Lipase-catalyzed synthesis of acetylated EGCG and antioxidant properties of the acetylated derivatives |
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| Affiliation: | 1. State Key Laboratory of Dairy Biotechnology, Technology Center of Bright Dairy and Food Company Ltd., Shanghai 200436, People''s Republic of China;2. State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, People''s Republic of China;3. Processed Food Research, Agricultural Research Service, U.S. Department of Agriculture, Albany, CA 94710, United States;1. College of Standardization, China Jiliang University, Hangzhou 310018, China;2. Institute of Food Science, Zhejiang Academy of Agricultural Science, Hangzhou 310021, China;3. Key Laboratory of Marine Food Quality and Hazard Controlling Technology of Zhejiang Province, China Jiliang University, Hangzhou 310018, China;1. Mountain Research Centre (CIMO), ESA, Polytechnic Institute of Bragança, Campus de Santa Apolónia, 1172, 5301–855 Bragança, Portugal;2. REQUIMTE, Science Chemical Department, Faculty of Pharmacy of University of Porto, Rua Jorge Viterbo Ferreira, 228, 4050–313 Porto, Portugal;3. GIP-USAL, Facultad de Farmacia, Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain |
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| Abstract: | (−)-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 °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′,3″,5″-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. |
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