Potential antihyperglycaemic effect of myricetin derivatives from Syzygium malaccense

Myricitrin, a flavonoid-3-O-glycoside, found present in many plant parts is reported to have the potential to serve as a functional food ingredient. In the present study, myricetin derivatives (F2) isolated from leaf extract of Syzygium malaccense, consisted of predominantly myricitrin (77%), were evaluated for in vitro anti-hyperglycaemic activity. The ability of the samples to inhibit carbohydrate hydrolyzing enzymes, stimulate adipogenesis, glucose uptake, adiponectin secretion and affect gene expression in differentiated 3T3-L1 pre-adipocytes was assessed. F2 significantly inhibited both α-glucosidase and α-amylase. It exhibited 'insulin-like' effects by enhancing accumulation of lipid, glucose uptake and adiponectin secretion by activating insulin signalling pathway similar to insulin. It upregulated Akt1 (protein kinase B), PPARγ (peroxisome proliferator activated receptor gamma) and Slc2a4 (glucose transporter) genes in addition to PRKAG2 (protein kinase, AMP activated) and adiponectin to stimulate glucose uptake. The above findings suggest that the myricetin derivatives may serve as functional food ingredient.