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Nuclear export factor chromosome region maintenance 1 (CRM1) is an attractive anticancer and antiviral drug target that spurred several research efforts to develop its inhibitor. Noncovalent CRM1 inhibitors are desirable, but none is reported to date. Here, we present the crystal structure of yeast CRM1 in complex with S109, a substructure of CBS9106 (under clinical test). Superimposition with the LFS-829 (another covalent CRM1 inhibitor) complex inspired the design of a noncovalent CRM1 inhibitor. Among nine synthesized compounds, noncovalent CRM1 inhibitor 1 (NCI-1) showed a high affinity to human and yeast CRM1 in the absence or presence of GST-bound Ras-related nuclear protein (RanGTP). Unlike covalent inhibitors, the crystal structure showed that NCI-1 is bound in the "open" nuclear export signal (NES) groove of CRM1, simultaneously occupying two hydrophobic pockets. NCI-1 additionally inhibited the nuclear export and proliferation of cells harboring the human CRM1-C528S mutant. Our work opens up the avenue of noncovalent CRM1 inhibitor development toward a more potent, less toxic, and broad-spectrum anticancer/antiviral therapy.

Proteostasis is the process of regulating intracellular proteins to maintain the balance of the cell proteome, which is crucial for cancer cell survival. Several proteases located in the cytoplasm, mitochondria, lysosome, and extracellular environment have been identified as potential antitumor targets because of their involvement in proteostasis. Although the discovery of small-molecule inhibitors targeting proteases faces particular challenges, rapid advances in chemical biology and structural biology, and the new technology of drug discovery have facilitated the development of promising protease modulators. In this review, the protein structure and function of important tumor-related proteases and their inhibitors are presented. We also provide a prospective on advances and the outlook of new drug strategies that target these proteases.

Diarylureas are widely used in self-assembly and supramolecular chemistry owing to their outstanding characteristics as both H-bond donors and acceptors. Unfortunately, this bonding property is rarely applied in the development of urea-containing drugs. Herein, seven related dimethyl sulfoxide (DMSO) complexes were screened from 12 substrates involving sorafenib and regorafenib, mainly considering the substitution effect following a robust procedure. All complexes were structurally confirmed by spectroscopic means and thermal analysis. Specially, five cocrystals with three deuterated, named sorafenib·DMSO, donafenib·DMSO, deuregorafenib·DMSO, 6·DMSO, and 7·DMSO were obtained. The crystal structures revealed that all host molecules consistently bonded with DMSO in intermolecular interaction in a 1:1 stoichiometry. However, further comparison with documented DMSO complexes and parent motifs presented some arrangement diversities especially for 6·DMSO which offered a counter-example to previous rules. Major changes in the orientation of meta-substituents and the packing stability for sorafenib·DMSO and deuregorafenib·DMSO were rationalized by theory analysis and computational energy calculation. Cumulative data implied that the planarization of two aryl planes in diarylureas may play a crucial role in cocrystallization. Also, a polymorph study bridged the transformation between these ureas and their DMSO complexes.

Human dihydroorotate dehydrogenase (hDHODH) is an attractive target for cancer therapy. Based on its crystal structure, we designed and synthesized a focused compound library containing the structu...

Caseinolytic protease P (ClpP) is considered as a promising target for the treatment of Staphylococcus aureus infections. In an unbiased screen of 2632 molecules, a peptidomimetic boronate, MLN9708, was found to be a potent suppressor of SaClpP function. A time-saving and cost-efficient strategy integrating in silico position scanning, multistep miniaturized synthesis, and bioactivity testing was deployed for optimization of this hit compound and led to fast exploration of structure-activity relationships. Five of 150 compounds from the miniaturized synthesis exhibited improved inhibitory activity. Compound 43Hf was the most active inhibitor and showed reversible covalent binding to SaClpP while did not destabilize the tetradecameric structure of SaClpP. The crystal structure of 43Hf-SaClpP complex provided mechanistic insight into the covalent binding mode of peptidomimetic boronate and SaClpP. Furthermore, 43Hf could bind endogenous ClpP in S. aureus cells and exhibited significant efficacy in attenuating S. aureus virulence in vitro and in vivo.

Background Limitations of current intracanal irrigants such as sodium hypochlorite (NaOCl) and chlorhexidine (CHX) necessitate the development of novel antimicrobial agents to control endodontic infection. Aim This study investigated the antimicrobial activities of a small molecule II-6s against Enterococcus faecalis associated with endodontic diseases. Methods The susceptibility of E. faecalis to II-6s was evaluated by the microdilution method and time-kill assay. Microbial resistance was assessed by repeated exposure of E. faecalis to II-6s. Cytotoxicity of II-6s was evaluated by CCK-8 assay. Virulence gene expression of the II-6s-treated E. faecalis cells was measured by RT-qPCR. Bacterial reductions in the dentinal tubules were further assessed by confocal laser scanning microscopy. Results II-6s exhibited potent antimicrobial activity against E. faecalis and down-regulated virulence-associated genes in E. faecalis. II-6s induced no drug resistance in E. faecalis with lower cytotoxicity as compared to NaOCl and CHX. More importantly, 0.003125% II-6s exhibited significant bactericidal effect against E. faecalis residing in the dentinal tubules, which was comparable to 5.25% NaOCl and 2% CHX. Conclusions II-6s has excellent antimicrobial activity, moderate cytotoxicity and induces no drug resistance, and thus is a promising agent for the treatment of endodontic infection.

A novel scalable four-step process has been developed to improve the synthesis of obeticholic acid (OCA). The key step of this process was the isolation of the amide intermediate, which underwent hydrogenation, basic epimerization, ketone reduction, and amide hydrolysis in a one-pot procedure. The use of efficient single recrystallization for the final purification in this process made the corresponding work-up procedure more concise and environmentally friendly. A kilogram-scale production of OCA following this process could achieve over 70% yield with all impurities controlled below 0.10%.

Human dihydroorotate dehydrogenase (DHODH), the enzyme that catalyzes the rate‐limiting step in de novo pyrimidine biosynthesis, is considered to be an attractive target for potential treatment of autoimmune disease and cancer. Here, we present a novel class of human DHODH inhibitors with high inhibitory potency. The high‐resolution crystal structures of human DHODH complexed with various agents reveal the details of their interactions. Comparisons with the binding modes of teriflunomide and brequinar provide insights that may facilitate the development of new inhibitors targeting human DHODH.

