Study on extraction, isolation, and biological activity of saponins from quinoa bran

Abstract

Quinoa (Chenopodium quinoa Willd) contains 2 to 5% of saponins, which are mainly exist in the bran of seeds in the form of oleanane-type triterpenoid glycosides or sapogenins. In this study, the extraction process of total saponins from quinoa bran has been optimized. The results showed that the optimal extraction conditions for quinoa saponins were extraction time of 2 h, ethanol concentration of 70%, solid–liquid ratio of 1:25 (g/ml), and extraction temperature of 70°C. Macroporous resin separation test demonstrated that HPD600 resin had an excellent adsorption and desorption capacities for the separation of quinoa saponins. The antioxidant experiment demonstrated that the EC50 of quinoa saponins against DPPH-free radical, ABTS-free radical, ·OH-free radical, and O2−-free radical were 0.10, 0.51, 0.57, and 0.17 mg/ml, respectively. The scavenging effect of the saponins on O2−-free radical was stronger than that of Vc. The reducing power was equivalent to 1.28% of that of Vc. The anticancer test showed that when the concentration of quinoa saponins was 0.5 mg/ml, the inhibitory rate on HepG-2 cell was 58%. This study contributes to further exploration on the biological activities of quinoa saponin. Novelty impact statement A macroporous resin suitable for separating quinoa saponins was screened. The adsorption isotherms and kinetics of quinoa saponins on HPD600 were studied. The in vitro biological activities of quinoa saponins were studied.