儿茶素单体EGCG酶法修饰研究及其产物抗氧化活性评价

Enzymatic Modification of Epigallocatechin Gallate and Antioxidant Activity Evaluation of the Synthesized Products

利用Novozym 435脂肪酶在非水介质中催化儿茶素单体EGCG(表没食子儿茶素没食子酸酯)的酶促酰化反应,以增加EGCG的脂溶性。探讨了溶剂种类、水活度、加酶量、反应时间、反应温度、酰基供体等条件对酰化反应的影响。借助液质联用仪及红外光谱仪对合成产物进行鉴定,表明在叔戊醇体系中,脂肪酶可催化EGCG与丁酸乙烯酯的反应,酰化后EGCG主体结构不变,其分子中引入了四碳链的烷基。对修饰后EGCG抗氧化活性的评价表明:在相同的添加量下,酶修饰EGCG活性略低于未改性EGCG,但是清除DPPH·、O-·2自由基能力总体高于TBHQ、维生素C,清除·OH自由基能力低于TBHQ,高于维生素C。

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 Vit C,and its capacity of scavenging hydroxyl free radical was lower than that of TBHQ,higher than that of Vit C.