Water extracts from Momordica charantia increase glucose uptake and adiponectin secretion in 3T3-L1 adipose cells

To examine the effects of Momordica charantia on glucose uptake and adiponectin secretion in adipose cells, 3T3-L1 adipocytes were treated with three concentrations (0.2, 0.3 and 0.4 mg/ml) of water and ethanol extracts of Momordica charantia fruit and seeds alone and in combination with either 0.5 nM or 50 nM insulin. The treatment combination of 0.2 mg/ml water extract and 0.5 nM insulin was associated with significant (p < 0.05) increases in glucose uptake (61%) and adiponectin secretion (75%) over control levels. The ethanol extract was not associated with an increase in glucose uptake; however, a dose-dependent decrease in basal glucose uptake and insulin-mediated glucose uptake was observed with the ethanol extract in combination with 50 nM insulin. In the absence of insulin, no effects on glucose uptake were observed in adipocytes exposed to the water extracts whereas the highest concentration (0.4 mg/ml) of the ethanol extract was associated with a significant (p < 0.05) decrease in glucose uptake relative to controls. The present results indicate that water-soluble component(s) in Momordica charantia enhance the glucose uptake at sub-optimal concentrations of insulin in 3T3-L1 adipocytes, which is accompanied by and may be a result of increased adiponectin secretion from the 3T3-L1 adipocytes.