Plasma Proteomics Identify Biomarkers and Pathogenesis of COVID-19.

The coronavirus disease 2019 (COVID-19) pandemic is a global public health crisis. However, little is known about the pathogenesis and biomarkers of COVID-19. Here, we profiled host responses to COVID-19 by performing plasma proteomics of a cohort of COVID-19 patients, including non-survivors and survivors recovered from mild or severe symptoms, and uncovered numerous COVID-19-associated alterations of plasma proteins. We developed a machine-learning-based pipeline to identify 11 proteins as biomarkers and a set of biomarker combinations, which were validated by an independent cohort and accurately distinguished and predicted COVID-19 outcomes. Some of the biomarkers were further validated by enzyme-linked immunosorbent assay (ELISA) using a larger cohort. These markedly altered proteins, including the biomarkers, mediate pathophysiological pathways, such as immune or inflammatory responses, platelet degranulation and coagulation, and metabolism, that likely contribute to the pathogenesis. Our findings provide valuable knowledge about COVID-19 biomarkers and shed light on the pathogenesis and potential therapeutic targets of COVID-19.

Echovirus 11 infection induces pyroptotic cell death by facilitating NLRP3 inflammasome activation.

Echovirus 11 (ECHO 11) is a positive-strand RNA virus belonging to the genus Enterovirus of the family Picornaviridae. ECHO 11 infections can cause severe inflammatory illnesses in neonates, including severe acute hepatitis with coagulopathy. The activation of NLRP3 inflammasome is important for host defense against invading viruses, which also contributes to viral pathogenicity. However, whether and how ECHO 11 induces NLRP3 inflammasome activation remains unclear. In this study, we isolated a clinical strain of ECHO 11 from stools of an ECHO 11-infected newborn patient with necrotizing hepatitis. This virus shared 99.95% sequence identity with the previously published ECHO 11 sequence. The clinically isolated ECHO 11 can efficiently infect liver cells and strongly induces inflammation. Moreover, we showed that ECHO 11 induced IL-1ß secretion and pyroptosis in cells and mouse bone marrow-derived macrophages (BMDMs). Furthermore, ECHO 11 infection triggered NLRP3 inflammasome activation, as evidenced by cleavages of GSDMD, pro-IL-1ß and pro-caspase-1, and the release of LDH. ECHO 11 2B protein was required for NLRP3 inflammasome activation via interacting with NLRP3 to facilitate the inflammasome complex assembly. In vivo, expression of ECHO 11 2B also activated NLRP3 inflammasome in the murine liver. Besides, 2Bs of multiple EVs can also interact with NLRP3 and induce NLRP3 inflammasome activation. Together, our findings demonstrate a mechanism by which ECHO 11 induces inflammatory responses by activating NLRP3 inflammasome, providing novel insights into the pathogenesis of ECHO 11 infection.

Preclinical Study on a Novel Fluoroderivative of Dabigatran Etexilate in Animal Models.

ABSTRACT: Here, the fluorinated derivative, R1, was synthesized from the fluorinated dabigatran derivative (R0). The in vivo pharmacokinetic characteristics of orally administered R1, R0 injection, and dabigatran etexilate in rats were compared. Safety evaluation results showed no significant changes in the QRS wave or PR and QT intervals in rat lead II electrocardiograms. The possible toxicity of R1 was studied using the limit test method, and no obvious toxicity occurred in mice after the acute oral administration of R1. R1 inhibited thrombin-induced platelet aggregation in a dose-dependent manner, had an inhibitory effect on platelet aggregation induced by arachidonic acid and adenosine diphosphate, could significantly prolong prothrombin time and activated partial thromboplastin time, and increased fibrinogen levels. R1 is the optimal candidate compound from among more than 100 candidate compounds designed and synthesized by our research group. It was first selected through preliminary in vitro anticoagulant activity screening and further through in vivo mouse activity testing. A systematic pharmacodynamic study showed that R1 was superior to the raw material drug dabigatran ester; particularly, the absolute bioavailability of R1 increased by 206%, and this can overcome the low bioavailability defect associated with the marketed drug dabigatran ester. Another safety assessment of R1 indicated that there were no risks of acute poisoning in rats and cardiac toxicity in mice or rats. Therefore, R1 can be considered a new candidate anticoagulant compound with great potential and significance for further clinical research.

