Isolation of (−)-Epigallocatechin from Green Tea Extract by Means of Immobilized Tannase

Abstract

(−)-Epigallocatechin is a chemoprotective polyphenolic compound found in green tea. Its low abundance in tea increases the cost and difficulty of obtaining sufficient (−)-epigallocatechin to conduct research on (−)-epigallocatechin-mediated health benefits. We developed a convenient and economical method for preparing (−)-epigallocatechin from a commercial green tea extract in a sufficient quantity to carry out mechanistic studies of the pure compound. Crude epigallocatechin gallate was isolated from the tea extract by silica gel column chromatography, and was then hydrolyzed with immobilized tannase. The (−)-epigallocatechin found in the hydrolyzed products was extracted into ethyl acetate and purified by Sephadex LH-20 to produce (−)-epigallocatechin. Very pure (−)-epigallocatechin (93.7 %) was obtained and its identity was confirmed by ESI-MS and HPLC. The overall yield was 10 % by mass of the initial green tea extract obtained as pure (−)-epigallocatechin. No specialized equipment was required, and the solvents and chromatographic supports used were inexpensive and readily available.