A novel, centrally acting mammalian aminosterol, ENT-03, induces weight loss in obese and lean rodents.

ENT-03, a spermine bile acid we recently discovered in the brain of newborn mice acts centrally to regulate energy and metabolism. Obese, diabetic (ob/ob) mice treated with five doses of ENT-03 over 2 weeks, demonstrated a rapid decrease in blood glucose levels into the range seen in non-obese animals, prior to any significant weight loss. Weight fell substantially thereafter as food intake decreased, and serum biochemical parameters normalized compared with both vehicle and pair-fed controls. To determine whether ENT-03 could be acting centrally, we injected a single dose of ENT-03 intracerebroventricularly to Sprague-Dawley rats. Weight fell significantly and remained below vehicle injected controls for an extended period. By autoradiography, ENT-03 localized to the arcuate nucleus of the hypothalamus, the choroid plexus and cerebrospinal fluid. Significant cFos activation occurred in multiple anatomical regions within the hypothalamus and brainstem involved in appetite suppression, food-entrained circadian rhythmicity, autonomic function, and growth. These data support a role for ENT-03 in the treatment of type 2 diabetes and obesity. Phase 1 studies in subjects with obesity and diabetes are currently in progress.

Discovery of inhibitors targeting protein tyrosine phosphatase 1B using a combined virtual screening approach.

Protein tyrosine phosphatase 1B (PTP1B) acts as a therapeutic target for type 2 diabetes. However, the major challenges of PTP1B drug discovery are the poor selectivity and the weak oral bioavailability. In this study, we performed a combined virtual screening approach including multicomplex pharmacophore, molecular docking-based screening, van der Waals energy normalization, pose scaling factor, ADMET evaluation, and molecular dynamics simulation to select PTP1B inhibitors from three databases (PubChem, ChEMBL, and ZINC). We identified three potential PTP1B inhibitors, compounds 1, 4, and 5, with favorable binding energy and good oral bioavailability. The energetic and geometrical analyses show that the three compounds are stably bound to PTP1B, via occupying both the catalytic site (site A) and the proximal noncatalytic site (site B or C). Such occupancy may improve the selectivity. This work not only provided a feasible virtual screening protocol, but also suggested three potential PTP1B inhibitors for the treatment of type 2 diabetes.

Design, synthesis, biological evaluation and molecular dynamics simulation studies of imidazolidine-2,4-dione derivatives as novel PTP1B inhibitors.

Protein tyrosine phosphatase 1B (PTP1B) is a member of the phosphotyrosine phosphatase family and plays an important role in the signal transduction of diabetes. Inhibition of PTP1B activity can increase insulin sensitivity and reduce blood sugar levels. Therefore, it is urgent to find compounds with novel structures that can inhibit PTP1B. This study designed imidazolidine-2,4-dione derivatives through the computer-aided drug design (CADD) strategy, and the Comp#10 showed outstanding inhibitory ability. (IC50 = 2.07 µM) and selectivity. The inhibitory mechanism at molecular level of Comp#10 on PTP1B was studied by molecular dynamics simulation. The results show that the catalytic region of PTP1B protein is more stable, which makes the catalytic sites unsuitable for exposure. Interestingly, the most obvious changes in the interaction between residues in the P-loop region (such as: His214, Cys215, and Ser216). In short, this study reported for the first time that imidazolidine-2,4-dione derivatives as novel PTP1B inhibitors had good inhibitory activity and selectivity, providing new ideas for the development of small molecule PTP1B inhibitors.

5-Aryl-furan derivatives bearing a phenylalanine- or isoleucine-derived rhodanine moiety as potential PTP1B inhibitors.

Two series of 5-aryl-furan derivatives bearing a phenylalanine- or isoleucine-derived rhodanine moiety were identified as competitive protein tyrosine phosphatase 1B (PTP1B) inhibitors. Among the compounds studied, 5g was found to have the best PTP1B inhibitory potency (IC50 = 2.66 ± 0.16 µM) and the best cell division cycle 25 homolog B (CDC25B) inhibitory potency (IC50 = 0.25 ± 0.02 µM). Enzymatic data together with molecular modeling results demonstrated that the introduction of a sec-butyl group at the 2-position of the carboxyl group remarkably improved the PTP1B inhibitory activity.

