Inhibitory effect on α-glucosidase by Adhatoda vasica Nees
2008
Gao, Hong | Huang, Yi-Na | Gao, Bo | Li, Peng | Inagaki, Chika | Kawabata, Jun
Methanolic extracts from the medicinal parts of 40 traditional Chinese herbs were tested in screening experiments for rat intestinal α-glucosidase. The methanolic extract from the leaves of Adhatoda vasica Nees (Acanthaceae) showed the highest sucrase inhibitory activity with sucrose as a substrate. Enzyme assay-guided fractionation of this extract afforded vasicine (1) and vasicinol (2), and the structures of these compounds were elucidated on the basis of MS and NMR analysis. Compounds 1 and 2 showed a high sucrase inhibitory activity, and the IC₅₀ values were 125μM and 250μM, respectively. Both 1 and 2 were shown to be reversible inhibitors of sucrase. Kinetic data revealed that compounds 1 and 2 inhibited sucrose-hydrolysing activity of rat intestinal α-glucosidase competitively with K i values of 82μM and 183μM, respectively. This is the first report on the mammalian α-glucosidase inhibition of A. vasica and the inhibitory effect on sucrase by 1 and 2 from this herb species. These results suggest a use of the extract of A. vasica as an antidiabetic agent and show a possibility that compounds 1 and 2 could be an useful treatment for metabolic disorders.
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