Evaluation of neuroprotective and anti-amnesic effects of the chloroform fraction of Nigella sativa L. on scopolamine-induced memory impairment in rats

The aim of this study was to investigate the neuroprotective and anti-amnesic effects of total extract (NTE) and chloroform fraction of Nigella sativa (NCE) on scopolamine (SCO)-induced memory impairment in the rat. After plant extraction and fractionation, the rats were treated with different doses of NTE (200, 400, and 800 mg/kg) and NCE (50, 100 or 200 mg/kg) before scopolamine administration for 7 successive days compared to donepezil (DON). Learning power and memory capacity of the treated animals were evaluated and the rat brain samples were further assessed for in vivo acetylcholinesterase (AChE) activity, lipid peroxidation, and finally validated by histopathological examination. Pretreatment with NTE and NCE effectively increased antioxidant activity, decreased cholinesterase activity and malondialdehyde (MDA) content in the hippocampal and cortical tissues as well as mitigated scopolamine-induced behavioral, and histological changes in a manner comparable to DON. Based on the pathology results, the most toxicity of NCE was observed at 200 mg/kg. The observed neuroprotective and anti-amnesic effects of NCE indicate that this fraction could be a promising candidate both for further studies to isolate the active components and for use in clinical trials in patients with cognitive impairment.