drf-2725 and Insulin-Resistance

Clinical trials of cardiovascular disease (CVD) prevention in patients with type 2 diabetes mellitus primarily have been directed at the modification of a single major risk factor; however, in trials that enroll patients with and without diabetes, the absolute risk in CVD events remains higher in patients with diabetes. Efforts to reduce the macrovascular and microvascular residual risk have been directed toward a multifactorial CVD risk-factor modification; nonetheless, long-term complications remain high. Dual-peroxisome proliferator-activated receptor (PPAR) α/γ agonists may offer opportunities to lower macrovascular and microvascular complications of type 2 diabetes mellitus beyond the reductions achieved with conventional risk-factor modification. The information presented elucidates the differentiation of compound-specific vs class-effect properties of PPARs as the basis for future development of a new candidate molecule. Prior experience with thiazolidinediones, an approved class of PPARγ agonists, and glitazars, investigational class of dual-PPARα/γ agonists, also provides important lessons about the risks and benefits of targeting a nuclear receptor while revealing some of the future challenges for regulatory approval.

Topics: Alkanesulfonates; Diabetic Angiopathies; Glycine; Humans; Hypoglycemic Agents; Insulin Resistance; Ligands; Oxazines; Oxazoles; Phenylpropionates; Phosphorylation; PPAR alpha; PPAR delta; PPAR gamma; Thiazolidinediones; Thiophenes; United States; United States Food and Drug Administration

Ragaglitazar is a novel and potent dual peroxisome proliferators activated receptor (PPAR) alpha and gamma activator. The aim of this study is to investigate the effect of ragaglitazar on blood pressure and endothelial function in insulin resistant animal model and non-insulin resistant hypertensive models. The effects ragaglitazar were tested in Zucker fa/fa, spontaneously hypertensive rats (SHR), 2 kidney 1clip rat (2K1C) and Wistar Kyoto rats (WKY). Pioglitazone was taken as a comparative standard. Ragaglitazar showed significant reduction (P<0.001) of systolic blood pressure (SBP) in insulin resistant fa/fa rats, with concomitant reduction in plasma triglycerides (TG) and insulin levels while pioglitazone (10 mg kg(-1)) showed significant (P<0.05) but comparatively less reduction. Ragaglitazar in contrast to pioglitazone showed significant reduction (P<0.05) of SBP in SHR, 2K1C while the same dose did not have any effect on normotensive WKY. Ragaglitazar also showed significant improvement in acetylcholine-induced relaxation in isolated aorta of Zucker fa/fa, SHR, 2K1C and also potentiated the insulin-induced vasorelaxation in Zucker fa/fa rats. These findings summarize that ragaglitazar shows significant reduction of BP and improvement in endothelial function not only in insulin resistant but also in non-insulin resistant hypertensive models where standard thiazolidinediones are ineffective. These data indicates that dual PPARalpha and gamma activator ragaglitazar can be beneficial for the treatment of hypertension and vascular disease commonly associated with type 2 diabetes.

Topics: Acetylcholine; Animals; Antihypertensive Agents; Aorta, Thoracic; Dose-Response Relationship, Drug; Insulin Resistance; Male; Oxazines; Phenylpropionates; PPAR alpha; PPAR gamma; Random Allocation; Rats; Rats, Inbred SHR; Rats, Inbred Strains; Rats, Inbred WKY; Rats, Zucker; Reference Standards; Triglycerides; Vasodilator Agents