The emergence of various drug-resistant Mycobacterium tuberculosis (Mtb) strains has necessitated the exploration of new drugs that lack cross-resistance with existing therapeutics. By screening the MedChemExpress bioactive compound library, ceritinib was identified as a compound with activity against Mtb H37Ra. Ceritinib had a MIC value of 9.0 μM in vitro and demonstrated in vivo efficacy in a BALB/c mouse model infected with autoluminescent H37Ra. Then, 32 novel ceritinib derivatives were synthesized, and their antimycobacterial activities were evaluated in vitro. The antimycobacterial activities of the synthesized compounds were drastically affected by substitutions at position 4 of the pyrimidine nucleus and were enhanced by the presence of 2-isopropoxy-5-methyl-4-(piperidin-4-yl)aniline at position 2 of the pyrimidine nucleus. The in vivo antitubercular activities of the three most potent compounds were evaluated. 5-Chloro-N2-(2-isopropoxy-5-methyl-4-(piperidin-4-yl) phenyl)-N4-(naph thalen-1-yl) pyrimidine-2,4-diamine (16j) remarkably reduced the Mtb burden of mice. This result suggested the potential of 16j as a novel drug with superior antitubercular activities. The results of experiments on the combination of sulfamethoxazole with 16j and in silico modeling suggest that dihydrofolate reductase is the potential molecular target of 16j.

By coupling in situ [2+3] Huisgen cycloaddition with an in vitro transcription/translation luminescence assay in a crude ribosomal extract, a robust and accurate high-throughput platform was successfully developed and applied for efficient identification of novel structural types of ribosomal inhibitors with antimicrobial activity against drug-resistant bacteria.

Serine, the source of the one-carbon units essential for de novo purine and deoxythymidine synthesis plays a crucial role in the growth of cancer cells. Phosphoglycerate dehydrogenase (PHGDH) which catalyzes the first, rate-limiting step in de novo serine biosynthesis has become a promising target for the cancer treatment. Here we identified H-G6 as a potential PHGDH inhibitor from the screening of an in-house small molecule library based on the enzymatic assay. We adopted activity-directed combinatorial chemical synthesis strategy to optimize this hit compound. Compound b36 was found to be the noncompetitive and the most promising one with IC50 values of 5.96 ± 0.61 μM against PHGDH. Compound b36 inhibited the proliferation of human breast cancer and ovarian cancer cells, reduced intracellular serine synthesis, damaged DNA synthesis, and induced cell cycle arrest. Collectively, our results suggest that b36 is a novel PHGDH inhibitor, which could be a promising modulator to reprogram the serine synthesis pathway and might be a potential anticancer lead worth further exploration.

Dental caries is a chronic oral infectious disease caused by cariogenic biofilm adhered on the tooth surface. Our previous study demonstrated that a repurposed natural compound napabucasin (NAP) showed good antimicrobial activity against oral streptococcal biofilms. The current study designed a novel small molecule, namely LCG-N25, using NAP as a lead compound, and aimed to investigate its potential as an antimicrobial agent in the control of dental caries. LCG-N25 was designed and synthesized with reference to the structure of NAP. The minimal inhibitory concentrations and the minimal bactericidal concentrations of LCG-N25 against Streptococcus mutans, Streptococcus sanguinis, and Streptococcus gordonii were evaluated by microdilution method. The antimicrobial activity of LCG-N25 was further evaluated by crystal violet staining, colony forming units counting, biofilm metabolism assay, dead/live fluorescent staining, and scanning electron microscopy. The effect of LCG-N25 on the extracellular polysaccharides of biofilms was determined by both anthrone-sulfuric acid method and fluorescent staining. The microbial composition of streptococcal biofilms after LCG-N25 treatment was further visualized and quantified by fluorescence in situ hybridization. Besides, the cytotoxicity of LCG-N25 was evaluated by Cell Counting Kit-8 assay, and repeated exposure of S. mutans to LCG-N25 treatment was performed to assess if this novel compound could induce drug resistance of this cariogenic bacterium. We found that LCG-N25 exhibited a good antibacterial activity, low-cytotoxicity, and did not induce drug resistance of cariogenic S. mutans. These findings suggest that LCG-N25 may represent a promising antimicrobial agent that can be used as an adjuvant to the management of dental caries.

Background: The side effects of present antimicrobials like chlorhexidine (CHX) and the emergence of drug resistance necessitate the development of alternative agents to control dental caries. Aim: This study developed a novel small molecule, namely II-6s, and investigated its antimicrobial activities against common oral streptococci associated with dental caries. Methods: The susceptibility of streptococci to II-6s was evaluated by the microdilution method, time-kill assay and scanning electron microscopy. The exopolysaccharides, dead/live bacteria and bacterial composition of the II-6s-treated Streptococcus mutans/Streptococcus gordonii/Streptococcus sanguinis 3-species biofilms were analyzed by confocal laser scanning microscopy, fluorescent in situ hybridization and quantitative PCR. The anti-demineralization effect and cytotoxicity of II-6s were evaluated by transverse microradiography and CCK-8 assay, respectively. Repeated exposure of S. mutans to II-6s was performed to assess if II-6s could induce drug resistance. Results: II-6s exhibited antimicrobial activity similar to CHX against S. mutans, S. gordonii and S. sanguinis and significantly inhibited exopolysaccharides production, live bacteria and the demineralizing capability of the 3-species streptococcal biofilms. Besides, II-6s showed reduced cytotoxicity relative to CHX and did not induce drug resistance in S. mutans after 15 passages. Conclusion: - II-6s may serve as a promising part of a successful caries management plan.

Aberrant activation of ERK signaling pathway usually leads to oncogenesis, and small molecular agents targeting this pathway are impeded by the emergence of drug resistance due to reactivation of ERK signaling. Compound DEL-22379 has been reported to inhibit ERK dimerization which was unaffected by drug-resistant mechanism reactivating the ERK signaling. Here, we discussed a structure-activity relationship study of DEL-22379. Forty-seven analogues were designed and synthesized. Each synthesized compound was biologically evaluated for their inhibitory rates on several tumor cell lines and compounds with high inhibitory rates were further evaluated for IC50 values. The structure-activity relationship of idolin-2-one scaffold and the impact of Z/E configuration on potency were discussed. Potential safety of two synthesized analogues was investigated and in silico docking study of five compounds was performed to understand the structural basis of ERK dimerization inhibition.

