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.

Design, synthesis, biological activity and molecular dynamics studies of specific protein tyrosine phosphatase 1B inhibitors over SHP-2.

Over expressing in PTPN1 (encoding Protein tyrosine phosphatase 1B, PTP1B), a protein tyrosine phosphatase (PTP) that plays an overall positive role in insulin signaling, is linked to the pathogenesis of diabetes and obesity. The relationship between PTP1B and human diseases exhibits PTP1B as the target to treat these diseases. In this article, small weight molecules of the imidazolidine series were screened from databases and optimized on silicon as the inhibitors of PTP1B based on the steric conformation and electronic configuration of thiazolidinedione (TZD) compounds. The top three candidates were tested using an in vitro biological assay after synthesis. Finally, we report a novel inhibitor, Compound 13, that specifically inhibits PTP1B over the closely related phosphatase Src homology 2 (SH2) domain-containing phosphatase 2 (SHP-2) at 80 µΜ. Its IC50 values are reported in this paper as well. This compound was further verified by computer analysis for its ability to combine the catalytic domains of PTP1B and SHP-2 by molecular dynamics (MD) simulations.

Anti-inflammatory effect of soyasaponins through suppressing nitric oxide production in LPS-stimulated RAW 264.7 cells by attenuation of NF-κB-mediated nitric oxide synthase expression.

The anti-inflammatory properties of soyasaponins (especially soyasaponins with different chemical structures) have scarcely been investigated. We investigated the inhibitory effects of five structural types of soyasaponins (soyasaponin A(1), A(2), I and soyasapogenol A, B) on the induction of nitric oxide (NO) and inducible NO synthase (iNOS) in murine RAW 264.7 cells activated with lipopolysaccharide (LPS). Soyasaponin A(1), A(2) and I (25-200 µg/mL) dose-dependently inhibited the production of NO and tumor necrosis factor α (TNF-α) in LPS-activated macrophages, whereas soyasapogenol A and B did not. Furthermore, soyasaponin A(1), A(2) and I suppressed the iNOS enzyme activity and down-regulated the iNOS mRNA expression both in a dose-dependent manner. The reporter gene assay revealed that soyasaponin A(1), A(2) and I decreased LPS-induced nuclear factor kappa B (NF-κB) activity. Soyasaponin A(1), A(2) and I exhibit anti-inflammatory properties by suppressing NO production in LPS-stimulated RAW 264.7 cells through attenuation of NF-κB-mediated iNOS expression. It is proposed that the sugar chains present in the structures of soyasaponins are important for their anti-inflammatory activities. These results have important implication for using selected soyasaponins towards the development of effective chemopreventive and anti-inflammatory agents.

1-(4-Methoxy-phen-yl)imidazolidine-2,4-dione.

In the title compound, C(10)H(10)N(2)O(3), the dihedral angle between the benzene and imidazolidine rings is 6.0 (4)°, consistent with an essentially planar mol-ecule. In the crystal, inter-molecular N-H⋯O hydrogen bonding between centrosymmetrically related mol-ecules leads to loosely associated dimeric aggregates. These are connected into a three-dimensional network by C-H⋯O inter-actions, as well as π-π inter-actions [centroid-centroid distances = 3.705 (3) and 3.622 (3) Å] between the imidazolidine and benzene rings.

Synthesis, biological evaluation and 3D-QSAR studies of imidazolidine-2,4-dione derivatives as novel protein tyrosine phosphatase 1B inhibitors.

Protein tyrosine phosphatase 1B (PTP1B) plays a vital role in the regulation of insulin sensitivity and dephosphorylation of the insulin receptor, so PTP1B inhibitors may be potential agents to treat type 2 diabetes. In this work, a series of novel imidazolidine-2,4-dione derivatives were designed, synthesized and assayed for their PTP1B inhibitory activities. These compounds exhibited potent activities with IC50 values at 0.57-172 µM. A 3D-QSAR study using CoMFA and CoMSIA techniques was carried out to explore structure activity relationship of these molecules. The CoMSIA model was more predictive with q(2) = 0.777, r(2) = 0.999, SEE = 0.013 and r(2)pred = 0.836, while the CoMFA model gave q(2) = 0.543, r(2) = 0.998, SEE = 0.029 and r(2)pred = 0.754. The contour maps derived from the best CoMFA and CoMSIA models combined with docking analysis provided good insights into the structural features relevant to the bioactivity, and could be used in the molecular design of novel imidazolidine-2,4-dione derivatives.

