Evaluation of the Memory Enhancing Activity of Dichloromethane Fraction of the Methanolic Extract of Pycnanthus angolensis Stem Bark on Experimental Models of Memory Impairment

Abstract

Pycnanthus angolensis (Welw) Warb., Myristicaceae, is used extensively in ethnomedicine. Numerous health benefits have been ascribed to the use of different parts of P. angolensis including its role in cognitive function and inflammatory conditions. Hence, this study was undertaken to investigate the effect of stem bark of the plant on memory function in mice.The plant material was pulverized into powder and extracted by maceration with 80% methanol at room temperature for 48 h. This was subsequently fractionated using N-hexane, Dichloromethane (DCM) and Ethyl acetate. The Dichloromethane fraction which is the most potent fraction (25, 50 and 100 mg/kg) was evaluated for memory enhancing activity using the Y-maze (YMT), morris water maze (MWM) and the elevated plus maze (EPM) on D-galactose plus scopolamine and ketamine induced amnesia. The antioxidant markers and acetylcholinesterase (AChE) inhibiting effect of DCM were also investigated.The results obtained from the behavioural study indicates that the DCM fraction significantly (p<0.05) increased alternation behaviour of mice in the YMT, decreased the escape latency in the MWM paradigm and decreased the transfer latency in the EPM. Biochemically, DCM increased glutathione, and superoxide dismutase, but decreased malondialdehyde and AChE activity in the brain.The findings therefore suggests that the DCM possesses significant memory enhancing activity, which may be due to enhancement of antioxidant activity and cholinergic transmission. The attenuation of the effect of ketamine by the DCM may possibly result from an increase in NMDA receptor mediated neurotransmission and attenuation of oxidative stress.

A Case for the Neuroprotective Potential of African Phytochemicals in the Management of Alzheimer’s Disease

“…There have been many preclinical experiments showing the neuroprotective potentials of African plants [217][218][219][220][221][222][223][224][225][226], but there have been no clinical trials for the agents. Therefore, future studies of these medicinal agents may present contrasting results in biological systems in the form of low catalytic activity in the CNS compared to preclinical and in vitro studies.…”

Ketamine as a pharmacological tool for the preclinical study of memory deficit in schizophrenia

“…For example, exposure to this agent can cause a reduction in serum and hippocampal levels of brain-derived neurotrophic factor Meng et al, 2020) and increases AKT and ERK phosphorylation in this brain structure (Meng et al, 2020;. In addition, various studies show that the administration of KET rises oxidative stress markers, mediated by increased levels of nitrite, lipid peroxidation, and myeloperoxidase activity in Hp (Sampio et al, 2018;Ekwutosi et al, 2019) as well as the reduction in malondialdehyde and acetylcholinesterase activities in the brain of rodents (Ekwutosi et al, 2019). Moreover, there are reports showing the presence of neuronal death in Hp, after the administration of this agent (Meng et al, 2020).…”