Salicylanilides and Their Anticancer Properties.

Salicylanilides are pharmacologically active compounds with a wide spectrum of biological effects. Halogenated salicylanilides, which have been used for decades in human and veterinary medicine as anthelmintics, have recently emerged as candidates for drug repurposing in oncology. The most prominent example of salicylanilide anthelmintic, that is intensively studied for its potential anticancer properties, is niclosamide. Nevertheless, recent studies have discovered extensive anticancer potential in a number of other salicylanilides. This potential of their anticancer action is mediated most likely by diverse mechanisms of action such as uncoupling of oxidative phosphorylation, inhibition of protein tyrosine kinase epidermal growth factor receptor, modulation of different signaling pathways as Wnt/ß-catenin, mTORC1, STAT3, NF-κB and Notch signaling pathways or induction of B-Raf V600E inhibition. Here we provide a comprehensive overview of the current knowledge about the proposed mechanisms of action of anticancer activity of salicylanilides based on preclinical in vitro and in vivo studies, or structural requirements for such an activity.

Study of Biological Activities and ADMET-Related Properties of Salicylanilide-Based Peptidomimetics.

A series of eleven benzylated intermediates and eleven target compounds derived from salicylanilide were tested against Staphylococcus aureus ATCC 29213 and Enterococcus faecalis ATCC 29212 as reference strains and against three clinical isolates of methicillin-resistant S. aureus (MRSA) and three isolates of vancomycin-resistant E. faecalis. In addition, the compounds were evaluated against Mycobacterium tuberculosis H37Ra and M. smegmatis ATCC 700084. The in vitro cytotoxicity of the compounds was assessed using the human monocytic leukemia cell line THP-1. The lipophilicity of the prepared compounds was experimentally determined and correlated with biological activity. The benzylated intermediates were found to be completely biologically inactive. Of the final eleven compounds, according to the number of amide groups in the molecule, eight are diamides, and three are triamides that were inactive. 5-Chloro-2-hydroxy-N-[(2S)- 4-(methylsulfanyl)-1-oxo-1-{[4-(trifluoromethyl)phenyl]amino}butan-2-yl]benzamide (3e) and 5-chloro-2-hydroxy-N-[(2S)-(4-methyl-1-oxo-1-{[4-(trifluoromethyl)phenyl]amino)pentan-2-yl)benzamide (3f) showed the broadest spectrum of activity against all tested species/isolates comparable to the used standards (ampicillin and isoniazid). Six diamides showed high antistaphylococcal activity with MICs ranging from 0.070 to 8.95 µM. Three diamides showed anti-enterococcal activity with MICs ranging from 4.66 to 35.8 µM, and the activities of 3f and 3e against M. tuberculosis and M. smegmatis were MICs of 18.7 and 35.8 µM, respectively. All the active compounds were microbicidal. It was observed that the connecting linker between the chlorsalicylic and 4-CF3-anilide cores must be substituted with a bulky and/or lipophilic chain such as isopropyl, isobutyl, or thiabutyl chain. Anticancer activity on THP-1 cells IC50 ranged from 1.4 to >10 µM and increased with increasing lipophilicity.

NSC828779 Alleviates Renal Tubulointerstitial Lesions Involving Interleukin-36 Signaling in Mice.

Renal tubulointerstitial lesions (TILs), a common pathologic hallmark of chronic kidney disease that evolves to end-stage renal disease, is characterized by progressive inflammation and pronounced fibrosis of the kidney. However, current therapeutic approaches to treat these lesions remain largely ineffectual. Previously, we demonstrated that elevated IL-36α levels in human renal tissue and urine are implicated in impaired renal function, and IL-36 signaling enhances activation of NLRP3 inflammasome in a mouse model of TILs. Recently, we synthesized NSC828779, a salicylanilide derivative (protected by U.S. patents with US 8975255 B2 and US 9162993 B2), which inhibits activation of NF-κB signaling with high immunomodulatory potency and low IC50, and we hypothesized that it would be a potential drug candidate for renal TILs. The current study validated the therapeutic effects of NSC828779 on TILs using a mouse model of unilateral ureteral obstruction (UUO) and relevant cell models, including renal tubular epithelial cells under mechanically induced constant pressure. Treatment with NSC828779 improved renal lesions, as demonstrated by dramatically reduced severity of renal inflammation and fibrosis and decreased urinary cytokine levels in UUO mice. This small molecule specifically inhibits the IL-36α/NLRP3 inflammasome pathway. Based on these results, the beneficial outcome represents synergistic suppression of both the IL-36α-activated MAPK/NLRP3 inflammasome and STAT3- and Smad2/3-dependent fibrogenic signaling. NSC828779 appears justified as a new drug candidate to treat renal progressive inflammation and fibrosis.

