Potent PTP1B Inhibitors Research Articles

Accounting of ligand-receptor interactions to explore and design novel architecture for PTP 1B inhibition: a legitimate approach

Computer-aided drug design was performed on a diverse set of 103 biphenyl derivatives that demonstrated antidiabetic activity by restraining the protein tyrosine phosphatase 1B (PTP 1B) receptor. A four-point pharmacophore hypothesis using the PHASE module of Schrödinger suite with one hydrogen bond acceptor (A) and three aromatic rings (R) as pharmacophoric features was generated. The hypothesis, ARRR.2, considered the best hypothesis in the present study is characterized by survival score (3.553), cross-validated r2 (Q2) (0.722), regression coefficient (0.949), Pearson R (0.867), and F value (492.6). The developed pharmacophore model was externally validated by predicting the activity of test set molecules. Docking algorithm combined with the drug–receptor binding free energetic and pharmacokinetic drug profile envisaged a novel concept, which may provide structural insights for the development of potential PTP 1B inhibitors. The study also provided a valid rapport between pharmacophore drug mapping, atom-based three-dimensional quantitative structure–activity relationship, molecular docking, sitemap, molecular simulations, and pharmacokinetic prediction approaches demonstrating the trends in activity. The results of these ligand–receptor relationship studies may account to design a legitimate template for the development and optimization of highly selective and potent PTP 1B inhibitors. Copyright © 2012 John Wiley & Sons, Ltd.

Cooperative fluctuations of PTP1B by an elastic network model analysis

Motivations. Protein tyrosine phosphorylation is essential in controlling many vital activities of the cell such as growth, differentiation, metabolism and immune response. Abnormal tyrosine phosphorylation leads to various human diseases including cancers, diabetes, rheumatoid arthritis and hypertension. PTP1B, which is a major negative regulator of insulin signaling, is one of the important forms of tyrosine specific phosphatases that hydrolyze phosphotyrosine containing proteins. As the loss of PTP1B activity leads to enhanced insulin sensitivity and resistance to weight gain, inhibiting PTP1B activity represents a novel approach for the treatment of diabetes and obesity. In this regard, understanding the molecular recognition mechanism in binding processes of PTP1B may provide guidelines for the development of potent PTP1B inhibitors. Methods. Here, the structural dynamics of both substrate- and inhibitor-bound PTP1B are studied comparatively using the Anisotropic Network Model (ANM) which performs harmonic vibrational analysis around the equilibrium states and predicts the directionalities of the collective motions as well as their magnitudes. Results. The mean-square fluctuations in the most cooperative ANM modes are similar in different PTP1B complex structures and the minimum fluctuating residues correspond to the dynamically correlated hinge regions. Further, the variation in the orientation of the fluctuations is caused mainly by the residues lying along the rotational axes that are responsible for the functional motions. Overall, the elaborated analysis of the structural fluctuations of PTP1B in interaction with its ligands helps to gain insight into the dynamics of the phosphatase in relation to its function.

New 4-[(5-arylidene-2-arylimino-4-oxo-3-thiazolidinyl)methyl]benzoic acids active as protein tyrosine phosphatase inhibitors endowed with insulinomimetic effect on mouse C2C12 skeletal muscle cells

In pursuing our research targeting the identification of potent inhibitors of PTP1B and LMW-PTP, we have identified new 4-[(5-arylidene-2-arylimino-4-oxo-3-thiazolidinyl)methyl]benzoic acids endowed with interesting in vitro inhibitory profiles. Most compounds proved to be inhibitors of PTP1B and LMW-PTP isoform IF1. The tested inhibitors also showed selectivity towards PTP1B over the closely related TC-PTP. These compounds were found to activate the insulin-mediated signalling on mouse C2C12 skeletal muscle cells by increasing the phosphorylation levels of the insulin receptor and promoting cellular 2-deoxyglucose uptake.Interestingly, 4-{[5-(4-benzyloxybenzylidene)-2-(4-trifluoromethylphenylimino)-4-oxo-3-thiazolidinyl]methyl}benzoic acid (7d), the best in vitro inhibitor of PTP1B and the isoform IF1 of LMW-PTP, provided the highest activation level of the insulin receptor and was found to be endowed with an excellent insulinomimetic effect on the selected cells. This compound therefore represents an interesting lead compound for developing novel PTP1B and LMW-PTP inhibitors which could be achieved by improving both its pharmacological profile and its potentiating effects on insulin signalling.

