Potential insulin secretagogue effects of isovitexin and swertisin isolated from Wilbrandia ebracteata roots in non-diabetic rats

The antihyperglycemic effect and mechanism of action of extracts, fractions and compounds from Wilbrandia ebracteata was studied. The crude extract reduced the glycemia, increased glycogen content and serum insulin in hyperglycemic rats. Also, a significant effect was observed with the n-butanol and metanol subfraction. However, the antihyperglycemic effect of the n-butanol fraction was not observed in diabetic rats. The C-glycosylflavones isovitexin and swertisin showed a strong antihyperglycemic action compared with the extracts and fractions. These results show that the extracts, fractions, and isolated C-glycosylflavones have an antihyperglycemic action that was reinforced by the stimulation on in vivo insulin secretion. (C) 2010 Elsevier B.V. All rights reserved.