The mechanisms underlying the pathophysiology of depression remain elusive, and the development of novel, effective antidepressant drugs remains necessary. A dihydroquinoline analog of agomelatine (AGO), N-(2-(7-methoxy-3,4-dihydroisoquinolin-1-yl)ethyl)acetamide hydrochloride (NMDEA), was synthesized by employing a scaffold-hopping strategy in our previous study. In this study, NMDEA was demonstrated to attenuate depression-related behaviors in mice models of chronic unpredictable mild stress (CUMS), using a sucrose preference test, a forced swimming test, and a tail suspension test. However, the antidepressant mechanism of NMDEA appears to differ from that for AGO. Based on the analysis of fecal microbiota from mice, stress can alter the richness of the gut bacterial community, increasing the expression of immune-modulating microbiota, such as Clostridia, and decreasing the expression of probiotic bacteria, such as Lactobacillus. Treatment with NMDEA was able to recover the richness and to regulate the dysbiosis among bacterial species. Several studies have demonstrated that the gut microbiota population can induce inflammatory processes. To explore the effects of NMDEA on the suppression of pro-inflammatory factors, we used Western blotting to analyze the levels of interleukin 1 beta (IL-1β), interleukin 6 (IL-6), p65, and inducible nitric oxide synthase (iNOS). NMDEA suppressed the activation of IL-1β and IL-6, in the hippocampus, and IL-1β, IL-6, p65, and iNOS, in lipopolysaccharide (LPS)-induced BV-2 cells. These results suggested that NMDEA may affect the microbiota-inflammasome-brain axis, regulating relevant neuro-inflammatory markers and gut microbiota. Our data also suggested that using small molecules to modify the gut microbiota population or alter inflammasome signaling may represent a new therapeutic opportunity for the mitigation of depression.

Objectives. Disruption of microbial biofilms is an effective way to control dental caries. Drug resistance and side effects of the existing antimicrobials necessitate the development of novel antibacterial agents. The current study was aimed at investigating the antibacterial activities of the repurposed natural compound napabucasin against oral streptococci. Methods. The minimum inhibitory concentration, minimum bactericidal concentration, minimum biofilm inhibition concentration, and minimum biofilm reduction concentration of Streptococcus mutans, Streptococcus gordonii, and Streptococcus sanguinis were examined by a microdilution method. Cytotoxicity of napabucasin against human oral keratinocytes, human gingival epithelia, and macrophage RAW264.7 was evaluated by CCK8 assays. The dead/live bacterium and exopolysaccharide in the napabucasin-treated multispecies biofilms were evaluated by confocal laser scanning microscopy. Microbial composition within the napabucasin-treated biofilms was further visualized by fluorescent in situ hybridization and qPCR. And the cariogenicity of napabucasin-treated biofilms was evaluated by transverse microradiography. Results. Napabucasin exhibited good antimicrobial activity against oral streptococcal planktonic cultures and biofilms but with lessened cytotoxicity as compared to chlorhexidine. Napabucasin reduced the cariogenic S. mutans and increased the proportion of the commensal S. gordonii in the multispecies biofilms. More importantly, napabucasin significantly reduced the demineralization capability of biofilms on tooth enamels. Conclusion. Napabucasin shows lessened cytotoxicity and comparable antimicrobial effects to chlorhexidine. Repurposing napabucasin may represent a promising adjuvant for the management of dental caries.

Drug-resistant bacteria pose an increasingly serious threat to mankind all over the world. However, the currently available clinical treatments do not meet the urgent demand.Therefore, it is desirable to find new targets and inhibitors to overcome the problems of antibiotic resistance. Dihydrofolate reductase (DHFR) is an important enzyme required to maintain bacterial growth, and hence inhibitors of DHFR have been proven as effective agents for treating bacterial infections. This review provides insights into the recent discovery of antimicrobial agents targeting DHFR. In particular, three pathogens, Escherichia coli (E. coli), Mycobacterium tuberculosis(Mtb) and Staphylococcus aureus(S. aureus), and research strategies are emphasized. DHFR inhibitors are expected to be good alternatives to fight bacterial infections.

A series of (E)-3-(aryl(arylamino)methylene)indolin-2-one derivatives were synthesised using an efficient synthetic approach. The method involved reaction of 3-bromo-3-(bromo(aryl)methyl)indolin-2-one with substituted anilines through nucleophilic substitution and a simultaneous elimination using NaHCO3 in DMF. The anticancer activity of the products against four cell lines, HCT-116, A549, SKOV3 and MDA-MB-231, was also evaluated, and several compounds showed moderate inhibitory activity.

The RET tyrosine kinase is an important therapeutic target for medullary thyroid cancer (MTC), and drug resistance mutations of RET, particularly V804M and V804L, are a main challenge for the current targeted therapy of MTC based on RET inhibitors. In this investigation, we report the structural optimization and structure-activity relationship studies of N -phenyl-7,8-dihydro-6 H -pyrimido[5,4-b][1,4]oxazin-4-amine derivatives as a new class of RET inhibitors. Among all the obtained kinase inhibitors, 1-(5-( tert -butyl)isoxazol-3-yl)-3-(4-((6,7,8,9-tetrahydropyrimido[5,4-b][1,4]oxazepin-4-yl)amino)phenyl)urea ( 17d) is a multi-kinase inhibitor and potently inhibits RET and its drug resistance mutants. It showed IC 50 (half maximal inhibitory concentration) values of 0.010 μM, 0.015 μM, and 0.009 μM against RET-wild-type, RET-V804M, and RET-V804L, respectively. 17d displayed significant anti-viability potencies against various RET-driving tumor cell lines. In a xenograft mouse model of NIH3T3-RET-C634Y, 17d exhibited potent in vivo anti-tumor activity, and no obvious toxicity was observed. Mechanisms of action were also investigated by Western blot and immunohistochemical assays. Collectively, 17d could be a promising agent for the treatment of MTC, hence deserving a further investigation.

