title: Differential activation of glucose transport in cultured muscle cells by polyphenolic compounds from Canna indica L. Root.
abstract: Effects of extracts of a plant, which has been used as a traditional medicine for treating diabetes on glucose transport activity was evaluated in cultured L8 muscle cells. The aqueous extract of Canna indica root (CI) at doses of 0.1-0.5 mg/ml, which contains total phenolic compounds equivalent to 6-30 microg of catechin caused a dose- and time-dependent induction of 2-deoxy-[3H]glucose (2-DG) uptake activity. The induced 2-DG uptake was significantly increased within 8 h and reached a maximum by 16 h. The CI extract increased the amount of glucose transporter isoforms 1 (GLUT1) and 4 (GLUT4) at the cell surface and enhanced expression of GLUT1 protein. Cycloheximide treatment almost completely reversed CI-induced 2-DG uptake to the basal level. Exposure of muscle cells to wortmannin and SB203580 diminished CI-mediated glucose uptake by 38 and 14%, respectively. The effect of CI and insulin was partially additive. Phytochemical analysis detected the presence of flavonoids and catechol in the CI. Taken together, these data provide evidence for differential effects of CI on regulated-glucose transport in muscle cells. Our findings suggest that GLUT1 protein synthesis and the activation of phosphatidylinositol 3-kinase (PI3K) are critical for the increase in glucose transporter activity at the plasma membrane and essential for the maximal induction of glucose transport by CI in L8 muscle cells.
authors.affiliation: Department of Biomedical Sciences, Faculty of Medicine, Prince of Songkla University, Hat-Yai, Songkhla, Thailand. pjuntipa@medicine.psu.ac.th
authors.forename: Juntipa
authors.initials: J
authors.lastname: Purintrapiban
authors.forename: Maitree
authors.initials: M
authors.lastname: Suttajit
authors.forename: Neil E
authors.initials: NE
authors.lastname: Forsberg
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002478:Cells, Cultured; D003847:Deoxyglucose / Q000378:metabolism; D005419:Flavonoids / Q000494:pharmacology*; D005947:Glucose / Q000378:metabolism*; D051272:Glucose Transporter Type 1 / Q000032:analysis; D051275:Glucose Transporter Type 4 / Q000032:analysis; D051379:Mice; D032342:Muscle Cells / Q000378:metabolism*; D010636:Phenols / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry; D010946:Plants, Medicinal; D059808:Polyphenols; D013785:Thailand
chemical_list: D005419:Flavonoids; D051272:Glucose Transporter Type 1; D051275:Glucose Transporter Type 4; D010636:Phenols; D010936:Plant Extracts; D059808:Polyphenols; C495678:Slc2a1 protein, mouse; C495693:Slc2a4 protein, mouse; D003847:Deoxyglucose; D005947:Glucose