Synthesis of 5,6-dehydrokawain and some fluorinated analogues

<p>An efficient methodology for the synthesis of 6-styrenylpyrone in a four-step sequence is reported. The reactions were performed under catalyst-free conditions with mild and affordable reagents to produce 5,6-dehydrokawain and fluorinated derivatives in good to excellent overall yields (72–86%) on a multigram scale. Two novel difluorinated derivatives are reported here for the first time.</p

Inhibitory effects of OD and MA on blood glucose increases in non-diabetic (A and B) and STZ-induced diabetic (C and D) rats after sucrose and starch loading for 2h.

<p>The area under the curve for glucose (AUC_glucose) was calculated by incremental method. Values are presented as means, and vertical bars indicate SEM (n = 6 rats in each group). ★p < 0.05 by comparison with control animals.</p

¹H (A) and ¹³C (B) NMR of oleanolic acid in dissolved in chloroform.

<p>¹H (A) and ¹³C (B) NMR of oleanolic acid in dissolved in chloroform.</p

Comparison of OGT responses to OA and MA in non-diabetic (A and B) and STZ- induced diabetic (C and D) rats after sucrose and starch loading.

<p>Values are presented as means, and vertical bars indicate SEM (n=6 rats in each group). ★ p<0.05 by comparison with control animals.</p

Effects of OA and MA on expression of SGLT1 (A) and GLUT2 (B) as determined by Western blotting of control, OA, MA, metformin and insulin -treated small intestine tissues of non-diabetic and STZ-induced diabetic rats.

<div><p>Values are expressed as mean ± S.E.M. Values were obtained from Western blots for six preparations.</p> <p>★ p <0.05 by comparison with respective control animals.</p> <p>◆ p <0.05 by comparison with respective non-diabetic animals.</p></div

Percent inhibition by OA (A), MA (B) and acarbose (C) sucrase on dextran sucrose and of α-glucosidase and α-amylase on starch.

<p>Values presented are means ± SEM (<i>n</i> = 8 for each concentration).</p

¹H (A) and ¹³C (B) NMR spectroscopic analysis of MA dissolved in deuterated methanol.

<p>¹H (A) and ¹³C (B) NMR spectroscopic analysis of MA dissolved in deuterated methanol.</p

Effects of OA and MA on expression of α-amylase as determined by Western blotting of control, OA, MA, metformin and insulin -treated pancreatic tissues of non-diabetic and STZ-induced diabetic rats.

<div><p>Values are expressed as mean ± S.E.M. Values were obtained from Western blots for six preparations.</p> <p>★ p <0.05 by comparison with respective control animals.</p> <p>◆ p <0.05 by comparison with respective non-diabetic animals.</p></div