Extraction and Study of Hypoglycemic Constituents from Myrica rubra Pomace

Abstract

Myrica rubra pomace 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 of Myrica rubra pomace, 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−1 total 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 the Myrica rubra polyphenols extract had strong antioxidant abilities. It is evident that the residual polyphenols present in Myrica rubra pomace have strong hypoglycemic activity and the juiced fruits can be further exploited for medicinal purposes.

Separation and Biological Activities of the Main Compounds from the Bark of Myrica rubra Siebold & Zucc

“…Moreover, myricetrin and myricetin showed excellent ROS scavenging ability. Similarly, Chang et al found that myricitrin, cyanidin-O-glucoside, hyperoside, and quercitrin in the pomace of Myrica rubra have good antioxidant and α-glucosidase inhibition abilities, and myricitrin showed the highest α-glucosidase inhibitory activity among the four compounds [27]. The phenolics of Myrica rubra exert anti-glycative actions by scavenging free radicals, trapping reactive α-dicarbonyls, inactivating transition metals, and interacting with glycation-related proteins [28].…”