Isoxazolone Derivatives as Potent Inhibitors of PTP1B

E-mail: hcho@inha.ac.krReceived June 27, 2011, Accepted September 15, 2011Key Words : Isoxazol-5(4H)-one, Protein tyrosine phosphatase, Inhibitor, PTP1BMetabolic syndromes such as obesity and diabetes poseserious health threats in modern society. These chronicailments can cause secondary complications including theincrease of cardiovascular risk, which is a leading cause ofdeath.

Synthesis and evaluation of oxovanadium(iv) complexes of Schiff-base condensates from 5-substituted-2-hydroxybenzaldehyde and 2-substituted-benzenamine as selective inhibitors of protein tyrosine phosphatase 1B

Five oxovanadium(IV) complexes, which were divided into two groups, [V(IV)O(bhbb, nhbb)(H(2)O)(2)] (tridentate ligands: H(2)bhbb = 2-(5-bromo-2-hydroxylbenzylideneamino)benzoic acid, 1; H(2)nhbb = 2-(5-nitro-2-hydroxylbenzylideneamino)benzoic acid, 2) and [V(IV)O(cpmp, bpmp, npmp)(2)] (bidentate ligands: Hcpmp = 4-chloro-2-((phenylimino)methyl)phenol, 3; Hbpmp = 4-bromo-2-((phenylimino)methyl)phenol, 4; Hnpmp = 4-nitro-2-((phenylimino)methyl) phenol, 5) have been prepared and characterized by elemental analysis, infrared, UV-visible and electrospray ionization mass spectrometry. The coordination in [V(IV)O(bhbb)(H(2)O)(2)] (1) was confirmed by X-ray crystal structure analysis. The oxidation state of V(IV) with d(1) configuration in 1-5 was confirmed by EPR. The speciation of VO/H(2)bhbb in methanol-aqueous solution was investigated by potentiometric pH titrations. The result indicated that the main species were [V(IV)O(bhbb)(OH)](-) and [V(IV)O(bhbb)(OH)(2)](2-) at the pH range 7.0-7.4. The structure-activity relationship of the vanadium complexes in inhibiting protein tyrosine phosphatases (protein tyrosine phosphatase 1B, PTP1B; T-cell protein tyrosine phosphatase, TCPTP; megakaryocyte protein-tyrosine phosphatase, PTP-MEG2; Src homology phosphatase 1, SHP-1 and Src homology phosphatase 2, SHP-2) was investigated. The oxovanadium(IV) complexes were potent inhibitors of PTP1B, TCPTP, PTP-MEG2, SHP-1 and SHP-2, but exhibited different inhibitory abilities over different PTPs. Complexes 2 and 4 displayed better selectivity to PTP1B over the other four PTPs. Kinetic data showed that complex 2 inhibited PTP1B, TCPTP and SHP-1 with a noncompetitive inhibition mode, but a classical competitive inhibition mode for PTP-MEG2 and SHP-2. The results demonstrated that both the structures of vanadium complexes and the conformations of PTPs influenced PTP inhibition activity. The proper modification of the organic ligand moieties may result in screening potent and selective vanadium-based PTP1B inhibitors.

Synthesis and Biological Evaluation of Oleanolic Acid Derivatives as Novel Inhibitors of Protein Tyrosine Phosphatase 1B

A series of oleanolic acid (OA) derivatives have been synthesized and their inhibitory effects on PTP1B, TCPTP and related PTPs are evaluated. Some compounds with five-membered heterocyclic ring-fused at C-2, C-3 positions showed a dramatic increase in inhibition, the two most potent PTP1B inhibitors 19 (IC50 = 0.91 μM) and 21 (IC50 = 0.98 μM) showed about 3-fold more potent than lead compound OA. Some C-ring modified OA analogs showed high selectivity for PTP1B over TCPTP, among them, 50 possessed the best selectivity of 6.6-fold.

