ANTIOXIDATIVE ACTIVITY OF WATER EXTRACTS OF LAGERSTROEMIA-SPECIOSA LEAVES

In order to develop naturally occurring antioxidants from edible plant s, the antioxidative effect of hot water extracts of Lagerstroemia spe ciosa speciosa leaves, known by the Tagalog name of banaba in the Phil lipines, was studied, The content of tannin in banaba extract was 36.8 % in dry weight. Banaba extract showed strong antioxidative activity i n a linoleic acid autoxidation system. Banaba extract was found to hav e a potent radical scavenging action on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and superoxide radicals (O2-) generated by a hypoxanth ine (HPX)/xanthine oxidase (XOD) system, In vitro lipid peroxidation o f rat liver homogenate induced by tert-butyl hydroperoxide (BHP) was i nhibited by the addition of banaba extract in a dose-dependent manner, From these results, banaba extract was demonstrated to be useful as a n antioxidant or free radical scavenger to protect biological systems against oxidative stress.