Effect of the plant flavonoid, rhoifolin, on memory and cognition in a rat model of Alzheimer's disease

Purpose: To investigate the neuroprotective effect of the natural flavonoid rhoifolin in rats with streptozotocin (STZ)-induced (AD). Methods: Morris water-maze and novel object recognition tests were carried out to estimate the effect of rhoifolin on memory and cognition. Histopathological analysis was made to observe thickness of hippocampal CA1 pyramidal layer. Analysis of oxidative stress markers was performed to estimate the effect of rhoifolin on oxidative stress in the hippocampus and frontal cortex. Results: Morris water maze and novel object recognition tests showed a significant improvement in the memory, cognition and spatial learning in rhoifolin treated AD animals (p < 0.05). Moreover, rhoifolin treatment resulted in a significant increase in the CA1 pyramidal layer of AD animals indicating its neuroprotective properties (p < 0.05). The increase in the hippocampal CA1 area further validated the reversal of cognitive dysfunctions caused by STZ treatment. Furthermore, analysis of oxidative stress markers SOD, CAT, GPX, GRX, and MDA showed a significant improvement in the oxidative stress in the hippocampus and frontal cortex (p < 0.05). Conclusion: The present study is the first report to demonstrate the effect of plant flavonoid, rhoifolin on STZ-induced AD in rat model. Rhoifolin improves spatial learning, cognition, and memory in STZ-treated rat model. Therefore, rhoifolin may be a promising therapeutic agent for the management of AD.