Effect of exogenous ATP on Momordica charantia Linn. (Cucurbitaceae) induced inhibition of D-glucose, L-tyrosine and fluid transport across rat everted intestinal sacs in vitro.
Momordica charantia (MC) is a common oriental vegetable with known antidiabetic, laxative and antimicrobial properties. This study investigates the effects of aqueous fruit extract of MC on the transport of d-glucose, l-tyrosine and fluid across rat-everted intestine in vitro. Everted intestinal sacs from rats were mounted in an organ bath containing Krebs-Henseleit bicarbonate buffer. Graded concentrations (1.5-12mg/ml) of MC fruit extract were incubated in the mucosal solution with and without exogenous ATP in the mucosal bathing fluid. The serosal appearance and mucosal disappearance of d-glucose, l-tyrosine and the fluid absorptive capacity of the intestine were significantly inhibited (p<0.05) with increasing graded concentrations of MC. The concentration of d-glucose accumulated or metabolized by the enterocytes in the intestinal tissues were significantly higher (p<0.05) when incubated with MC. Increasing graded concentrations of exogenous ATP (25-200 microM) were incubated with 3.0mg/ml MC to confirm inhibition of the ATP-dependent active transport of d-glucose, l-tyrosine and fluid across rat enterocytes. It was found that increasing concentrations of mucosal ATP from 25 to 100 microM significantly (p<0.05) reverses the MC-depression of the d-glucose, l-tyrosine and fluid uptake across rat everted intestinal sacs. It is hypothesized that bioactive phytochemicals such as saponins in MC fruit extract inhibits the active transport of d-glucose, l-tyrosine and fluid across rat intestine by inhibiting the production of ATP responsible for the active transport of these molecules. It is likely that MC can be a potential alternative drug therapy of postprandial hyperglycaemia via inhibition of glucose uptake across the small intestine.