Cognition enhancing effects of Clausena lansium (Lour.) peel extract attenuate chronic restraint stress-induced memory deficit in rats

Chronic stress exposure is now accepted as a problem that can produce deleterious effects on both brain structure and function. Numerous studies have proposed the potential of fruit peels as vital sources for acetylcholinesterase (AChE) inhibitors and antioxidants. Clausena lansium (Lour.) or wampee (WP) fruit peel is a rich source of antioxidants and flavonoids that could prove beneficial for human health. Currently, there has been no scientific evidence supporting the potency of WP peel extract to combat or reverse the memory impairment induced by chronic restraint stress (CRS). Therefore, we aimed to investigate the AChE-inhibiting and neuroprotective effects of WP peel extracts against CRS-mediated oxidative stress and cognitive dysfunction in rats. Initial assessment of the extract revealed antioxidant capacity and high concentrations of polyphenols. Further, Wistar rats were dosed orally with the WP peel extract (200, 400, and 600 mg/kg daily) and kept in a restrainer for 4 h a day for 28 consecutive days. The object recognition and Morris water maze tests were used to determine cognitive functions. After sacrifice, biomarkers of oxidative stress and AChE inhibitory activity in brain homogenates of rats were also investigated. CRS exposure produced oxidative stress and increased AChE activity, changes that led to learning and memory impairment in the cognition tests. Improved memory, reduced AChE activity, and a decreased oxidative stress status were seen in rats treated with WP peel extract. Overall, supplementation with WP peel extract may exert cognitive-enhancing effects through antioxidative neuroprotection and inhibition of AChE activity against CRS-induced oxidative stress.