In this study, the ultrasound-assisted extraction of total saponins from Abelmoschus sagittifolius was presented. The response surface methodology was used to optimize the extraction conditions including sonication time, ultrasound power, and extraction time after sonication. The extracts were then condensed by a vacuum evaporator system and their biological activities were determined. The results showed that the optimal conditions included sonication time of 11.4 min, ultrasound power of 57.2 W/g and extraction time after ultrasound treatment of 17.3 min. Under this optimum condition, the amount of total saponins obtained was 2.577 ± 0.056 g/100g, which was 1.25 times higher than that from the samples without ultrasonic treatment. Additionally, the SEM images proved that the ultrasonic treatment changed the cell structure of raw material and supported the total saponins extraction process. Moreover, the concentrated extract exhibited strong antioxidant capacity and α-amylase inhibitory activity with IC₅₀ values of 340.221 (µg/mL) for the DPPH radical scavenging activity and 325.49 (µg/mL) for α-amylase inhibitory capacity.

Keywords: Antioxidant activity, α-amylase inhibition capacity, Abelmoschus sagittifolius Gingseng, ultrasound, total saponin extraction.