This research investigates the phytochemical constituents of an ethanolic extract derived from the leaves of Leucaena leucocephala. Soxhlet extraction was followed by phytochemical screening, TLC profiling, and isolation of bioactive components through column chromatography. The isolated compound was characterized using IR, ^1H NMR, ^13C NMR, and mass spectrometry, which confirmed its identity as quercetin. The extract revealed the presence of carbohydrates, alkaloids, saponins, tannins, flavonoids, lipids, fixed oils, and phenols. Furthermore, the extract exhibited significant nootropic activity in scopolamine-induced memory-impaired rats, suggesting potential neuroprotective benefits of its secondary metabolites.