title: α-Glucosidase inhibitors from the bark of Mangifera mekongensis.
abstract: BACKGROUND
  Mangifera mekongensis (Anacardiaceae) is cultivated for its edible fruit and has been used in traditional Vietnamese medicine for its anti-aging properties and for treating diabetes, vermifuge, and dysentery. As part of a search for biologically active compounds with reduction of the rate of glucose absorption, a screening has been initiated to evaluate natural product extracts for the inhibition of enzyme α-glucosidase. A n-hexane extract of the bark of M. mekongensis showed strong α-glucosidase inhibitory activity with IC50 value of 1.71 µg/mL. Thus, the constituents of this plant were examined.
  
  
  RESULTS
  Two new steroids named mekongsterol A (1) and mekongsterol B (2), were isolated from the n-hexane extract of the bark of M. mekongensis (Anacardiaceae), together with seven known compounds (3-9). Their chemical structures were elucidated on the basis of spectroscopic data. All compounds possessed significant α-glucosidase inhibitory activity in a concentration-dependent manner, except for 3 and 4. Compounds 1, 2, 5-9 showed more potent inhibitory activity, with IC50 values ranging from 1.2 to 112.0 µM, than that of a positive control acarbose (IC50, 214.5 µM).
  
  
  CONCLUSIONS
  These results suggested that the traditional use of the bark of M. mekongensis for the treatment of diabetes diseases in Vietnam may be attributable to the α-glucosidase inhibitory activity of its steroid and cycloartane constituents.
authors.affiliation: Faculty of Chemistry, University of Science, Vietnam National University Hochiminh City, 227 Nguyen Van Cu, District 5, Hochiminh City, Vietnam ; Cancer Research Laboratory, Vietnam National University Hochiminh City, 227 Nguyen Van Cu, District 5, Hochiminh City, Vietnam.
authors.forename: Hai Xuan
authors.initials: HX
authors.lastname: Nguyen
authors.affiliation: Faculty of Chemistry, University of Science, Vietnam National University Hochiminh City, 227 Nguyen Van Cu, District 5, Hochiminh City, Vietnam.
authors.forename: Tri Cong
authors.initials: TC
authors.lastname: Le
authors.affiliation: Faculty of Chemistry, University of Science, Vietnam National University Hochiminh City, 227 Nguyen Van Cu, District 5, Hochiminh City, Vietnam.
authors.forename: Truong Nhat Van
authors.initials: TN
authors.lastname: Do
authors.affiliation: Faculty of Chemistry, University of Science, Vietnam National University Hochiminh City, 227 Nguyen Van Cu, District 5, Hochiminh City, Vietnam.
authors.forename: Tho Huu
authors.initials: TH
authors.lastname: Le
authors.affiliation: Faculty of Chemistry, University of Science, Vietnam National University Hochiminh City, 227 Nguyen Van Cu, District 5, Hochiminh City, Vietnam ; Cancer Research Laboratory, Vietnam National University Hochiminh City, 227 Nguyen Van Cu, District 5, Hochiminh City, Vietnam.
authors.forename: Nhan Trung
authors.initials: NT
authors.lastname: Nguyen
authors.affiliation: Faculty of Chemistry, University of Science, Vietnam National University Hochiminh City, 227 Nguyen Van Cu, District 5, Hochiminh City, Vietnam ; Cancer Research Laboratory, Vietnam National University Hochiminh City, 227 Nguyen Van Cu, District 5, Hochiminh City, Vietnam.
authors.forename: Mai Thanh Thi
authors.initials: MT
authors.lastname: Nguyen
keywords: Anacardiaceae; Mangifera mekongensis; Sterols; α-Glucosidase inhibition