Reversible chemically stimulated cyclization/cycloreversion reactions are of great interest and highly demanding for developing molecular switches, such as fluorescent probes. Herein, ultrafast and reversible cyclization/cycloreversion reactions of 4-imino-4H-quinolizine-1-carbonitrile (IMQU) derivatives, induced by H+/OH−, were developed as a new strategy for pH sensing. 1H NMR, HRMS techniques and quantum chemical methods applied to the pH sensing behavior of IMQUs reveal its legitimate mechanism. The IMQU derivatives targeted lysosomes and displayed bright emission, large Stokes shifts, robust fatigue resistance, and superior photostability over commercially available Lyso-Tracker Red. A good correlation was found between pKa values and natural atomic charges at the C-1 atom of the aromatic substituents, which should enable rational tuning of the pKa values.

Antibiotic-resistance by bacteria is a growing global concern within the healthcare field, and it has provided an impetus for continued antimicrobial development. Pyrinezolid (PZ), a novel oxazolidinone compound, can effectively inhibit most gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE). Though PZ is a promising antimicrobial candidate, the druggability of PZ is limited by its poor water solubility. Therefore, the amphipathic mPEG-PLLA copolymer was used to prepare the pyrinezolid micelles (PZ-M). Herein, we described the preparation, pharmacokinetic properties, tissue distribution, efficacy and toxicity of PZ-M. In vivo studies show that PZ-M possess prolonged blood circulation time and increased oral bioavailability compared with free PZ. Meanwhile, PZ-M increase lung PZ exposure and reduce liver and kidney exposure, which indicates that PZ-M may enhance the efficacy in vivo in MRSA-related pneumonia patients and decrease potential renal and hepatic toxicities.

A series of 1 H-thieno[2,3-c]chromen-4(2 H)-one derivatives were synthesised through Knoevenagel condensation of substituted flavanones with thiazolidine-2,4-dione in ethanol in the presence of piperidine. The mechanism of the reaction was proposed. All synthesised compounds were characterised by IR, 1H NMR, 13C NMR, HRMS, and elemental analysis. The structure of 2-(3-chlorophenyl)-1 H-thieno[2,3- c]chromen-4(2 H)-one was confirmed by a single crystal X-ray diffraction analysis. A preliminary antitumour screening showed that 2-(2-fluorophenyl)-1 H-thieno [2,3- c]chromen-4(2 H)-one had moderate to good activity against A549, BGC-823, HCT116 and MDA-MB-453 cancer cell lines, and 2-(3,4-dimethoxyphenyl)-1 H-thieno[2,3- c]chromen-4(2 H)-one displayed similar activity against these four kinds of cancer cells compared with the reference drug.

In the current study, we used an integrated approach combining bioinformatics, rational drug design, one-pot synthesis, and biological experiments in vitro for the potential discovery of novel tryptophanyl-tRNA synthetase (TrpRS) inhibitors. Atom economic and diastereoselective syntheses were used to generate several Spirooxindole–indenoquinoxaline derivatives in situ from isatin and amino acids viz. proline, phenylglycine, and sarcosine through targeting the 1,3-dipolar cycloaddition of azomethine ylides. These compounds were assayed by biochemical TrpRS inhibition, using in vitro experiments to test against various gram-positive and gram-negative strains, and using diffuse large B cell lymphoma (DLBCL) cell lines. Compound 6e was found to be the most active in vitro with IC50 values of 225 and 74 nM for tests against hmTrpRS and ecTrpRS, respectively. We also found a MIC90 value of 4 µg/mL for tests against S. aureus and IC50 values which ranged from 2.9 to 4.8 µM for tests against proliferation of DLBCL cell lines. Moreover, compound 6e was remarkably good at inducing bacterial autolysis in MRSA strains. Our results suggested that such an integrated approach could be an attractive and viable strategy for the discovery of novel TrpRS inhibitors as potential lead compounds for antibiotics and as novel anticancer agents. Discovery of novel spirooxindole-indenoquinoxaline TrpRS inhibitors as potential lead compounds with antibacterial and antitumor activities.

Chromosome region maintenance 1 (CRM1) exports nuclear export signal (NES) containing cargos from nucleus to cytoplasm and plays critical roles in cancer and viral infections. Biochemical and biophysical studies on this protein were often obstructed by its low purification yield and stability. With the help of PROSS server and NES protection strategy, we successfully designed three small fragments of CRM1, each made of four HEAT repeats and capable of binding to NESs in the absence of RanGTP. One of the fragments, C7, showed dramatically improved purification yield, thermostability, mechanostability, and resistance to protease digestion. We showed by isothermal titration that the protein kinase inhibitor NES binds to C7 at 1.18 μM affinity. Direct binding to C7 by several reported CRM1 inhibitors derived from plants were verified using pull-down assays. These fragments might be useful for the development of CRM1 inhibitors towards treatment of related diseases. The strategy applied here might help to tackle similar problems encountered in different fields.

Unlike other bacterial ClpP systems, mycobacterial ClpP1P2 complex is essential for mycobacterial survival. The functional details of Mycobacterium tuberculosis (Mtb) ClpP1P2 remains largely elusive and selectively targeting ClpP of different species is a big challenge. In this work, cediranib was demonstrated to significantly decrease the activity of MtbClpP1P2. By solving the crystal structure of cediranib-bound MtbClpP1P2, we found that cediranib dysregulates MtbClpP1P2 by interfering with handle domain of the equatorial region of MtbClpP1, indicating that the inter-ring dynamics are crucial for its function. This finding provides direct evidence for the notion that a conformational switch in the equatorial handle domain is essential for ClpP activity. We also present biochemical data to interpret the distinct interaction pattern and inhibitory properties of cediranib toward MtbClpP1P2. These results suggest that the variable handle domain region is responsible for the species-selectivity of cediranib, which suggests the equatorial handle domain as a potential region for screening pathogen-specific ClpP inhibitors.

Tuberculosis is the contagious disease responsible for the highest number of deaths worldwide. Here, we screened a commercially available compound library and found napabucasin to possess a moderate anti-tubercular activity against M. tuberculosis H37Ra (MIC 2.5 μg mL(–1), 10.4 μM). Three series of napabucasin derivatives were further evaluated for their in vitro anti-tubercular activities against Mtb H37Ra. The activity of most derivatives was either retained or enhanced compared with that of napabucasin. Compound 3s was the most active compound showing a MIC value of 0.3125 μg mL(–1) (0.9 μM). Furthermore, several compounds were selected and evaluated against the Mtb H37Rv standard strain and six Mtb clinical isolates. Importantly, these compounds were found to be effective against Mtb clinical isolates with multi-resistance to isoniazid, rifampicin, and ethambutol.