Exploiting the HSP60/10 chaperonin system as a chemotherapeutic target for colorectal cancer.

Over the past few decades, an increasing variety of molecular chaperones have been investigated for their role in tumorigenesis and as potential chemotherapeutic targets; however, the 60 kDa Heat Shock Protein (HSP60), along with its HSP10 co-chaperone, have received little attention in this regard. In the present study, we investigated two series of our previously developed inhibitors of the bacterial homolog of HSP60/10, called GroEL/ES, for their selective cytotoxicity to cancerous over non-cancerous colorectal cells. We further developed a third "hybrid" series of analogs to identify new candidates with superior properties than the two parent scaffolds. Using a series of well-established HSP60/10 biochemical screens and cell-viability assays, we identified 24 inhibitors (14%) that exhibited > 3-fold selectivity for targeting colorectal cancer over non-cancerous cells. Notably, cell viability EC50 results correlated with the relative expression of HSP60 in the mitochondria, suggesting a potential for this HSP60-targeting chemotherapeutic strategy as emerging evidence indicates that HSP60 is up-regulated in colorectal cancer tumors. Further examination of five lead candidates indicated their ability to inhibit the clonogenicity and migration of colorectal cancer cells. These promising results are the most thorough analysis and first reported instance of HSP60/10 inhibitors being able to selectively target colorectal cancer cells and highlight the potential of the HSP60/10 chaperonin system as a viable chemotherapeutic target.

Inhibition mechanism of SARS-CoV-2 main protease by ebselen and its derivatives.

The SARS-CoV-2 pandemic has triggered global efforts to develop therapeutics. The main protease of SARS-CoV-2 (Mpro), critical for viral replication, is a key target for therapeutic development. An organoselenium drug called ebselen has been demonstrated to have potent Mpro inhibition and antiviral activity. We have examined the binding modes of ebselen and its derivative in Mpro via high resolution co-crystallography and investigated their chemical reactivity via mass spectrometry. Stronger Mpro inhibition than ebselen and potent ability to rescue infected cells were observed for a number of derivatives. A free selenium atom bound with cysteine of catalytic dyad has been revealed in crystallographic structures of Mpro with ebselen and MR6-31-2 suggesting hydrolysis of the enzyme bound organoselenium covalent adduct and formation of a phenolic by-product, confirmed by mass spectrometry. The target engagement with selenation mechanism of inhibition suggests wider therapeutic applications of these compounds against SARS-CoV-2 and other zoonotic beta-corona viruses.

Osalmid, a Novel Identified RRM2 Inhibitor, Enhances Radiosensitivity of Esophageal Cancer.

PURPOSE: Esophageal cancer (EC) is an aggressive malignancy and is often resistant to currently available therapies. Inhibition of ribonucleotide reductase small subunit M2 (RRM2) in tumors is speculated to mediate chemosensitization. Previous studies have reported that Osalmid could act as an RRM2 inhibitor. We explored whether RRM2 was involved in radioresistance and the antitumor effects of Osalmid in EC. METHODS AND MATERIALS: RRM2 expression was detected by immunohistochemistry in EC tissues. The effects of Osalmid on cell proliferation, apoptosis, and cell cycle were assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphhenyl tetrazolium, colony formation, and flow cytometry assays. DNA damage, cell apoptosis, and senescence induced by Osalmid or ionizing radiation (IR) alone, or both, were detected with immunofluorescence, flow cytometry, Western blot, and ß-galactosidase staining. A xenograft mouse model of EC was used to investigate the potential synergistic effects of Osalmid and IR in vivo. RESULTS: The expression of RRM2 in treatment-resistant EC tissues is much higher than in treatment-sensitive EC, and strong staining of RRM2 was correlated with shorter overall survival. We observed direct cytotoxicity of Osalmid in EC cells. Osalmid also produced inhibition of the ERK1/2 signal transduction pathway and substantially enhanced IR-induced DNA damage, apoptosis, and senescence. Furthermore, treatment with Osalmid and IR significantly suppressed tumor growth in xenograft EC models without additional toxicity to the hematologic system and internal organs. CONCLUSIONS: Our study revealed that RRM2 played a vital role in radioresistance in EC, and Osalmid synergized with IR to exert its antitumor effects both in vitro and in vivo.