The current goal in the treatment of diabetes is not only to enhance the glycemic control but also to improve the associated cardiovascular risk factors. Among many of the strategies available, a co-ligand of PPARalpha and gamma in a single molecule which combines the insulin sensitizing potential of PPARgamma and the beneficial lipid modulating properties of PPARalpha agonism, has gained attention in the recent past. Here we report the biochemical mechanism by which a dual PPAR alpha/gamma agonist Ragaglitazar (Raga) achieves this goal. The PPARalpha component of Raga appears to contribute to a significant increase in beta oxidation, ApoA1 secretion and inhibition of TG biosynthesis in HepG2 cells. These effects of Raga at 60 microM were similar to that shown by Fenofibrate (Feno) at 250 microM. The PPARgamma component of Raga showed significant G3PDH activity and TG accumulation with a corresponding increase in aP2 expression in 3T3L1 cells. Significantly reduced levels of IL-6 and TNFalpha were observed in the culture supernatants of Raga treated 3T3L1 cells. Raga resulted in significant insulin dependent glucose uptake in 3T3L1 with a corresponding increase in GLUT4 expression. Further, Raga showed a significant cholesterol efflux with a corresponding increase in ABCA1 protein expression in THP-1 macrophages. In conclusion, Raga activates both PPARalpha and gamma regulated pathway in adipocytes as well as in hepatocytes which together contributes for its insulin sensitizing and lipid lowering activity. In addition the dual activation of PPAR alpha/gamma also shows an athero-protective potential by inducing reverse cholesterol efflux and inhibiting the pro-inflammatory cytokines.

Topics: Adipocytes; Animals; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Evaluation, Preclinical; Fenofibrate; Gene Expression Regulation; Hepatocytes; Humans; Hypolipidemic Agents; Inflammation Mediators; Insulin Resistance; Lipid Metabolism; Macrophages; Mice; Oxazines; Phenylpropionates; PPAR alpha; PPAR gamma; Rats

In 6- and 10-week-old obesity-prone (fa/fa) Zucker diabetic fatty (ZDF) rats, effects of prevention and intervention therapies, respectively, were compared between PPARalpha/gamma agonist, ragaglitazar (RAGA) and separate PPARgamma and alpha agonists, pioglitazone (PIO) and bezafibrate (BF). In a separate study, lean (+/+) ZDF rats fed highly palatable chow to induce dietary obesity and insulin resistance were treated similarly. To test insulin-secretory capacity, all animals underwent a hyperglycaemic clamp. Insulin sensitivity was improved equally by RAGA and PIO in fa/fa rats subjected to both prevention and intervention treatments (e.g., prevention HOMA-IR: -71 and -72%, respectively), as was hyperglycaemia (both -68%). BF had no effect on either parameter in any study. Plasma lipids were markedly reduced (by 48-77%) by RAGA in all studies, equivalent to PIO, but to a greater extent than BF. RAGA improved beta-cell function (HOMA-beta) more than three-fold with prevention and intervention therapies, whereas PIO showed improvement only in intervention therapy. Consistent with improved insulin sensitivity, glucose infusion rate during the clamp was 60% higher in RAGA-treated animals subjected to prevention therapy, but there was little additional insulin-secretory response, suggesting that insulin secretion was already maximal.Thus, RAGA and PIO equally improve metabolic profile in ZDF rats, particularly when administered early in the course of diabetes. They also improve beta-cell function, although this is better demonstrated through indices incorporating fasting insulin and glucose concentrations than through the hyperglycaemic clamp technique in this model.

Topics: Adipose Tissue; Animals; Bezafibrate; Body Composition; Body Weight; Diabetes Mellitus; Diet; Energy Metabolism; Glucose Clamp Technique; Hypoglycemic Agents; Hypolipidemic Agents; Insulin; Insulin Resistance; Obesity; Organ Size; Oxazines; Pancreas; Phenylpropionates; Pioglitazone; PPAR alpha; PPAR gamma; Rats; Rats, Inbred Strains; Receptors, Cell Surface; Receptors, Leptin; Thiazolidinediones