Biofilm control is a critical approach to the better management of dental caries. Antimicrobial small molecules have shown their potential in the disruption of oral biofilm and control of dental caries. The objectives of this study were to examine the antimicrobial activity and cytotoxicity of a newly designed small-molecule compound, ZY354. ZY354 was synthesized, and its cytotoxicity was evaluated in human oral keratinocytes (HOK), human gingival epithelial cells (HGE), and macrophages (RAW) by CCK-8 assays. Minimal inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), minimum biofilm inhibition concentrations (MBICs), and minimum biofilm reduction concentrations (MBRCs) of ZY354 against common oral streptococci (i.e., Streptococcus mutans, Streptococcus gordonii, and Streptococcus sanguinis) were determined by microdilution method. The exopolysaccharide (EPS)/bacterium ratio and the dead/live bacterium ratio in the ZY354-treated multispecies biofilms were determined by confocal laser scanning microscopy, and the microbial composition was visualized and quantified by fluorescent in situ hybridization and quantitative PCR (qPCR). The demineralizing activity of ZY354-treated biofilms was evaluated by transverse microradiography. The results showed that ZY354 exhibited low cytotoxicity in HOK, HGE, and RAW cells and exhibited potent antimicrobial activity against common oral streptococci. The EPS and the abundance of S. mutans were significantly reduced after ZY354 treatment, along with an increased dead/live microbial ratio in multispecies biofilms compared to the level with the nontreated control. The ZY354-treated multispecies biofilms exhibited reduced demineralizing activity at the biofilm/enamel interface. In conclusion, the small-molecule compound ZY354 exhibits low cytotoxicity and remarkable antimicrobial activity against oral streptococci, and it may have a great potential in anticaries clinical applications.

Human caseinolytic protease proteolytic subunit (HsClpP) is a highly conserved serine protease that plays an essential role in cell homeostasis through removal of the damaged and/or misfolded proteins. Recently, due to its critical role in cancer proliferation and metastasis, HsClpP has been considered as a promising target for the cancer treatment. In this paper, through a random screening toward a library of 2086 bioactive chemicals, a novel compound I, 3-(3,5-dibromo-4-hydroxybenzylidene) -5-iodoindolin-2-one, was identified as a potent suppressor of HsClpP. Herein, a series of compound I derivatives were synthesized, and evaluated for their anti-cancer activities on a variety of cancers cells. Through the preliminary biological assay in vitro, including MTT assay and proteolytic activity assay, compound I was identified as the most potent inhibitor. Treatment with compound I impaired the migration of Hela cells. In addition, compound I disrupted the mitochondrial function, and reduced the level of the SDHB and induced the production of the ATF4. In general, compound I is a promising probe of HsClpP for cancer treatment, and is a good lead compound for the development of novel anti-cancer agent.

Antibiotics have been a key part of clinical treatments for more than 70 years. Long-term use of antimicrobial treatments has led to the development of severe bacterial resistance, which has become increasingly serious due to antibiotic abuse, resulting in the treatment of bacterial infections becoming challenging. The repurposing of approved drugs presents a promising strategy to address current bottlenecks in the development of novel antibacterial agents. Drug repurposing is a cost-effective emerging strategy, which aims to treat resistant infectious diseases by identifying known drugs with predicted efficacy for diseases other than the target disease. This strategy has potential in the treatment of tuberculosis (TB), particularly drug-resistant TB. In recent years, a panel of drugs approved for clinical use or clinical trials, such as linezolid, vancomycin and celecoxib, have been found to have anti-TB activities. However, the utility of drug repurposing is limited by the number of candidate compounds and their low activities. The low activities of repurposed drugs have slowed the development of a drug-repurposing strategy for anti-TB drugs. The present review discusses progress in the discovery of new anti-TB agents through drug repurposing since 2014. We also discuss the challenges faced and analyze the innovative ways that are being used to overcome these difficulties. This review may provide a useful guide for researchers in the field of drug repurposing.

The transcription factor STAT3 is an attractive target for a variety of cancers therapy. Napabucasin, applied in phase III clinical trials for the treatment of a variety of cancers, was regarded as one of the most promising anticancer drug by targeting STAT3. Herein, a novel series of napabucasin derivatives were designed and synthesized, which presented a potent inhibitory activity on a variety of cancers cells. Among the derivatives compound 8q exhibited potent inhibitory activity on U251, HepG2, HT29 and CT26 cells with the IC50 values of 0.22, 0.49, 0.07 and 0.14 μM, respectively, which was over 10-fold more potent than napabucasin. Treatment with compound 8q decreased protein expression level of total STAT3 and p-STAT3Y705 in vitro. The binding of compound 8q with STAT3 were further validated by electrophoretic mobility shift assay and surface plasmon resonance analysis. Compound 8q has a KD of 110.2 nM for full-length STAT3 recombinant protein. Moreover, the aqueous solubility of 8q was over 4.5-fold than that of napabucasin. In addition, compound 8q in vivo significantly reduced tumor growth compared to untreated mice, and exhibited good safety profile, indicating its great potential as an efficacious drug candidate for oncotherapy.

In an effort to discover novel inhibitors of M. tuberculosis Caseinolytic proteases (ClpP1P2), a combination strategy of virtual high-throughput screening and in vitro assay was employed and a new pyrrole compound, 1-(2-chloro-6-fluorobenzyl)-2, 5-dimethyl-4-((phenethylamino)methyl)-1H-pyrrole-3-carboxylate was found to display inhibitory effects against H37Ra with an MIC value of 77 µM. In order for discovery of more potent anti-tubercular agents that inhibit ClpP1P2 peptidase in M. tuberculosis, a series of pyrrole derivatives were designed and synthesized based on this hit compound. The synthesized compounds were evaluated for in vitro studies against ClpP1P2 peptidase and anti-tubercular activities were also evaluated. The most promising compounds 2-(4-bromophenyl)-N-((1-(2-chloro-6-fluorophenyl)-2, 5-dimethyl-1H- pyrrolyl)methyl)ethan-1-aminehydrochloride 7d, ethyl 4-(((4-bromophenethyl) amino) methyl)-2,5-dimethyl-1-phenyl-1H-pyrrole-3-carboxylate hydrochloride 13i, ethyl 1-(4-chlorophenyl)-4-(((2-fluorophenethyl)amino)methyl)-2-methyl-5-phenyl-1H-pyrrole-3-carboxylate hydrochloride 13n exhibited favorable anti-mycobacterial activity with MIC value at 5 µM against Mtb H37Ra, respectively.