Study on the mechanism and reaction characteristics of metal-supported phosphogypsum as oxygen carrier in a chemical looping gasification application.

This study aimed to explore the chemical looping gasification (CLG) reaction characteristics of the metal-supported composite phosphogypsum (PG) oxygen carriers (OCs) and the thermodynamic mechanism. The FactSage 7.1 thermodynamic simulation was used to explore the oxygen release and H2S removal mechanisms. The experimental results showed that the syngas yield of CLG with PG-CuFe2O4 was more than that with PG-Fe2O320/CuO40 or PG-Fe2O330/CuO30 OC at 1023 K when the water vapor content was 0.3. Furthermore, the maximum syngas yield of the CO selectivity was 70.3% and of the CO2 selectivity was 23.8%. The H2/CO value was 0.78, and the highest carbon conversion efficiency was 91.9% in PG-CuFe2O4 at the gasification temperature of 1073 K. The metal-supported PG composite oxygen carrier was proved not only as an oxygen carrier to participate in the preparation of syngas but also as a catalyst to catalyze coal gasification reactions. Furthermore, both the experimental results and FactSage 7.1 thermodynamic analysis revealed that the trapping mechanism of H2S by composite OCs was as follows: CuO first lost lattice oxygen as an oxygen carrier to generate Cu2O, which, in turn, reacted with H2S to generate Cu2S. This study provided efficient guidance and reference for OC design in CLG.

Resource utilization of drinking water treatment aluminum sludge in green cementing materials: Hydration characteristics and hydration kinetics.

As a byproduct of water treatment, drinking water treatment aluminum sludge (DWTAS) has challenges related to imperfect treatment and disposal, which has caused potential harm to human health and the environment. In this paper, heat treatment DWTAS as a supplement cementitious material was used to prepare a green cementing material. The results show that the 800°C is considered as the optimum heat treatment temperature for DWTAS. DWTAS-800°C is fully activated after thermal decomposition to form incompletely crystallized highly active γ-Al2O3 and active SiO2. The addition of DWTAS promoted the formation of ettringite and C-(A)-S-H gel, which could make up for the low early compressive strength of cementing materials to a certain extent. When cured for 90 days, the compressive strength of the mortar with 30% DWTAS-800°C reached 44.86 MPa. The dynamic process was well simulated by Krstulovic-Dabic hydration kinetics model. This study provided a methodology for the fabrication of environmentally friendly and cost-effective compound cementitious materials and proposed a "waste-to-resource" strategy for the sustainable management of typical solid wastes.

Ultrasound-guided thermal ablation for papillary thyroid microcarcinoma: the devil is in the details.

Thermal ablation (TA) has harvested favorable outcomes in treating low-risk papillary thyroid microcarcinoma (PTMC). Preoperative assessment, intraoperative procedures and postoperative follow-up are all closely linked with the success and safety of TA on PTMC. However, many details in these aspects have not been systematically reviewed. This review firstly described the influence of preoperative assessment, especially for the risk of lymph node metastasis (LNM), as well as the molecular testing on the selection of TA for PTMC. Besides, we also summarized the experiences in treating special PTMC cases by TA, like multifocal lesions, PTMC located in the isthmus or adjacent to the dorsal capsule. At last, we discussed the follow-up strategies, the influence of the thyroid-stimulating hormone (TSH) level on the prognosis of PTMCs, and the management for recurrent cases. In conclusion, the procedures during the entire perioperative period should be standardized to improve the outcomes of TA in treating PTMC patients.

