog of (E)-3,5,4'-Tribenzyloxystilbene (T770300); the impurity E of Resveratrol (R150000) which is 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.