Ragaglitazar: a novel PPAR alpha PPAR gamma agonist with potent lipid-lowering and insulin-sensitizing efficacy in animal models

Ragaglitazar [(-) DRF 2725; NNC 61-0029] is a coligand of PPARalpha and PPARgamma. In ob/ob mice, ragaglitazar showed significant reduction in plasma glucose, triglyceride and insulin (ED50 values <0.03, 6.1 and <0.1 mg kg-1). These effects are three-fold better than rosiglitazone and KRP-297. In Zucker fa/fa rats, ragaglitazar showed dose-dependent reduction in triglyceride and insulin, hepatic triglyceride secretion and triglyceride clearance kinetics (maximum of 74, 53, 32 and 50% at 3 mg kg-1), which are better than rosiglitazone and KRP-297. In a high-fat-fed hyperlipidaemic rat model, the compound showed an ED50 of 3.95, 3.78 mg kg-1 for triglyceride and cholesterol lowering, and 0.29 mg kg-1 for HDL-C increase. It also showed improvement in clearance of plasma triglyceride and hepatic triglyceride secretion rate. All these effects are 3-10-fold better than fenofibrate and KRP-297. Ragaglitazar treatment showed significant reduction in plasma Apo B and Apo CIII levels, and increase in liver CPT1 and CAT activity and ACO mRNA. Significant increase of both liver and fat LPL activity and fat aP2 mRNA was also observed. In a high-fat-fed hamster model, ragaglitazar at 1 mg kg-1 showed 83 and 61% reduction in triglyceride and total cholesterol, and also 17% reduction in fat feed-induced body weight increase. In these hyperlipidaemic animal models, PPARgamma ligands failed to show any significant efficacy. Taken together, ragaglitazar shows better insulin-sensitizing and lipid-lowering potential, as compared to the standard compounds.     

Rodent carcinogenicity profile of the antidiabetic dual PPAR alpha and gamma agonist muraglitazar.

The carcinogenic potential of muraglitazar, a dual human peroxisome proliferator-activated receptor alpha/gamma agonist, was evaluated in 2-year studies in mice (1, 5, 20, and 40 mg/kg) and rats (1, 5, 30, and 50 mg/kg). Benign gallbladder adenomas occurred at low incidences in male mice at 20 and 40 mg/kg (area under the curve [AUC] exposures > or = 62 times human exposure at 5 mg/day) and were considered drug related due to an increased incidence of gallbladder mucosal hyperplasia at these doses. There was a dose-related increased incidence of transitional cell papilloma and carcinoma of the urinary bladder in male rats at 5, 30, and 50 mg/kg (AUC exposures > or = 8 times human exposure at 5 mg/day). At 30 and 50 mg/kg, the urinary bladder tumors were accompanied by evidence of increased urine solids. Subsequent investigative studies established that the urinary bladder carcinogenic effect was mediated by urolithiasis rather than a direct pharmacologic effect on urothelium. Incidences of subcutaneous liposarcoma in male rats and subcutaneous lipoma in female rats were increased at 50 mg/kg (AUC exposures > or = 48 times human exposure at 5 mg/day) and attributed, in part, to persistent pharmacologic stimulation of preadipocytes. Toxicologically relevant nonneoplastic changes in target tissues included thinning of cortical bone in mice and hyperplastic and metaplastic adipocyte changes in mice and rats. Considering that muraglitazar is nongenotoxic, the observed tumorigenic effects in mice and rats have no established clinical relevance since they occurred at either clinically nonrelevant exposures (gallbladder and adipose tumors) or by a species-specific mechanism (urinary bladder tumors).     

Antidiabetic effect of a novel non-thiazolidinedione PPAR γ/α agonist on ob/ob mice

AIM: To study whether T33, a new synthesized non-thiazolidinedione (TZD) peroxisome proliferator-activated receptor (PPAR) gamma/alpha dual agonist has an antidiabetic effect on ob/ob mice. METHODS: Ob/ob mice were treated with 4 mg/kg or 8 mg/kg T33 by gavage for 20 d. Blood glucose levels were measured regularly. An oral glucose tolerance test (OGTT) and an insulin tolerance test (ITT) were preformed on d 8 and d 12, respectively. The levels of insulin, triglyceride and free fatty acid (FFA) in the serum were measured at the end of administration. The intramuscular and liver triglyceride content was also determined. RESULTS: T33 reduced the hyperglycemia, hyperinsulinemia and hyperlipidemia of the ob/ob mice. The OGTT and ITT showed that the insulin resistance state of the ob/ob mice was obviously ameliorated after T33 treatment. After 20 d treatment with 8 mg/kg T33, the triglyceride content in the gastrocnemius muscle decreased significantly. T33 did not have any effect on triglyceride content in the liver, whereas rosiglitazone significantly increased the hepatocyte lipid deposition. CONCLUSION: The PPARgamma/alpha dual agonist T33 has antidiabetic and insulin-sensitizing effects in ob/ob mice. It has the potential to be a new therapeutic candidate for the treatment of type 2 diabetes.     