Design, synthesis, and biological evaluation of novel sulfamoylbenzamide derivatives as HBV capsid assembly modulators.

Capsid assembly modulators (CAMs) represent a novel class of antiviral agents targeting hepatitis B virus (HBV) capsid to disrupt the assembly process. NVR 3-778 is the first CAM to demonstrate antiviral activity in patients infected with HBV. However, the relatively low aqueous solubility and moderate activity in the human body halted further development of NVR 3-778. To improve the anti-HBV activity and the drug-like properties of NVR 3-778, we designed and synthesized a series of NVR 3-778 derivatives. Notably, phenylboronic acid-bearing compound 7b (EC50 = 0.83 ± 0.33 µM, CC50 = 19.4 ± 5.0 µM) displayed comparable anti-HBV activity to NVR 3-778 (EC50 = 0.73 ± 0.20 µM, CC50 = 23.4 ± 7.0 µM). Besides, 7b showed improved water solubility (328.8 µg/mL, pH 7) compared to NVR 3-778 (35.8 µg/mL, pH 7). Size exclusion chromatography (SEC) and quantification of encapsidated viral RNA were used to demonstrate that 7b behaves as a class II CAM similar to NVR 3-778. Moreover, molecular dynamics (MD) simulations were conducted to rationalize the structure-activity relationships (SARs) of these novel derivatives and to understand their key interactions with the binding pocket, which provide useful indications for guiding the further rational design of more effective anti-HBV drugs.

Critical Roles of Circular RNA in Tumor Metastasis via Acting as a Sponge of miRNA/isomiR.

Circular RNAs (circRNAs), a class of new endogenous non-coding RNAs (ncRNAs), are closely related to the carcinogenic process and play a critical role in tumor metastasis. CircRNAs can lay the foundation for tumor metastasis via promoting tumor angiogenesis, make tumor cells gain the ability of migration and invasion by regulating epithelial-mesenchymal transition (EMT), interact with immune cells, cytokines, chemokines, and other non-cellular components in the tumor microenvironment, damage the normal immune function or escape the immunosuppressive network, and further promote cell survival and metastasis. Herein, based on the characteristics and biological functions of circRNA, we elaborated on the effect of circRNA via circRNA-associated competing endogenous RNA (ceRNA) network by acting as miRNA/isomiR sponges on tumor angiogenesis, cancer cell migration and invasion, and interaction with the tumor microenvironment (TME), then explored the potential interactions across different RNAs, and finally discussed the potential clinical value and application as a promising biomarker. These results provide a theoretical basis for the further application of metastasis-related circRNAs in cancer treatment. In summary, we briefly summarize the diverse roles of a circRNA-associated ceRNA network in cancer metastasis and the potential clinical application, especially the interaction of circRNA and miRNA/isomiR, which may complicate the RNA regulatory network and which will contribute to a novel insight into circRNA in the future.

Design, Synthesis, and Evaluation of a Set of Carboxylic Acid and Phosphate Prodrugs Derived from HBV Capsid Protein Allosteric Modulator NVR 3-778.

Hepatitis B virus (HBV) capsid protein (Cp) is necessary for viral replication and the maintenance of viral persistence, having become an attractive target of anti-HBV drugs. To improve the water solubility of HBV capsid protein allosteric modulator (CpAM) NVR 3-778, a series of novel carboxylic acid and phosphate prodrugs were designed and synthesized using a prodrug strategy. In vitro HBV replication assay showed that these prodrugs maintained favorable antiviral potency (EC50 = 0.28−0.42 µM), which was comparable to that of NVR 3-778 (EC50 = 0.38 µM). More importantly, the cytotoxicity of prodrug N8 (CC50 > 256 µM) was significantly reduced compared to NVR 3-778 (CC50 = 13.65 ± 0.21 µM). In addition, the water solubility of prodrug N6 was hundreds of times better than that of NVR 3-778 in three phosphate buffers with various pH levels (2.0, 7.0, 7.4). In addition, N6 demonstrated excellent plasma and blood stability in vitro and good pharmacokinetic properties in rats. Finally, the hemisuccinate prodrug N6 significantly improved the candidate drug NVR 3-778's water solubility and increased metabolic stability while maintaining its antiviral efficacy.

