Preparation of extracts
Extraction of polyphenolsfrom GTPs were carried out accord-
ing to the method of Kim et al. (2002), with some modifications. 2gof dried leaves and2gof powdereddried leaves
were macerated during 24 h under stirring, in 20 mL
methanol/water 70/30(v/v). Then, the methanol/water extract
was centrifuged at 20,000 rpm for 20 min. The supernatant
layer was filtered, broughtto 15 mL andstored at 4°C before
analysis.