Neuroprotective and Cognitive-Enhancing Effects of a Phytoestrogen Rich Fraction from Ochna schweinfurthiana Bark in a Rat Model of Menopause and Cholinergic Dysfunction

Abstract

In postmenopausal women, a substantial decrease in circulating estrogen levels has been strongly associated with an increased risk of cognitive dysfunction. Both clinical and preclinical studies have demonstrated that estrogen positively affects synaptic plasticity, hippocampal neurogenesis, and cholinergic transmission, which are crucial processes in learning and memory. The present study investigated the neuroprotective and memory-enhancing effects of a phytoestrogen-rich fraction (PERF) of Ochna schweinfurthiana bark in a combined model of menopause and cholinergic deficits. Ovariectomized rats were treated with PERF (264 and 528 mg/kg) or estradiol valerate for 12 weeks, followed by scopolamine administration to induce memory impairments. Cognitive performance was assessed using the Morris water maze test, and biochemical parameters, including serum estradiol levels, brain acetylcholinesterase (AChE) activity, and oxidative stress markers, were evaluated. PERF treatment significantly increased serum estradiol levels, reduced escape latency, and increased the time spent in the target quadrant during the probe trial, indicating improved spatial memory. PERF also inhibits AChE activity and attenuates oxidative stress by increasing antioxidant enzyme levels (catalase and superoxide dismutase) and reducing lipid peroxidation (malondialdehyde) in the brain. The neuroprotective effects of PERF were comparable to those of estradiol valerate. These findings suggest that PERF of O. schweinfurthiana ameliorates the cognitive deficits associated with menopause and cholinergic dysfunction, potentially through estrogenic, cholinergic, and antioxidant mechanisms. Further studies are warranted to elucidate the molecular pathways involved and to assess the long-term efficacy and safety of this phytoestrogen-rich fraction in clinical populations.