Antioxidant activity of two dibenzocyclooctene lignans on the aged and ischemic brain in rats.

The effects of two dibenzocyclooctene lignans on peroxidative damage of aging and ischemic rat brain were studied. Incubation of eight-month-old rat brain mitochondria and membrane suspension with Fe(2+)-cysteine resulted in the formation of malondialdehyde (MDA) and decrease of ATPase activity. Schisanhenol (Sal) (10(-4) M) completely inhibited the peroxidative damages of brain mitochondria and membrane of rats. The swelling and disintegration of brain mitochondria, as well as the reduction of brain membrane fluidity induced by Fe(2+)-cysteine were also prevented by Sal. The results of imitative experiment of ischemia and reperfusion of brain mitochondria and membrane in vitro indicated that Sal significantly impeded production of MDA and loss of ATPase activity induced by reoxygenation following anoxia. Oral administration of Sal induced increase of cytosol glutathione-peroxidase of brain in mice under the condition of reoxygenation following anoxia. The other compound schizandrin (Sin B) also has similar activity. But its potency is weaker than that of Sal. All these results indicate that Sal and Sin B have protective action against oxidative stress.