Reduced intracellular chloride concentration impairs angiogenesis by inhibiting oxidative stress-mediated VEGFR2 activation.

Chloride (Cl-) homeostasis is of great significance in cardiovascular system. Serum Cl- level is inversely associated with the mortality of patients with heart failure. Considering the importance of angiogenesis in the progress of heart failure, this study aims to investigate whether and how reduced intracellular Cl- concentration ([Cl-]i) affects angiogenesis. Human umbilical endothelial cells (HUVECs) were treated with normal Cl- medium or low Cl- medium. We showed that reduction of [Cl-]i (from 33.2 to 16.18 mM) inhibited HUVEC proliferation, migration, cytoskeleton reorganization, tube formation, and subsequently suppressed angiogenesis under basal condition, and VEGF stimulation or hypoxia treatment. Moreover, VEGF-induced NADPH-mediated reactive oxygen species (ROS) generation and VEGFR2 axis activation were markedly attenuated in low Cl- medium. We revealed that lowering [Cl-]i inhibited the expression of the membrane-bound catalytic subunits of NADPH, i.e., p22phox and Nox2, and blunted the translocation of cytosolic regulatory subunits p47phox and p67phox, thereby restricting NADPH oxidase complex formation and activation. Furthermore, reduced [Cl-]i enhanced ROS-associated protein tyrosine phosphatase 1B (PTP1B) activity and increased the interaction of VEGFR2 and PTP1B. Pharmacological inhibition of PTP1B reversed the effect of lowering [Cl-]i on VEGFR2 phosphorylation and angiogenesis. In mouse hind limb ischemia model, blockade of Cl- efflux using Cl- channel inhibitors DIDS or DCPIB (10 mg/kg, i.m., every other day for 2 weeks) significantly enhanced blood flow recovery and new capillaries formation. In conclusion, decrease of [Cl-]i suppresses angiogenesis via inhibiting oxidase stress-mediated VEGFR2 signaling activation by preventing NADPH oxidase complex formation and promoting VEGFR2/PTP1B association, suggesting that modulation of [Cl-]i may be a novel therapeutic avenue for the treatment of angiogenic dysfunction-associated diseases.

A Novel PTP1B Inhibitor-Phosphate of Polymannuronic Acid Ameliorates Insulin Resistance by Regulating IRS-1/Akt Signaling.

Protein tyrosine phosphatase 1B (PTP1B) is a critical negative modulator of insulin signaling and has attracted considerable attention in treating type 2 diabetes mellitus (T2DM). Low-molecular-weight polymannuronic acid phosphate (LPMP) was found to be a selective PTP1B inhibitor with an IC50 of 1.02 ± 0.17 µM. Cellular glucose consumption was significantly elevated in insulin-resistant HepG2 cells after LPMP treatment. LPMP could alleviate oxidative stress and endoplasmic reticulum stress, which are associated with the development of insulin resistance. Western blot and polymerase chain reaction (PCR) analysis demonstrated that LPMP could enhance insulin sensitivity through the PTP1B/IRS/Akt transduction pathway. Furthermore, animal study confirmed that LPMP could decrease blood glucose, alleviate insulin resistance, and exert hepatoprotective effects in diabetic mice. Taken together, LPMP can effectively inhibit insulin resistance and has high potential as an anti-diabetic drug candidate to be further developed.

CYC31, A Natural Bromophenol PTP1B Inhibitor, Activates Insulin Signaling and Improves Long Chain-Fatty Acid Oxidation in C2C12 Myotubes.

3-bromo-4,5-Bis(2,3-dibromo-4,5-dihydroxybenzyl)-1,2-benzenediol (CYC31) is a bromophenol protein tyrosine phosphatase 1B (PTP1B) inhibitor isolated from the red alga Rhodomela confervoides. Here, the effect of CYC31 on the insulin signaling and fatty-acid-induced disorders in C2C12 myotubes was investigated. Molecular docking assay showed that CYC31 was embedded into the catalytic pocket of PTP1B. A cellular study found that CYC31 increased the activity of insulin signaling and promoted 2-NBDG uptake through GLUT4 translocation in C2C12 myotubes. Further studies showed that CYC31 ameliorated palmitate-induced insulin resistance in C2C12 myotubes. Moreover, CYC31 treatment significantly increased the mRNA expression of carnitine palmitoyltransferase 1B (CPT-1B) and fatty acid binding protein 3 (FABP3), which was tightly linked with fatty acid oxidation. These findings suggested that CYC31 could prevent palmitate-induce insulin resistance and could improve fatty acid oxidation through PTP1B inhibition.