A dual PPAR alpha/gamma agonist increases adiponectin and improves plasma lipid profiles in healthy subjects

BACKGROUND: The objective of these studies was to evaluate the pharmacokinetics and pharmacodynamics of MK-0767, a prototypical dual peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist, following administration of single and multiple oral doses in healthy male subjects. METHODS: The first study was a double-blind, randomised, placebo-controlled, alternating two-panel, rising dose protocol in which single doses of 1-80 mg of MK-0767 were administered. The second study was a double-blind, randomised, placebo-controlled, staggered incremental dose, parallel-group protocol in which multiple doses of 0.3-25 mg of MK-0767 were administered once daily for 14 days. In both studies at each dose level, six subjects received MK-0767 and two subjects received placebo. RESULTS: Plasma area under the concentration-time curve and maximum plasma concentration increased with single and multiple doses of MK-0767 over the dose ranges studied. The apparent terminal half-life of MK-0767 averaged approximately 36 hours following single and multiple doses. Steady-state plasma concentrations were achieved following approximately 8 days of multiple doses. Compared with placebo, MK-0767 produced dose-dependent reductions in triglycerides (-26 +/- 8% [p = 0.002] and -33 +/- 13% [p = 0.008]) and free fatty acids (-50 +/- 11% [p < 0.001] and -67 +/- 23% [p = 0.008]) following single and multiple doses, respectively. Significant (p < or = 0.050) dose-dependent alterations in adiponectin (332 +/- 36%), low-density lipoprotein cholesterol (-29 +/- 5%), total cholesterol (-19 +/- 3%), non-high-density lipoprotein cholesterol (-28 +/- 4%), and fasting plasma glucose (-6 +/- 2%; only in the 25 mg group) were observed after multiple doses. CONCLUSIONS: The observed effects of MK-0767 on adiponectin, free fatty acids and lipids, even after single doses, demonstrate that this prototypical dual PPAR alpha/gamma agonist has clinically meaningful activity in vivo.     

Review of the expression of peroxisome proliferator-activated receptors alpha (PPAR alpha), beta (PPAR beta), and gamma (PPAR gamma) in rodent and human development

The peroxisome proliferator-activated receptors (PPAR) belong to the nuclear hormone receptor superfamily and there are three primary subtypes, PPARalpha, beta, and gamma. These receptors regulate important physiological processes that impact lipid homeostasis, inflammation, adipogenesis, reproduction, wound healing, and carcinogenesis. These nuclear receptors have important roles in reproduction and development and their expression may influence the responses of an embryo exposed to PPAR agonists. PPARs are relevant to the study of the biological effects of the perfluorinated alkyl acids as these compounds, including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), activate PPARalpha. Exposure of the rodent to PFOA or PFOS during gestation results in neonatal deaths, developmental delay and growth deficits. Studies in PPARalpha knockout mice demonstrate that the developmental effects of PFOA, but not PFOS, depend on expression of PPARalpha. This review provides an overview of PPARalpha, beta, and gamma protein and mRNA expression during mouse, rat, and human development. The review presents the results from many published studies and the information is organized by organ system and collated to show patterns of expression at comparable developmental stages for human, mouse, and rat. The features of the PPAR nuclear receptor family are introduced and what is known or inferred about their roles in development is discussed relative to insights from genetically modified mice and studies in the adult.     

Effect of pioglitazone, a peroxisome proliferator-activated receptor gamma agonist, on ischemia-reperfusion injury in rats

