ABSTRACT
Objective:To investigate the nootropic components of Hovenia dulcis.Methods: Six saponins were isolated from Hovenia dulcis and Step-down test was used to examine the memory ability of mice.The escape latency and the times of wrong performance within 3 min were used to evaluate the memory ability of mice.To study the effects of saponins on learning and memory in mice,we divided the mice into 6 groups:youth group,aged group,aged plus piracetam(0.3 g/kg) group,aged plus saponins(0.6 g/kg) group,aged plus saponins(0.3 g/kg) group,and aged plus saponins(0.15 g/kg) group.To study the influence of saponins on impairment of memory acquirement,consolidation,and reoccurrence(induced by scopolamine,sodium nitrite and 40% ethanol,respectively),mice were also divided into the following 7 groups:control group,untreated group,piracetam group(0.3 g/kg),compound 3 group(0.3 g/kg),compound 4 group(0.3 g/kg),compound 5 group(0.3 g/kg),and compound 6 group(0.3 g/kg).Results: The chemical structures of six saponins were elucidated as 3-O-stigmasterol-(6-O-palmitoyl)-?-D-glucopyranoside(1),?-daucosterin(2),hovenidulcioside A1(3),hoduloside Ⅰ(4),hoduloside Ⅳ(5),and saponins C2(6).Among them,compounds 1 and 2 were isolated from this plant for the first time.Compounds 5 and 6 had enhancing effect on the learning and memory ability of natural senile mice,and they could improve the impairment of memory acquirement,consolidation and recurrence in mice induced by scopolamine,sodium nitrite and 40% ethanol,respectively.Conclusion: The aglycone of jujubogenin might be the main saponins contributing to the nootropic effect of total saponins from Hovenia dulcis.