In prostate cancer (PCa), the TMPRSS2-ERG fusion gene drives aberrant activation of androgen receptor (AR) signaling, while TMPRSS2 protease activity contributes to remodeling the tumor microenvironment. Targeting TMPRSS2 can suppress cancer metastasis and represents a potential therapeutic strategy for castration-resistant prostate cancer (CRPC). This study aimed to screen and identify promising TMPRSS2-binding lead candidates via integrated virtual screening and experimental validation. Screening of the ChemDiv, ChemBridge, and TargetMol compound libraries yielded 53 hit compounds. Surface plasmon resonance (SPR) assays were subsequently performed to evaluate binding affinities. Six candidate compounds (15, 26, 29, 31, 41, and 42) exhibited higher affinity for TMPRSS2 compared to the reference inhibitor Nafamostat (KD = 6.09 × 10-5 M). Among them, compound 26 showed the highest affinity (KD = 3.88 × 10-6 M). Subsequent in vitro inhibition assays using LNCaP clone FGC cells demonstrated that compound 26 possessed the strongest anti-proliferative activity (IC50 = 10.95 μM), indicating its therapeutic potential against PCa. Confocal microscopy showed apparent reduced TMPRSS2 staining after 24 h compound 26 treatment, implying potential TMPRSS2 modulation. Further mechanistic insights were gained through molecular dynamics (MD) simulations, alanine scanning mutagenesis, quantum mechanics/molecular mechanics (QM/MM) calculations, and dynamical cross-correlation matrix (DCCM) analysis, which revealed specific ligand-protein interactions in the compound 26-TMPRSS2 complex and reinforced the reliability of our findings. Collectively, these results identify compound 26 as a promising TMPRSS2-binding lead candidate, providing a solid foundation for further biochemical verification and structural optimization.

Influenza A virus continues to pose a significant global health threat, causing seasonal epidemics and occasional pandemics. Viral transcription and replication rely on the heterotrimeric polymerase complex where the PB2 subunit initiates RNA synthesis through binding to the host mRNA cap structure. In this study, we began with a structure-activity relationship analysis of the pioneering PB2 inhibitor VX-787. Through computer-aided drug design, combined with considerations of molecular docking scores, ADMET property predictions, and a prodrug esterification strategy, we ultimately designed eight novel compounds. Cytopathic effect assays demonstrated that all compounds exhibited superior inhibitory activity against both H1N1 and H3N2 strains compared to oseltamivir acid. In particular, compounds 11 and 15 displayed nanomolar-level activity against H1N1, while compound 18 showed activity against H3N2 superior to that of VX-787. These findings propose a rational design strategy that may offer new avenues for addressing the resistance and metabolic limitations associated with VX-787 and hold potential for advancing the development of next-generation PB2-targeted anti-influenza therapeutics.

COVID-19, caused by SARS-CoV-2, is a highly contagious disease with significant transmissibility and pathogenicity. The main protease of SARS-CoV-2 (Mpro or 3CLpro) is crucial for viral replication, making it a key therapeutic target. Nirmatrelvir, a promising Mpro inhibitor, contains a trifluoroacetyl group in its P4 fragment, which presents opportunities for further optimization. This study aims to enhance the inhibitory activity of nirmatrelvir through structural modification of the P4 fragment. Using a computer-aided drug design (CADD) approach, 11 novel compounds were identified based on molecular docking scores, binding free energy, predicted ADMET properties, structural diversity, synthetic feasibility, and inhibitory activity. IC50 measurements and molecular dynamics (MD) simulations demonstrated significant inhibitory potential for most compounds, with IC50 values ranging from 0.0435-0.9989 μM. Notably, compounds 2-5a and 2-5f exhibited inhibitory activity against SARS-CoV-2 Mpro comparable to that of nirmatrelvir. These findings offer valuable insights for the development of anti-SARS-CoV-2 therapeutics.

