Evaluation of Nootropic Activity of <i>Persicaria flaccida</i> on Cognitive Performance, Brain Antioxidant Markers and Acetylcholinesterase Activity in Rats: Implication for the Management of Alzheimer’s Disease

Abstract

Oxidative stress is the leading cause of neurodegenerative diseases, especially Alzheimer´s disease (AD). The plant Persicaria flaccida (PF) is known in Bengali as red Biskatali belongs to family Polygonaceae. Preliminary studies have shown the antioxidant, anti-inflammatory, analgesic, neuroprotective activities of Biskatali. In this consequence, methanolic extract of PF (MEPF) was selected to explore the ability of this plant to enhance cognitive functions, brain antioxidant enzymes and anti-acetylcholinesterase activity which can be used for the treatment of AD. The objective of this study was to investigate the effects of MEPF on cognitive performance, brain antioxidant enzymes and acetylcholinesterase activity in rats by using behavioral and biochemical study. Treatment with MEPF (i.e., 100 and 200 mg/kg b.w.) was investigated for 14 days in Swiss albino male rats and its effects on different types of memory were examined using Elevated Plus Maze (EPM) test, Passive Avoidance (PA) test, Morris Water Maze (MWM) test as well as level of antioxidant enzymes such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), glutathione reductase (GSR), glutathione-S-transferase (GST) and contents of thiobarbituric acid reactive substances (TBARS) in rat brain tissue homogenates. Acetylcholinesterase (AChE) activity was determined by colorimetric method. Administration of highest dose of MEPF significantly (P < 0.05, P < 0.01) decreased retention transfer latency (RTL) of rats on 7th and 14th day compared to the control group in EPM test. In PA test highest dose of MEPF meaningfully (P < 0.05, P < 0.01) increased step-through latency (STL) of rats on 7th, 12th, 13th and 14th day with respect to control group. Both doses of MEPF markedly (P < 0.01, P < 0.001) decreased escape latency (EL), increased time spent in the target quadrant (TSTQ) and time spent in the annuli (TSA) of rats on successive days as compared to that of control group in MWM test. MEPF administration, especially highest dose significantly (P < 0.05, P < 0.01, P < 0.001) increased the level of CAT, SOD, GSR, GST & GSH-Px and considerably (P < 0.01, P < 0.001) decreased TBARS level & AChE activity in the brain tissue homogenates of rats compared to the control group. Behavioral and biochemical studies suggest that MEPF promotes cognitive function by improving different types of memory and reduces oxidative stress by increasing the level of brain antioxidant markers and anti-acetylcholinesterase activity. Therefore, this plant extract can be used for enhancing memory in neurodegenerative disorders like AD.