Identification of osalmid metabolic profile and active metabolites with anti-tumor activity in human hepatocellular carcinoma cells.

BACKGROUNDS: Ribonucleotide reductase (RR) catalyzes the essential step in the formation of all four deoxynucleotides. Upregulated activity of RR plays an active role in tumor progression. As the regulatory subunit of RR, ribonucleotide reductase subunit M2 (RRM2) is regarded as one of the effective therapeutic targets for DNA replication-dependent diseases, such as cancers. Recent studies have revealed that osalmid significantly inhibits the activity of RRM2, but the metabolic profile of osalmid remains unknown. OBJECTIVE: The aim of this study was to clarify the metabolic profile including metabolites, isoenzymes and metabolic pathways of osalmid. The anti-human hepatocellular carcinoma activity and mechanism of metabolites were further investigated. MATERIALS AND METHODS: Ultra high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) was used for identifying metabolites and for characterizing phase I and phase II metabolic pathways with recombinant enzymes or in human liver microsomes of osalmid. The eHiTS docking system was used for potential RRM2 inhibitor screening among metabolites. Cytotoxicity assays were performed for evaluating cell proliferation inhibitory activity of metabolites. Cell cycle assays and cell apoptosis assays were assessed by flow cytometry. Western blotting analysis of RRM2, cyclin D1, p21, p53, phosphorylated p53, Bcl-2 and Bax was performed to explore the anti-hepatocellular carcinoma mechanism of the active metabolites. RESULTS: Ten metabolites of osalmid were identified, and none of them have been reported previously. Hydroxylation, glucuronidation, sulfonation, acetylation and degradation were recognized as the main metabolic processes of osalmid. Isozymes of CYP1A2, CYP2C9, UGT1A1, UGT1A6, UGT1A9, UGT2B7 and UGT2B15 were involved in phase I and phase II metabolism of osalmid. Metabolites M7, M8 and M10 showed higher binding affinities with the RRM2 active site than osalmid. Metabolite M7 exhibited potent inhibitory activity to hepatocellular carcinoma cell lines by both competitive inhibition and down-regulation of RRM2. Moreover, M7 significantly induced cell cycle arrest and apoptosis by activating p53-related pathways. CONCLUSIONS: The metabolic profile of osalmid was identified. M7 significantly inhibited human hepatocellular carcinoma progression by inhibiting RRM2 activity. Furthermore, M7 induced cell cycle arrest and apoptosis by activating p53-related signaling pathways.

Repositioning of Anthelmintic Drugs for the Treatment of Cancers of the Digestive System.

Tumors of the digestive system, when combined together, account for more new cases and deaths per year than tumors arising in any other system of the body and their incidence continues to increase. Despite major efforts aimed at discovering and validating novel and effective drugs against these malignancies, the process of developing such drugs remains lengthy and costly, with high attrition rates. Drug repositioning (also known as drug repurposing), that is, the process of finding new uses for approved drugs, has been gaining popularity in oncological drug development as it provides the opportunity to expedite promising anti-cancer agents into clinical trials. Among the drugs considered for repurposing in oncology, compounds belonging to some classes of anthelmintics-a group of agents acting against infections caused by parasitic worms (helminths) that colonize the mammalian intestine-have shown pronounced anti-tumor activities and attracted particular attention due to their ability to target key oncogenic signal transduction pathways. In this review, we summarize and discuss the available experimental and clinical evidence about the use of anthelmintic drugs for the treatment of cancers of the digestive system.

Ring-Substituted 1-Hydroxynaphthalene-2-Carboxanilides Inhibit Proliferation and Trigger Mitochondria-Mediated Apoptosis.

Ring-substituted 1-hydroxynaphthalene-2-carboxanilides were previously investigated for their antimycobacterial properties. In our study, we have shown their antiproliferative and cell death-inducing effects in cancer cell lines. Cell proliferation and viability were assessed by WST-1 assay and a dye exclusion test, respectively. Cell cycle distribution, phosphatidylserine externalization, levels of reactive oxygen or nitrogen species (RONS), mitochondrial membrane depolarization, and release of cytochrome c were estimated by flow cytometry. Levels of regulatory proteins were determined by Western blotting. Our data suggest that the ability to inhibit the proliferation of THP-1 or MCF-7 cells might be referred to meta- or para-substituted derivatives with electron-withdrawing groups -F, -Br, or -CF3 at anilide moiety. This effect was accompanied by accumulation of cells in G1 phase. Compound 10 also induced apoptosis in THP-1 cells in association with a loss of mitochondrial membrane potential and production of mitochondrial superoxide. Our study provides a new insight into the action of salicylanilide derivatives, hydroxynaphthalene carboxamides, in cancer cells. Thus, their structure merits further investigation as a model moiety of new small-molecule compounds with potential anticancer properties.

