Inhibition of apical sodium-dependent bile acid transporter as a novel treatment for diabetes.

Bile acids are recognized as metabolic modulators. The present study was aimed at evaluating the effects of a potent Asbt inhibitor (264W94), which blocks intestinal absorption of bile acids, on glucose homeostasis in Zucker Diabetic Fatty (ZDF) rats. Oral administration of 264W94 for two wk increased fecal bile acid concentrations and elevated non-fasting plasma total Glp-1. Treatment of 264W94 significantly decreased HbA1c and glucose, and prevented the drop of insulin levels typical of ZDF rats in a dose-dependent manner. An oral glucose tolerance test revealed up to two-fold increase in plasma total Glp-1 and three-fold increase in insulin in 264W94 treated ZDF rats at doses sufficient to achieve glycemic control. Tissue mRNA analysis indicated a decrease in farnesoid X receptor (Fxr) activation in small intestines and the liver but co-administration of a Fxr agonist (GW4064) did not attenuate 264W94 induced glucose lowering effects. In summary, our results demonstrate that inhibition of Asbt increases bile acids in the distal intestine, promotes Glp-1 release and may offer a new therapeutic strategy for type 2 diabetes mellitus.

Structure-based design of potent retinoid X receptor alpha agonists.

A series of tetrahydrobenzofuranyl and tetrahydrobenzothienyl propenoic acids that showed potent agonist activity against RXRalpha were synthesized via a structure-based design approach. Among the compounds studied, 46a,b showed not only very good potency against RXRalpha (K(i) = 6 nM) but was also found to be greater than 167-fold selective vs RARalpha (K(i) > 1000 nM). This compound profiled out as a full agonist in a cell-based transient transfection assay (EC(50) = 3 nM). The two antipodes were separated via chiral chromatography, and 46b was found to be 40-fold more potent than 46a. Interestingly, cocrystallization of 46a,b with the RXRalpha protein generated a liganded structure whereby the (S)-antipode was found in the binding pocket. Given orally in db/db mice or ZDF rats, 46a,b showed a significant glucose-lowering effect and an increase in liver mass. Triglycerides decreased significantly in db/db mice but increased in the ZDF rats. A dose-dependent decrease of nonesterified free fatty acids was seen in ZDF rats but not in db/db mice. These differences indicate a species specific effect of RXR agonists on lipid metabolism.

Discovery of 6,7-dihydro-5H-pyrrolo[2,3-a]pyrimidines as orally available G protein-coupled receptor 119 agonists.

GPR119 is a 7-transmembrane receptor that is expressed in the enteroendocrine cells in the intestine and in the islets of Langerhans in the pancreas. Indolines and 6,7-dihydro-5H-pyrrolo[2,3-a]pyrimidines were discovered as G protein-coupled receptor 119 (GPR119) agonists, and lead optimization efforts led to the identification of 1-methylethyl 4-({7-[2-fluoro-4-(methylsulfonyl)phenyl]-6,7-dihydro-5H-pyrrolo[2,3-d]pyrimidin-4-yl}oxy)-1-piperidinecarboxylate (GSK1104252A) (3), a potent and selective GPR119 agonist. Compound 3 showed excellent pharmacokinetic properties and sufficient selectivity with in vivo studies supporting a role for GPR119 in glucose homeostasis in the rodent. Thus, 3 appeared to modulate the enteroinsular axis, improve glycemic control, and strengthen previous suggestions that GPR119 agonists may have utility in the treatment of type 2 diabetes.

2-Cyano-4-fluoro-1-thiovalylpyrrolidine analogues as potent inhibitors of DPP-IV.

We report the synthesis and biological activity of a series of 2-cyano-4-fluoro-1-thiovalylpyrrolidine inhibitors of DPP-IV. Within this series, compound 19 provided a potent, selective, and orally active DPP-IV inhibitor which demonstrated a very long duration of action in both rat and dog.

Reduced serum dipeptidyl peptidase-IV after metformin and pioglitazone treatments.

Dipeptidyl peptidase-IV (DPP-IV) regulates metabolism by degrading incretins involved in nutritional regulation. Metformin and pioglitazone improve insulin sensitivity whereas glyburide promotes insulin secretion. Zucker diabetic rats were treated with these antidiabetic agents for 2 weeks and DPP-IV activity and expression were determined. Serum DPP-IV activity increased whereas tissue activity decreased as the rats aged. Treatment of rats with metformin, pioglitazone, and glyburide did not alter DPP-IV mRNA expression in liver or kidney. Metformin and pioglitazone significantly (P<0.05) reduced serum DPP-IV activity and glycosylated hemoglobin. Glyburide did not lower DPP-IV activity or glycosylated hemoglobin. Regression analysis showed serum DPP-IV activity correlated with glycosylated hemoglobin (r=0.92) and glucagon-like peptide-1 levels (r=-0.49). Metformin, pioglitazone, and glyburide had no effect on serum DPP-IV activity in vitro, indicating these are not competitive DPP-IV inhibitors. We propose the in vivo inhibitory effects observed with metformin and pioglitazone on serum DPP-IV activity results from reduced DPP-IV secretion.