| Summary: | In the present study, the methanol extract from the flower buds of Lonicera japonica Thunb. was investigated on rat intestinal α-glucosidase inhibitory activity. This extract enriched in polyphenols, showed a potent α-glucosidase inhibitory activity with maltose as a substrate in enzyme assay. The extract was then applied to MCI-gel column chromatography with a water–methanol gradient to give three fractions: fraction 1 (F-1, water), fraction 2 (F-2, 80% methanol in water), and fraction 3 (F-3, 100% methanol). F-2 showed the highest maltase inhibitory activity compared with F-1 and F-3, and down-regulated α-glucosidase activity for the maltose hydrolysis in Caco-2 monolayer. In maltose-loaded SD-rats, F-2 significantly reduced postprandial blood glucose level. 3,5-Dicaffeoylquinic acid was found to be the potent maltase inhibitor, whereas chlorogenic acid and rutin showed a weak inhibitory activity against maltase. This is the first report on the mammalian α-glucosdiase inhibition of L. japonica. The result presented here suggests a use of the extract of L. japonica for antidiabetes.
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