Discovery of 1,3-diphenyl-1H-pyrazole derivatives containing rhodanine-3-alkanoic acid groups as potential PTP1B inhibitors.

Two series of 1,3-diphenyl-1H-pyrazole derivatives containing rhodanine-3-alkanoic acid groups were identified as competitive protein tyrosine phosphatase 1B (PTP1B) inhibitors. Among the compounds studied, IIIv was found to have the best in vitro inhibition activity against PTP1B (IC50 = 0.67 ±â€¯0.09 µM) and the best selectivity (9-fold) between PTP1B and T-cell protein tyrosine phosphatase (TCPTP). Molecular docking studies demonstrated that compounds IIIm, IIIv and IVg could occupy simultaneously at both the catalytic site and the adjacent pTyr binding site. These results provide novel lead compounds for the design of inhibitors of PTP1B as well as other PTPs.

Therapeutic effects of the allosteric protein tyrosine phosphatase 1B inhibitor KY-226 on experimental diabetes and obesity via enhancements in insulin and leptin signaling in mice.

The anti-diabetic and anti-obesity effects of the allosteric protein tyrosine phosphatase 1B (PTP1B) inhibitor 4-(biphenyl-4-ylmethylsulfanylmethyl)-N-(hexane-1-sulfonyl)benzoylamide (KY-226) were pharmacologically evaluated. KY-226 inhibited human PTP1B activity (IC50 = 0.28 µM), but did not exhibit peroxisome proliferator-activated receptor γ (PPARγ) agonist activity. In rodent preadipocytes (3T3-L1), KY-226 up to 10 µM had no effects on adipocyte differentiation, whereas pioglitazone, a PPARγ agonist, markedly promoted it. In human hepatoma-derived cells (HepG2), KY-226 (0.3-10 µM) increased the phosphorylated insulin receptor (pIR) produced by insulin. In db/db mice, the oral administration of KY-226 (10 and 30 mg/kg/day, 4 weeks) significantly reduced plasma glucose and triglyceride levels as well as hemoglobin A1c values without increasing body weight gain, while pioglitazone exerted similar effects with increases in body weight gain. KY-226 attenuated plasma glucose elevations in the oral glucose tolerance test. KY-226 also increased pIR and phosphorylated Akt in the liver and femoral muscle. In high-fat diet-induced obese mice, the oral administration of KY-226 (30 and 60 mg/kg/day, 4 weeks) decreased body weight gain, food consumption, and fat volume gain with increases in phosphorylated STAT3 in the hypothalamus. In conclusion, KY-226 exerted anti-diabetic and anti-obesity effects by enhancing insulin and leptin signaling, respectively.

Function-Oriented Synthesis of Marine Phidianidine Derivatives as Potential PTP1B Inhibitors with Specific Selectivity.

Phidianidines A and B are two novel marine indole alkaloids bearing an uncommon 1,2,4-oxadiazole ring and exhibiting various biological activities. Our previous research showed that the synthesized phidianidine analogs had the potential to inhibit the activity of protein tyrosine phosphatase 1B (PTP1B), a validated target for Type II diabetes, which indicates that these analogs are worth further structural modification. Therefore, in this paper, a series of phidianidine derivatives were designed and rapidly synthesized with a function-oriented synthesis (FOS) strategy. Their inhibitory effects on PTP1B and T-cell protein tyrosine phosphatase (TCPTP) were evaluated, and several compounds displayed significant inhibitory potency and specific selectivity over PTP1B. The structure-activity relationship (SAR) and molecular docking analyses are also described.

Evaluation of oral pharmacokinetics, in vitro metabolism, blood partitioning and plasma protein binding of novel antidiabetic agent, S009-0629 in rats.

