Lipase-catalyzed synthesis of acetylated EGCG and antioxidant properties of the acetylated derivatives

详细信息    查看全文

• 作者：Song Zhu ; Yue Li ; Zhe Li ; Chaoyang Ma ; Zaixiang Lou ; Wallace Yokoyama ; Hongxin Wang
• 关键词：EGCG ; Acetylation ; Lipase ; Organic media ; Antioxidant activity
• 刊名：Food Research International
• 出版年：February, 2014
• 年：2014
• 卷：56
• 期：Complete
• 页码：279-286
• 全文大小：715 K

文摘

(鈭?-Epigallocatechin-3-O-gallate (EGCG) acetylated derivatives were prepared by lipase catalyzed acylation of EGCG with vinyl acetate to improve its lipophilicity and expand its application in lipophilic media. The immobilized lipase, Lipozyme RM IM, was found to be the optimum catalyst. The optimized conditions were as follows, 1:1 of the molar ratio of EGCG to vinyl acetate, 2.0% (w/w of both substrates) of enzyme amount, and 84.5% conversion was obtained after 8 h reaction at 40 掳C in acetonitrile. The presence of mono-, di- and tri-acetylated derivatives in acetylated EGCG were confirmed by LC-MS-MS and the tri-acetylated EGCG was identified as 5鈥?3鈥?5鈥?3-O-acetyl-EGCG by NMR. Their enhanced lipophilicity was confirmed by octanol-water partition coefficient. The antioxidant activity of the acetylated EGCG derivatives were superior to butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ) and EGCG as determined by peroxide values (POVs) in sunflower oil as well as by the p-anisidine method. Acetylated EGCG exhibited the highest 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀ of 0.09 mg/mL) compared to EGCG, BHT and TBHQ. Acetylated EGCG might be used as a potent antioxidant for controlling oxidation of sunflower oil.