Discovery of potent, selective and orally bioavailable triaryl-sulfonamide based PTP1B inhibitors

A novel series of pTyr mimetics containing triaryl-sulfonamide derivatives (5a-r) are reported as potent and selective PTP1B inhibitors. Some of the test compounds (5o and 5p) showed excellent selectivity towards PTP1B over various PTPs, including TCPTP (in vitro). The lead compound 5o showed potent antidiabetic activity (in vivo), along with improved pharmacokinetic profile. These preliminary results confirm discovery of highly potent and selective PTP1B inhibitors for the treatment of T2DM.

Facile fabrication of promising protein tyrosine phosphatase (PTP) inhibitor entities based on ‘clicked’ serine/threonine–monosaccharide hybrids

Protein tyrosine phosphatases (PTPs) are well-validated therapeutic targets for many human major diseases. The development of their potent inhibitors has therefore become a main focus of both academia and the pharmaceutical industry. We report herein a facile strategy toward the fabrication of new and competent PTP inhibitor entities by simply ’clicking’ alkynyl amino acids onto diverse azido sugar templates. Triazolyl glucosyl, galactosyl, and mannosyl serine and threonine derivatives were efficiently synthesized via click reaction, which were then identified as potent CDC25B and PTP1B inhibitors selective over a panel of homologous PTPs tested. Their inhibitory activity and selectivity were found to largely lie on the structurally and configurationally diversified monosaccharide moieties whereon serinyl and threoninyl residues were introduced. In addition, MTT assay revealed the triazole-connected sugar-amino acid hybrids may also inhibit the growth of several human cancer cell lines including A549, Hela, and especially HCT-116. On the basis of such compelling evidence, we consider that this compound series could furnish promising chemical entities serving as new CDC25B and PTP1B inhibitors with potential cellular activity. Furthermore, the ‘click’ strategy starting from easily accessible and biocompatible amino acids and sugar templates would allow the modular fabrication of a rich library of new PTP inhibitors efficaciously and productively.

Tea contains potent inhibitors of tyrosine phosphatase PTP1B

Tea is widely consumed all over the world. Studies have demonstrated the role of tea in prevention and treatment of various chronic diseases including diabetes and obesity, but the underlying mechanism is unclear. PTP1B is a widely expressed tyrosine phosphatase which has been defined as a target for therapeutic drug development to treat diabetes and obesity. In screening for inhibitors of PTP1B, we found that aqueous extracts of teas exhibited potent PTP1B inhibitory effects with an IC50 value of 0.4–4 g dry tea leaves per liter of water. Black tea shows the strongest inhibition activities, followed by oolong and then by green tea. Biochemical fractionations demonstrated that the major effective components in tea corresponded to oxidized polyphenolic compounds. This was further verified by the fact that tea catechins became potent inhibitors of PTP1B upon oxidation catalyzed by tyrosinases. When applied to cultured cells, tea extracts induced tyrosine phosphorylation of cellular proteins. Our study suggests that some beneficial effects of tea may be attributed to the inhibition of PTP1B.

MOLECULAR DOCKING, 3D-QSAR AND DE NOVO DESIGN OF BENZIMIDAZOLES AND IMIDAZOLINES (S)-ISOTHIAZOLIDINONES DERIVATIVES AS PTP 1B INHIBITORS

A study of the relationship-dimensional quantitative structure (3D-QSAR) with 40 molecules derived from benzimidazole and imidazoline (s)-isotiazolidinonas and their union with the active site of Protein Tyrosine Phosphatase 1B using the program GOLD 3.0 was carried out. The molecular supression of the ligands in the grid was performed by the Database Alignment method. The best model formed by combining the esteric field and electrostatic fields of CoMFA, yielded the following parameters: q2 = 0.659 and r2 = 0.997. Using LeapFrog module of Sybyl was possible to generate more than 10,000 new molecules of which 46 showed theoretically a better value of biological activity than their forerunner. The data generated by this study could promote the design of new and more potent PTP 1B inhibitors as agents for the treatment of diabetes.