S009-0629 [methyl-8-(methylthio)-2-phenyl-6-p-tolyl-4,5-dihydro-2H-benzo[e]indazole-9-carboxylate] is a novel antidiabetic agent with PTP1B inhibitory activity. In this study, we have investigated the in vitro metabolic stability, plasma protein binding, blood partitioning, and oral pharmacokinetic study of S009-0629 in rats. The plasma protein binding, blood partitioning, and metabolic stability were determined by HPLC method. The oral pharmacokinetic study was analyzed by liquid chromatography coupled mass spectrometry (LC-MS/MS) method. The plasma protein binding of S009-0629 using modified charcoal adsorption method at 5 and 10 µg/mL was 80.58 ± 1.04% and 81.95 ± 1.15%, respectively. The KRBC/PL of S009-0629 was independent of concentration and time. The in-vitro half-life of S009-0629 at 5 and 10 µM using rat liver microsomes was determined as 273 ± 24.46 and 281.67 ± 26.53 min, respectively. After oral administration, S009-0629 exhibited Cmax 55.51 ± 1.18 ng/mL was observed at 18 hr (tmax ). S009-0629 was found to have the large apparent volume of distribution (1,894.93 ± 363.67 L/kg). Oral in-vivo t1/2 of S009-0629 was found to be 41.23 ± 5.96 hr. A rapid and highly sensitive LC-MS/MS method was validated for S009-0629 in rat plasma. S009-0629 has high plasma protein binding and low hepatic extraction. S009-0629 has no affinity with human P-gp and BCRP in ATPase assay. After oral dosing, S009-0629 has slow absorption and elimination in rats.

Discovery of core-structurally novel PTP1B inhibitors with specific selectivity containing oxindole-fused spirotetrahydrofurochroman by one-pot reaction.

Protein tyrosine phosphatase 1B (PTP1B) has been proposed to be an ideal target for treatment of type II diabetes and obesity. However, no druggable PTP1B inhibitor has been established and there is still an urgent demand for the development of structurally novel PTPIB inhibitor. Herein, we reported core-structurally novel PTP1B inhibitors with low micromole-ranged inhibitory activity by one-pot reaction from simple starting materials. Further studies demonstrated some of these active compounds had a specific selectivity over other PTPs. The structure and activity relationship was also described. The best active and selective compound 5e inhibited PTP1B activity with an IC50 of 4.53µM. Molecular docking analysis further demonstrated that compound 5e bound to the active pocket of PTP1B. The results might provide some insights for further development of new drugs for type II diabetes and obesity.

Design, synthesis and in vitro activity of phidianidine B derivatives as novel PTP1B inhibitors with specific selectivity.

A series of phidianidine B derivatives were synthesized by introducing various heterocyclic rings. Their inhibitory effects on PTP1B and other PTPs (TCPTP, SHP1, SHP2 and LAR) were evaluated. A majority of them displayed significant inhibitory potency and specific selectivity over PTP1B. The SAR and molecular docking analysis were also described.

The design strategy of selective PTP1B inhibitors over TCPTP.

Protein tyrosine phosphatase 1B (PTP1B) has already been well studied as a highly validated therapeutic target for diabetes and obesity. However, the lack of selectivity limited further studies and clinical applications of PTP1B inhibitors, especially over T-cell protein tyrosine phosphatase (TCPTP). In this review, we enumerate the published specific inhibitors of PTP1B, discuss the structure-activity relationships by analysis of their X-ray structures or docking results, and summarize the characteristic of selectivity related residues and groups. Furthermore, the design strategy of selective PTP1B inhibitors over TCPTP is also proposed. We hope our work could provide an effective way to gain specific PTP1B inhibitors.

Design and synthesis of novel 1,2-dithiolan-4-yl benzoate derivatives as PTP1B inhibitors.

A series of novel 1,2-dithiolan-4-yl benzoate compounds were synthesized and evaluated for in vitro PTP1B inhibitory activity. Some derivatives exhibited improved PTP1B inhibitory activity and selectivity compared to hit 6a, a compound from in-house library screening inspired by marine cyclic disulfide. The preliminary SAR analysis with assistance of molecular modeling approach revealed 6j (IC50=0.59µM) as the most potent PTP1B inhibitor among all derivatives.

Strongylophorines, new protein tyrosine phosphatase 1B inhibitors, from the marine sponge Strongylophora strongilata collected at Iriomote Island.

