PMT13, a pyrimidone analogue of thiazolidinedione improves insulin resistance-associated disorders in animal models of type 2 diabetes

AIM

To evaluate the antidiabetic and hypolipidaemic potential of a novel thiazolidinedione, PMT13, in different animal models of insulin resistance.

METHODS

PPAR transactivation study was performed in HEK293T cells using ligand binding domains of PPARalpha, gamma and delta. Insulin-resistant db/db and ob/ob mice were treated orally with different doses of PMT13 at 0.3-10 mg/kg/day for 15 and 14 days respectively. Zucker fa/fa rats were treated with 3 mg/kg (p.o.) dose of the compound. Plasma glucose, triglyceride, free fatty acid and insulin levels were measured. Liver glucose 6-phosphatase (G6-Ptase) and adipose lipoprotein lipase activity was measured in treated mice. Isolated rat aortic preparations preconstricted with phenylephrine were used to study the vascular relaxation potential of PMT13 in presence of insulin. A 28-day oral toxicity study was performed in Wistar rats.

RESULTS

PMT13 showed similar PPARgamma activation as rosiglitazone, but failed to show any activity against PPARalpha or PPARdelta. In obese and diabetic db/db and ob/ob mice, PMT13 showed better reduction in plasma glucose, triglyceride and insulin levels than rosiglitazone and an improvement in glucose tolerance. In insulin-resistant Zucker fa/fa rat model, PMT13 treatment showed better reduction in plasma triglyceride, free fatty acid and insulin levels than that of rosiglitazone. Treated mice showed decreased G6-Ptase activity in liver. The LPL activity was increased in post-heparin plasma and epididymal fat of treated db/db mice. In an isolated, precontracted rat aortic preparation, PMT13 treatment significantly increased insulin-induced relaxation. A 28-day oral toxicity study in rats showed no treatment-related adverse effects.

CONCLUSION

Our studies indicate that PMT13 is a potent activator of PPARgamma with antidiabetic, hypolipidaemic and insulin-sensitizing properties. Additionally, PMT13 inhibited liver G6-Ptase activity and increased lipoprotein lipase activity. It showed improvement in insulin-induced vasorelaxation. The compound also showed a good safety margin. Therefore, PMT13 can be a potential drug candidate for future development.

(-)3-[4-[2-(Phenoxazin-10-yl)ethoxy]phenyl]-2-ethoxypropanoic acid [(-)DRF 2725]: a dual PPAR agonist with potent antihyperglycemic and lipid modulating activity

(-)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.

Euglycemic and hypolipidemic activity of PAT5A: a unique thiazolidinedione with weak peroxisome proliferator activated receptor gamma activity

The euglycemic and hypolipidemic activities of PAT5A, a novel pyridine analog of thiazolidinedione, have been evaluated in different animal models. Administration of PAT5A to db/db mice resulted in dose-dependent decreases in plasma glucose, triglyceride, and insulin levels, and an improved glucose tolerance. The glucose-lowering activity of PAT5A was better than that of troglitazone and comparable to that of rosiglitazone. In addition, PAT5A showed better lipid-lowering activity than troglitazone or rosiglitazone. A similar profile was seen in ob/ob mice. In high-fat-fed Sprague Dawley rats, PAT5A treatment reduced plasma triglyceride and total cholesterol levels. An in vitro peroxisome proliferator activated receptor gamma (PPARgamma) transactivation assay in HEK-293 cells showed poor transactivation for PAT5A compared with rosiglitazone. PAT5A did not show any PPARalpha- or PPARdelta-activating properties. Ex vivo study in db/db mice treated with PAT5A showed decreased activity of liver glucose 6-phosphatase, a key enzyme in gluconeogenesis. A 28-day probe toxicity study in Wistar rats did not show any treatment-related alterations in hematologic and biochemical parameters, nor any macroscopic and microscopic changes in the vital organs, whereas rosiglitazone treatment increased liver and heart weights. Our results indicate that PAT5A is a potent insulin sensitizer and hypolipidemic compound with a weak PPARgamma activation potential. Both in vivo and in vitro results suggest that PAT5A improves glucose kinetics and lipid levels through mechanisms not related to PPAR activation.

Studies on the euglycemic and hypolipidemic potentials of the novel indole analogue of thiazolidinedione, DRF 2189

Euglycemic and hypolipidemic activities of a novel indole analogue of thiazolidinedione, DRF 2189 (CAS 172647-53-9), have been evaluated in different animal models. Compared to troglitazone (CAS 97322-87-7), DRF 2189 exhibited interesting plasma glucose and triglyceride lowering activity in genetically diabetic and obese db/db mice. It also produced a significant reduction in plasma glucose, triglyceride, total cholesterol levels and improvement in oral glucose tolerance in another genetic mouse model, the ob/ob mice. In high-fat diet fed Sprague-Dawley rats, DRF 2189 treatment showed improvement in plasma lipid parameters. Like other thiazolidinediones, this compound also possesses peroxisome proliferator activated receptor gamma (PPAR gamma) transactivation potential. In anaesthetized rat experiment, DRF 2189 produced a transient fall in blood pressure without any change in the ECG pattern. It showed non-specific smooth muscle relaxant activity against acetylcholine, histamine and potassium chloride induced contractions in isolated guinea pig ileum. A twenty-eight-day toxicity study in Wistar rats did not show any signs of treatment related adverse effects. The overall antidiabetic and hypolipidemic activities of DRF 2189 are comparable with rosiglitazone (CAS 155141-29-0) and superior to troglitazone. In conclusion, results from these preclinical studies indicate that DRF 2189, a novel thiazolidinedione, has a marked potential for the management of type-2 diabetes.

Novel antidiabetic and hypolipidemic agents. 5. Hydroxyl versus benzyloxy containing chroman derivatives

Several thiazolidinediones having chroman moieties were synthesized and evaluated for their euglycemic and hypolipidemic activities. Some of the analogues having an aminoalkyl group as a linker between the chroman ring and 4-[5-(2,4-dioxo-1, 3-thiazolidinyl)methyl]phenoxy moiety seem to be better than troglitazone. In vitro transactivation assays of PPARgamma have been carried out with these glitazones to understand their molecular mechanism. For the first time we have found that some of the unsaturated thiazolidinediones are superior to their saturated counterpart in the in vivo assay. A more potent thiazolidinedione analogue than troglitazone is reported. Pharmacokinetic studies have shown that protection of the OH group in the chroman moiety leads to a decrease in metabolism, thereby resulting in a superior pharmacological profile.

Novel euglycemic and hypolipidemic agents. 1

A series of [[(heterocyclyl)ethoxy]benzyl]-2,4-thiazolidinediones have been synthesized by the condensation of corresponding aldehyde 1 and 2,4-thiazolidinedione followed by hydrogenation. Both unsaturated thiazolidinedione 2 and its saturated counterpart 3 have shown antihyperglycemic activity. Many of these compounds have shown superior euglycemic and hypolipidemic activity compared to troglitazone (CS 045). The indole analogue DRF-2189 (3g) was found to be a very potent insulin sensitizer, comparable to BRL-49653 in genetically obese C57BL/6J-ob/ob and 57BL/KsJ-db/db mice. Pharmacokinetic and tissue distribution studies conducted on BRL-49653 and DRF-2189 (3g) indicate that these drugs are well-distributed in target tissues. On the basis of euglycemic activity as well as enhanced selectivity against reduction of triglycerides in plasma, DRF-2189 (3g) has been selected for further evaluation.