Discovery and Structure Relationships of Salicylanilide Derivatives as Potent, Non-acidic P2X1 Receptor Antagonists.

Antagonists for the ATP-gated ion channel receptor P2X1 have potential as antithrombotics and for treating hyperactive bladder and inflammation. In this study, salicylanilide derivatives were synthesized based on a screening hit. P2X1 antagonistic potency was assessed in 1321N1 astrocytoma cells stably transfected with the human P2X1 receptor by measuring inhibition of the ATP-induced calcium influx. Structure-activity relationships were analyzed, and selectivity versus other P2X receptor subtypes was assessed. The most potent compounds, N-[3,5-bis(trifluoromethyl)phenyl]-5-chloro-2-hydroxybenzamide (1, IC50 0.0192 µM) and N-[3,5-bis(trifluoromethyl)phenyl]-4-chloro-2-hydroxybenzamide (14, IC50 0.0231 µM), displayed >500-fold selectivity versus P2X2 and P2X3, and 10-fold selectivity versus P2X4 and P2X7 receptors, and inhibited collagen-induced platelet aggregation. They behaved as negative allosteric modulators, and molecular modeling studies suggested an extracellular binding site. Besides selective P2X1 antagonists, compounds with ancillary P2X4 and/or P2X7 receptor inhibition were discovered. These compounds represent the first potent, non-acidic, allosteric P2X1 receptor antagonists reported to date.

Novel cyclophosphamide of natural products osalmide and pterostilbene induces cytotoxicity and cell cycle arrest in diffuse large B-cell lymphoma cells.

Diffuse large B-cell lymphoma (DLBCL) is the most common category and disease entity of non-Hodgkin lymphoma. Osalmide and pterostilbene are natural products with anticancer activities via different mechanism. In this study, using a new synthetic strategy for the two natural products, we obtained the compound DCZ0801, which was previously found to have anti-multiple myeloma activity. We performed both in vitro and in vivo assays to investigate its bioactivity and explore its underlying mechanism against DLBCL cells. The results showed that DCZ0801 treatment gave rise to a dose- and time-dependent inhibition of cell viability as determined by CCK-8 assay and flow cytometry assay. Western blot analysis results showed that the expression of caspase-3, caspase-8, caspase-9 and Bax was increased, while BCL-2 and BCL-XL levels were decreased, which suggested that DCZ0801 inhibited cell proliferation and promoted intrinsic apoptosis. In addition, DCZ0801 induced G0/G1 phase arrest by downregulating the protein expression levels of CDK4, CDK6 and cyclin D1. Furthermore, DCZ0801 exerted an anti-tumor effect by down-regulating the expressions of p-PI3K and p-AKT. There also existed a trend that the expression of p-JNK and p-P38 was restrained. Intraperitoneal injection of DCZ0801 suppressed tumor development in xenograft mouse models. The preliminary metabolic study showed that DCZ0801 displayed a rapid metabolism within 30 min. These results demonstrated that DCZ0801 may be a new potential anti-DLBCL agent in DLBCL therapy.

A Novel Salicylanilide Derivative Induces Autophagy Cell Death in Castration-Resistant Prostate Cancer via ER Stress-Activated PERK Signaling Pathway.

