Abstract: The regioselective acylation of epigallocatechin gallate (EGCG) was catalyzed by Novozym 435 in a non-aqueous phase reaction system to increase the lipophilicity of EGCG.The effects of different organic solvents,water activity,enzyme amount,reaction time,reaction temperature and acyl donor on the enzymatic regioselective acylation of EGCG were discussed.The synthesized products were identified by LC-MS and infrared spectroscopy.The results showed that under tert-amyl alcohol media,Novozym 435 can catalyze selective acylation of EGCG with vinyl acetate butyrate.A single modified product was found in reaction mixture by LC-MS analysis.Infrared spectral analysis showed that the main structure of acylated EGCG was similar to that of EGCG,but a four-carbon alkyl chain was connected to EGCG.The antioxidant activity of modified EGCG indicated that the antioxidant activity of modified EGCG was slightly lower than that of EGCG with the same concentration,but its capacity of scavenging DPPH·and O₂^-· free radical was higher than that of TBHQ and VitC,and its capacity of scavenging hydroxyl free radical was lower than that of TBHQ,higher than that of VitC.

Key words: enzymatic method, enzymatic acylation, EGCG, antioxidant activity evaluation