Chemical constituents and their alpha-glucosidase inhibitory activity from the stems of taxotrophis ilicifolius

Taxotrophis ilicifolius, called "Gai quít" in Vietnam, belonged to the family of Moraceae. The stems of T. ilicifolius are used in traditional medicine to cure pimples, anti-inflammatory, antibacterial... By column chromatography method together with thin layer chromatography on the ethyl acetate extract of its stems, six compounds were isolated including wogonin (1), 4-hydroxybenzoic acid (2), vanillic acid (3), vanillin (4), syringic acid (5), and syringaldehyde (6). Their chemical structures were elucidated by extensive NMR spectroscopic analysis and comparison with the literature data. The isolated compounds were tested fora-glucosidase inhibitory activity. All compounds showed more potent inhibitory activity with IC50 values 42–142 mM, than that of a positive control acarbose (IC50, 214.5 mM). Among all isolates, compounds 2, 4 and 6 exhibited significant a-glucosidase inhibitory activity with the IC50 values of 49.7, 42.6 and 55.9 mM, respectively. From the present investigation, all these compounds were isolated for the first time as well as their a-glucosidase inhibitoryactivity of T. ilicifolius. These results suggested that the traditional use of T. ilicifolius for the treatment of diabetes disease in Vietnam may be due to thea-glucosidase inhibitory activity of its phenolic constituents.