Human glutaminyl cyclase (hQC) has emerged as a critical target in Alzheimer's disease (AD) due to its role in generating pyroglutamate-modified amyloid (3 (pE-A(3). In this study, 13 compounds were designed as target compounds by fragment-based drug design (FBDD) and molecular docking, and subsequently assessed for druglike properties and predicted inhibitory activities through ADMET analysis and Uni-QSAR modeling. Target compounds were synthesized via systematic multi-step approaches, with acceptable yields. The in vitro hQC enzyme inhibition assay revealed that all target compounds exhibited superior inhibitory activity compared to the reference compound PBD150 (140.50 f 0.93 nM), with compounds A3 (3.36 f 0.90 nM), A4 (3.20 f 1.15 nM), B1 (3.99 f 0.99 nM), and B2 (3.64 f 0.98 nM) standing out for further investigation. Further, molecular dynamics (MD) simulations were conducted on compounds A3, A4, B1, and B2, revealing the stability and binding interactions of the compounds within the hQC active site over a 200 ns simulation period. Then, the results of binding free energy calculations validated the superior binding affinities of compounds A3, A4, B1, and B2 than PBD150. These findings highlight A3, A4, B1, and B2 as promising hQC inhibitors, offering insights for AD drug development.

The COVID-19 pandemic, caused by SARS-CoV-2, has posed significant global health challenges and there is an urgent need for effective therapeutic agents. The main protease (Mpro) plays a crucial role in viral replication, making it an attractive target for the development of antiviral drugs. In this study, by screening over 8.06 million compounds obtained from Enamine, Vitas-M, ChemDiv, and TargetMol (USA) databases, 52 top-ranking compounds were obtained as promising candidates through molecular docking, followed by Uni-QSAR modeling and ADMET predictions to evaluate their binding affinities and pharmacokinetic properties. Biological activity assays confirmed the efficacy of four standout candidates L17, L26, L37, and L50 with IC50 values of 5.61 ± 0.58 μM, 6.00 ± 0.63 μM, 4.21 ± 0.89 μM, and 2.84 ± 1.20 μM, respectively, comparable to that of reference ML188 (2.41 ± 0.70 μM). Further insights were gained through density functional theory (DFT) analyses, which provided valuable information regarding the electronic and structural properties of the candidate compounds. Additionally, extensive molecular dynamics (MD) simulations were conducted, revealing critical information about the stability and binding interactions of the compounds within the Mpro active site over a 500 ns simulation period. Besides, the results of binding free energy calculations demonstrated that compounds had higher binding affinity than ML188, and dcTMD simulations further revealed that L26, L37, and L50 followed more favorable and cooperative unbinding pathways with higher energy barriers and lower dissipation compared to ML188. Overall, the results highlight the therapeutic potential of these compounds as effective Mpro inhibitors, laying a solid foundation for further development into novel antiviral agents against SARS-CoV-2.

The DENV-NS5 RNA-dependent RNA polymerase (RdRp) is essential for viral replication, and one of the targets of anti-virus. In this study, the Uni-VSW module was used to virtual screen 1.6 million compounds in the ChemDiv and TargetMol (USA) database, 27 candidates were obtained. Thereby 23 candidates were selected based on their binding free energies by 50 ns MD simulations. The biological activity of the candidates and the reference compounds (BCX4430 and Compound 27) were evaluated on their IC50 values against DENV-NGC, CC50 values, and selectivity index. Among these, the IC50 values of D1 and D8 were 13.06 ± 1.17 μM and 14.79 ± 7.76 μM, respectively, which were better than that of Compound 27 (IC50 =19.67 ± 1.12 μM). The comprehensive MD simulations were performed on the candidates to assess the stability behaviour and binding mechanisms. The density functional theory (DFT) analysis was also conducted to explore the structural and electronic properties.

