Neuroprotective effects of emodin-8-O-beta-D-glucoside in vivo and in vitro

Emodin-8-O-beta-D-glucoside extracted from the traditional Chinese medicinal herb Polygonum cuspidatum Sieb. et Zucc is widely used to treat acute hepatitis possibly by antioxidative mechanisms. The present study was designed to investigate whether emodin-8-O-beta-D-glucoside exerted neuroprotective effects on the focal cerebral injury induced by ischemia and reperfusion in vivo and on the neuronal damage induced by glutamate in vitro, and to study the possible mechanisms. Male Wistar rats were used to establish the model of ischemia and reperfusion. The behavioral test was performed and the cerebral infarction area was assessed in the brain slices stained with 2% 2,3,5-triphenyl tetrazolium chloride to evaluate the neuroprotective effects of emodin-8-O-beta-D-glucoside. Superoxide dismutase (SOD) activity, total antioxidative capability and malondialdehyde (MDA) level in the brain tissue were determined with spectrophotometrical methods to probe the primary mechanisms of emodin-8-O-beta-D-glucoside. In vitro, the neuroprotective effects of emodin-8-O-beta-D-glucoside were tested in the cultured cortical cells of fetal rats exposed to glutamate. Emodin-8-O-beta-D-glucoside concentration in plasma and brain tissue was also measured to examine distribution of emodin-8-O-beta-D-glucoside in the brain. The results showed that the treatment of rats with emodin-8-O-beta-D-glucoside reduced the neurological deficit score and the cerebral infarction area, increased SOD activity and total antioxidative capability, and decreased MDA level in the brain tissue in dose-dependent way. Emodin-8-O-beta-D-glucoside also inhibited the neuronal damage induced by glutamate. Besides, emodin-8-O-beta-D-glucoside was able to penetrate blood-brain barrier and distribute in the brain tissue. These findings demonstrate that emodin-8-O-beta-D-glucoside is able to provide neuroprotection against cerebral ischemia-reperfused injury and glutamate induced neuronal damage through exerting antioxidative effects and inhibiting glutamate neurotoxicity.