In vitro studies on the activity of japanese kampo herbal medicines Oren-Gedoku-To (TJ-15) and Toki-Shakuyaku-San (TJ-23) as scavengers of free radicals

Oren-Gedoku-To (TJ-15) inhibited enzymatically (NADPH or CumOOH) and non-enzymatically (Fe-ascorbate) induced lipid peroxidation in rat liver microsomes as assessed by TBA-reactive product accumulation. Toki-Shakuyaku-San (TJ-23) had little effect on either system. The protective effect of TJ-15 against lipid peroxidation was not dependent upon the presence of microsomal drug-metabolizing activity and could not be fully accounted for by its action on microsomal electron transfer, as evaluated by studying the kinetics of cytochrome c reduction. Both TJ-15 and TJ-23 reduced the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), indicating their free radical scavenging ability. The reactivity of TJ-15 was comparable with that of standard ascorbate, while the activity of TJ-23 was approximately 10 times lower. In a free solution TJ-15 and TJ-23 effectively scavenged OH* radicals, as indicated by the inhibition of ethylene production from 2-keto-4-methiolbutyric acid (KMBA), and O2*- anion radicals, as assessed by the inhibitory effect on the rate of nitro blue tetrazolium (NBT) reduction by the O2*- generating system xanthine/xanthine oxidase.