Human rhinovirus 14 (HRV-14) is a leading cause of the common cold, with its 3C protease (3Cpro) playing a crucial role in viral replication by cleaving polyproteins into functional proteins and enzymes. This makes 3Cpro a promising target for therapeutic intervention. In this study, to identify novel HRV-14 3Cpro non-covalent inhibitors, we performed a virtual screening of the TopScience and TargetMol (United States) database and selected 44 potential compounds for HRV-14 3Cpro inhibitory activity evaluation. Preliminary assays at 50 μM showed that compounds S21, S33, S34, and S43 exhibited inhibition rates of 80.51%, 96.5%, 75.59%, and 88.79%, respectively. Further characterization revealed that S21 and S34 exhibited moderate activity with IC50 values of 30.40 ± 0.67 μM and 24.11 ± 0.55 μM, respectively, while S33 and S43 displayed stronger inhibition with IC50 values of 11.32 ± 0.71 μM and 2.33 ± 0.5 μM, respectively. To elucidate the binding mode of S33 and S43 to HRV-14 3Cpro, we conducted all-atom molecular dynamics (MD) simulations and density functional theory (DFT) calculations on the docked complexes of compounds S33 and S43 with HRV-14 3Cpro. MD analyses, including principal component analysis (PCA), free energy landscapes (FEL), and dynamic cross-correlation matrices (DCCM), revealed that both compounds enhanced the structural stability of the HRV-14 3Cpro while reducing its flexibility and internal dynamics. These findings suggested that S33 and S43 are promising candidates for optimization and clinical development as novel non-covalent HRV-14 3Cpro inhibitors.

Dengue virus (DENV) is a significant significant mosquito-borne pathogen. Its RNA-dependent RNA polymerase (RdRp) plays a crucial role in viral replication, making it a critical target for antiviral drug development. The goal of this study was to identify potential inhibitors of the DENV RdRp through virtual screening and experimental assays. In this study, based on Topscience and TargetMol database. 47 compounds were stand out from 1.1 million compounds with high binding energies between - 77.24 kcal/mol and - 44.08 kcal/mol by initial virtual screening. Their inhibition activity against dengue virus was evaluated by cell-based antiviral and RdRp enzyme assays, and 4 compounds (R2, R29, R37, and R39) identified in our study demonstrated promising in vitro activity, with IC50 values of less than 10 mu M, indicating their strong potential as antiviral agents against DENV. The RdRp enzyme inhibition assay revealed that R37 demonstrated significant activity against the DENV RdRp enzyme, with an IC50 of 10.86 +/- 2.06 mu M, which was lower than that of 3'-dATP (IC50 = 30.09 +/- 8.26 mu M). These 4 compounds were further subjected to DFT calculations and MD simulation, which not only provided valuable structural insights but also enhanced the reliability of our findings by offering a detailed understanding of the stability and binding interactions of the top compounds with the DENV RdRp enzyme. These results suggest that the identified compounds are promising candidates for novel DENV RdRp inhibitors and provide both theoretical and experimental groundwork for further optimization and validation.

IntroductionSARS-CoV-2 pandemic has presented a significant threat to global health and the economy, necessitating urgent efforts to develop effective antiviral drugs. The main protease (3CLpro) of SARS-CoV-2 is a critical target for antiviral therapy due to its essential role in viral replication.MethodsIn order to find new structural types of 3CLpro inhibitors to facilitate the solution to the problem of new virus resistance. Six potential pharmacologically bioactive compounds were identified by utilizing structure-based virtual screening and in vitro assays from the Topscience database containing 10 million compounds.Results and DiscussionAmong these, compounds 34 and 36 exhibited potent inhibitory activity with IC50 values of 6.12 ± 0.42 μM and 4.47 ± 0.39 μM, respectively. To elucidate their binding mechanisms with 3CLpro, all-atom molecular dynamics (MD) simulations were conducted. Principal component analysis (PCA), free energy landscapes (FEL) and dynamic cross-correlation maps (DCCM) revealed that the binding of compounds 34 and 36 to 3CLpro significantly enhanced the structural stability of 3CLpro, reducing conformational flexibility and internal motions. The results of protein-ligand interaction showed that compounds 34 and 36 formed strong and stable interactions to key residues at active site of 3CLpro with different binding modes from S-217622. And HOMO-LUMO gap and molecular electrostatic potential distribution revealed the quantum chemical properties of compounds 34 and 36. These findings suggested that compounds 34 and 36 can be as novel SARS-CoV-2 3CLpro inhibitors and promising lead-like drug candidates for developing COVID-19 treatments.

