Optimization of Extraction Technology of Polyphenols from Morus australis Leaves and Its Antioxidant Activity

The study was aimed to optimize the extraction technology of polyphenols from Morus australis leaves and investigate its antioxidant activity. The effecting factors involving ethanol concentration,extraction time,liquid-to-material ratio and extraction temperature on the extraction yield of polyphenols were investigated using the Morus australis leaves as raw material and with the polyphenols yield as the response value. Moreover,the extraction technologies were designed and optimized by response surface experiment. Antioxidant activity of polyphenols was investigated by free radical removal method. The optimal extraction conditions were identified as follows:ethanol concentration 72%,extraction time 116 min,liquid-to-material ratio 37:1 mL/g,and extraction temperature 76℃. The extraction yield of polyphenols was 87.63 mg/g. Compared to the predictive value(87.97 mg/g),the relative error was 0.39%. The polyphenols had a scavenging effect and dose-effect on DPPH,OH and O₂^- free radicals with IC₅₀ of 54.68 mg/L,207.16 mg/L and 416.05 mg/L respectively,which were lower than that of ascorbic acid. The model of optimization extraction technology of polyphenols from Morus australis leaves by response surface methodology was effective and highly accurate. Polyphenols obtained in this study had a certain antioxidant activity.