Antioxidant activity and protection of human umbilical vein endothelial cells from hydrogen peroxide-induced injury by DMC, a chalcone from buds of Cleistocalyx operculatus

► 2′,4′-Dihydroxy-6′-methoxy-3′,5′-dimethylchalcone was extracted from C. operculatus. ► The antioxidant activities of the chalcone were evaluated in vitro. ► Protection of the chalcone in human umbilical vein endothelial cells was determined.