title: Punica granatum flower extract, a potent alpha-glucosidase inhibitor, improves postprandial hyperglycemia in Zucker diabetic fatty rats.
abstract: Postprandial hyperglycemia plays an important role in the development of type 2 diabetes and has been proposed as an independent risk factor for cardiovascular diseases. The flowering part of Punica granatum Linn. (Punicaceae) (PGF) has been recommended in Unani literature as a remedy for diabetes. We investigated the effect and action mechanism of a methanolic extract from PGF on hyperglycemia in vivo and in vitro. Oral administration of PGF extract markedly lowered plasma glucose levels in non-fasted Zucker diabetic fatty rats (a genetic model of obesity and type 2 diabetes), whereas it had little effect in the fasted animals, suggesting it affected postprandial hyperglycemia in type 2 diabetes. In support of this conclusion the extract was found to markedly inhibit the increase of plasma glucose levels after sucrose loading, but not after glucose loading in mice, and it had no effect on glucose levels in normal mice. In vitro, PGF extract demonstrated a potent inhibitory effect on alpha-glucosidase activity (IC50: 1.8 microg/ml). The inhibition is dependent on the concentration of enzyme and substrate, as well as on the length of pretreatment with the enzyme. These findings strongly suggest that PGF extract improves postprandial hyperglycemia in type 2 diabetes and obesity, at least in part, by inhibiting intestinal alpha-glucosidase activity.
authors.affiliation: Herbal Medicines Research and Education Centre, Faculty of Pharmacy, A15, The University of Sydney, Sydney, NSW 2006, Australia. yuhao@pharm.usyd.edu.au
authors.forename: Yuhao
authors.initials: Y
authors.lastname: Li
authors.forename: Suping
authors.initials: S
authors.lastname: Wen
authors.forename: Bhavani Prasad
authors.initials: BP
authors.lastname: Kota
authors.forename: Gang
authors.initials: G
authors.lastname: Peng
authors.forename: George Qian
authors.initials: GQ
authors.lastname: Li
authors.forename: Johji
authors.initials: J
authors.lastname: Yamahara
authors.forename: Basil D
authors.initials: BD
authors.lastname: Roufogalis
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000187:drug effects; D003921:Diabetes Mellitus, Experimental / Q000201:enzymology / Q000517:prevention & control*; D004305:Dose-Response Relationship, Drug; D035264:Flowers; D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D029561:Lythraceae; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D008517:Phytotherapy; D010936:Plant Extracts / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D019518:Postprandial Period; D051381:Rats; D011924:Rats, Zucker; D000520:alpha-Glucosidases / Q000187:drug effects*
chemical_list: D001786:Blood Glucose; D065089:Glycoside Hydrolase Inhibitors; D007004:Hypoglycemic Agents; D010936:Plant Extracts; D000520:alpha-Glucosidases