Treatment with the EtOH extract of B.H. stimulated glucose transporter and inhibited Protein-tyrosine phosphatase 1B (PTP1B) expression in muscle of streptozotocin-diabetic mice

Diabetes mellitus is one of most common metabolic disorders in the world [1] and is characterized by hyperglycaemia resulting from defects on insulin action, secretion or both [2]. Genus Bauhinia (B.H. is a special extract to be patented of a Bauhinia species) is used in folk medicine to treat many diseases like inflammation, infections and diabetes [3]. Previous studies from our laboratory showed that the treatment with the EtOH extract of B.H. for 14 days at a dose of 400 mg/kg was able to decrease fasting glycaemia, modulating processes as gluconeogenesis, glycogenolisis and glycogenesis. The aim of this study was to verify others mechanism of action for the observed hypoglycaemic effect of the extract of B.H. Male Swiss mice (90 days old, 40 g) were divided in 4 groups: CTLSAL (normal mice treated with saline), CTLEXT (normal mice treated with the extract of B.H, 14 days, 400 mg/kg.day), STZSAL (diabetic mice treated with saline) and STZEXT (diabetic mice treated with the extract of B.H, 14 days, 400 mg/kg.day). The chemical screening showed glycosides of flavonols, as quercitrin and guajavarin in addition to other flavonoids, such as myricitrin. Our results showed that the treatment with the EtOH extract of B.H. increased the AKT, PI3K and GLUT4 expression in muscle leading to an increase in glucose transport and decreased PTP1B expression, an important down regulator of insulin receptor. Furthermore, the treatment also increased the AMPK expression, which probably contributes for stimulation of lipids oxidation and glucose intake.

References:

[1] Song C, Huang L, Rong L, Zhou Z, Peng X, Yu S, Fang N. Anti-hyperglycemic effect of Potentilla discolor decoction on obese-diabetic (Ob-db) mice and its chemical composition. Fitoterapia 2012; 83: 1474 – 1483

[2] American Diabetes Association. Diabetes Care 2012; 34: S62-S69

[3] Cechinel-Filho V. Chemical Composition and Biological Potential of Plants from the Genus Bauhinia. Phytother Res 2009; 23: 1347 – 1354