Metastatic castration-resistant prostate cancer (CRPC) is currently incurable. Cancer growth and progression is intimately affected by its interaction with host microenvironment. Cotargeting of the stroma and prostate cancer is therefore an emerging therapeutic strategy for metastatic CRPC. Cancer-induced osteoclastogenesis is known to contribute to CRPC bone metastasis. This study is to extend pharmacologic value of our synthesized LCC03, a derivative of 5-(2',4'-difluorophenyl)-salicylanilide that has previously testified for its osteoclastogenesis activity, by exploring its additional cytotoxic properties and underlying mechanism in CRPC cells. LCC03 was chemically synthesized and examined for cell growth inhibition in a serial of CRPC cell lines. We demonstrated that LCC03 dose-dependently suppressed proliferation and retarded cell-cycle progression in CRPC cells. The classical autophagy features, including autophagosome formation and LC3-II conversion, were dramatically shown in LCC03-treated CRPC cells, and it was associated with the suppressed AKT/mTOR signaling pathways, a major negative regulator of autophagy. Moreover, an expanded morphology of the endoplasmic reticulum (ER), increased expression of the ER stress markers GRP78 and PERK, and eIF2α phosphorylation were observed. Blockage of autophagy and PERK pathways using small molecule inhibitors or shRNA knockdown reversed LCC03-induced autophagy and cell death, thus indicating that the PERK-eIF2α pathway contributed to the LCC03-induced autophagy. Furthermore, treatment of tumor-bearing mice with intraperitoneal administered LCC03 suppressed the growth of CRPC xenografts in mouse bone without systemic toxicity. The dual action of 5-(2',4'-difluorophenyl)-salicylanilide on targeting both the osteoclasts and the tumor cells strongly indicates that LCC03 is a promising anticancer candidate for preventing and treating metastatic CRPC.

Phenolic N-monosubstituted carbamates: Antitubercular and toxicity evaluation of multi-targeting compounds.

The research of novel antimycobacterial drugs represents a cutting-edge topic. Thirty phenolic N-monosubstituted carbamates, derivatives of salicylanilides and 4-chlorophenol, were investigated against Mycobacterium tuberculosis H37Ra, H37Rv including multidrug- and extensively drug-resistant strains, Mycobacterium avium, Mycobacterium kansasii, Mycobacterium aurum and Mycobacterium smegmatis as representatives of nontuberculous mycobacteria (NTM) and for their cytotoxic and cytostatic properties in HepG2 cells. Since salicylanilides are multi-targeting compounds, we determined also inhibition of mycobacterial isocitrate lyase, an enzyme involved in the maintenance of persistent tuberculous infection. The minimum inhibitory concentrations were from ≤0.5 µM for both drug-susceptible and resistant M. tuberculosis and from ≤0.79 µM for NTM with no cross-resistance to established drugs. The presence of halogenated salicylanilide scaffold results into an improved activity. We have verified that isocitrate lyase is not a key target, presented carbamates showed only moderate inhibitory activity (up to 18% at a concentration of 10 µM). Most of the compounds showed no cytotoxicity for HepG2 cells and some of them were without cytostatic activity. Cytotoxicity-based selectivity indexes of several carbamates for M. tuberculosis, including resistant strains, were higher than 125, thus favouring some derivatives as promising features for future development.

Zygocotyle lunata as a model for in vivo screening of anthelmintic activity against paramphistomes: Evaluation of efficacy of praziquantel, albendazole and closantel in experimentally infected mice.

Paramphistomes are important parasites in veterinary medicine. There are few anthelmintic drugs available against them. The development of new drugs is urgently needed and this process can be accelerated through the development of rodent models for in vivo testing. Among the few paramphistomes that develop in rodents is the caecal fluke Zygocotyle lunata, a species with which several biological studies have been performed over several decades. Nevertheless, its use as a model for evaluation of anthelmintic drugs had not yet been evaluated. In the present study, we evaluated the efficacy of praziquantel (PZQ 300 mg/kg 5x), albendazole (ABZ 200 mg/kg 5x) and closantel (CLO 50 mg/kg single dose, 50 mg/kg 3x and 25 mg/kg 3x) for treatment of mice experimentally infected with Z. lunata. The animals were infected with 20 metacercariae of the parasite and were treated 30 days post-infection. Untreated groups were maintained as controls. Seven days after the treatments, the animals were euthanized for recovery and counting of parasites. We found that PZQ and ABZ, at the dosages and therapeutic schedule employed here, did not cause significant alterations in worm burden [worm counts 16.0 ±â€¯2.8 (13-19), 17.6 ±â€¯2.1 (14-19) and 16.2 ±â€¯1.9 (13-18) (p = 0.51) in PZQ, ALB and control, respectively]. CLO 50 mg/kg in a single dose caused significant reduction in the number of parasites [treated: 1.8 ±â€¯0.9 (1-3); control: 15.6 ±â€¯2.5 (12-19)], although it did not result in complete elimination of the parasites in any animal. Despite the fact that three doses of CLO 50 mg/kg or CLO 25 mg/kg caused complete elimination of the parasites in most surviving animals, there was significant host mortality. In general, results here obtained are concordant with those of studies performed on ruminant paramphistomes. Given that Z. lunata can be maintained in laboratory rodents, it is a suitable model for screening anthelmintic drugs against paramphistomes.