Detection of the high-pathogenicity island of Yersinia enterocolitica in enterotoxigenic and enteropathogenic E.coli strains.

OBJECTIVE: To describe the distribution of high-pathogenicity island (HPI) of Yersinia enterocolitica in enterotoxingenic E.coli (ETEC) and enteropathogenic E.coli (EPEC), and to understand the structure and function of HPI. METHODS: PCR was used to detect irp2, fyua and asn-intB genes with subsequent sequence analysis of these genes. Nucleic acid in situ hybridization was employed to identify the specificity of irp2 and fyua. RESULTS: Thirty irp2-positive strains were isolated from 93 ETEC strains and 3 from 10 EPEC strains, making a positivity rate of 32.25% and 30% respectively, and the positivity rates of fyua gene in ETEC and EPEC were 21.51% and 30% respectively. In most of these positive isolates, HPI was bordered by an asn tRNA locus, as in Yersinia sp. CONCLUSIONS: This study demonstrates that the high positivity rate of HPI of Yersinia enterocolitica in ETEC and EPEC strains may be crucial to the virulence changes, virulence evolution and virulence regulation in E.coli.

Expression and purification of invasion plasmid antigen C of Shigella flexneri.

OBJECTIVE: To induce the expression of and purify invasion plasmid antigen C (IpaC) of Shigella flexneri for studying the pathogenesis of Shigella flexneri. METHODS: Prokaryotic expression plasmid pET32a-ipaC was constructed and incorporated into E.coli BL21 (lambda DE3). The engineered bacteria were induced by isopropyl-beta-D-thiogalactopyranoside (IPTG) to express IpaC, which was identified by SDS-PAGE and purified by QIA expressionist system. RESULTS: SDS-PAGE presented a band for the fusion protein with the relative molecular mass of approximately 63 000, whose expression reached up to 11% of the total protein of E.coli BL21(lambda DE3). After proper purification, a purity of the target fusion protein of over 90% was achieved when the concentration of imidazole for elution was 350 mmol/L. CONCLUSION: The recombinant plasmid pET32a-ipaC has been stably and efficiently expressed in E.coli BL21 (lambda DE3), and QIA expressionist purification system proves to be simple and highly efficient.

Design and synthesis of imidazolidine-2,4-dione derivatives as selective inhibitors by targeting protein tyrosine phosphatase-1B over T-cell protein tyrosine phosphatase.

Owing to its special role as a negative regulator in both insulin and leptin signaling, protein tyrosine phosphatase-1B (PTP1B) has drawn considerable attention as a target for treating type 2 diabetes and obesity. It, however, is a great challenge to discover inhibitors specific to each PTP due to the highly homologous. In this study, a series of compounds were discovered to inhibit PTP1B based on imidazolidine-2,4-dione by means of 'core hopping'. A selective PTP1B inhibitor (comp#h) was identified, and molecular dynamics simulation and binding free energy calculation were carried out to propose the most likely binding mode of comp#h with PTP1B. The findings reported here may provide a new strategy in discovering selective and effective inhibitors for treating diabetes.

Glutathione S-transferase gene polymorphisms and risk of gastric cancer in a Chinese population.

