Neuroprotective effects of Dioscorea opposita on scopolamine-induced memory impairment in in vivo behavioral tests and in vitro assays

Ethnopharmacological relevance: Plants belong to the genus Dioscorea have long been used as edible tuber crops in many tropical and subtropical areas and as a traditional herbal medicine in oriental countries including China, Japan and Korea. Aim of the study: In this study, in vivo and in vitro tests were carried out to evaluate the cognitive enhancing effects of CHCl₃-soluble extract from Dioscorea opposita against scopolamine-induced amnesic mice and glutamate- and H₂O₂-treated cortical neurons of rats. Materials, methods and results: Acute treatment (200 mg/kg body weight, p.o.) and 10 days' daily administration (50 mg/kg body weight, p.o.) of CHCl₃-soluble extract showed significant spatial learning and memory improvement on mice. Furthermore, the neuroprotective effects on glutamate- and H₂O₂-induced neurotoxicity in primary cultured cortical neurons of rats were assessed. Pretreatment with the extract was found to impart significant protection against neurotoxicity. Conclusions: These in vivo and in vitro results suggest that the Dioscorea opposita has neuroprotective effects on memory impairment related neurodegenerative diseases.