Two groups of rats were used to examine the effect of pioglitazone, a peroxisome proliferator-activated receptor gamma (PPARgamma) agonist, on rat hearts using an in vivo model of ischemia-reperfusion (I/R) to elucidate potential mechanisms. One group was the 30-min reperfusion group, which was further subdivided into sham (n=5), vehicle (n=6) and pioglitazone (3 mg x kg(-1), n=7) treatment groups with 30 min ischemia followed by 30 min reperfusion to detect data related to cardiac function and the area of myocardial infarction. The other group was the 120-min reperfusion group, subdivided into sham (n=5), vehicle (n=6), and pioglitazone 0.3 mg x kg(-1) (n=6), 1 mg x kg(-1) (n=7) and 3 mg x kg(-1) (n=6) treatment groups. Immunohistochemistry, in situ hybridization, terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) and DNA agarose gel electrophoresis were performed to detect apoptosis and expressions of Bax, Bcl-2, caspase 3, MMP-2 and PPARgamma protein, and MMP-2 and PPARgamma mRNA. We found that, after acute treatment with pioglitazone, the ratio of necrosis to area at risk decreased by 28% (p<0.01) and that of necrosis to left ventricle was reduced by 32% (p<0.01), compared with the vehicle group. Heart rate and +dp/dt(max), representing the cardiac systolic function, as well as -dp/dt(max), the indicator of cardiac diastolic function, improved significantly at 1 and 30 min after reperfusion (p<0.05-0.01). Furthermore, myocardial apoptosis was significantly suppressed by acute treatment with pioglitazone as evidenced by the decreased number of TUNEL-positive myocytes and DNA ladder, enhanced Bcl-2 protein expression, reduced Bax and caspase 3 protein expression in a dose-dependent manner compared with vehicle-treated rats. In addition, acute treatment with pioglitazone dose-dependently increased PPARgamma expression and decreased MMP-2 expression at protein and mRNA levels. Our findings demonstrate that a PPARgamma agonist may protect the heart from I/R injury. The protective effect is likely to occur by reducing cardiomyocyte apoptosis and inhibiting MMP-2.     

PPARδ激动剂GW501516的合成研究

目的 研究PPARδ激动剂GW501516的合成方法.方法 以4-三氟甲基苯硫酰胺为原料间体氯甲基噻唑,再经"一勺烩"操作的Williamson反应,依次进行硫醚化与酚的醚化、水解共5步反应制得GW501516.结果与结论 合成GW501516的总收率为64.9%,其结构经1H-NMR和13C-NMR确证."一勺烩"操作中以K2CO3代替昂贵的Cs2CO3,降低了成本,简化了其他后处理操作.     

A novel PPAR alpha／gamma dual agonist inhibits cell growth and induces apoptosis in human glioblastoma T98G cells

AIM: To examine the effect of a novel peroxisome proliferator-activated receptor (PPAR) α/γ dual agonist TZD 18 on cell proliferation and apoptosis in human glioblastoma T98G cells and its possible mechanism. METHODS: RTPCR, MTT, TUNEL, Flow cytometry, and Western blot analysis were employed. RESULTS: TZD18 inhibited the growth of T98G cells in a concentration-dependent manner, which was associated with a GI to S cell cycle arrest. Besides, significant apoptosis was induced after treatment with a non-toxic dose of TZD 18. During the process, the expression of Bcl-2 protein was down-regulated, while that of Bax and p27^kip proteins was up-regulated, and the activity of caspase-3 was elevated. However, this effect appeared to be PPARα and PPARγ/independent since their antagonists could not reverse this effect. CONCLUSIONS: TZD18, a novel PPARα/γ dual agonist, inhibited cell growth and induce apoptosis in human glioblastoma T98G cells in vitro, indicating a therapeutic potential for TZD18 in the treatment of glioblastoma.     

Ragaglitazar: the pharmacokinetics, pharmacodynamics, and tolerability of a novel dual PPAR alpha and gamma agonist in healthy subjects and patients with type 2 diabetes

Ragaglitazar is a novel dual peroxisome proliferator-activated receptor (PPAR) alpha and gamma agonist intended to restore insulin sensitivity and correct diabetic dyslipidemia. These studies assessed single-dose pharmacokinetics and tolerability of ragaglitazar in healthy subjects, as well as multiple-dose pharmacokinetics, pharmacodynamics, and tolerability of ragaglitazar in healthy subjects and in patients with type 2 diabetes. Healthy subjects received a single oral dose (1-120 mg), and healthy subjects and type 2 diabetic patients received a loading dose and thereafter once-daily doses (0.5-16 mg) of ragaglitazar for 6 and 20 days, respectively. Ragaglitazar was rapidly absorbed (tmax: 1.5-1.7 h), with mean AUC0-24 h and Cmax proportional to dose after single and multiple dosing; t1/2 was 80 hours following a single dose and 104 hours in healthy subjects and 122 hours in patients after multiple dosing. Administration of 4 mg ragaglitazar to patients (n = 4) for 21 days resulted in mean decreases from baseline in fasting levels of plasma glucose (18%), C-peptide (18%), fructosamine (6%), triglycerides (36%), free fatty acids (49%), total cholesterol (11%), low-density lipoprotein (LDL) cholesterol (21%), and very low-density lipoprotein (VLDL) cholesterol (15%), as well as an increase in high-density lipoprotein (HDL) cholesterol (33%). Overall, ragaglitazar was well tolerated; with multiple dosing, there was a higher incidence of adverse events for patients that, at the highest dose level (16 mg), included peripheral edema and anemia.     