Indoleamine 2,3-dioxygenase 1 (IDO1) is the key enzyme that catalyzes the conversion of l-tryptophan (Trp) to N-formyl-kynurenine in the tryptophan-kynurenine (Trp-Kyn) pathway. Overexpression of IDO1 contributes to the depletion of Trp and the accumulation of Kyn, which can result in tumor immune escape. Inhibition of IDO1 can restore the host immune response to eradicate cancer cells. 5-(Pyridin-3-yl)-1H-indole-4,7-dione was developed as the scaffold for a type of IDO1 inhibitors from simplification of the structure of exiguamine A in our previous work. In the present study, we designed and synthesized a series of compounds with different side-chain substituents, and linkers of varying lengths, at the 3-position, to design compounds with an aryl motif that can occupy pocket B of the IDO1 protein. Most compounds exhibited potent IDO1 inhibitory activity with IC50 values at the micromolar level, and 3-(2-((4-fluorobenzyl)amino)ethyl)-5-(3-pyridyl)-1H-indole-4,7-dione (1d) displayed the most potent inhibition with a half-maximal inhibitory concentration (IC50) value of 0.125 μM in an enzymatic assay and a half-maximal effective concentration (EC50) value of 0.821 μM in a cellular assay. Compound 1d showed higher selectivity for IDO1 over indoleamine 2,3-dioxygenase 2 and tryptophan 2,3-dioxygenase at the effective concentration. Molecular docking studies and molecular dynamic simulations suggested that the phenyl ring of these inhibitors can enter into pocket B of IDO1 and interact with the residue Phe 226 through hydrophobic interactions.

The main severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protease (Mpro, also known as 3CLpro) plays a central role in virus replication, thereby constituting an appealing therapeutic target for coronavirus disease 2019 (COVID-19) treatment. In this study, we used recently reported crystal structures of SARS-CoV-2 Mpro complexed with small-molecule inhibitors. Using the established structure–activity relationships of small-molecule inhibitors of the Mpro of SARS-CoV-2, we used the Virtual Screening Workflow (with hydrogen bond constraints) implemented in Schrödinger Suite 2021 to screen approximately one million compounds in the ChemDiv compound library to identify potential novel noncovalent Mpro inhibitors. Our docking analysis yielded 65 promising lead compounds, the inhibitory activity of which against Mpro was assessed using a fluorescent SARS-CoV-2 Mpro inhibition assay. Notably, six compounds exhibited SARS-CoV-2 Mpro inhibition with IC50 values ranging 22.95–64.63 μM. These hit compounds exhibited good structural diversity, which prompted us to investigate their SARS-CoV-2 Mpro binding modes. We used a previously validated IFD-BPMD-MD workflow to predict the binding positions of these hit compounds. Our simulations showed that these hit complexes exhibited diverse and robust binding to the SARS-CoV-2 Mpro. Our study findings offer valuable insights into the development of novel noncovalent small-molecule protease inhibitor.