Protein Tyrosine Phosphatase 1B Inhibitors: A Molecular Level Legitimate Approach for the Management of Diabetes Mellitus

Diabetes mellitus is a systemic disease responsible for morbidity in the western world and is gradually becoming prevalent in developing countries too. The prevalence of diabetes is rapidly increasing in industrialized countries and type 2 diabetes accounts for 90% of the disease. Insulin resistance is a major pathophysiological factor in the development of type 2 diabetes, occurring mainly in muscle, adipose tissues, and liver leading to reduced glucose uptake and utilization and increased glucose production. The prevalence and rising incidence of diabetes emphasized the need to explore new molecular targets and strategies to develop novel antihyperglycemic agents. Protein Tyrosine Phosphatase 1B (PTP 1B) has recently emerged as a promising molecular level legitimate therapeutic target in the effective management of type 2 diabetes. PTP 1B, a cytosolic nonreceptor PTPase, has been implicated as a negative regulator of insulin signal transduction. Therefore, PTP 1B inhibitors would increase insulin sensitivity by blocking the PTP 1B-mediated negative insulin signaling pathway and might be an attractive target for type 2 diabetes mellitus and obesity. With X-ray crystallography and NMR-based fragment screening, the binding interactions of several classes of inhibitors have been elucidated, which could help the design of future PTP 1B inhibitors. The drug discovery research in PTP 1B is a challenging area to work with and many pharmaceutical organizations and academic research laboratories are focusing their research toward the development of potential PTP 1B inhibitors which would prove to be a milestone for the management of diabetes.

Sulphonamides as Inhibitors of Protein Tyrosine Phosphatase 1B: A Three-Dimensional Quantitative Structure-Activity Relationship Study Using Self-Organizing Molecular Field Analysis Approach

Protein tyrosine phosphatase 1B (PTP 1B), a cytosolic PTP involved in down-regulation of receptor tyrosine kinase activity following stimulation of the insulin or leptin receptors. Thus, PTP 1B inhibitors could potentially ameliorate insulin resistance and normalize plasma glucose and insulin levels without inducing hypoglycemia, and could therefore be a major advancement in the treatment of type 2 diabetes. A three-dimensional quantitative structure-activity relationship (3D-QSAR) study has been performed on a novel class of sulphonamides using self-organizing molecular field analysis (SOMFA) to correlate their chemical structures with their observed PTP 1B inhibitory activities. The master grid obtained for the various SOMFA models indicates electrostatic and shape potential contributions that can be mapped back onto structural features relating to the trends in inhibitory activities. On the basis of the spatial arrangement, steric and electrostatic factors should appropriately be taken into account for development of new potent inhibitors of PTP 1B for the management of type 2 diabetes.

Synthesis and biological evaluation of heterocyclic ring-substituted maslinic acid derivatives as novel inhibitors of protein tyrosine phosphatase 1B

A series of maslinic acid derivatives have been synthesized by introducing various fused heterocyclic rings at C-2 and C-3 positions. Their inhibitory effects on PTP1B, TCPTP and related PTPs are evaluated. Most of the compounds exhibited a dramatic increase in inhibitory potency and selectivity, the two most potent PTP1B inhibitors 20 (IC 50 = 0.61 μM) and 29 (IC 50 = 0.64 μM) showed about 10-fold more potent than lead compound maslinic acid. More importantly, 29 possesses the best selectivity of 6.9-fold for PTP1B over TCPTP.

Pyranocoumarins: A new class of anti-hyperglycemic and anti-dyslipidemic agents

A series of pyranocoumarin derivatives were synthesized and evaluated in vivo for their anti-hyperglycemic as well as anti-dyslipidemic activities. Compounds 7a, 7c, 8a, 8b, 8c, 8e and 8f have shown promising anti-hyperglycemic activities in sucrose loaded model (SLM) as well as sucrose challenged streptozotocin induced diabetic rat model (STZ). Compounds 8a and 8b were showing 38.0% and 42.0% blood glucose lowering activity in db/db mice model. In vitro anti-hyperglycemic activity evaluation exhibited that compounds 8a (IC 50 = 24.5 μM) and 8b (IC 50 = 36.2 μM) are potential PTP-1B inhibitors thereby revealing their possible mechanism of anti-diabetic action. Compounds 7a, 7b, 8a, 8b, 8d, 8e and 8f have shown significant anti-dyslipidemic activity in triton induced dyslipidemia in rats.

