Abstract:(-)-Epigallocatechin-3-O-gallate (EGCG) acetylated derivatives were prepared by enzymatic acylation with vinyl acetate and catalyzed by Lipozyme RM IM in acetonitrile. Liquid chromatography tandem mass spectrometry (LC-MS/MS) and infrared (IR) spectrometry were used to confirm the acylated EGCG product. It indicated that the product was a mixture of different degrees of substitutions. IR spectra showed that the acetylated EGCG derivatives had two strong absorption peaks of carbonyl and methyl, and the other parts were similar to EGCG. The antioxidant activity of acetylated EGCG in vitro was investigated by measuring scavenging effects of superoixide anion (O2-?), hydroxyl radical (?OH) and 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical. The acetylated EGCG was found to have good scavenging effects on O2-?, ?OH and DPPH? and the 50% inhibitory concentrations (IC50) were 0.52 mg/mL, 0.43 mg/mL and 11.5 mg/L, respectively. Anti-lipid peroxidation experiments showed that the inhibition rates of malonyldialdehyde (MDA) formation in rat liver mitochondria and hemolysis for rat red blood cells induced by H2O2 were 61.11% and 93.54% , respectively, when acetylated EGCG concentration was 320 mg/L. Therefore, acetylated EGCG had strong antioxidant activity in vitro, and their antioxidant activity is positively related to their concentration.