With antibiotics resistance developing rapidly, new antibacterial agents are needed to be discovered. We readily synthesized 11 indolin-2-one compounds and found a hybrid of indolin-2-one and nitroimidazole 3-((1-methyl-5-nitro-1H-imidazol-2-yl)methylene)indolin-2-one to be effective on Staphylococcus aureus strains. Six derivatives of this compound were further designed and synthesized in order to enhance its efficacy. After a second turn of structural refinement, a novel hybrid of indolin-2-one and nitroimidazole 3-((1-methyl-5-nitro-1H-imidazol-2-yl)methylene)-5-nitroindolin-2-one with a nitro group on C-5 position of indolin-2-one was shown to exhibit remarkable antibacterial activities with a low MIC value against MRSA ATCC 33591. Besides, this molecule demonstrated its potency on Gram-negative bacteria and VRE strain. The time-killing curve experiment showed its good bactericidal activity. Low hemolytic rate suggested its promising safety profile.

A series of small molecules with novel pyrrolo[1,2-a]quinoxaline-based scaffold was designed via molecular hybridization of privileged agents active against Mycobacterium tuberculosis. Twenty-three compounds were synthesized and investigated for their antitubercular activities in vitro where ten compounds showed appreciable activities and moderate cytotoxicity. Compound 12g with MIC values of 5 μg/ml as a representative may possess better oral bioavailability and indicated high permeability by the parallel artificial membrane permeation assay of the blood-brain barrier (PAMPA-BBB). Further, the determination of enzyme inhibition and molecular docking study indicated that InhA may be the biological target of the active compounds. The results suggest the pyrrolo[1,2-a]quinoxaline hybrids as potential antitubercular leads for the development of new antitubercular agents.

In our previous study, FYL-67, a novel linezolid analogue with the morpholinyl ring replaced by a 4-(pyridin-2-yl)-1H-pyrazol-1-yl group, was demonstrated to own an excellent activity against Gram-positive organisms,such as methicillin-resistant Staphylococcus aureus (MRSA). However, metabolic biotransformation was not investigated. This study was performed to identify the phase I metabolites of FYL-67 using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The chemical structures were confirmed by comparison with corresponding chemical standards obtained internal. Primary elucidation of the metabolic pathway of FYL-67 in vitro was performed using liver preparations (microsomes and hepatocytes) from rats and humans, and SD (Sprague Dawley, rat, rattus norvegicus) rats were used for the study of in vivo approach. To the end, two metabolites (M1 and M2 ) were detected after in vitro as well as in vivo experiments. Based on LC-MS/MS analyses, the metabolites were demonstrated to be 5-(aminomethyl)-3-(3-fluoro-4-(4-(pyridin-2-yl)-1H-pyrazol-1-yl)phenyl)oxazolidin-2-one (M1 ) and 3-(3-fluoro-4-(4-(pyridin-2-yl)-1H-pyrazol-1-yl)phenyl)-5-(hydroxymethyl)oxazolidin-2-one (M2 ). Amide hydrolysis at acetyl group of FYL-67 leading to the formation of M1 was observed and suggested to play a major role in both in vivo and in vitro phase I metabolism of FYL-67. M1 was demonstrated to undergo a further oxidation to form M2 . In addition, the results indicated no species difference existing between rats and humans. The outcomes of our research can be utilized for the development and validation of the analytical method for the quantification of FYL-67 as well as its metabolites in biological samples. Furthermore, it is helpful to conduct studies of pharmacodynamics and toxicodynamics. Copyright © 2015 John Wiley & Sons, Ltd.

The asymmetric synthesis of 3-alkyl-3-hydroxyindolin-2-ones via direct aldol reaction of isatin with ketones catalyzed by natural amino acid salts is described, in which the phenylalanine lithium salt was found to be the best catalyst. This strategy was then applied to a variety of isatin and ketone substrates and the corresponding aldol products were obtained in excellent yields (up to 97%) with good to excellent enantioselectivities (up to 90%).

A series of novel teraryl oxazolidinone compounds was designed, synthesized, and evaluated for their antimicrobial activity and toxicities. The compounds with aromatic N-heterocyclic substituents at the 4-position of pyrazolyl ring showed better antibacterial activity against the tested bacteria than other compounds with different patterns of substitution. Among all potent compounds, 10f exhibited promising safety profile in MTT assays and in hERG K(+) channel inhibition test. Furthermore, its phosphate was found to be highly soluble in water (47.1 mg/mL), which is beneficial for the subsequent in vivo test. In MRSA systemic infection mice models, 10f phosphate exerted significantly improved survival protection compared with linezolid. The compound also demonstrated high oral bioavailability (F = 99.1%). Moreover, from the results of in vivo toxicology experiments, 10f phosphate would be predicted to have less bone marrow suppression.

A series of scutellarein-O-alkylamine derivatives were designed, synthesized and tested as multifunctional agents for the treatment of Alzheimer's disease (AD). The results showed that most of these compounds exhibited good multifunctional activities. Among them, compound 16d demonstrated significant metal chelating properties, moderate acetylcholinesterase (AChE) inhibitory and anti-oxidative activity, and excellent inhibitory effects on self-induced Aβ(1-42) aggregation, Cu(2+)-induced Aβ(1-42) aggregation, human AChE-induced Aβ(1-40) aggregation and disassembled Cu(2+)-induced aggregation of the well-structured Aβ(1-42) fibrils. Both kinetic analysis of AChE inhibition and molecular modeling study suggested that 16d binds simultaneously to the catalytic active site and peripheral anionic site of AChE. Moreover, compound 16d showed a good protective effect against H2O2-induced PC12 cell injury, with low toxicity in SH-SY5Y cells. Furthermore, the step-down passive avoidance test showed this compound significantly reversed scopolamine-induced memory deficit in mice. Thus, 16d was shown to be an interesting multifunctional lead compound worthy of further study.

