Flavonoids from Tetrastigma obtectum enhancing glucose consumption in insulin-resistance HepG2 cells via activating AMPK.

Four new flavonoids including three C-glycosidic flavonoids, named tetrastigma A-D (1-4) and five known flavones (5-9) were isolated from the herbs of Tetrastigma obtectum (Wall.) Planch. The structures of 1-4 were elucidated by 1D- and 2D-NMR and HR mass spectrometric methods. Compound 1 caused significant enhancement in glucose consumption by insulin-resistant HepG2 cells compared with control cells. In addition, compound 1 stimulated phosphorylation of AMPK, which plays an important role in glycometabolism.