A new meroditerpene, 26-O-ethylstrongylophorine-14 (1), was isolated from the Okinawan marine sponge Strongylophora strongilata together with six known strongylophorines: 26-O-methylstrongylophorine-16 (2) and strongylophorines-2 (3), -3 (4), -8 (5), -15 (6), and -17 (7). The structure of 1 was assigned on the basis of its spectroscopic data. Compound 1 inhibited the activity of protein tyrosine phosphatase 1B (PTP1B) with an IC50 value of 8.7 µM, while known compounds 2-8 gave IC50 values of 8.5, >24.4, 9.0, 21.2, 11.9, and 14.8 µM, respectively. Oleanolic acid, a positive control, inhibited PTP1B activity at 0.7 µM (IC50). The inhibitory activities of strongylophorines possessing the acetal moiety at C-26 (1, 2, and 6) were stronger than those of the lactone derivatives (3 and 5). This is the first study to demonstrate that meroditerpenes inhibit PTP1B activity.

Two new protein tyrosine phosphatase 1B inhibitors, hyattellactones A and B, from the Indonesian marine sponge Hyattella sp.

Two unique sesterterpenes, hyattellactones A (1) and B (2), together with two known sesterterpenes, phyllofolactones F (3) and G (4), were isolated from the Indonesian marine sponge Hyattella sp. The structures of the two new compounds, 1 and 2 were assigned based on their spectroscopic data. Hyattellactone A (1) was a scalarane sesterterpene with an α,ß-unsaturated-γ-lactone ring and C-ethyl group, while B (2) was an epimer of 1 at the C-24 position. Compounds 1 and 3 inhibited PTP1B activity with IC50 values of 7.45 and 7.47µM, respectively. On the other hand, compounds 2 and 4 (24S-isomers of 1 and 3, respectively) showed much reduced activity than the 24R-isomers.

Effect of Hypericum perforatum L. extract on insulin resistance and lipid metabolic disorder in high-fat-diet induced obese mice.

Natural product Hypericum perforatum L. has been used in folk medicine to improve mental performance. However, the effect of H. perforatum L. on metabolism is still unknown. In order to test whether H. perforatum L. extract (EHP) has an effect on metabolic syndrome, we treated diet induced obese (DIO) C57BL/6J mice with the extract. The chemical characters of EHP were investigated with thin-layer chromatography, ultraviolet, high-performance liquid chromatography (HPLC), and HPLC-mass spectrometry fingerprint analysis. Oral glucose tolerance test (OGTT), insulin tolerance test (ITT), and the glucose infusion rate (GIR) in hyperinsulinemic-euglycemic clamp test were performed to evaluate the glucose metabolism and insulin sensitivity. Skeletal muscle was examined for lipid metabolism. The results suggest that EHP can significantly improve the glucose and lipid metabolism in DIO mice. In vitro, EHP inhibited the catalytic activity of recombinant human protein tyrosine phosphatase 1B (PTP1B) and reduced the protein and mRNA levels of PTP1B in the skeletal muscle. Moreover, expressions of genes related to fatty acid uptake and oxidation were changed by EHP in the skeletal muscle. These results suggest that EHP may improve insulin resistance and lipid metabolism in DIO mice.

New laurane-type sesquiterpenoids from the Chinese red alga Laurencia okamurai Yamada.

Two new laurane-type sesquiterpenoids, debromo-3α-hydroperoxy-3-epiaplysin (1) and debromo-3ß-hydroperoxyaplysin (2), together with seven known related compounds (3-9), were isolated from the Chinese red alga Laurencia okamurai. Their structures were elucidated by detailed analysis of spectroscopic data and by comparison with the literature. In bioassay, compounds 2, 4, 8, and 9 exhibited significant PTP1B inhibitory activity with IC50 values ranging from 4.9 to 14.9 µg/ml.

New triterpenoids with protein tyrosine phosphatase 1B inhibition from Cedrela odorata.

Two new apotirucallane-type triterpenoids, cedrodorols A-B (1 and 2), along with seven known compounds (3-9), were isolated from the twigs and leaves of Cedrela odorata. Their structures were elucidated on the basis of extensive spectroscopic analysis. Compounds 1 and 2 showed significant inhibitory activity against protein tyrosine phosphatase 1B (PTP1B) with the IC50 values of 13.09 and 3.93 µg/ml, respectively.