Optimization of Proanthocyanidin Extraction from Cerasus humilis Pomace and Evaluation of Its in Vitro Antioxidant and Hypoglycemic Activity

In this study, the ultrasonic-assisted extraction process of proanthocyanidins from Cerasus humilis pomace was optimized using single-factor combined with orthogonal experiments. The in vitro antioxidant activity and hypoglycemic activity of the purified proanthocyanidins from Cerasus humilis pomace were determined using the DPPH radical scavenging test, ABTS⁺ radical scavenging test, FRAP method and α-glucosidase activity inhibition test. The extraction rate of proanthocyanidins was influenced in the following order:Sonication temperature>material-liquid ratio>sonication time>ethanol concentration. The best extraction process was that using 70% ethanol, sonication temperature of 60 ℃, sonication time of 40 min, and material-liquid ratio of 1:30 g/mL. Under these conditions, the yield of proanthocyanidins was 15.37 mg/g. The IC₅₀ values of DPPH and ABTS⁺ radicals scavenged by purified proanthocyanidins were 0.10 mg/mL and 7 µg/mL, respectively, and the IC₅₀ value for inhibiting α-glucosidase activity was 0.056 mg/mL. The extraction process was stable and feasible, the yield of proanthocyanidins was high, and the purified proanthocyanidins had strong in vitro antioxidant activity and hypoglycemic activity.