Extraction and Study of Hypoglycemic Constituents from Myrica rubra Pomace

Myrica rubrapomace accounts for 20% of the fruit’s weight that is not utilized when it is juiced. The pomace contains bioactive phenolic substances such as anthocyanins and flavonoids. To improve the utilization value ofMyrica rubrapomace, an optimized extraction method for the residual polyphenols was developed using response surface methodology (RSM). The resulting extract was analyzed by high performance liquid chromatography (HPLC), and the in vitro hypoglycemic activity and antioxidant activity of the polyphenolic compounds obtained were also investigated. The optimum extraction conditions (yielding 24.37 mg·g−1total polyphenols content) were: extraction temperature 60 °C, ultrasonic power 270 W, ethanol concentration 53%, extraction time 57 min, and solid to liquid ratio 1:34. Four polyphenolic compounds were identified in the pomace extract by HPLC: myricitrin, cyanidin-O-glucoside, hyperoside, and quercitrin. DPPH and hydroxyl radical scavenging tests showed that theMyrica rubrapolyphenols extract had strong antioxidant abilities. It is evident that the residual polyphenols present inMyrica rubrapomace have strong hypoglycemic activity and the juiced fruits can be further exploited for medicinal purposes.Keywords:Myrica rubraresidue;diabetes management;polyphenols;α-Glucosidase inhibition;HPLC