NEUROBEHAVIOURAL AND HIPPOCAMPAL EFFECTS OF ETHANOLIC COSTUS DUBIUS LEAF EXTRACT IN DIAZEPAM-ASSOCIATED AMNESIA IN MICE: IMPLICATIONS FOR SUSTAINABLE BIOPROSPECTING

Abstract

Benzodiazepine-associated memory impairment has encouraged the search for neuroprotective agents from medicinal plants, but cognitive rescue must be distinguished from non-specific behavioural activation. This study evaluated ethanolic *Costus dubius* leaf extract in a diazepam-induced amnesia model. Twenty-five mice were allocated to five groups (n = 5). The normal control received saline; the reference group received *Ginkgo biloba* (40 mg/kg); and treatment groups received extract at 100, 200 or 400 mg/kg. All groups except the normal control received diazepam (3 mg/kg) for 14 days. Tail-suspension behaviour, novel-object recognition and hippocampal histology were assessed. Polyphenols, tannins, flavonoids, saponins, steroids, terpenoids, glycosides and alkaloids were detected. Behavioural effects were non-linear. The 400 mg/kg dose increased mobility, but immobility was not consistently reduced across extract doses. Novel-object exploration was most clearly enhanced at 100 and 200 mg/kg, whereas 400 mg/kg did not show a comparable preference. Histology showed preserved hippocampal architecture with variable reactive glial and pyramidal-cell changes. *C. dubius* demonstrated dose-dependent neurobehavioural potential, but the evidence does not support a uniform antidepressant-like response. The study identifies promising intermediate doses and provides a basis for mechanistic, toxicological and sustainable-bioprospecting research.