Identification of natural product inhibitors of PTP1B based on high-throughput virtual screening strategy: In silico, in vitro and in vivo studies.

Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of the insulin signaling pathway, which is a potential therapeutic target for the treatment of type 2 diabetes mellitus (T2DM). In this study, we identified several PTP1B inhibitors with high activity by using high-throughput virtual screening and in vitro enzyme inhibition activity verification strategies. Among them, baicalin was first reported as a selective mixed inhibitor of PTP1B, with IC50 value of 3.87 ± 0.45 µM, and its inhibitory activity against homologous proteins TCPTP, SHP2, and SHP1 exceeded 50 µM. Molecular docking study found that baicalin and PTP1B could bind stably, and revealed that baicalin had a dual inhibitory effect. Cell experiments showed that baicalin was almost non-toxic and could significantly enhance the phosphorylation of IRS-1 in C2C12 myotube cells. Animal experiments showed that baicalin could significantly reduce the blood sugar of STZ-induced diabetic mice models, and had a liver protective effect. In conclusion, this study can provide new ideas for the development of PTP1B selective inhibitors.

CX08005, a Protein Tyrosine Phosphatase 1B Inhibitor, Attenuated Hepatic Lipid Accumulation and Microcirculation Dysfunction Associated with Nonalcoholic Fatty Liver Disease.

Nonalcoholic fatty liver disease (NAFLD) is one of the common metabolic diseases characterized by hepatic lipid accumulation. Insulin resistance and microcirculation dysfunction are strongly associated with NAFLD. CX08005, an inhibitor of PTP1B with the IC50 of 0.75 ± 0.07 µM, has been proven to directly enhance insulin sensitivity. The present study aimed to investigate the effects of CX08005 on hepatic lipid accumulation and microcirculation dysfunction in both KKAy mice and diet-induced obesity (DIO) mice. Hepatic lipid accumulation was evaluated by hepatic triglyceride determination and B-ultrasound analysis in KKAy mice. Insulin sensitivity and blood lipids were assessed by insulin tolerance test (ITT) and triglyceride (TG)/total cholesterol (TC) contents, respectively. In addition, the hepatic microcirculation was examined in DIO mice by in vivo microscopy. The results showed that CX08005 intervention significantly reduced the TG and echo-intensity attenuation coefficient in the livers of KKAy mice. Furthermore, we found that CX08005 treatment significantly enhanced insulin sensitivity, and decreased plasma TG and/or TC contents in KKAy and DIO mice, respectively. In addition, CX08005 treatment ameliorated hepatic microcirculation dysfunction in DIO mice, as evidenced by increased RBCs velocity and shear rate of the blood flow in central veins and in the interlobular veins, as well as enhanced rate of perfused hepatic sinusoids in central vein area. Additionally, CX08005 administration decreased the adhered leukocytes both in the center veins and in the hepatic sinusoids area. Taken together, CX08005 exhibited beneficial effects on hepatic lipid accumulation and microcirculation dysfunction associated with NAFLD, which was involved with modulating insulin sensitivity and leukocyte recruitment, as well as restoration of normal microcirculatory blood flow.

Design, synthesis and evaluation of phenoxyacetic acid-based PTP1B inhibitors / 药学学报

Protein tyrosine phosphatase (PTP) 1B is a potential therapeutic target for type 2 diabetes. Phosphotyrosine (pTyr) mimetics still dominate the currently available PTP1B inhibitors. The phenoxyacetic acid moiety was taken as a pTyr mimetic herein and phenoxyacetic acid-based compounds 2a-2g and 3a-3c were designed. Among them, compounds 2a-2g exhibited potent inhibition against PTP1B, and compound 2g showed an IC50 of 0.42 μmol·L-1 against PTP1B. Compound 2f exhibited pharmacological profiles similar to that of rosiglitazone, and could improve the insulin sensitivity and the serum total cholesterol level. The results suggest that PTP1B inhibitors might be effective in treating type 2 diabetes as well as associated metabolic syndromes.

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.

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.

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.

Screening and tissue distribution of protein tyrosine phosphatase 1B inhibitors in mice following oral administration of Garcinia mangostana L. ethanolic extract.

Garcinia mangostana L. (mangosteen) is a tropical fruit that is rich in xanthones and is thought to have an anti-diabetic effect. In this study, we screened for the xanthones in mangosteen that could inhibit the activity of protein tyrosine phosphatase 1B (PTP1B), an enzyme that is targeted by diabetic drugs. Mice were orally administered mangosteen extract and blood samples were screened for the presence of PTP1B-interacting xanthones. Six such compounds (1-6) were identified by UF-HPLC-QTOF-MS and their inhibition against PTP1B was confirmed by activity assay. Among them, garcinone E (5) was found to be the most effective PTP1B inhibitor (IC50 = 0.43 µM). Tissue distribution analysis showed that the six compounds were distributed in eleven tissues, including the liver, muscle, fat, stomach, large intestine, small intestine, brain, kidney, heart, lung, and spleen. The results demonstrated that mangosteen might be a promising source of natural compounds with high PTP1B-inhibitory activity.

