|ZHU, SONG - Jiangnan University|
|LI, YUE - Jiangnan University|
|LI, ZHE - Jiangnan University|
|MA, CHAOYANG - Jiangnan University|
|LOU, ZAIXIANG - Jiangnan University|
|Yokoyama, Wallace - Wally|
|WANG, HONGXIN - Jiangnan University|
Submitted to: Food Research International
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/17/2013
Publication Date: 2/17/2014
Citation: Zhu, S., Li, Y., Li, Z., Ma, C., Lou, Z., Yokoyama, W.H., Wang, H. 2014. Lipase-catalyzed synthesis of acetylated EGCG and antioxidant properties of the acetylated derivatives. Food Research International. 56:279-286.
Interpretive Summary: Unsaturated and polyunsaturated fats become rancid due to oxidation. Synthetic antioxidants are soluble in fat and efficiently prevent oxidation. Epigallocatechin-3-O-gallate is a natural, water soluble antioxidant found in green tea. This study shows that acetylation can increase its oil solubility and delay the oxidation of fat.
Technical 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 amountt, 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 (POV) 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.