In vitro activity: Metformin (500 μM) activates AMPK in hepatocytes, as a result, acetyl-CoA carboxylase (ACC) activity is reduced, fatty acid oxidation is induced, and expression of lipogenic enzymes is suppressed. Metformin (2 mM) activates muscle AMPK and promotes glucose uptake. Metformin (500 μM) or AICAR strongly suppresses SREBP-1 mRNA expression in rat hepatocytes. Metformin ameliorates hyperglycemia without stimulating insulin secretion, promoting weight gain, or causing hypoglycemia. Metformin has beneficial effects on circulating lipids linked to increased cardiovascular risk. Metformin decreases hepatic glucose production and increases skeletal myocyte glucose uptake. Metformin requires LKB1 in the liver to lower blood glucose levels. Metformin (2 mM) leads to a significant increase in the activity of both α1- and α2-containing complexes in muscle cells. Metformin (2 mM) also increases threonine 172 phosphorylation in muscle cells.

Cell Assay: ESCs are plated in 96-well plates at a concentration of 1×103cells/well. After attachment, cells are treated with different doses of metformin/compound C for 0 min, 15 min, 1 h, and 24 h. MTT assays are performed as described previously. In brief, MTT (5 mg/mL) is added to the 96-well plates at a volume of 10 μL/well, and the plates are incubated for 4 h. The MTT reaction is terminated by removal of the culture medium containing MTT, and 100 μL DMSO per well are added and incubated at RT on a shaker for 10 min to ensure that the crystals had dissolved sufficiently. Absorbance values are measured at 595 nm. Cell proliferation (percentage of control) is calculated as follows: absorbance (experimental group)/absorbance (control group). Cell proliferation inhibition (percentage of control) is calculated as follows: 100%–cell proliferation (percentage of control). Each experiment is performed in duplicate and repeated six times to assess result consistency.

J Clin Invest. 2001 Oct;108(8):1167-74; Science. 2005 Dec 9;310(5754):1642-6.