Acylsulfonamide-containing PTP1B inhibitors designed to mimic an enzyme-bound water of hydration

Copper-catalysed synthesis of 3-hydroxyisoindolin-1-ones from benzylcyanide 2-iodobenzamides

An efficient one-pot two-step sequential reaction for the synthesis of biologically active 3-hydroxyisoindolin-1-one derivatives from 2-iodobenzamide derivatives and various substituted benzyl cyanides in the presence of CuCl and cesium carbonate in DMSO is reported. Furthermore, 3-hydroxyisoindolinone derivatives possessing bromo substituents were obtained from 2-iodobenzamide and 2-bromobenzyl cyanide substrates in two steps. Benzyl cyanide has been successfully used for the first time as a benzoyl synthon for the synthesis of 3-hydroxyisoindolin-1-ones. Interestingly, the mechanism of formation of 3-hydroxyisoindolin-1-ones is a novel pathway that involves carbon degradation followed by ring contraction.

Synthesis, X-ray crystal structure, DNA/protein binding and cytotoxicity studies of five α-aminophosphonate N-derivatives

Five new α-aminophosphonates are synthesized and characterized by EA, FT-IR, ¹H NMR, ¹³C NMR, ³¹P NMR, ESI-MS and X-ray crystallography. The X-ray analyses reveal that the crystal structures of 1-5 are monoclinic or triclinic system with the space group P 21/c, P-1, P-1, P2(1)/c and P-1, respectively. All P atoms of 1-5 have tetrahedral geometries involving two O-ethyl groups, one C_α atom, and a double bond O atom. The binding interaction of five new α-aminophosphonate N-derivatives (1-5) with calf thymus(CT)-DNA have been investigated by UV-visible and fluorescence emission spectrometry. The apparent binding constant (Kapp) values follows the order: 1 (3.38×10⁵M^-1)>2 (3.04×10⁵M^-1)>4 (2.52×10⁵M^-1)>5 (2.32×10⁵M^-1)>3 (2.10×10⁵M^-1), suggesting moderate intercalative binding mode between the compounds and DNA. In addition, fluorescence spectrometry of bovine serum albumin (BSA) with the compounds 1-5 showed that the quenching mechanism might be a static quenching procedure. For the compounds 1-5, the number of binding sites were about one for BSA and the binding constants follow the order: 1 (2.72×10⁴M^-1)>2 (2.27×10⁴M^-1)>4 (2.08×10⁴M^-1)>5 (1.79×10⁴M^-1)>3 (1.17×10⁴M^-1). Moreover, the DNA cleavage abilities of 1 exhibit remarkable changes and the in vitro cytotoxicity of 1 on tumor cells lines (MCF-7, HepG2 and HT29) have been examined by MTT and shown antitumor effect on the tested cells.

Hepatic PTP1B Expression Involvement in the Effects of Chinese Medicine Formula Xiao-Gao-Jiang-Zhuo Using an Obese Rat Model

In this study, we investigated the effects of a Chinese herbal medicine formula Xiao-Gao-Jiang-Zhuo (XGJZ) in obese rats induced by a high-fat diet. Ten male rats in the normal group were fed with a standard diet. Another 50 male obese rats were induced by a 12-week high-fat diet feeding, and were randomly divided into five groups (n = 10 per group): the model group, the high-dose XGJZ group, the middle-dose XGJZ group, the low-dose XGJZ group, and the sibutramine group. After 14 weeks of treatment, body weight, abdominal fat, blood lipid and serum insulin level were measured, and the protein and gene expression of PTP1B in liver tissue was tested. Our data showed that the body weight of the high-dose and middle-dose groups and the sibutramine group had significant differences in comparison with the model group (p < 0.05), and all three dose groups had significantly reduced abdominal fat (p < 0.05). The triglyceride level of the three dose groups and the sibutramine group, and the total cholesterol level of the middle-dose group were all significantly reduced (p < 0.05). The serum insulin of the high-dose and middle-dose groups also decreased significantly (p < 0.05). The expression of hepatic PTP1B mRNA of the three dose groups decreased significantly in comparison with the model group (p < 0.05 or 0.01). The expression of hepatic PTP1B protein of the high-dose and middle-dose groups decreased significantly (p < 0.05). Our data suggested that XGJZ can modulate the body weight, abdominal fat and blood lipid in the obese rats, and this modulation might improve insulin resistance by inhibiting the PTP1B signal pathway.

Effect of a novel proteoglycan PTP1B inhibitor from Ganoderma lucidum on the amelioration of hyperglycaemia and dyslipidaemia in db/db mice

Protein tyrosine phosphatase 1B (PTP1B) is implicated in the negative regulation of the insulin signalling pathway by dephosphorylating the insulin receptor (IR) and IR substrates. Ganoderma lucidum has traditionally been used for the treatment of diabetes in Chinese medicine; however, its anti-diabetic potency and mechanism in vivo is still unclear. Our previously published study reported a novel proteoglycan PTP1B inhibitor, named Fudan-Yueyang-Ganoderma lucidum (FYGL) from G. lucidum, with a half-maximal inhibitory concentration (IC₅₀) value of 5·12 (sem 0·05) μg/ml, a protein:polyglycan ratio of 17:77 and 78 % glucose in polysaccharide, and dominant amino acid residues of aspartic acid, glycine, glutamic acid, alanine, serine and threonine in protein. FYGL is capable of decreasing plasma glucose in streptozotocin-induced diabetic mice with a high safety of median lethal dose (LD₅₀) of 6 g/kg. In the present study, C57BL/6 db/db diabetic mice were trialed further using FYGL as well as metformin for comparison. Oral treatment with FYGL in db/db diabetic mice for 4 weeks significantly (P < 0·01 or 0·05) decreased the fasting plasma glucose level, serum insulin concentration and the homeostasis model assessment of insulin resistance. FYGL also controlled the biochemistry indices relative to type 2 diabetes-accompanied lipidaemic disorders. Pharmacology research suggests that FYGL decreases the plasma glucose level by the mechanism of inhibiting PTP1B expression and activity, consequently, regulating the tyrosine phosphorylation level of the IR β-subunit and the level of hepatic glycogen, thus resulting in the improvement of insulin sensitivity. Therefore, FYGL is promising as an insulin sensitiser for the therapy of type 2 diabetes and accompanied dyslipidaemia.

