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The phytochemical yield of a plant material is related directly to the method as well as solvent of extraction. Lots of African herbs have proven over time to be highly medicinal both for the prevention, management and cure of various ailments. The aim of this research is to compare the neuroprotective potency of the aqueous and methanolic extracts of Vernonia amygdalina on the hippocampus of mercury chloride intoxicated Wistar rats. Thirty male Wistar rats weighing between 180 to 200 g were divided into 6 groups of 5 rats each. Group A was the negative control and had food and water only. Groups B was the positive control and groups C1, C2, D1 and D2 were the test groups. Rats in group B to D2 were exposed to 0.5 mg/kg/b.w of mercury chloride two times a week for 2 weeks. Groups C1 and C2 were treated with 200 mg/kg/bw of aqueous and methanolic extracts respectively while groups D1 and D2 received 400 mg/kg/bw of aqueous and methanolic extracts of Vernonia amygdalina respectively. Qualitative and quantitative phytochemical analysis shows that water extracted more flavonoids while methanol extracted more phenols from the plant. The results of antioxidant studies show that the methanolic extract conferred more protection against oxidative stress than the aqueous extract. Neurobehavioural and histological results show that aqueous extract conferred more protection on the cells and tissue structure of the hippocampus than the methanolic extract. We therefore conclude that both the aqueous and methanolic extracts of Vernonia amygdalina confer some form of neuroprotection on the hippocampus of Wistar rats but the aqueous extract gave better results.
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