title: Inhibitory effect on α-glucosidase by Adhatoda vasica Nees.
abstract: 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 Ki 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.
authors.affiliation: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Hong
authors.initials: H
authors.lastname: Gao
authors.affiliation: Department of Public Health, Hua Xi Medical Center of Sichuan University, Chengdu, PR China.
authors.forename: Yi-Na
authors.initials: YN
authors.lastname: Huang
authors.affiliation: Department of Public Health, Hua Xi Medical Center of Sichuan University, Chengdu, PR China.
authors.forename: Bo
authors.initials: B
authors.lastname: Gao
authors.affiliation: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Peng
authors.initials: P
authors.lastname: Li
authors.affiliation: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Inagaki
authors.affiliation: Division of Applied Bioscience, Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo 060-8589, Japan. Electronic address: junk@chem.agr.hokudai.ac.jp.
authors.forename: Jun
authors.initials: J
authors.lastname: Kawabata
keywords: Adhatoda vasica; Postprandial hyperglycemia; Sucrase inhibitor; α-Glucosidase