Abstract
An EtOAc-soluble partition of the MeOH extract of a branch of Tetracera scandens (Dilleniaceae family) was subjected to a glucose-uptake assay, which led to the isolation and identification of five isoflavones of previously known structure namely, genistein (1), its derivatives 3′,5′-diprenylgenistein (2), 6,8-diprenylgenistein (3), derrone (4) and alpinumisoflavone (5). Of these, compounds 2—5 exhibited significant glucose-uptake activity in basal and insulin-stimulated L6 myotubes. The findings from adenosine monophosphate-activated kinase (AMPK) activation and glucose transport protein4 (GLUT4) and GLUT1 over-expression revealed certain characteristics of compounds 2—5. These compounds inhibited protein tyrosine phosphatase 1B (PTP1B) activities with IC50 values ranging from 20.63±0.17 to 37.52±0.31 μM. No muscle cell toxicity was reported with compounds 3—5, while compounds 1 and 2 reduced muscle cell viability with IC50 values of 34.27±0.35 and 18.69±0.19 μM, respectively. It was concluded that T. scandens and its constituents exerted highly desirable activities on type 2 diabetes mellitus treatment since they significantly stimulated the uptake of glucose, AMPK phosphorylation, GLUT4 and GLUT1 mRNA expressions and PTP1B inhibition in L6 myotubes.
