Total saponins from Oplopanax elatus Nakai: An optimization study of the extraction process using response surface methodology and its psychopharmacological activities

Abstract Background: Oplopanax elatus Nakai is an ancient angiosperm plant member. It belongs to the Araliaceae family and has biological activities similar to those of Panax ginseng. However, the psychopharmacological effects of O. elatus Nakai have not been characterized. Thus, in the present study, we determined the optimal process for extracting total saponins and then screened the psychopharmacological activities of O. elatus Nakai extract (ONE).Methods: A three-level Box-Behnken design with 3 variables was used to evaluate the treatment variables that influenced the total saponin content (TSC) extracted from O. elatus Nakai. ONE was orally administered to mice and drosophila to evaluate its psychomotor, sedative-hypnotic, anti-stress, and anxiolytic effects.Results: The optimal variables for ethanol extraction were 60 min, 70% ethanol, 30 g/mL and 80 °C, and the total saponin yield reached 18.06±0.17%. Treatment with ONE extended cold swimming endurance time, reduced anxiety-like behaviour, decreased spontaneous locomotor activity, prolonged sleep duration, and ameliorated the sleep-wake rhythm. The ginseng extract (GE) is characterized by low-dose excitation and high-dose inhibition of the central nervous system.Conclusion: Some of the properties of ONE and GE were not identical, but ONE has potentially psychopharmacological activities.