Evaluation of Antioxidant and Cerebroprotective Effect of Medicago sativa Linn. against Ischemia and Reperfusion Insult

Antioxidants have been the focus of studies for developing neuroprotective agents to be used in the therapy for stroke, which is an acute and progressive neurodegenerative disorder. Medicago sativa (MS) has a long tradition of use as ayurvedic and homoeopathic medicine in central nervous system disorders. The plant has been reported to have antioxidant, anti-inflammatory and antidiabetic effects. Therefore, the present study was designed to investigate the neuroprotective effect of methanol extract of MS on ischemia and reperfusion-induced cerebral injury in mice. Bilateral carotid artery occlusion (BCAO) for 15min followed by 24-h reperfusion, resulted in significant elevation in infarct size, xanthine oxidase (XO) activity, superoxide anion (O-2(center dot-)) production and thiobarbituric acid-reactive substance (TBARS) levels, and significant depletion in endogenous antioxidant [reduced glutathione (GSH), superoxide dismutase (SOD) and total tissue sulfhydryl (T-SH) groups] systems in mice brain. Further, BCAO led to impairment in short-term memory and motor coordination. Pre-treatment with MS (100 or 200 mg kg(-1), p.o.) markedly reduced cerebral infarct size, XO, O-2(center dot-) and TBARS levels, significantly restored GSH, SOD and T-SH levels and attenuated impairment in short-term memory and motor coordination. In addition, MS directly scavenged free radicals generated against a stable radical 1,1-diphenyl-2-picrylhydrazyl and O-2(center dot-) generated in phenazine methosulphate-nicotinamide adenine dinucleotide systems, and also inhibited XD/XO conversion and resultant O-2(center dot-) production. The data from this study suggest that treatment with MS enhances the antioxidant defense against BCAO-induced global cerebral ischemia and exhibits neuroprotective activity.