Comparison of different extraction techniques and optimization of the microwave-assisted extraction of saponins from Aralia elata (Miq.) Seem fruits and rachises

Abstract

The total saponins from Aralia elata (Miq.) Seem fruits and rachises were isolated by microwave-assisted extraction (MAE), ultrasonic extraction, heat reflux extraction, and soxhlet extraction. These techniques were compared from four perspectives: extraction kinetics, saponin yield, disintegration to the raw materials, and antioxidant activity. MAE had the highest extraction efficiency, shortest time, and greatest disintegration to the raw materials. The extracts obtained with MAE had the highest antioxidant activities, as the DPPH free radical scavenging abilities of the fruit and rachis extracts were 70.86 ± 1.33 and 50.85 ± 1.68 mg VC g−1md, respectively. The MAE parameters were optimized by the response surface methodology. The optimum conditions (92% and 91% ethanol, solid-to-liquid ratios of 1:30 and 1:22, microwave powers of 530 W and 400 W, microwave times of 40 s and 54 s) provided extraction yields of 2.98 ± 0.037 mg g−1 and 0.94 ± 0.026 mg g−1 from the fruits and rachises, respectively.