Introduction: Quorum sensing (QS) is a bacterial intracellular and intercellular communication system that regulates virulence factor production, biofilm formation, and antibiotic sensitivity. Quorum-sensing inhibitors (QSIs) are a novel class of antibiotics that can effectively combat antibiotic resistance. Autoinducer-2 (AI-2) is a universal signaling molecule that mediates inter- and intraspecies QS systems among different bacteria. Furthermore, LsrK plays an important role in regulating the activity and stability of the intracellular AI-2 signaling pathway. Thus, LsrK is considered an important target for the development of QSIs.Methods: We designed a workflow integrating molecular dynamic (MD) simulations, virtual screening, LsrK inhibition assays, cell-based AI-2-mediated QS interference assays, and surface plasmon resonance (SPR)-based protein affinity assays to screen for potential LsrK kinase inhibitors.Results: MD simulation results of the LsrK/ATP complex revealed hydrogen bonds and salt bridge formation among four key residues, namely, Lys 431, Tyr 341, Arg 319, and Arg 322, which are critical for the binding of ATP to LsrK. Furthermore, MD simulation results indicated that the ATP-binding site has an allosteric pocket that can become larger and be occupied by small molecule compounds. Based on these MD simulation results, a constraint of forming at least one hydrogen bond with Arg 319, Arg 322, Lys 431, or Tyr 341 residues was introduced when performing virtual screening using Glide’s virtual screening workflow (VSW). In the meantime, compounds with hydrophobic group likely to interact with the allosteric hydrophobic pocket are preferred when performing visual inspection. Seventy-four compounds were selected for the wet laboratory assays based on virtual screening and the absorption, distribution, metabolism, and excretion (ADME) properties of these compounds. LsrK inhibition assays revealed 12 compounds inhibiting LsrK by more than 60% at a 200 μM concentration; four of these (Y205-6768, D135-0149, 3284–1358, and N025-0038) had IC50 values below 50 μM and were confirmed as ATP-competitive inhibitors. Six of these 12 LsrK inhibitors exhibited high AI-2 QS inhibition, of which, Y205-6768 had the highest activity with IC50 = 11.28 ± 0.70 μM. The SPR assay verified that compounds Y205-6768 and N025-0038 specifically bound to LsrK. MD simulation analysis of the docking complexes of the four active compounds with LsrK further confirmed the importance of forming hydrogen bonds and salt bridges with key basic amino acid residues including Lys 431, Tyr 341, Arg 319, and Arg 322 and filling the allosteric hydrophobic pocket next to the purine-binding site of LsrK.Discussion: Our study clarified for the first time that there is an allosteric site near the ATP-binding site of Lsrk and that it enriches the structure–activity relationship information of Lsrk inhibitors. The four identified compounds showed novel structures, low molecular weights, high activities, and novel LsrK binding modes, rendering them suitable for further optimization for effective AI-2 QSIs. Our work provides a valuable reference for the discovery of QSIs that do not inhibit bacterial growth, thereby avoiding the emergence of drug resistance.

The dopamine D3 receptor (D3R) is an important central nervous system target for treating various neurological diseases. D3R antagonists modulate the improvement of psychostimulant addiction and relapse, while D3R agonists can enhance the response to dopaminergic stimulation and have potential applications in treating Parkinson’s disease, which highlights the importance of identifying novel D3R ligands. Therefore, we performed auto dock Vina-based virtual screening and D3R-binding-affinity assays to identify human D3R ligands with diverse structures. All molecules in the ChemDiv library (>1,500,000) were narrowed down to a final set of 37 molecules for the binding assays. Twenty-seven compounds exhibited over 50% inhibition of D3R at a concentration of 10 μM, and 23 compounds exhibited over 70% D3R inhibition at a concentration of 10 μM. Thirteen compounds exhibited over 80% inhibition of D3R at a concentration of 10 μM and the IC50 values were measured. The IC50 values of the five compounds with the highest D3R-inhibition rates ranged from 0.97 μM to 1.49 μM. These hit compounds exhibited good structural diversity, which prompted us to investigate their D3R-binding modes. After trial and error, we combined unbiased molecular dynamics simulation (MD) and molecular mechanics generalized Born surface area (MM/GBSA) binding free-energy calculations with the reported protein–ligand-binding pose prediction method using induced-fit docking (IFD) and binding pose metadynamics (BPMD) simulations into a self-consistent and computationally efficient method for predicting and verifying the binding poses of the hit ligands to D3R. Using this IFD-BPMD-MD-MM/GBSA method, we obtained more accurate and reliable D3R–ligand-binding poses than were obtained using the reported IFD-BPMD method. This IFD-BPMD-MD-MM/GBSA method provides a novel paradigm and reference for predicting and validating other protein–ligand binding poses.

