A traditional Chinese herbal medicine, Qizhu Tang (QZT) was studied for its in vitro
antioxidant activity and the effect on cerebral oxidative damage after forebrain
ischemia followed by reperfusion in rats. The QZT decoction was shown to have strong
hydroxyl radical (*
OH) scavenging activity (approx. 0.1 mM as
Trolox equivalent) when determined by ESR using DMPO as a spin trap
reagent and H2O2/UV as the *
OH source. When the QZT decoction was injected into rat duodenum 2 h before
cerebral ischemia, the oxidative brain damage after 45 min reperfusion was strongly inhibited in terms of two biochemical indications,
thiobarbituric acid reactive substance formation and the loss of
glutathione peroxidase. Since the QZT formula consists of 4 herbal constituents (Rhizoma atractylodis, Poria, Radix notoginseng and
Radix astragali), each of the component herbs and their combinations were also examined for their protective effects on the
cerebral ischemia/
reperfusion injury and the effects were compared with their in vitro
antioxidant potential. Although some of the incomplete formulas showed as strong
antioxidant activities as complete QZT in vitro, only the complete QZT formula was effective in preventing cerebral oxidative injury in rats, and other preparations showed limited activity in vivo.