FYL-66 and its hydrochloride FYL-67 have been identified as new chemical entities (NCE) with pronounced in vitro and in vivo activities against MRSA and MSSA. Aiming to explore the structure–activity relationship at the C-5 side chain of FYL-66 and find novel potential antibacterial agents, a series of analogues were designed and synthesized by the introduction of various substituents at the C-5 position of the oxazolidinone ring. Their in vitro antibacterial activities were also evaluated by the microdilution method. Novel compounds 31, 33, 37, 39 and 40 demonstrated potent antibacterial activities with MIC values in the range of 2–4 μg mL−1. Difluoro-substituted analogue 40 was found to possess a good balance between antibacterial efficacy, physicochemical properties and safety profile. In a murine systemic infection model, analogue 40 showed comparable protection rates with FYL-66. The absolute bioavailability of 40 was 89.6% with half-lives of 8.87 ± 3.25 h (p.o.) and 5.40 ± 1.40 h (i.v.), respectively. Meanwhile, our findings show the importance of the C-5 side chain of FYL-66 and imply compounds with small C-5 substituents mimicking the acetamide group display better activities. It is also quite intriguing that different antibacterial effects are presented by analogues of FYL-66, Linezolid and other oxazolidinones with the same fluoro-substitution patterns of the acetyl group at the C-5 position.

DB-6, with an IUPAC name of (Z)-5-(2,4-di-tert-butyl-6-((2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-5'-methyl-7,7'-dimethoxy-[4,4'-bibenzo[d][1,3]dioxole]-5,5'-dicarboxylate, is an investigational agent for acute liver failure. The focus of this study is the identification and characterization of major unknown impurities in DB-6 bulk drug samples. Four major impurities of DB-6 were detected by a high-performance liquid chromatography (HPLC) method and designated as IMP-I, IMP-II, IMP-III and IMP-IV. Accurate masses of these impurities were determined by using a Q-TOF mass spectrometer. Based on chromatographic, spectrometric data and plausible chemical transformation mechanism, the structures of IMP-I, IMP-II, IMP-III and IMP-IV were identified, respectively, as bifendate, (E)-5-(2,4-di-tert-butyl-6-((2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-5'-methyl-7,7'-dimethoxy-[4,4'-bibenzo[d][1,3]dioxole]-5,5'-dicarboxylate, (Z)-5-(3,5-di-tert-butyl-2-hydroxybenzylidene) thiazolidine-2,4-dione and bis(2,4-di-tert-butyl-6-((Z)-(2,4-dioxothiazolidin-5-ylidene)methyl)phenyl)-7,7'-dimethoxy-[4,4'-bibenzo[d][1,3]dioxole]-5,5'-icarboxylate. The impurities were isolated by preparative-HPLC or preparative high-speed counter-current chromatography and their structures were confirmed by NMR spectroscopy.

OBJECTIVES Infections of hospitalized patients caused by biofilms formed by Staphylococcus aureus represent a major problem. Using in vitro and in vivo biofilm models, we evaluated the efficacy of the novel oxazolidinone FYL-67, by using linezolid (the only clinically approved oxazolidinone antibiotic) as a control, for inhibiting S. aureus biofilm formation. METHODS Antibiofilm activity was determined using strains of methicillin-susceptible S. aureus and methicillin-resistant S. aureus. We studied the mechanism(s) and pharmacodynamics of antibiofilm activity as follows: (i) effects of pre- and post-exposure to FYL-67 or linezolid on biofilm formation; (ii) the effect of FYL-67 on biofilm structure; (iii) the role of FYL-67 in biofilm composition; (iv) effects on cell morphology; and (v) efficacy of FYL-67 and linezolid using an in vivo murine model of catheter infection. RESULTS FYL-67 effectively inhibited biofilm formation using in vitro and in vivo assays. CONCLUSIONS Our data suggest that oxazolidinone compounds, such as FYL-67, may serve as antibiofilm agents.

In this study, a series of novel naphthalene compounds were synthesized and screened for their antidepressant-like activities in vitro and in vivo. Their values for two descriptors (ClogP, tPSA) of the blood-brain barrier (BBB) were calculated for early assessment of the central nervous system (CNS) drug-likeness. Seven of them (6d, 6i, 6k, 6o, 6p, 6s and 6t) demonstrated potential protective effects on corticosterone-induced lesion of PC12 cells although they cannot repair the irreversible oxidant injury to PC12 cells by hydrogen peroxide. Compounds with promising neurorestorative activities (6k, 6o and 6p) were further evaluated for their in vivo effects by forced swim test (FST) and open field test (OFT) in C57 mice models. The FST results showed that compounds 6k, 6o and 6p remarkably reduced the immobility time of the tested mice. Among them, compound 6k was the most potent one, much more effective than Agomelatine and comparable to Fluoxetine. The OFT results showed that mice treated with compound 6k traveled a longer distance than those treated with Agomelatine or Fluoxetine, indicating a better general locomotor activity. The paper also proposed a possible binding mode of compound 6k with glucocorticoid receptor by docking study. The in vitro cytotoxicity data on HEK293 and L02 cells suggested compound 6k to be a promising antidepressant candidate for subsequent investigation.

A concise, environmentally benign, and cost-effective route was developed for the large-scale preparation of 1, a novel oxazolidinone antibacterial candidate. The key intermediate 2-(1-(2-fluoro-4-nitrophenyl)-1H-pyrazol-4-yl)pyridine 7 was prepared with high purity by mild deamination of the regioisomeric mixture 21. The mixture was prepared from a nucleophilic SNAr reaction by selective C–N coupling of the secondary amine functionality of 4-(pyridin-2-yl)-1H-pyrazol-3-amine 14 with 1,2-difluoro-4-nitrobenzene 10 in optimized conditions with the primary amine group remaining intact. The gaseous nitrogen release rate and reaction mixture temperature of the deamination step can be well controlled by altering the feeding manner, thereby providing safety guarantees. The optimized synthetic strategy of 1 with an overall yield of 27.6%, including seven sequential transformations by only five solid–liquid isolations, significantly improved the product separation workup. The strategy bypassed time-consuming and ...

