Asian Journal of Biology

Alzheimer’s disease is a progressive neurodegenerative disorder characterized by cognitive decline, memory impairment, and oxidative damage. This study assessed the neuroprotective potential of Psidium guajava (guava) leaf extract in cognitive and oxidative functions in Alzheimer’s disease. Forty-two Wistar rats were assigned to six groups: control, scopolamine-only, Donepezil (5 mg/kg), and guava extract-treated groups at 100 mg/kg and 300 mg/kg. Behavioral evaluations were carried out over 12 weeks using the navigation test (to assess spatial learning and memory) and the beam walk test (to assess motor coordination). Cognitive results revealed that scopolamine significantly impaired spatial memory and motor coordination, as shown by a 448.6% increase in navigation escape time and a 291.1% rise in beam walk time. Treatment with 100 mg/kg Psidium guajava extract improved cognitive function, reducing navigation latency by 272.9% and beam walk time by 93.0%. The 300 mg/kg dose resulted in less improvement (navigation 148.6%; beam walk 346.5%), suggesting cognitive effect at higher concentrations. Donepezil treatment produced the most favorable cognitive outcomes (Barnes maze 132.4%; beam walk 120.9%).Biomarker results showed that scopolamine induced significant oxidative damage, with a 62.5% decrease in SOD, a 16.1% reduction in CAT, and an 86.2% increase in MDA at 90 days. The 100 mg/kg guava extract dose reversed these effects, increasing SOD by 37.2%, CAT by 24.5%, and reducing MDA by 62%. In contrast, the 300 mg/kg dose showed weaker antioxidant effects, with SOD rising only 6.7%, CAT 16.7%, and MDA reducing by 13.7%. Donepezil treatment demonstrated strong antioxidant protection (CAT 143.8%, SOD 4.6%, MDA 10.3%).In conclusion, Psidium guajava extract at 100 mg/kg exhibited both cognitive enhancement and antioxidant potential in scopolamine-induced alzheimer’s disease in rats. Keywords: Psidium guajava, Alzheimer’s disease, cognitive function, Brain markers.