Dengue virus (DENV) is a major mosquito-borne human pathogen in tropical countries; however, there are currently no targeted antiviral treatments for DENV infection. Compounds 27 and 29 have been reported to be allosteric inhibitors of DENV RdRp with potent inhibitory effects. In this study, the structures of compounds 27 and 29 were optimized using computer-aided drug design (CADD) approaches. Nine novel compounds were synthesized based on rational considerations, including molecular docking scores, free energy of binding to receptor proteins, predicted Absorption, Distribution, Metabolism, Excretion, and Toxicity (ADMET) parameters, structural diversity, and feasibility of synthesis. Subsequently, the anti-DENV activity was assessed. In the cytopathic effect (CPE) assay conducted on BHK-21 cells using the DENV2 NGC strain, both SW-b and SW-d demonstrated comparable or superior activity against DENV2, with IC50 values of 3.58 ± 0.29 μM and 23.94 ± 1.00 μM, respectively, compared to that of compound 27 (IC50 = 19.67 ± 1.12 μM). Importantly, both SW-b and SW-d exhibited low cytotoxicity, with CC50 values of 24.65 μmol and 133.70 μmol, respectively, resulting in selectivity indices of 6.89 and 5.58, respectively. Furthermore, when compared to the positive control compound 3′-dATP (IC50 = 30.09 ± 8.26 μM), SW-b and SW-d displayed superior inhibitory activity in an enzyme inhibitory assay, with IC50 values of 11.54 ± 1.30 μM and 13.54 ± 0.32 μM, respectively. Molecular dynamics (MD) simulations elucidated the mode of action of SW-b and SW-d, highlighting their ability to enhance π–π packing interactions between benzene rings and residue W795 in the S1 fragment, compared to compounds 27 and 29. Although the transacylsulphonamide fragment reduced the interaction between T794 and NH, it augmented the interaction between R729 and T794. In summary, our study underscores the potential of SW-b and SW-d as allosteric inhibitors targeting the DENV NS5 RdRp domain. However, further in vivo studies are warranted to assess their pharmacology and toxicity profiles.

The PB2 subunit of the influenza RNA-dependent RNA polymerase (RdRp) has been identified as a promising target for the treatment of influenza. To expand the chemical space of the known influenza polymerase PB2 inhibitor–pimodivir (formerly VX-787) and improve its pharmacokinetic profile, two pimodivir analogs containing 2,3-dihydro-imidazopyridine fragment (comp. I and comp. II) were designed, synthesized, and evaluated for anti-influenza virus activity. In the cytopathic effect (CPE) inhibition assay, comp. I and comp. II showed IC50 values of 0.07 and 0.09 μM for A/Puerto Rico/8/34 (H1N1) and 0.04 and 0.07 μM for A/Hong Kong/8/68 (H3N2), respectively. Protein-binding affinity assay results showed a concentration-dependent association and dissociation pattern, with KD values of 1.398 and 1.670 μM, respectively. In vitro metabolic stability assays showed that comp. I and comp. II exhibited good stability to liver microsomes and considerably less sensitivity to aldehyde oxidase compared to pimodivir. The binding modes of comp. I and comp. II were similar to those of VX-787; however, comp. I and comp. II had lower structural adaptability to PB2 than VX-787. Our results provide helpful information regarding the structure–activity relationship for the design of novel PB2 inhibitors and a reference for the development of drugs containing 2,3-dihydro-imidazopyridine fragments.

Quorum sensing (QS) is a cell-to-cell communication mechanism that regulates bacterial pathogenicity, biofilm formation, and antibiotic sensitivity. Among the identified quorum sensing, AI-2 QS exists in both Gram-negative and Gram-positive bacteria and is responsible for interspecies communication. Recent studies have highlighted the connection between the phosphotransferase system (PTS) and AI-2 QS, with this link being associated with protein-protein interaction (PPI) between HPr and LsrK. Here, we first discovered several AI-2 QSIs targeting the LsrK/HPr PPI site through molecular dynamics (MD) simulation, virtual screening, and bioassay evaluation. Of the 62 compounds purchased, eight compounds demonstrated significant inhibition in LsrK-based assays and AI-2 QS interference assays. Surface plasmon resonance (SPR) analysis confirmed that the hit compound 4171-0375 specifically bound to the LsrK-N protein (HPr binding domain, KD = 2.51 × 10−5 M), and therefore the LsrK/HPr PPI site. The structure-activity relationships (SARs) emphasized the importance of hydrophobic interactions with the hydrophobic pocket and hydrogen bonds or salt bridges with key residues of LsrK for LsrK/HPr PPI inhibitors. These new AI-2 QSIs, especially 4171-0375, exhibited novel structures, significant LsrK inhibition, and were suitable for structural modification to search for more effective AI-2 QSIs.

