Nootropic and neuroprotective effects of ethanol extract of Vateria indica L bark on scopolamine-induced cognitive deficit in mice

Abstract

Purpose: To investigate the neuroprotective and memory-boosting properties of ethanol extract of Vateria indica bark on scopolamine-mediated defects in learning and memory in young mice. Methods: The ethanol extract of V. indica bark was prepared via Soxhlet extraction and subjected to qualitative and quantitative phytochemical assessment. The acute toxicity of the extract was also evaluated in mice. Six groups of 3-month-old Swiss albino mice (6 per group) were used: normal control, negative control, piracetam group, 250 mg/kg V. indica extract alone group, 500 mg/kg V. indica extract alone group, 250 mg/kg V. indica extract + scopolamine group and 500 mg/kg V. indica extract + scopolamine group. The mice were pretreated with piracetam (standard nootropic drug) or varied doses of the extract for 14 days prior to induction of amnesia. With the exception of normal control group, amnesia induction using scopolamine (3 mg/kg) i.p. on day 14 at 1½ h after the last extract dose. Mice in normal and negative control groups received 0.5 % tragacanth orally at a dose of 10 mL/kg. Cognitive deficit was assessed using elevated plus maze (EPM), step-down avoidance, and Morris water maze (MWM) tests. Results: Qualitative phytochemical screening of V. indica bark extract showed flavonoids, phenolics, glycosides, tannins, carbohydrate, saponins and steroids. The total phenol and total flavonoid contents were 580.96 ± 0.95 mg GAE/g extract and 66.89 ± 0.56 mg RE/g extract, respectively. The mice tolerated the extract up to 5000 mg/kg bwt. They all survived during and after the acute toxicity study and no significant changes in appearance or general behavior were noticed. The extract significantly enhanced learning and memory, and improved spatial recognition in scopolamine-induced amnesic mice (p < 0.05). Acetylcholinesterase (AChE) activity and levels of dopamine and noradrenaline were markedly higher in negative control mice than in normal control, but were significantly reduced after pretreatment with ethanol extract of V. indica bark (p < 0.05). The results of histopathological examination provided evidence in support of the protective effect of the extract on hippocampal and cortical neurons. Conclusion: Pretreatment with ethanol extract of V. indica bark confers neuroprotection and enhances memory in young amnesic mice. Therefore, the extract of the plant can potentially be develpoed for the management of degenerative brain conditions. Keywords: Alzheimer’s disease, Cognitive deficit, Neuroprotection, Phytochemicals, Vateria indica