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.

Novel 2-aryl-naphtho[1,2- d]oxazole derivatives as potential PTP-1B inhibitors showing antihyperglycemic activities

A series of 2-aryl-naphtho[1,2- d]oxazole derivatives have been synthesized and evaluated for PTP-1B inhibitory activity. The compounds have been screened in vivo for antidiabetic activity under sucrose loaded model (SLM), sucrose-challenged streptozotocin-induced diabetic rat model (STZ-S) and db/db mice model. Compounds 8 and 12 have shown promising PTP-1B inhibitory activity, significant antidiabetic activity, moderate lipid and triglyceride lowering activity.

Mono- and disalicylic acid derivatives: PTP1B inhibitors as potential anti-obesity drugs

A series of compounds containing one or two salicylic acid moieties were synthesized, and their efficacy to inhibit the phosphohydrolase activity of PTP1B examined. Some of the methylenedisalicylic acid derivatives were potent inhibitors of PTP1B. Of those derivatives, 3c exhibited about a 14-fold selectivity against TC-PTP, and this compound was tested in a mouse model for its efficacy to prevent diet-induced obesity. It effectively suppressed the increases in body weight and adipose mass, without any noticeable toxic effect. The compound also prevented increases in the plasma triglyceride, cholesterol, and nonesterified fatty acid concentrations; thus, expanding its therapeutic potential to other related metabolic diseases, such as hyperlipidemia and hypercholesterolemia.

Molecular dynamics simulations of interaction between protein-tyrosine phosphatase 1B and a bidentate inhibitor1

To investigate the dynamic properties of protein-tyrosine phosphatase (PTP) 1B and reveal the structural factors responsible for the high inhibitory potency and selectivity of the inhibitor SNA for PTP1B. We performed molecular dynamics (MD) simulations using a long time-scale for both PTP1B and PTP1B complexed with the inhibitor SNA, the most potent and selective PTP1B inhibitor reported to date. The trajectories were analyzed by using principal component analysis. Trajectory analyses showed that upon binding the ligand, the flexibility of the entire PTP1B molecule decreases. The most notable change is the movement of the WPD-loop. Our simulation results also indicated that electrostatic interactions contribute more to PTP1B-SNA complex conformation than the van der Waals interactions, and that Lys41, Arg47, and Asp48 play important roles in determining the conformation of the inhibitor SNA and in the potency and selectivity of the inhibitor. Of these, Arg47 contributed most. These results were in agreement with previous experimental results. The information presented here suggests that potent and selective PTP1B inhibitors can be designed by targeting the surface residues, for example the region containing Lys41, Arg47, and Asp48, instead of the second phosphate binding site (besides the active phosphate binding site).

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 IC 50 or K i 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.

Small molecule approach to studying protein tyrosine phosphatase

Understanding the function of protein tyrosine phosphatases (PTPs) is crucial to deciphering cellular signaling in higher organisms. Of the 100 putative PTPs in human genome, only a little is known about their precise biological functions. Thus establishing novel ways to study PTP function remains a top priority among researchers. Classical genetics and more recently the use of RNA interference (RNAi) for gene silencing remains a popular choice to study function. However, the one gene-one function hypothesis is now recognized as an oversimplified scenario, especially among the signaling proteins such as PTPs. Therefore, there is a need to understand gene function in an appropriate cellular context. Since proteins are the work horses of the cell, alteration of protein function by various means is a particularly attractive strategy. In this context, the chemical approach, where a small molecule is used to affect the function of the desired protein is increasingly being recognized as a method of choice. In this review, we describe how small molecules can be used to study the function of a prototypical PTP, PTP1B, which is a negative regulator in insulin signaling. This includes our initial strategies for finding the most potent and specific PTP1B inhibitor to date, synthesizing cell permeable analogues suitable for cellular studies, and using them to dissect the role of PTP1B in the insulin signaling pathway. This approach is potentially general and thus could be utilized to study the function of other PTPs.