Optimization of Ultrasonic-Assisted Aqueous Two-phase Extraction of Gypenosides and Its Hypoglycemic Activity

The extraction process of gypenosides by using ultrasonic-assisted aqueous two-phase system and its hypoglycemic activity were investigated. Six kinds of aqueous two-phase systems (ATPS) composed with different components were prepared. The yield of gypenosides served as an indicator, and ATPS with the highest yield were selected. According to the single factor experiments and response surface methods, liquid material ratio, ultrasonic time and extraction temperature were optimized for the optimum extraction parameters of gypenosides. Meanwhile, the advantages of aqueous two-phase extraction was evaluated by principal component analysis, molecular docking and hypoglycemic activity. As results, 30% ethanol-20% ammonium sulfate was chosen as the optimal extraction solvent system of gypenoside, and the optimum extraction parameters were as follow: Liquid-solid ratio (28:1 mL/g), ultrasonic time (52 min) and extraction temperature (52 ℃). Under the above extraction condition, the yield of gypenoside and the inhibition IC₅₀ value of gypenoside on α-glucosidase were 7.91% and 20.2 μg/mL, respectively. The yield of gypenoside XLIX, ginsenoside Rb₃, gypenoside A and gypenoside XVII were 0.83%, 0.09%, 1.42% and 4.04%, respectively. And the binding energy between gypenoside XLIX, ginsenoside Rb₃, gypenoside A and gypenoside XVII and α-glucosidase were −9.4, −7.7, −7.7, −7.7 kcal/mol, respectively. Compared with the ethanol extract, the yield and content of gypenoside, the hypoglycemic activity of ATPS extract was enhanced. Therefore, ATPS could effectively improve the extraction of gypenosides, and would provide the scientific evidence for the resource development and utilization of Gynostemma pentaphyllum.