Three-dimensional Ag2S cubes for switchable multi-wavelength ultrashort pulse application.

Three-dimensional (3D) materials are widely used in optoelectronics, thermodynamics and ultrafast fiber lasers because of their excellent nonlinear optical properties. Silver sulfide (Ag2S) is a kind of 3D material with a unique cubic structure and large absorption coefficient. In this paper, a double-balance detection system is used to measure the saturation absorption intensity of Ag2S as 226.6 MW cm-2and the modulation depth as 13.9%. In the ring fiber laser, Ag2S is used as a saturable absorber (SA) to obtain a stable dual-wavelength mode locking. The center wavelengths of the mode locking are 1536.9 and 1544.5 nm, and the corresponding 3 dB bandwidths are 1.3 and 1.5. nm. By adjusting the polarization controller, a tuning process from two wavelengths to multiple wavelengths is realized, and the tunable width is 13.1 nm. This phenomenon is due to the combined effect of birefringence and nonlinear effects in the cavity. To our knowledge, this is the first report of a multiplexed fiber laser with Ag2S as a SA. The emergence of this result provides a valuable reference information for the multifunctional compact fiber laser, and the formed system can be applied in the fields of fiber sensing, telecommunications and optical communication.

Clinical value of miR-135 and miR-20a combined with multi-detector computed tomography in the diagnosis of gastric cancer.

BACKGROUND: To study the clinical value of miR-135 and miR-20a combined with multi-detector computed tomography (MDCT) in the diagnosis of gastric cancer (GC). METHOD: A total of 146 patients with GC admitted to our hospital from January 2017 to June 2019 were selected and enrolled in the GC group. Another 103 patients with gastritis received in the same period were selected for the non-GC group. Besides, 95 healthy subjects who received physical examination in our hospital were selected into the healthy control group. Real-time fluorescence quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression of serum miR-135 and miR-20a for each group. MDCT was used for detecting the clinical staging map of the enrolled patients. Pearson's correlation analysis was used to analyze the correlation between serum miR-135 and miR-20a in patients with GC. The receiver operating characteristic (ROC) curve was drawn to analyze value of miR-135 and miR-20a in the diagnosis of GC. RESULTS: Compared with non-GC group and healthy control group, the levels of serum miR-135 and miR-20a increased significantly in the GC group, while no significant difference was found between non-GC group and healthy control group (P > 0.05). Analysis of the relationship with clinical characteristics showed that the expression of serum miR-135 and miR-20a in the GC group was significantly correlated with the progression of GC, TNM stage, degrees of differentiation, status of lymph node metastasis, and distant metastasis (P < 0.01). Pearson's correlation analysis results showed positive correlations between miR-135 and miR-20a (r = 0.634, P = 0.000). The ROC analysis results showed that the optimal diagnostic values of miR-135 and miR-20a for GC were 7.56 and 5.82 respectively. The area under the curve (AUC) was 0.873 and 0.793 respectively. The 95% confidence interval (CI) was 0.811-0.935 and 0.697-0.890 respectively. The sensitivity and specificity of miR-135 and miR-20a combined with MDCT in the diagnosis of GC were 90.41% and 93.20% respectively. The sensitivity of combined use was significantly higher than that of single detection (P < 0.01). CONCLUSION: There are high expression levels of serum miR-135 and miR-20a in patients with GC. A combined detection of miR-135 and miR-20a with MDCT can improve the diagnostic sensitivity of GC and improve the accuracy of the final diagnosis. Therefore, multiple combined detection is valuable in the diagnosis of GC.

Cardiac ß-adrenergic receptor activation mediates distinct and cell type-dependent changes in the expression and distribution of connexin 43.

