Inhibition of radical reaction of apolipoprotein B-100 and alpha-tocopherol in human plasma by green tea catechins

(-)-Epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate ( ECg), (-)-epigallocatechin gallate (EGCg), and Trolox inhibited the decreas es of apolipoprotein B-100 (apoB) and alpha -tocopherol in a radical reacti on of human plasma initiated by Cu2+. The concentrations of EC, EGG, ECg, E GCg, and Trolox for 50% inhibition (IC50) Of apoB fragmentation were 39.1, 42.2, 14.6, 21.3, and 36.2 muM respectively. Similar IC50 values were obser ved for cx-tocopherol consumption, indicating the close relationship betwee n apoB fragmentation and alpha -tocopherol consumption. These results demon strate that tea catechins serve as an effective antioxidant in plasma and t hat the gallate group has a strong antioxidative activity.