AMPK Activation of Flavonoids from Psidium guajava Leaves in L6 Rat Myoblast Cells and L02 Human Hepatic Cells

Objective. To isolate the hypoglycemic bioactive components from leaves of Psidium guajava and evaluate their AMP-activated protein kinase (AMPK) activities. Methods. A variety of column chromatography was used for the isolation of compounds, and nuclear magnetic resonance (NMR) and mass spectrum (MS) were used for the structure identification of compounds. AMP-activated protein kinase (AMPK) activity of compounds obtained from leaves of Psidium guajava was evaluated in L6 rat myoblast cells and L02 human hepatic cells by western blot. Results. Six principal flavonoids largely present in the leaves of Psidium guajava, quercetin (1), quercetin-3-O-alpha-L-arabinofuranoside (2), quercetin-3-O-alpha-L-arabinopyranoside (3), quercetin-3-O-beta-D-galactopyranoside (4), quercetin-3-O-beta-D-glucopyranoside (5), and quercetin-3-O-beta-D-xylopyranoside (6), were obtained and compound 1-6 exhibited significant activity on AMPK activation both in L6 cells and L02 cells (p<0.01) compared with Control. In particular, the effects of quercetin on AMPK activation were extremely significant compared with Control (p<0.001). Conclusions. These findings demonstrated that these flavonoids had potential for the activation of AMPK and hypoglycemic activity.