Novel biphenyl compound, VMNS2e, ameliorates streptozotocin-induced diabetic nephropathy in rats

AIM

To study the effect of a new biphenyl synthetic compound showing interactions with the active site of protein tyrosine phosphatase 1B by docking and molecular dynamics, VMNS2e in streptozotocin-induced diabetic nephropathy in rats with various renal function parameters and renal ultrastructure.

METHODS

Streptozotocin (55 mg/kg)-induced diabetic rats were orally treated once daily with VMNS2e (30, 60, and 120 mg/kg) for 8 weeks. The body weight and blood glucose levels of the rats were recorded during the study period. After 8 weeks of treatment creatinine clearance, urinary protein, blood urea nitrogen, urinary albumin excretion rate, and insulin levels were measured. An ultrastructure study of the kidney tissue was performed and the glomerular basement membrane thickness was measured.

RESULTS

Eight weeks of VMNS2e treatment significantly reduced the fasting blood glucose level, attenuated elevating blood urea nitrogen levels, and reduced glomerular basement membrane thickness.

CONCLUSION

It is concluded that VMNS2e treatment at 30 and 60 mg/kg, when given for 8 weeks, partly ameliorated early diabetic nephropathy in diabetic rats.

Free Energy Calculations of Mutations Involving a Tightly Bound Water Molecule and Ligand Substitutions in a Ligand-Protein Complex

The accurate calculation of the free energy of interaction of protein-water-ligand systems has an important role in molecular recognition and drug design that is often not fully considered. We report free energy thermodynamic integration calculations used to evaluate the effects of inclusion, neglect, and targeting and removal (i.e., systematic substitution by ligand functional groups) of an important, tightly bound, water molecule in the SH3 domain of Abl tyrosine kinase. The effects of this water molecule on the free energies of interaction of several Abl-SH3 domain-ligand systems reveal that there is an unfavourable free energy change associated with its removal into the bulk solvent. Only three substitutions by an additional functional group (out of methyl, ethyl, hydroxyl, amino, and amide groups) in the phenyl ring of a tyrosine in the peptide ligand resulted in a favourable change in the free energy of binding upon replacement of the ordered water molecule. This computational approach provides a direct route to the systematic and rigorous prediction of the thermodynamic influence of ordered, structural water molecules on ligand modification and optimization in drug design by calculating free energy changes in protein-water-ligand systems.

Synthesis of 2-oxoamides based on sulfonamide analogs of gamma-amino acids and their activity on phospholipase A2

A variety of lipophilic 2-oxoamides containing sulfonamide analogs of gamma-amino acids as well as acyl sulfonamides of gamma-aminobutyric acid were synthesized. Their ability to inhibit intracellular GIVA cPLA2 and GVIA iPLA2 as well as secreted GV sPLA2 was evaluated. The sulfonamide group seems a bioisosteric group suitable to replace the carboxyl group in 2-oxoamide inhibitors of GVIA cPLA2.

Discovery of [(3-bromo-7-cyano-2-naphthyl)(difluoro)methyl]phosphonic acid, a potent and orally active small molecule PTP1B inhibitor

A series of quinoline/naphthalene-difluoromethylphosphonates were prepared and were found to be potent PTP1B inhibitors. Most of these compounds bearing polar functionalities or large lipophilic residues did not show appreciable oral bioavailability in rodents while small and less polar analogs displayed moderate to good oral bioavailability. The title compound was found to have the best overall potency and pharmacokinetic profile and was found to be efficacious in animal models of diabetes and cancer.

PTP-1B inhibitors: Cyclopenta[d][1,2]-oxazine derivatives

A series of novel cyclopenta[d][1,2]-oxazine derivatives was prepared and evaluated for their inhibitory activity toward protein tyrosine phosphatase 1B (PTP-1B). Compound 6s was found to be an inhibitor of PTP-1B with nanomolar IC(50) value and high level of selectivity over other recombinant phosphatases.

Discovery and structure–activity relationships of novel sulfonamides as potent PTP1B inhibitors

A series of novel sulfonamides containing a single difluoromethylene-phosphonate group were discovered to be potent inhibitors of protein tyrosine phosphatase 1B. Structure-activity relationships around the scaffold were investigated, leading to the identification of compounds with IC50 or Ki values in the low nanomolar range. These sulfonamide-based inhibitors exhibit 100 and 30 times higher inhibitory activity than the corresponding tertiary amines and carboxamides, respectively.

Recent advances in protein tyrosine phosphatase 1B inhibitors

Type 2 diabetes and obesity are characterised by insulin and leptin resistance. Studies suggest that these may be due to defects in the insulin and leptin signalling pathways. Over the last decade, a considerable body of evidence has been amassed indicating that protein tyrosine phosphatase 1B (PTP1B) is involved in the downregulation of insulin and leptin signalling. Consequently, compounds that inhibit PTP1B have potential as therapeutics for treating Type 2 diabetes and obesity. This review covers recent advances in PTP1B inhibitors with an emphasis on recent attempts to create potent, selective and cell-permeable small-molecule inhibitors.