AIM: The potential role of GSTM1, GSTT1 and GSTP1 polymorphisms in risk of gastric cancer in Chinese was studied. METHODS: We collected 194 gastric cancers by pathologic examination and 412 controls from southern China during January 2007 to January 2011. Genotyping was based upon duplex polymerase-chain-reaction with the PCR-CTPP method. RESULTS: Individuals carrying null GSTM1 and GSTT1 had 1.49 and 1.96 fold risk sof gastric cancer when compared with respective non-null genotypes. We also found a non-significant 37% excess risk of gastric cancer among carriers of GSTP1 1b/1b genotype when compared with 1a/1a genotype (OR=1.37, 95% CI=0.81-2.25). The combination of null/null GSTM1 and GSTT1 genotypes showed higher increased risk of gastric cancer (OR=3.17, 95% CI=1.68-4.21). Moreover, cancers in ever smokers and ever drinkers were observed to be strongly associated with null GSTM1 and GSTT1, and a significant cancer risk was observed in positive H.pylori infection individuals with null GSTT1. CONCLUSION: Our study provided evidence that genetic deletion of GSTM1 and GSTT1 may contribute to increased susceptibility to gastric cancer in our Chinese population, while the GSTP1a/b polymorphism may not.

[A field trial for evaluating the safety of recombinant human interferon alpha-2b for nasal spray].

OBJECTIVE: To evaluate the safety of recombinant human interferon alpha-2b for nasal spray for the prevention of SARS and other upper respiratory viral infections. METHODS: Field epidemiologic evaluation was conducted, the design was randomized and had a synchronously parallel control group. In the study, the drugs were given for five days and all subjects were followed up for ten days. RESULTS: During the period of using interferon, body temperature of the experimental group was normal compared to the control group. Experimental group had more influenza-like symptoms than the control group (P < 0.05), such as headache (4.83%-7.09%), dizziness (7.17%-11.63%), lassitude (8.55%-15.06%), muscular soreness (4.43%-7.09%), pharynx dryness (12.10%-17.85%), angina (6.25%-8.72%), abdominal pain (2.30%-5.50%) and diarrhea (2.45%-5.66%). Most of side effects reached their peak with in the first 3 days. Except for pharynx dryness, the incidences of all other side effects declined after completion of the use of the trial drug, and incidences of some symptoms in experimental group were lower than those of the control group. There were no significant differences in the symptoms of cough and expectoration between the experimental group and the control group. The incidence of exanthem in the control group was significantly higher than that in the experimental group. The side effect of bloody nasal mucus was not observed in experimental group, which had been reported by other authors in several volunteer studies. CONCLUSION: Using recombinant human interferon alpha-2b for nasal spray could lead to some influenza-like symptoms, however, all those symptoms were mild , reversible, and relieved after completion of the use of the trial drug. No serious side effects were found during the period of following up. The authors conclude that the drug is safe.

[Study on the prevalence of the "high pathogenicity island" of Yersinia enterocolitica WA in Enterotoxigenic, Enteropathogenic and Enteroaggregative E. coli strains].

OBJECTIVE: To detect the "high pathogenicity island" of Yersinia enterocolitica WA in E. coli and the to provide evidence for theory base of bacterial evolution process and the different structures in different E. coil. METHODS: Polymerase chain reaction (PCR), nucleic acid hybridization in situ were used to detect and identify HPI. DNA sequencing was used to compare the gene homology of HPI among E. coli with Yersinia enterocolitica (Yen). RESULTS: The irp2 and fyua genes of Yen HPI were investigated in E. coli strains. Among them, 30 strains were isolated from 93 Enterotoxigenic E. coli (ETEC) strains and 3 strains were positive in 10 strains Enteropathogenic (EPEC). HPI was also detected in Enteroaggregative E. coli (EAggEC) strain. In most of these isolates, HPI was bordered by an asntRNA locus, as in Yersinia sp. Through sequential comparison, the gene sequence homology was higher between in EPEC and EAggEC than ETEC and Yersinia enterocolica. CONCLUSIONS: ETEC, EPEC and EAggEC were pathogenicity bacterias and many of them harboring HPI of Yen and the HPI had the same position in E. coli chromosome as Yersinia enterocolitica but the diversity of structure and sequence in these E. coli might suggest that the HPI of these different serotype E. coli were from different ancient bacterias. At the same time, the high positivity rate of HPI in E. coli might be crucial to virulence change, virulence evolution and virulence regulation in E. coli.