Activation of the sympatho-ß-adrenergic receptors (ß-ARs) system is a hallmark of heart failure, leading to fibrosis and arrhythmias. Connexin 43 (Cx43) is the most abundant gap junctional protein in the myocardium. Current knowledge is limited regarding Cx43 remodelling in diverse cell types in the diseased myocardium and the underlying mechanism. We studied cell type-dependent changes in Cx43 remodelling due to ß-AR overactivation and molecular mechanisms involved. Mouse models of isoproterenol stimulation or transgenic cardiomyocyte overexpression of ß2 -AR were used, which exhibited cardiac fibrosis and up-regulated total Cx43 abundance. In both models, whereas Cx43 expression in cardiomyocytes was reduced and more laterally distributed, fibroblasts exhibited elevated Cx43 expression and enhanced gap junction communication. Mechanistically, activation of ß2 -AR in fibroblasts in vitro elevated Cx43 expression, which was abolished by the ß2 -antagonist ICI-118551 or protein kinase A inhibitor H-89, but simulated by the adenylyl cyclase activator forskolin. Our in vitro and in vivo data showed that ß-AR activation-induced production of IL-18 sequentially stimulated Cx43 expression in fibroblasts in a paracrine fashion. In summary, our findings demonstrate a pivotal role of ß-AR in mediating distinct and cell type-dependent changes in the expression and distribution of Cx43, leading to pathological gap junction remodelling in the myocardium.

Duck Tembusu Virus Nonstructural Protein 1 Antagonizes IFN-ß Signaling Pathways by Targeting VISA.

Duck Tembusu virus (DTMUV) is an emergent infectious pathogen that has caused severe disease in ducks and huge economic losses to the poultry industry in China since 2009. Previously, we showed that DTMUV inhibits IFN-ß induction early in infection; however, the mechanisms of the inhibition of innate immune responses remain poorly understood. In this study, we screened DTMUV-encoded structural and nonstructural proteins using reporter assays and found that DTMUV NS1 markedly suppressed virus-triggered IFN-ß expression by inhibiting retinoic acid-inducible gene I-like receptor signaling. Moreover, we found that DTMUV NS1 specifically interacted with the C-terminal domain of virus-induced signaling adaptor and impaired the association of retinoic acid-inducible gene I or melanoma differentiation-associated gene 5 and virus-induced signaling adaptor, thereby downregulating the retinoic acid-inducible gene I-like receptor-mediated signal transduction and cellular antiviral responses, leading to evasion of the innate immune response. Together, our findings reveal a novel mechanism manipulated by DTMUV to circumvent the host antiviral immune response.

Induction of USP25 by viral infection promotes innate antiviral responses by mediating the stabilization of TRAF3 and TRAF6.

Host pathogen-recognition receptors detect nucleic acid from invading viruses and initiate a series of signaling pathways that lead to the production of type I interferons (IFNs) and proinflammatory cytokines. Here, we found that a viral infection-induced deubiquitinase (DUB), ubiquitin-specific protease 25 (USP25) was required for host defense against RNA and DNA viruses. The activation of transcription factors IRF3 and NF-κB was impaired and the production of type I IFNs and proinflammatory cytokines was inhibited in Usp25-/- cells compared with the wild-type counterparts after RNA or DNA viruses infection. Consistently, USP25 deficient mice were more susceptible to H5N1 or HSV-1 infection compared with the wild-type mice. USP25 was associated with TRAF3 and TRAF6 after infection by RNA or DNA viruses and protected virus-induced proteasome-dependent or independent degradation of TRAF3 and TRAF6, respectively. Moreover, reconstitution of TRAF3 and TRAF6 into Usp25-/- MEFs restored virus-triggered production of type I IFNs and proinflammatory cytokines. Our findings thus reveal a previously uncovered positive feedback regulation of innate immune responses against RNA and DNA viruses by USP25.

Molecular Modeling and Design Studies of Purine Derivatives as Novel CDK2 Inhibitors.