Improvement of insulin sensitivity and lipid and glucose metabolism by coactivation of both nuclear peroxisome proliferator-activated receptor (PPAR)gamma and PPARalpha potentially provides beneficial effects over existing PPARgamma and alpha preferential drugs, respectively, in treatment of type 2 diabetes. We examined the effects of the dual PPARalpha/gamma agonist ragaglitazar on hyperglycemia and whole body insulin sensitivity in early and late diabetes stages in Zucker diabetic fatty (ZDF) rats and compared them with treatment with the PPARgamma preferential agonist rosiglitazone. Despite normalization of hyperglycemia and Hb A(1c) and reduction of plasma triglycerides by both compounds in both prevention and early intervention studies, ragaglitazar treatment resulted in overall reduced circulating insulin and improved insulin sensitivity to a greater extent than after treatment with rosiglitazone. In late-intervention therapy, ragaglitazar reduced Hb A(1c) by 2.3% compared with 1.1% by rosiglitazone. Improvement of insulin sensitivity caused by the dual PPARalpha/gamma agonist ragaglitazar seemed to have beneficial impact over that of the PPARgamma-preferential activator rosiglitazone on glycemic control in frankly diabetic ZDF rats.

Topics: Animals; Body Composition; Body Weight; Diabetes Mellitus, Type 2; Dose-Response Relationship, Drug; Eating; Fatty Acids, Nonesterified; Glucose Clamp Technique; Glycated Hemoglobin; Glycogen; Hypoglycemic Agents; Insulin Resistance; Islets of Langerhans; Liver; Male; Oxazines; Phenylpropionates; Rats; Rats, Zucker; Receptors, Cytoplasmic and Nuclear; Rosiglitazone; Thiazoles; Thiazolidinediones; Transcription Factors

Peroxisome proliferator-activated receptor (PPAR)alpha and PPARgamma agonists lower lipid accumulation in muscle and liver by different mechanisms. We investigated whether benefits could be achieved on insulin sensitivity and lipid metabolism by the dual PPARalpha/gamma agonist ragaglitazar in high fat-fed rats. Ragaglitazar completely eliminated high-fat feeding-induced liver triglyceride accumulation and visceral adiposity, like the PPARalpha agonist Wy-14643 but without causing hepatomegaly. In contrast, the PPARgamma agonist rosiglitazone only slightly lessened liver triglyceride without affecting visceral adiposity. Compared with rosiglitazone or Wy-14643, ragaglitazar showed a much greater effect (79%, P < 0.05) to enhance insulin's suppression of hepatic glucose output. Whereas all three PPAR agonists lowered plasma triglyceride levels and lessened muscle long-chain acyl-CoAs, ragaglitazar and rosiglitazone had greater insulin-sensitizing action in muscle than Wy-14643, associated with a threefold increase in plasma adiponectin levels. There was a significant correlation of lipid content and insulin action in liver and particularly muscle with adiponectin levels (P < 0.01). We conclude that the PPARalpha/gamma agonist ragaglitazar has a therapeutic potential for insulin-resistant states as a PPARgamma ligand, with possible involvement of adiponectin. Additionally, it can counteract fatty liver, hepatic insulin resistance, and visceral adiposity generally associated with PPARalpha activation, but without hepatomegaly.

Topics: Animals; Dietary Fats; Fatty Liver; Glucose; Glucose Clamp Technique; Insulin; Insulin Resistance; Lipid Metabolism; Liver; Male; Muscle, Skeletal; Oxazines; Phenylpropionates; Pyrimidines; Rats; Rats, Wistar; Receptors, Cytoplasmic and Nuclear; Rosiglitazone; Thiazoles; Thiazolidinediones; Transcription Factors

(-)DRF 2725 (6) is a phenoxazine analogue of phenyl propanoic acid. Compound 6 showed interesting dual activation of PPAR alpha and PPAR gamma. In insulin resistant db/db mice, 6 showed better reduction of plasma glucose and triglyceride levels as compared to rosiglitazone. Compound 6 has also shown good oral bioavailability and impressive pharmacokinetic characteristics. Our study indicates that 6 has great potential as a drug for diabetes and dyslipidemia.

Topics: Animals; Biological Availability; Blood Glucose; Diabetes Complications; Diabetes Mellitus; Hyperlipidemias; Hypoglycemic Agents; Insulin Resistance; Mice; Oxazines; Phenylpropionates; Rats; Rats, Wistar; Receptors, Cytoplasmic and Nuclear; Stereoisomerism; Transcription Factors; Triglycerides