Role of protein tyrosine phosphatase 1B inhibitor in central insulin resistance and associated cognitive deficits.

BACKGROUND: Protein tyrosine phosphatase 1B (PTP1B) inhibitors are potential candidates for the treatment of peripheral insulin resistance and diabetes mellitus. Similar to peripheral action within the brain also, PTP1B activation impairs insulin signaling pathways. Activation of PTP1B in brain also accentuates neuroinflammation, oxidative stress and decreases neurotrophic factors in various brain dysfunctions including cognitive decline. OBJECTIVES: The main objective of our study was to elucidate the role of alendronate, a potent PTP1B inhibitor (blood brain barrier crossing bisphosphonate) in central insulin resistance and associated memory deficits. METHODOLOGY: To induce central insulin resistance, streptozotocin (3 mg/kg) intracerebroventricular (ICV) was administered in two alternate days (1st and 3rd). After 21 days, memory was assessed via using the passive avoidance and Morris water maze paradigm. At the end of behavioral studies, animals were sacrificed to assess a variety of biochemical and molecular parameters in the hippocampus and cerebral cortex region of the brain. Treatment drug alendronate (3 mg/kg/day, p.o) and standard drug donepezil (3 mg/kg/i.p.) were administered from the 3rd day of STZ administration till the end of the study. Inhibition of PTP1B activates phosphoinsotide-3 kinase (PI3 K) (down-stream regulator of insulin signaling pathway).Thus, to illuminate the mechanism of action of alendronate, PI3 K inhibitor, wortmannin was administered in presence of alendronate in one group. RESULTS: Administration of alendronate to ICV streprozotocin treated rats resulted in modulation of the insulin signaling pathway and associated behavioral, biochemical and molecular changes in central insulin resistance. However, the protective effect of alendronate was entirely vanished when it was administered in the presence of wortmannin. CONCLUSION: Alendronate can be an important treatment strategy in central insulin signaling pathway dysfunction and associated cognitive deficits. Protective effect of alendronate is via modulation of PI3-K/Akt signaling pathway.

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.

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.

Antidiabetic activity in vitro and in vivo of BDB, a selective inhibitor of protein tyrosine phosphatase 1B, from Rhodomela confervoides.

BACKGROUND AND PURPOSE: Protein tyrosine phosphatase (PTP) 1B (PTP1B) plays a critical role in the regulation of obesity, Type 2 diabetes mellitus and other metabolic diseases. However, drug candidates exhibiting PTP1B selectivity and oral bioavailability are currently lacking. Here, the enzyme inhibitory characteristics and pharmacological benefits of 3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)-1,2-benzenediol (BDB) were investigated in vitro and in vivo. EXPERIMENTAL APPROACH: Surface plasmon resonance (SPR) assay was performed to validate the direct binding of BDB to PTP1B, and Lineweaver-Burk analysis of the enzyme kinetics was used to characterise the inhibition by BDB. Both in vitro enzyme-inhibition assays and SPR experiments were also conducted to study the selectivity exhibited by BDB towards four other PTP-family proteins: TC-PTP, SHP-1, SHP-2, and LAR. C2C12 myotubes were used to evaluate cellular permeability to BDB. Effects of BDB on insulin signalling, hypoglycaemia and hypolipidaemia were investigated in diabetic BKS db mice, after oral gavage. The beneficial effects of BDB on pancreatic islets were examined based on insulin and/or glucagon staining. KEY RESULTS: BDB acted as a competitive inhibitor of PTP1B and demonstrated high selectivity for PTP1B among the tested PTP-family proteins. Moreover, BDB was cell-permeable and enhanced insulin signalling in C2C12 myotubes. Lastly, oral administration of BDB produced effective antidiabetic effects in spontaneously diabetic mice and markedly improved islet architecture, which was coupled with an increase in the ratio of ß-cells to α-cells. CONCLUSION AND IMPLICATIONS: BDB application offers a potentially practical pharmacological approach for treating Type 2 diabetes mellitus by selectively inhibiting PTP1B.

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.

Design, synthesis, biological evaluation and molecular dynamics studies of 4-thiazolinone derivatives as protein tyrosine phosphatase 1B (PTP1B) inhibitors.

Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of insulin signaling pathway, and more and more studies have shown that it is a potential target for the treatment of type 2 diabetes mellitus (T2DM). In this study, 17 new 4-thiazolinone derivatives were designed and synthesized as novel PTP1B inhibitors, and ADMET prediction confirmed that these compounds were to be drug-like. In vitro enzyme activity experiments were performed on these compounds, and it was found that a plurality of compounds had good inhibitory activity and high selectivity against PTP1B protein. Among them, compound 7p exhibited the best inhibitory activity with an IC50 of 0.92 µM. The binding mode of compound 7p and PTP1B protein was explored, revealing the reason for its high efficiency. In addition, molecular dynamics simulations for the PTP1BWT and PTP1Bcomp#7p systems revealed the effects of compound 7p on PTP1B protein at the molecular level. In summary, the study reported for the first time that 4-thiazolinone derivatives as a novel PTP1B inhibitor had good inhibitory activity and selectivity for the treatment of T2DM, providing more options for the development of PTP1B inhibitors. AbbreviationsBBBblood-brain barrierCDC25Bcell division cycle 25 homolog BCYP2D6Cytochrome P450 2D6 bindingDCCMdynamic cross-correlation mapDSDiscovery StudioH bondhydrogen bondHIAhuman intestinal absorptionLARleukocyte antigen-related phosphataseMDmolecular dynamicsMEG-2maternal-effect germ-cell defective 2MM-PBSAmolecular mechanics Poisson Boltzmann surface area)PCAprincipal component analysisPDBProtein Data BankpNPPp-nitrophenyl phosphatePPBplasma protein bindingPTP1Bprotein tyrosine phosphotase 1BRMSDroot mean square deviationRMSFroot mean square fluctuationSHP-1src homologous phosphatase-1SHP-2src homologous phosphatase-2SPCsingle-point chargeTCPTPT cell protein tyrosine phosphataseT2DMType 2 diabetes mellitusVDWvan der WaalsCommunicated by Ramaswamy H. Sarma.

Synthesis and biological evaluation of tryptophan-derived rhodanine derivatives as PTP1B inhibitors and anti-bacterial agents.

Several series of novel tryptophan-derived rhodanine derivatives were synthesized and identified as potential competitive PTP1B inhibitors and antibacterial agents. Among the compounds studied, 10b was found to have the best in vitro inhibition activity against PTP1B (IC50 = 0.36 ±â€¯0.02 µM). In addition, the compounds also showed potent inhibition against other PTPs, especially CDC25B. Molecular docking analysis demonstrated that compounds 7c and 10b could occupy both the catalytic site and the adjacent pTyr binding site simultaneously. The compounds also showed higher levels of activity against gram-positive strains, the gram-negative strain Escherichia coli 1924, and multidrug-resistant gram-positive bacterial strains. Compounds 7c, 8c, 9e, 10a, and 10c had comparable or more potent antibacterial activity than the positive controls.

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.

Toward a treatment of diabesity: In vitro and in vivo evaluation of uncharged bromophenol derivatives as a new series of PTP1B inhibitors.

Protein tyrosine phosphatase 1B (PTP1B) has been considered as a validated biological target for type 2 diabetes treatment, but past endeavors to develop inhibitors of PTP1B into drugs have been unsuccessful. Two challenging aspects are selective inhibition and cell permeability. A structure-based strategy was employed to develop uncharged bromophenols as a new series of PTP1B inhibitors. The most potent compound 22 (LXQ46) inhibited PTP1B with an IC50 value of 0.190 µM, and showed remarkable selectivity over other protein tyrosine phosphatases (PTPs, 20-200 folds). In the SPR study, increasing concentrations of compound 22 led to concentration-dependent increases in binding responses, indicating that compound 22 could bind to the surface of PTP1B via noncovalent means. By treating insulin-resistant C2C12 myotubes with compound 22, enhanced insulin and leptin signaling pathways were observed. Long-term oral administration of compound 22 reduced the blood glucose level of diabetic BKS db mice. The glucose tolerance tests (OGTT) and insulin tolerance tests (ITT) in BKS db mice showed that oral administration of compound 22 could increase insulin sensitivity. In addition, long-term oral administration of compound 22 could protect mice from obesity, which was not the result of toxicity. Our pharmacokinetics results from the rat-based assays showed that orally administered compound 22 was absorbed rapidly from the gastrointestinal tract, extensively distributed to the tissues, and rapidly eliminated from the body. All these results indicate that compound 22 could serve as a qualified agent to treat type II diabetes.

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.

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.

Hypoglycemic mechanism of a novel proteoglycan, extracted from Ganoderma lucidum, in hepatocytes.

Protein tyrosine phosphatase 1 B (PTP1B) is one of main causes involved in type 2 diabetes, it dephosphorylates insulin receptor substrate (IRS) and dysregulates insulin signaling pathway, thus inducing insulin resistance. Our previous work first reported that FYGL, a neutral hyperbranched proteoglycan ingredient extracted from Ganoderma lucidum, has hypoglycemic activity in vivo and inhibitory potency on PTP1B in vitro, but the underlying mechanism was still unclear. In this study, we sought to investigate effects of FYGL on insulin signaling pathway involved with PTP1B as the targeting point in hepatocytes. We found that FYGL inhibited overexpression of PTP1B in liver tissues of ob/ob mice and HepG2 cells, significantly improved the phosphorylation of IRS1 on tyrosine residues, activated phosphatidylinositol-3 kinase (PI3K)/protein kinase B (Akt) cascades and increased phosphorylation of glycogen synthesis kinase-3ß (GSK3ß), finally enhanced insulin-stimulated glycogen synthesis in HepG2 cells and decreased blood glucose in insulin resistance model mice. Our study clearly illustrated the hypoglycemic mechanism of a novel proteoglycan possibly used in type 2 diabetes management in vivo.