Green tea extract solutions were prepared in 3 different media;
water, diluted HCl pH 4.8 and acetate buffer pH 4.8, each
consisting of 4.0 g ground dry green tea leaves and 150 ml of
solvent. The suspension was shaken for 20 min. Then, the
suspension was filtered through a piece of No. 1 filter paper
(Whatman). The filtrate was diluted to a volume of 500 ml with
each medium. The extract was prepared daily.