Design and synthesis of 2-methyl-2-[4-(2-[5-methyl-2-aryloxazol-4-yl]ethoxy)phenoxy]propionic acids: a new class of dual PPARalpha/gamma agonists.

Propionic acid derivative 8, which was designed and synthesized based on putative pharmacophores of known PPARgamma- and PPARalpha-selective compounds, exhibits potent dual PPARalpha/gamma agonist activity as demonstrated by in vitro binding and dose overlap in the newly introduced EOB mouse model for glucose lowering and lipid/cholesterol homeostasis.

Competitive particle concentration fluorescence immunoassays for measuring anti-diabetic drug levels in mouse plasma.

Two competitive particle concentration fluorescence immunoassays were developed to measure blood levels of analogs of anti-diabetic drugs being tested in diabetic mice. Ligands that contained the active pharmacophores were conjugated to PPD for immunization and to beta-phycoerythrin for use as a tracer in the immunoassays. Approximately 90% of 262 compounds assayed were detectable at less than 120 nM in plasma which was well below the estimated therapeutic level of 1 microM for lowering blood glucose. These data were used to define the bioavailability of test compounds and assist in decisions of constructing active analogs. Of additional interest, we noted crossreactivity of one monoclonal antibody for 3 different compound classes that are all known to bind with varying affinities to peroxisome proliferator-activated receptors.

Monoclonal antibodies as surrogate receptors in a high throughput screen for compounds that enhance insulin sensitivity.

Monoclonal antibodies (MoAbs) were made to a known insulin sensitivity enhancer (ISE) compound, CS-045. The MoAbs were characterized with respect to binding other known thiazolidinedione ISE compounds using a CS-045 labeled with b-phycoerythrin in a competitive particle concentration fluorescence immunoassay (PCFIA). By comparing the rank order of IC50 values for each compound to its respective potency as an ISE, one MoAb (13E3) was selected for further characterization. This MoAb was also used as a surrogate receptor in a high throughput screen to identify novel compounds that compete for binding to CS-045. Some of the hits were found to have efficacy in reducing blood glucose. Subsequently, another group reported that several compounds with the core thiazolidinedione structure of the ISE compounds bound with high affinity to peroxisome proliferator-activating receptors (PPAR). Therefore, we used the MoAb assay to test these and other compounds that are known to bind to PPARgamma and noted crossreactivity with some of the compounds.

Regulation of net hepatic substrate balance by phenacylimidazolium ions in the conscious dog.

Phenacylimidazolium ions have the capacity to promote hepatic glycogen synthesis in vitro via activation of glycogen synthase and inactivation of phosphorylase. The purpose of the present study was to determine whether these compounds alter net hepatic substrate balance in vivo. Following a control period somatostatin was infused into 42h-fasted, conscious dogs and insulin (3X-basal) and glucagon (basal) were replaced intraportally. The glucose load to the liver was doubled with a peripheral glucose infusion and the phenacylimidazolium compound, 254236 (EX; n = 5) was infused intraportally at varying rates in four separate periods (0 (P1), 0.5 (P2), 1.0 (P3), 2.0 (P4) mumol kg-1 min-1). In a separate group of animals (C; n = 5) saline was infused intraportally during P1-P4 to match the volume rate of delivery that occurred in EX. In C net hepatic glucose uptake was 8.5 +/- 1.7 mumol kg-1 min-1 during P1 and did not change significantly throughout the study. In EX net hepatic glucose uptake increased (p < 0.05) from 9.0 +/- 2.5 during P1 to 16.2 +/- 3.1 mumol kg-1 min-1 during P4. Whereas net hepatic lactate output was evident throughout P1-P4 in C, the liver consistently switched to net lactate uptake during P3 (1.2 +/- 1.7 mumol kg-1 min-1) and P4 (2.2 +/- 1.0 mumol kg-1 min-1) in EX. Sympathoadrenal activation (increased catecholamines) was evident in EX during period 4. The increased hepatic retention of carbon (glucose and lactate) coincident with 254236 infusion in conscious dogs is less than that observed in vitro but is consistent with a role for phenacylimidazolium ions in promoting hepatic glycogen synthesis.

Metabolic effects of proglycosyn.

Proglycosyn, a phenylacyl imidazolium compound that lowers blood glucose levels, was demonstrated previously to promote hepatic glycogen synthesis, stabilize hepatic glycogen stores, activate glycogen synthase, inactivate glycogen phosphorylase, and inhibit glycolysis. In the present study proglycosyn was found to inhibit fatty acid synthesis, stimulate fatty acid oxidation, and lower fructose 2,6-bisphosphate levels, but to have no significant effects on cell swelling and the levels of cAMP in hepatocytes prepared from fed rats. Verapamil and atropine blocked the effects of proglycosyn on glycogen metabolism, but these compounds inhibit proglycosyn accumulation by hepatocytes. Proglycosyn stimulated phosphoprotein phosphatase activity in postmitochondrial extracts, as measured by dephosphorylation of phosphorylase a and glycogen synthase D, but this action required a very high concentration of the compound, making it unlikely to be the actual mechanism involved. It is proposed that a metabolite of proglycosyn is responsible for its metabolic effects.

Oral hypoglycemic agents. Discovery and structure-activity relationships of phenacylimidazolium halides.

Blood glucose levels in viable, yellow, obese, diabetic mice are reduced following oral administration of phenacylimidazolium halides. Compounds 2 and 3 produced reductions of ca. 40% 2 h after doses of 100 mg/kg po. Since these mice do not respond to sulfonylureas, the glucose-lowering activity of phenacylimidazolium salts in this model suggests a mechanism other than that of stimulating insulin secretion. Only phenacylimidazolium halides with electron-donating groups were active; other azolium salts or variations in the phenacyl portion (alterations in the keto function; chain lengthening or extensive branching) produced inactive compounds.

Stabilization of glycogen stores and stimulation of glycogen synthesis in hepatocytes by phenacyl imidazolium compounds.

LY177507 is representative of a series of phenacyl imidazolium compounds that cause marked lowering of blood glucose levels in animal models of noninsulin-dependent diabetes mellitus. In studies conducted with isolated rat hepatocytes, LY177507 inhibited net glucose production from a variety of substrates, inhibited glycolysis from exogenous glucose and endogenous glycogen, inhibited glycogenolysis, and stimulated glycogenesis. These effects of LY177507 appear to be the consequence of activation of glycogen synthase and inactivation of glycogen phosphorylase. In vivo studies with normal fed rats demonstrated a decrease in blood glucose, an increase in hepatic glycogen stores, and an inactivation of glycogen phosphorylase. Phenacyl imidazolium compounds appear to lower blood glucose levels and affect hepatic carbohydrate metabolism by a mechanism unlike other known hypoglycemic compounds.