Comparison Of Fruit Quality Of Different Chinese Bayberry (Myrica Rubra Sieb. Et Zucc.) Cultivars And Biological Evaluation Of Their Effects On Glucose Consumption And Hypolipidemic Activity

In order to fully understand the variation of fruit quality among Chinese bayberry (Myrica rubra Sieb. et Zucc.) varieties,21 bayberry cultivars from Zhejiang and Jiangsu province were used to study the postharvest fruit quality, including color, firmness, soluble sugars and organic acids, total phenolics, anthocyanins and antioxidant capacity, etc. Besides, composition and content of phenolic compounds in different varieties were studied and the contribution of individual flavonoid for anti-diabetes activities in vivo and hypolipidemic activity in C57BL/6 mice were analyzed and discussed as well. The main results are as follows:1. There were significant differences in the postharvest quality among different cultivars. Results showed that anthocyanins (main phenolics) were significant difference; The 21 bayberry cultivars showed strong antioxidant capacities and there was significant difference among cultivars, where ’Wandao’ had the strongest antioxidant activity among all cultivars tested. Our results showed the genet diversity of Chinese bayberry germplasm resources remain here.2. Six flavonoid compounds, including two flavanone glycosides, Cyanidin-3-O-glucoside, myricetin-3-O-rhamnoside, quercetin-3-O-galactoside, quercetin-3-O-glucoside, quercetin deoxyhexoside and myricetin deoxyhexoside-gallate were identified from bayberry fruit. Bayberry cultivars which have quercetin-3-O-galactoside showed significant enhancement of glucose consumption in HepG2 cells in a dose-dependent manner. Results of individual flavonoid showed that cells treated with quercetin-3-O-galactoside showed significant increased consumption of glucose, which was similar to that of metformin(MET). These results indicated that quercetin-3-O-galactoside may have hypoglycemic effect.3. By using C57BL/6 animal model,’Xiaoyexidi’ bayberry extract and quercetin-3-O-galactoside sifinificantly decreased the level of body lipid, total cholesterol, and significantly reduced blood glucose in mice and increased the glucose tolerance in an oral glucose tolerance test (OGTT) (p< 0.05). Such results indicated that bayberry extract and quercetin-3-O-galactoside might be useful in prevention and control of diabetes mellitus and prevent obesity development in vivo.Our results showed that bayberry fruits are rich sources of flavonoids. Bayberry fruit extract may exhibit anti-diabetic activity and hypolipidemic activity, Quercetin-3-O-galactoside may play important role in these activities.