There is growing interest in flavonoids for their wide array of biological actions. In neurodegenerative disorders these naturally occurring polyphenolic compounds, are known to inhibit proinflammatory mediators such as in TNF–? and IL-6 in lipopolysaccharide (LPS) stimulated neuronal degeneration, which are associated with Alzheimer’s and Parkinson’s disease. Recent studies on flavonoids have yielded an impressive array of novel structures, which acts as neuroprotective agents. The current study investigated the ability of flavonoid rich fraction from the leaves of plant Araucaria bidwilli on the cognitive performance in LPS-treated rats using passive avoidance step through behavior and elevated plus maze paradigm. Administration of LPS (100 mg/kg b.wt.) in rats exhibited impaired acquisition and retention memory in step-through passive avoidance and in elevated plus-maze tasks. Chronic administration of the flavonoid-rich fraction (50-200 mg/kg per oral) of the plant Araucaria bidwillii hook reversed the LPS-induced retention deficits in both behavioral paradigms. Furthermore, the extract was found to rejuvenate the antioxidants defense system in different brain regions. The present investigation showed that treatment with the flavonoid-rich fraction reverses cognitive deficits in LPS-intoxicated rats and are found to rejuvenate the brain antioxidants thereby preventing the memory deficits, which is found to be one of the symptoms related to AD.