Determination of chiglitazar, a dual alpha/gamma peroxisome proliferator-activated receptor (PPAR) agonist, in human plasma by liquid chromatography-tandem mass spectrometry

Chiglitazar is a dual alpha/gamma peroxisome proliferator-activated receptor (PPAR) agonist. A LC-MS/MS method for the determination of chiglitazar was developed and validated. The assay used 0.2 mL of plasma. 90% acetonitrile containing internal standard was used for protein precipitation. The mobile phase contained 70/30 (v/v) of methanol and water at a flow rate of 0.25 mL/min. Detection was by negative ion electrospray tandem mass spectrometry on a Sciex API 3000. The standard curve, which ranged from 2 to 1500 ng/mL, was fitted to a 1/x weighted quadratic regression model. The validation results demonstrated that the method was sensitive, rapid, selective and robust and provided satisfactory precision and accuracy. The method has been successfully used for the analysis of clinical samples in pharmacokinetic studies of chiglitazar.     

Fetal alcohol-induced hyperactivity is reversed by treatment with the PPARα agonist fenofibrate in a rat model

Introduction  

Exposure to alcohol in utero is linked to the development of a wide range of psychobehavioral changes, notably hyperactivity and attention deficit, with complex underlying pathological and functional mechanisms. Although the currently available treatments for hyperactivity have been studied in children exposed to alcohol in utero, the efficacy of these compounds is subject to debate and has prompted efforts to identify new pharmacological targets.     

Quinoline-based derivatives of pirinixic acid as dual PPAR alpha/gamma agonists

Pirinixic acid is known for its peroxisome proliferator-activated receptor (PPAR) agonistic action. In a recent publication, we have shown that aliphatic alpha-substitution of pirinixic acid enhances both PPARalpha and PPARgamma agonism. The goal of this study was to evaluate, whether the PPAR agonism of pirinixic acid may be also maintained in quinoline-based derivatives. The present study revealed that the mere substitution of the dimethyl aniline moiety of pirinixic acid by quinoline leads to a total loss of PPARalpha/gamma agonism, whereas concomitant alpha-substitution with n-butyl or n-hexyl groups restores and even enforces PPAR activation, leading to potent dual PPARalpha/gamma agonists. In the following we report the synthesis of quinoline-based derivatives of pirinixic acid, which in a Gal4-based luciferase-reporter gene assay proved to be potent dual PPARalpha/gamma agonists. Molecular docking of compound 4 with FlexX suggests a binding mode resembling to that of tesaglitazar.     

Relationship between peroxisome proliferator-activated receptors (PPAR alpha and PPAR gamma) and endothelium-dependent relaxation in streptozotocin-induced diabetic rats

(1) The aim of the present study was to investigate the causal relationship between peroxisome proliferator-activated receptor (PPAR) and endothelium-dependent relaxation in streptozotocin (STZ)-induced diabetic rats. (2) Acetylcholine (ACh)-induced endothelium-dependent relaxation was significantly weaker in diabetic rats than in age-matched controls. The decreased relaxation in diabetes was improved by the chronic administration of bezafibrate (30 mg kg-1, p.o., 4 weeks). (3) The expressions of the mRNAs for PPARalpha and PPARgamma were significantly decreased in STZ-induced diabetic rats (compared with the controls) and this decrease was restored partially, but not completely, by the chronic administration of bezafibrate. (4) Superoxide dismutase activity in the aorta was not significantly different between diabetic rats and bezafibrate-treated diabetic rats. (5) The expression of the mRNA for the p22phox subunit of NAD(P)H oxidase was significantly higher in diabetics than in controls, but it was lower in bezafibrate-treated diabetic rats than in nontreated diabetic rats. Although the expression of the mRNA for prepro ET-1 (ppET-1) was markedly increased in diabetic rats (compared with controls), this increase was prevented to a significant extent by the chronic administration of bezafibrate. (6) These results suggest that downregulations of PPARalpha and PPARgamma may lead to an increased expression of ppET-1 mRNA in diabetic states and this increment may trigger endothelial dysfunction.     

Molecular modelling of the peroxisome proliferator-activated receptor alpha (PPAR alpha) from human, rat and mouse, based on homology with the human PPAR gamma crystal structure.

