Suppression of Glucose Absorption by sylvestre Leaves Some Fractions Extractedfrom Gymnema

ABsTRAcr. Extracts centaining gyrnnemic acids, which were extracted from the leaves of Gymnema sytvestre (GS) as nine fractions, were evahiated for theiT effects on a high K"-induced contractien ef guinea-pig ileal longitudinal musc]es, on glucose transport mediated by the difference ofglucose-evoked transmural potential difference {APD) in the inverted intestine of guinea-pig and rat, and on b]ood g]ucese in rat. ATnong nine fractions obtained by high perfonmance liquid chromatography from the extract, f-2 and f-4 strongly suppressed the high K'-induced contraetion of the i]eal muscle, fi3 and f-5 did so moderately, and f-8 and f-9 did so weakly, whereas the other fractions did not affect it. The degree of suppressien ef high K"-induced contractien by f-2 at 74% was a]most the same as that of f-4 at 67%, at concentrations of O.1 mglmt. The suppressed contraction by f-2 or f-4 was recovered by adding 5.5 mM pyruvate. The APD increased by 5,5 mM glucose in the inverted intestines of guinea-pig and rat were equally svppressed by O,1 mglml of f-2 or f-4 to 40%, In a rat sucrose tolerance test, f-2 and f-4 suppressed thc e]cvation of blood glucose level. Both f-2 and f-4 suppressed lhe eontraction of guineapig ilea] iongitudina] muscle, interfered with the increase in APD induced by glucose in the invertecl intestines of guinea-pig and ra{, and inhibited the elevation of blood glucose ]cvel. In conclusion, it is suggested that sorne of the extract$ eontaining gymnerni ¢ acids from GS ]eaves uppress the elevation of blood glucose level by inhibiting glucose uptake in the intestine. KEy woRDs: blood glucose, gymnema extract, intestine, musc}e contraction, potcntiai difference. J. Vet. Med. Sci. 59<4): 245-251, 1997