BACKGROUND:The broad-spectrum antiparasitic drug nitazoxanide (N) has been repositioned as a broad-spectrum antiviral drug. Nitazoxanide's in vivo antiviral activities are mainly attributed to its metabolite-tizoxanide, the deacetylation product of nitazoxanide. In reference to the pharmacokinetic profile of nitazoxanide, we proposed the hypotheses that the low plasma concentrations and the low system exposure of tizoxanide after dosing with nitazoxanide result from significant first-pass effects in the liver. It was thought that this might be due to the unstable acyloxy bond of nitazoxanide.OBJECTIVE:Tizoxanide prodrugs, with the more stable formamyl substituent attached to the hydroxyl group rather than the acetyl group of nitazoxanide, were designed with the thought that they might be more stable in plasma. It was anticipated that these prodrugs might be less affected by the first pass effect, which would improve plasma concentrations and system exposure of tizoxanide.METHOD:These O-carbamoyl tizoxanide prodrugs were synthesized and evaluated in a mouse model for pharmacokinetic (PK) properties and in an in vitro model for plasma stabilities.RESULTS:The results indicated that the plasma concentration and the systemic exposure of tizoxanide (T) after oral administration of O-carbamoyl tizoxanide prodrugs were much greater than that produced by the equimolar dosage of nitazoxanide. It was also found that the plasma concentration and the systemic exposure of tizoxanide glucuronide (TG) were much lower than that produced by nitazoxanide.CONCLUSION:Further analysis showed that the suitable plasma stability of O-carbamoyl tizoxanide prodrugs is the key factor in maximizing the plasma concentration and the systemic exposure of the active ingredient tizoxanide.

Influenza A virus is the main cause of worldwide epidemics and annual influenza outbreaks in humans. In this study, a virtual screen was performed to identify compounds that interact with the PB2 cap-binding domain (CBD) of influenza A polymerase. A virtual screening workflow based on Glide docking was used to screen an internal database containing 8417 molecules, and then the output compounds were selected based on solubility, absorbance, and structural fingerprints. Of the 16 compounds selected for biological evaluation, six compounds were identified that rescued cells from H1N1 virus-mediated death at non-cytotoxic concentrations, with EC50 values ranging from 2.5–55.43 μM, and that could bind to the PB2 CBD of H1N1, with Kd values ranging from 0.081–1.53 μM. Molecular dynamics (MD) simulations of the docking complexes of our active compounds revealed that each compound had its own binding characteristics that differed from those of VX-787. Our active compounds have novel structures and unique binding modes with PB2 proteins, and are suitable to serve as lead compounds for the development of PB2 inhibitors. An analysis of the MD simulation also helped us to identify the dominant amino acid residues that play a key role in binding the ligand to PB2, suggesting that we should focus on increasing and enhancing the interaction between inhibitors and these major amino acids during lead compound optimization to obtain more active PB2 inhibitors.

Transcription is the fundamental process in all living organisms. A variety of important proteins, such as NRs, BETs, HDACs and many others are involved in transcription process. In general, overexpression of these proteins would cause many diseases. Some approved therapeutics employed inhibitors to regulate the transcription process, however, the results are far from satisfying. Therefore, it is in high demand to develop new technology to improve the therapeutic effects. In recent years, proteolysis-targeting chimaera (PROTAC) turned out to be a novel efficient therapeutic method to treat various diseases which were caused by proteins overexpression. PROTAC molecules are bifunctional small molecules that simultaneously bind a target protein and an E3-ubiquitin ligase, thus causing ubiquitination and subsequent degradation of the target protein by the proteasome. In contrast to traditional inhibitors, PROTACs showed higher efficiency to tackle the diseases which were caused by protein overexpression due to their excellent performance for degrading target proteins in transcription regulation. In this review, 29 kinds of PROTACs targeting transcription regulator proteins are summarized, and meanwhile the advantages of PROTACs are highlighted. Furthermore, several examples of PROTACs regulating the transcription for the treatment of diseases and functioning as tools for biological research are also disscussed.