Isoxazol-5(4H)one derivatives as PTP1B inhibitors showing an anti-obesity effect.

In developing inhibitors of therapeutic target enzymes, significant time and effort are committed to the preparation of large numbers of compounds. In an effort to develop a potent inhibitor of protein tyrosine phosphatase (PTP) 1B as an anti-obesity and/or anti-diabetic agent, we constructed an isoxazolone chemical library by using a simplified procedure that circumvents tedious workup and purification steps. The 10×7 isoxazolone derivatives were synthesized by coupling the two halves of the target compounds. When mixed and heated in test tubes, the precursors produced the reaction products as precipitates. After brief washing, the products were pure enough to be used for enzymatic experiments. With the precursors for the coupling reactions prepared, the 10×7 library compounds could be prepared in a day by using the present protocol. The library compounds thus obtained were examined for their inhibitory activities against PTP1B. Among them, compound C3 was the most potent inhibitor of PTP1B with an IC(50) of 2.3 µM. The in vivo effect of C3 was also examined in an obesity-prone mouse strain. Diet-induced obese (DIO)/diabetic mice were divided into two groups and each group was fed a high-fat diet (HFD) or HFD+C3 for four weeks. The group of C3-fed mice gained significantly less weight relative to the HFD-fed control group during the four weeks of the drug feeding period. In contrast to the anti-obesity effect of C3, no difference was observed in the glycemic control of the HFD and HFD+C3 mice groups.

Novel thiazolidinedione derivatives with anti-obesity effects: dual action as PTP1B inhibitors and PPAR-γ activators.

Benzylidene-2,4-thiazolidinedione derivatives with substitutions at both the ortho and para-positions of the phenyl group were synthesized as PTP1B inhibitors with IC(50) values in a low micromolar range. Compound 18l, the lowest, bore an IC(50) of 1.3 µM. In a peroxisome proliferator-activated receptor-γ (PPAR-γ) promoter reporter gene assay, 18l was found to activate the transcription of the reporter gene with potencies comparable to those of troglitazone, rosiglitazone, and pioglitazone. In vivo efficacy of 18l as an anti-obesity and hypoglycemic agent was evaluated in a mouse model system. Compound 18l significantly suppressed weight gain and significantly improved blood parameters such as TG, total cholesterol and NEFA without overt toxic effects.

Inhibition of IKK-beta: a new development in the mechanism of the anti-obesity effects of PTP1B inhibitors SA18 and SA32.

In a previous study, protein tyrosine phosphatase 1B (PTP1B) inhibitors, SA18 and SA32, exhibited anti-obesity effects in a mouse model by suppressing weight gain and improving blood parameters, including free fatty acid (FFA) levels. In a separate study, depletion of the PTP1B gene in mice suppressed weight gain without significant change in FFA levels. The discrepancy in FFA concentrations between the two studies suggested that the in vivo target of the SA compounds might not be limited to PTP1B. In this study, SA18 and SA32 were found to be potent inhibitors of IkappaB Kinase-beta (IKK-beta). In vivo relevance of the inhibitory activity was evaluated in differentiated adipocytes. Inhibition of IKK-beta, in addition to inhibition of PTP1B, in mice treated with the SA compounds, could be a possible mechanism of the compound's biological response including the resistance to diet-induced weight gain and improvement in blood parameters. As potent and cell-permeable IKK-beta inhibitors, SA18 and SA32 could also be valuable in biological experiments.

Thiazolidinedione derivatives as PTP1B inhibitors with antihyperglycemic and antiobesity effects.

Benzylidene-2,4-thiazolidinedione derivatives with substitutions on the phenyl ring at the ortho or para positions of the thiazolidinedione (TZD) group were synthesized as PTP1B inhibitors with IC50 values in a low micromolar range. Compound 3e, the lowest, bore an IC50 of 5.0 microM. In vivo efficacy of 3e as an antiobesity and hypoglycemic agent was evaluated in a mouse model system. Significant improvement of glucose tolerance was observed. This compound also significantly suppressed weight gain and significantly improved blood parameters such as TG, total cholesterol and NEFA. Compound 3e was also found to activate peroxisome proliferator-activated receptors (PPARs) indicating multiple mechanisms of action.

Derivatives of 1,4-bis(3-hydroxycarbonyl-4-hydroxyl)styrylbenzene as PTP1B inhibitors with hypoglycemic activity.

Disalicylic acid derivatives with stilbene and bis-styrylbenzene skeleton were synthesized as PTP1B inhibitors. The most potent in this series exhibited a submicromolar IC(50) value. One of the compounds 7b was tested in an animal model for its efficacy as an anti-diabetic or an anti-obesity agent. In feeding compound 7b to diet-induced obese mice, no significant differences in weight gain and food consumption were observed between the drug-treated and the obese control mice. However, 7b significantly lowered the fasting glucose level and improved the glucose tolerance in the obesity-induced diabetic mice.