The generation of homology models of human, rat and mouse peroxisome proliferator-activated receptor alpha (PPAR alpha) are reported, based on the recently published crystal structure of the human PPAR gamma ligand-binding domain (LBD) with bound ligand, rosiglitazone. It is found that a template of peroxisome proliferating fibrate drugs and related compounds can fit within the putative ligand-binding site of rat PPAR alpha, via contacts with amino acid residues which are consistent with their biological potency for peroxisome proliferation, site-directed mutagenesis experiments and with quantitative structure-activity relationship (QSAR) analysis studies. The experimental binding affinity of leukotriene B(4) (LTB(4)) for the mouse PPAR alpha agrees closely with the calculated value based on the modelled interactions, whereas selective PPAR alpha ligands such as clofibric acid are able to fit the human PPAR alpha binding site in agreement with reported site-directed mutagenesis information.     

Antidiabetic and hypolipidemic effects of a novel dual peroxisome proliferator-activated receptor (PPAR) alpha/gamma agonist, E3030, in db/db mice and beagle dogs

We investigated the antidiabetic effects of E3030, which is a potent dual activator of peroxisome proliferator-activated receptor (PPAR) alpha and PPARgamma, in an animal model of diabetes, C57BL/KsJ-db/db mice (db/db mice), and the lipidemic effects of E3030 in beagle dogs, whose PPARalpha and PPARgamma transactivation responses to E3030 were similar to those of humans. E3030 activated human PPARalpha, mouse PPARalpha, dog PPARalpha, human PPARgamma, mouse PPARgamma, and dog PPARgamma with EC(50) values of 65, 920, 87, 34, 73, and 34 nM, respectively, in the chimeric GAL4-PPAR receptor transactivation reporter assay. In db/db mice orally administered E3030 decreased blood glucose, triglyceride (TG), non-esterified fatty acids (NEFA), and insulin levels and increased blood adiponectin levels during a 14-day experimental period. Significant effects on blood glucose and adiponectin levels were observed at a dose of 3 mg/kg or greater. Furthermore, significant effects on blood TG, NEFA, and insulin levels were observed at doses of 1 mg/kg or more. An oral glucose tolerance test (OGTT) performed on Day 15 showed that E3030 at 3 mg/kg improved glucose tolerance in this model. Fourteen days of oral treatment with E3030 at a dose of 0.03 mg/kg or greater showed remarkable TG- and non high-density lipoprotein (non-HDL) cholesterol-lowering effects in beagle dogs. These results were similar to those observed for the PPARalpha agonist fenofibrate. E3030 also reduced apo C-III levels on Days 7 and 14, and elevated lipoprotein lipase (LPL) levels on Day 15. These results indicate that the TG- and non-HDL cholesterol-lowering actions of E3030 involve combined effects on reduction of apo C-III and elevation of LPL, resulting in increased lipolysis. The experimental results in animals suggest that E3030 has potential for use in the treatment of various aspects of metabolic dysfunction in type 2 diabetes, including dyslipidemia, hyperglycemia, hyperinsulinemia, and impaired glucose disposal.     

Antinociceptive properties of fadolmidine (MPV-2426), a novel alpha2-adrenoceptor agonist

Fadolmidine (MPV-2426) is a novel alpha2 -adrenoceptor (alpha2) -AR) agonist developed for spinal analgesia. It is highly selective for alpha2 -ARs, but it lacks subtype selectivity. Due to its pharmacokinetic properties, it only poorly penetrates blood-brain barrier or spreads from the site of injection within the central nervous system. By intrathecal (i.t.) administration to laboratory animals, fadolmidine produces dose-dependent antinociception in healthy controls and in models of inflammatory, postoperative and neuropathic pain. Fadolmidine has been effective against various submodalities of pain such as heat pain, mechanical pain, and visceral pain. In general, the antinociceptive potency of fadolmidine, i.t., was equal to that of dexmedetomidine. At antinociceptive i.t. doses fadolmidine did not suppress motoneurons or responses to innocuous stimulation. It produced no hemodynamic depression and considerably less sedation than dexmedetomidine. By peripheral administration fadolmidine had no or only a weak antinociceptive action, except following nerve injury, particularly that of the postganglionic sympathetic nerve fibers. Together these experimental animal studies indicate that i.t. administration of fadolmidine provides a segmentally restricted treatment of somatic and visceral pain, with only minor cardiovascular and sedative side effects. Additionally, peripheral administration of fadolmidine might provide a selective treatment for some hypersensitivity states that involve dysfunction of the sympathetic nervous system.