Twelve 2-(2-((4-substituted-phenoxy)methyl)-1H-benzo[d]imidazol-1-yl)-acetylhydrazone derivatives were synthesized. These synthesized compounds have been tested for their antitumor activity in vitro against A549, MDA-MB-231, A375, and HCT116 cancer cells using the MTT assay. Among them, the compounds containing hydroxyl on position 2 at phenyl of hydrazone displayed a good anticancer activity, especially those containing two hydroxyl on 2 and 4 place at phenyl of hydrazone, for example, N′-(2,4-dihydroxybenzylidene)-2-(2-((p-tolyloxy)methyl)-1H-benzo[d]imidazol-1-yl)acetohydrazide 7b, N′-(2,4-dihydroxybenzylidene)-2-(2-(phenoxymethyl)-1H-benzo[d]imidazol-1-yl) acetohydrazide 7f, 2-(2-((4-chlorophenoxy)methyl)-1H-benzo[d]imidazol-1-yl)-N′-(2,4-dihydroxybenzylidene)acetohydrazide 7j, have excellent antitumor activity. The results revealed that hydroxyl on position 2 at phenyl of hydrazone was necessary for anticancer activity, and another hydroxyl group on 4 place at phenyl can increase the inhibitory activity. An electron-withdrawing substituent at position 4 on phenyl ring of 2-phenoxylbenzimidazole was favorable to increasing anticancer activity toward MDA-MB-231, A375, and HCT116 cells.

Piperlongumine (PL) shows an inhibitory effect on tumor growth; however, lipophilicity has restricted its further applications. Nanotechnology provides an effective method to overcome the poor water solubility of lipophilic drugs. Polymeric micelles with small particle size can passively target tumors by the enhanced permeability and retention (EPR) effect, thus improving their anti-tumor effects. In this study, to improve the water solubility and anti-tumor activity of PL, PL encapsulated polymeric micelles (PL micelles) were prepared by a solid dispersion method. The prepared PL micelles showed a small particle size and high encapsulation efficiency, which could be lyophilized into powder, and the re-dissolved PL micelles are homogenous and stable in water. In addition, a sustained release behavior of PL micelles was observed in vitro. Encapsulation of PL into polymeric micelles could increase the cytotoxicity, cellular uptake, reactive oxygen species (ROS) and oxidized glutathione (GSSG), and reduce glutathione (GSH) levels in vitro. Encapsulation of PL into polymeric micelles enhanced its inhibitory effect on neovascularization both in vitro and in vivo. Compared with free PL, PL micelles showed a stronger inhibitory effect on the proliferation, migration, invasion and tube formation of human umbilical vein endothelial cells (HUVECs). Additionally, in a transgenic zebrafish model, embryonic angiogenesis was inhibited by PL micelles. Furthermore, PL micelles were more effective in inhibiting tumor growth and prolonging survival in a subcutaneous CT-26 murine tumor model in vivo. Therefore, our data revealed that the encapsulation of PL into biodegradable polymeric micelles enhanced its anti-angiogenesis and anti-tumor activities both in vitro and in vivo.

Small molecules with oxathiazol-2-one moiety were recently reported as potent inhibitors of Mycobacterium bovis var. bacilli Calmette–Guerin (BCG), among which HT1171 was the most potent and selective proteasome inhibitor. Herein we synthesized a series of novel compounds by bioisosteric replacement of the oxathiazol-2-one ring with 3H-1,2,4-dithiazol-3-one, and also fifteen 1,3,4-oxathiazol-2-one molecules in order for potency comparison and structure–activity relationship elucidation since their antibacterial effects on the virulent strains were not evaluated before. All the compounds were assessed for antitubercular activities on the virulent H37Rv strain by a serial dilution method. Among the tested compounds, 3H-1,2,4-dithiazol-3-one compound 4n was found to be the most active with a lowest MIC90 value of 1 μg/mL. Furthermore, the cytotoxicities of all the compounds against normal human liver cell line L02 were determined by an MTT method. Compound 4n displayed a lower inhibitory ratio than HT1171 at the concentration of 100 μM, indicating its better safety profile.

Dehydrosqualene synthase (CrtM) is a key enzyme in the synthesis of presqualene diphosphate in Staphylococcus aureus. In the current study, a combination of structure-based pharmacophore and 3D-QSAR methods are used to clarify the essential quantitative structure–activity relationship (QSAR) of known CrtM inhibitors; the multicomplex-based pharmacophore (MCBP) guided method has been suggested to generate a comprehensive pharmacophore of CrtM based on twenty crystal structures of CrtM inhibitor complex. Performances of the MCBP-based virtual screening approach were applied to screen specs chemical databases (202, 408 compounds). Thirty-eight compounds were selected from the final hits and should be shifted to experimental studies. The MCBP model has been successfully used to identify the bioactive conformation and align 24 structurally diverse CrtM inhibitors. The QSAR analyses have been performed on these CrtM inhibitors based on MCBP guided alignment. These results may provide important information for further design and discovery of novel CrtM inhibitors.

In this work, a novel oxazolidinone compound FYL-67 was synthesized, and the obtained FYL-67 could form nanoassemblies in aqueous solution by a self-assembly method without using any carrier, organic solvent, or surfactant. The prepared FYL-67 nanoassemblies had a particle size of 264.6 ± 4.3 nm. The FYL-67 nanoassemblies can be lyophilized into a powder form without any cryoprotector or excipient, and the re-dissolved FYL-67 nanoassemblies are stable and homogeneous. The in vitro release profile showed a significant difference between rapid release of free FYL-67 and much slower and sustained release of FYL-67 nanoassemblies. In vitro susceptibility tests were conducted in three strains of methicillin-susceptible Staphylococcus aureus (MSSA) and three strains of methicillin-resistant Staphylococcus aureus (MRSA), using linezolid as a positive control. FYL-67 nanoassemblies exhibited excellent in vitro activity, with a minimum inhibitory concentration (MIC) value of 0.5 μg mL(-1) against MRSA. In the in vitro post-antibiotic effect (PAE) evaluation, FYL-67 nanoassemblies showed a more powerful effect than linezolid. Besides, in vitro cytotoxicity tests indicated that FYL-67 nanoassemblies had a very low cytotoxicity on HEK293 cells and L02 cells. Furthermore, in both MSSA and MRSA systemic infection mouse models, FYL-67 nanoassemblies showed a lower ED(50) than linezolid. In a murine model of MRSA systemic infection, FYL-67 nanoassemblies displayed an ED(50) of less than 4.0 mg kg(-1), which is 2.3-fold better than that of linezolid. Our findings suggested that the FYL-67 nanoassemblies may be a potential drug candidate in MRSA therapy.