The α-glucosidase inhibitory activity of an aqueous extract and compounds from the aerial parts of
V. corymbosa was demonstrated with yeast and rat small intestinal α-glucosidases. The aqueous extract inhibited yeast α-glucosidase with a half maximal inhibitory concentration (IC
50) of 28.6
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The α-glucosidase inhibitory activity of an aqueous extract and compounds from the aerial parts of
V. corymbosa was demonstrated with yeast and rat small intestinal α-glucosidases. The aqueous extract inhibited yeast α-glucosidase with a half maximal inhibitory concentration (IC
50) of 28.6 μg/mL. Bioassay-guided fractionation of the extract led to the isolation of several compounds, including one cyanogenic glycoside [prunasin (
1)], five flavonoids [(−)-epi-catechin (
2), hyperoside (
3), isoquercetin (
4), quercitrin (
5) and quercetin-3-
O-(6′′-benzoyl)-β-galactoside (
6)] and two simple aromatic compounds [picein (
7) and methylarbutin (
8)]. The most active compound was
6 with IC
50 values of 30 μM in the case of yeast α-glucosidase, and 437 μM in the case of the mammalian enzyme. According to the kinetic analyses performed with rat and yeast enzymes, this compound behaved as mixed-type inhibitor; the calculated inhibition constants (
Ki) were 212 and 50 μM, respectively. Molecular docking analyses with yeast and mammalian α-glucosidases revealed that compound
6 bind differently to these enzymes. Altogether, the results of this work suggest that preparations of
V. corymbosa might delay glucose absorption
in vivo.
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