Cyclin-dependent kinase 2 (CDK2) is a potential target for treating cancer. Purine heterocycles have attracted particular attention as the scaffolds for the development of CDK2 inhibitors. To explore the interaction mechanism and the structure⁻activity relationship (SAR) and to design novel candidate compounds as potential CDK2 inhibitors, a systematic molecular modeling study was conducted on 35 purine derivatives as CDK2 inhibitors by combining three-dimensional quantitative SAR (3D-QSAR), virtual screening, molecular docking, and molecular dynamics (MD) simulations. The predictive CoMFA model (q² = 0.743, r pred 2 = 0.991), the CoMSIA model (q² = 0.808, r pred 2 = 0.990), and the Topomer CoMFA model (q² = 0.779, r pred 2 = 0.962) were obtained. Contour maps revealed that the electrostatic, hydrophobic, hydrogen bond donor and steric fields played key roles in the QSAR models. Thirty-one novel candidate compounds with suitable predicted activity (predicted pIC50 > 8) were designed by using the results of virtual screening. Molecular docking indicated that residues Asp86, Glu81, Leu83, Lys89, Lys33, and Gln131 formed hydrogen bonds with the ligand, which affected activity of the ligand. Based on the QSAR model prediction and molecular docking, two candidate compounds, I13 and I60 (predicted pIC50 > 8, docking score > 10), with the most potential research value were further screened out. MD simulations of the corresponding complexes of these two candidate compounds further verified their stability. This study provided valuable information for the development of new potential CDK2 inhibitors.

The Type I Interferon-IRF7 Axis Mediates Transcriptional Expression of Usp25 Gene.

Viral infection or lipopolysaccharide (LPS) treatment induces expression of a large array of genes, the products of which play a critical role in host antipathogen immunity and inflammation. We have previously reported that the expression of ubiquitin-specific protease 25 (USP25) is significantly up-regulated after viral infection or LPS treatment, and this is essential for innate immune signaling. However, the mechanism behind this phenomenon is unclear. In this study, we found that viral infection-induced up-regulation of Usp25 is diminished in cells lacking interferon regulatory factor 7 (IRF7) or interferon α receptor 1 (IFNAR1) but not p65. Sendai virus- or type I interferon-induced up-regulation of Usp25 requires de novo protein synthesis of IRF7. Furthermore, IRF7 directly binds to the two conserved IRF binding sites on the USP25 promoter to drive transcription of Usp25, and mutation of these two sites abolished Sendai virus-induced IRF7-mediated activation of the USP25 promoter. Our study has uncovered a previously unknown mechanism by which viral infection or LPS induces up-regulation of USP25.

Design, synthesis and antibreast cancer MCF-7 cells biological evaluation of heterocyclic analogs of resveratrol.

A new series of resveratrol heterocyclic analogs (4a-m) were designed and synthesized, and their inhibitiory effects on MCF-7 cells were evaluated to investigate structure-activity relationship. The effects of these analogs on human breast cancer MCF-7 cells were also determined. Results showed that MCF-7 cells could be inhibited more potently by these analogs than by resveratrol (IC50 = 80.0 µM). Among the analogs, compounds 4c, 4e, and 4k showed a significantly higher activity (IC50 = 42.7, 48.1, and 43.4 µM) than resveratrol. Furthermore, the derivatives without additional heterocyclic structure in the 4'-OH position exhibited a more potent activity than that with addition heterocyclic structure. In addition, docking simulation was performed to adequately position compound 4c in a human F1-ATPase active site to determine a probable binding model. These heterocyclic analogs could be effective candidates for the chemoprevention of human breast cancer.

The Anti-Inflammatory Properties of Citrus wilsonii Tanaka Extract in LPS-Induced RAW 264.7 and Primary Mouse Bone Marrow-Derived Dendritic Cells.

'Zhique' (Citrus wilsonii Tanaka) is a traditional Chinese medicine. Its fruits have been used to treat inflammation-related symptoms, such as cough and sputum, though the underlying mechanism remains poorly understood. The aim of this study was to investigate the anti-inflammatory properties of 'Zhique' pulp extract (ZQE) in lipopolysaccharide (LPS)-induced RAW 264.7 macrophages and primary mouse bone marrow-derived dendritic cells (BMDCs). The flavonoid profiles of the ZQE were determined by high performance liquid chromatography. The anti-inflammatory activity was evaluated in LPS-induced inflammatory RAW 264.7 macrophages and BMDCs through enzyme-linked immunosorbent assay, quantitative real-time polymerase chain reaction, and Western blot assays. Naringin was a predominant flavonoid occurring in ZQE, followed by eriocitrin, hesperidin, neohesperidin, rhoifolin, naringenin, and poncirin. ZQE exhibited a very low cytotoxicity in LPS-stimulated RAW 264.7 macrophages. Meanwhile, ZQE significantly inhibited the production of prostaglandins E2 and secretion of cyclooxygenase-2 protein in LPS-stimulated RAW 264.7 macrophages, and markedly suppressed the mRNA expression of inflammatory mediators, such as cyclooxygenase-2, tumor necrosis factor alpha, interleukin-1 beta (IL-1ß), and IL-6 in LPS-induced RAW 264.7 macrophages and/or primary BMDCs. The ZQE inhibited the inflammatory responses in RAW 264.7 macrophages and BMDCs triggered by LPS. The results suggested that 'Zhique' has a high potential as a novel therapeutic agent to treat chronic inflammatory diseases.

Molecular design, synthesis and anticoagulant activity evaluation of fluorinated dabigatran analogues.

In the present study, a series of unreported fluorinated dabigatran analogues, which were based on the structural scaffold of dabigatran, were designed by computer-aided simulation. Fifteen fluorinated dabigatran analogues were screened and synthesized. All target compounds were characterized by (1)H NMR, (13)C NMR, (19)F NMR and HRMS. According to the preliminary screening results of inhibition ratio, eleven analogues (inhibition ratio >90%) were evaluated for antithrombin activity in vitro (IC50). The test results expressed that all the analogues showed effective inhibitory activities against thrombin. Especially, compounds 8f, 8k and 8o, with IC50 values of 1.81, 3.21 and 2.16nM, respectively, showed remarkable anticoagulant activities which were in the range of reference drug dabigatran (IC50=1.23nM). Moreover, compounds 8k and 8o were developed to investigate their anticoagulant activities in vivo. In those part, compound 8o exhibited a fairly strong inhibitory action for arteriovenous thrombosis with inhibition ratio of 84.66%, which was comparable with that of dabigatran (85.07%). Docking simulations demonstrated that these compounds could act as candidates for further development of novel anticoagulant drugs.

Molecular modeling studies, synthesis and biological evaluation of dabigatran analogues as thrombin inhibitors.

In this work, 48 thrombin inhibitors based on the structural scaffold of dabigatran were analyzed using a combination of molecular modeling techniques. We generated three-dimensional quantitative structure-activity relationship (3D-QSAR) models based on three alignments for both comparative molecular field analysis (CoMFA) and comparative molecular similarity index analysis (CoMSIA) to highlight the structural requirements for thrombin protein inhibition. In addition to the 3D-QSAR study, Topomer CoMFA model also was established with a higher leave-one-out cross-validation q(2) and a non-cross-validation r(2), which suggest that the three models have good predictive ability. The results indicated that the steric, hydrophobic and electrostatic fields play key roles in QSAR model. Furthermore, we employed molecular docking and re-docking simulation explored the binding relationship of the ligand and the receptor protein in detail. Molecular docking simulations identified several key interactions that were also indicated through 3D-QSAR analysis. On the basis of the obtained results, two compounds were designed and predicted by three models, the biological evaluation in vitro (IC50) demonstrated that these molecular models were effective for the development of novel potent thrombin inhibitors.