A phenotypic small-molecule screen identifies halogenated salicylanilides as inhibitors of fungal morphogenesis, biofilm formation and host cell invasion.

A poorly exploited paradigm in the antimicrobial therapy field is to target virulence traits for drug development. In contrast to target-focused approaches, antivirulence phenotypic screens enable identification of bioactive molecules that induce a desirable biological readout without making a priori assumption about the cellular target. Here, we screened a chemical library of 678 small molecules against the invasive hyphal growth of the human opportunistic yeast Candida albicans. We found that a halogenated salicylanilide (N1-(3,5-dichlorophenyl)-5-chloro-2-hydroxybenzamide) and one of its analogs, Niclosamide, an FDA-approved anthelmintic in humans, exhibited both antifilamentation and antibiofilm activities against C. albicans and the multi-resistant yeast C. auris. The antivirulence activity of halogenated salicylanilides were also expanded to C. albicans resistant strains with different resistance mechanisms. We also found that Niclosamide protected the intestinal epithelial cells against invasion by C. albicans. Transcriptional profiling of C. albicans challenged with Niclosamide exhibited a signature that is characteristic of the mitochondria-to-nucleus retrograde response. Our chemogenomic analysis showed that halogenated salicylanilides compromise the potential-dependant mitochondrial protein translocon machinery. Given the fact that the safety of Niclosamide is well established in humans, this molecule could represent the first clinically approved antivirulence agent against a pathogenic fungus.

In vitro susceptibility of nematophagous fungi to antiparasitic drugs: interactions and implications for biological control / Suscetibilidade in vitro de fungos nematófagos à antiparasitários: interações e implicações para o controle biológico

Abstract The fast anthelmintic resistance development has shown a limited efficiency in the control of animal's endoparasitosis and has promoted research using alternative control methods. The use of chemicals in animal anthelmintic treatment, in association with nematophagous fungi used for biological control, is a strategy that has proven to be effective in reducing the nematode population density in farm animals. This study aims to verify the in vitro susceptibility of the nematophagous fungi Arthrobotrys oligospora, Duddingtonia flagrans and Paecilomyces lilacinus against the antiparasitic drugs albendazole, thiabendazole, ivermectin, levamisole and closantel by using the Minimum Inhibitory Concentration (MIC). MICs ranged between 4.0 and 0.031 µg/mL for albendazole, thiabendazole and ivermectin, between 0.937 and 0.117 µg/mL for levamisole, and between 0.625 and 0.034 µg/mL for closantel. The results showed that all antiparasitic drugs had an in vitro inhibitory effect on nematophagous fungi, which could compromise their action as agents of biological control. D. flagrans was the most susceptible species to all drugs.

Resumo O desenvolvimento rápido da resistência anti-helmíntica demonstrou a eficiência limitada no controle de endoparasitoses em animais, e promoveu a investigação em métodos de controles alternativos. O uso de produtos químicos no tratamento anti-helmíntico animal, em associação com fungos nematófagos utilizados para o controlo biológico, é uma estratégia que tem provado ser eficaz na redução da densidade da população de nematódeos em animais agrícolas. Este estudo teve como objetivo verificar a suscetibilidade in vitro dos fungos nematófagos Arthrobotrys oligospora, Duddingtonia flagrans e Paecilomyces lilacinus frente aos antiparasitários albendazol, tiabendazol, ivermectina, levamisol e closantel, usando a concentração inibitória mínima (MIC). Os MICs variaram entre 4,0 e 0,031 μg/mL para albendazol, tiabendazol e ivermectina, entre 0,937 e 0,117 μg/mL para o levamisol, e entre 0,625 e 0,034 μg/mL para closantel. Os resultados mostraram que todos os antiparasitários tiveram um efeito inibidor in vitro sobre os fungos nematófagos, o que poderia comprometer suas atividades como agentes de controle biológico. D. flagrans foi a espécie mais sensível a todas as drogas.

Suppression of the Growth and Invasion of Human Head and Neck Squamous Cell Carcinomas via Regulating STAT3 Signaling and the miR-21/ß-catenin Axis with HJC0152.

Signal transducer and activator of transcription 3 (STAT3) is involved in the tumor growth and metastasis of human head and neck squamous cell carcinoma (HNSCC) and is therefore a target with therapeutic potential. In this study, we show that HJC0152, a recently developed anticancer agent and a STAT3 signaling inhibitor, exhibits promising antitumor effects against HNSCC both in vitro and in vivo via inactivating STAT3 and downstream miR-21/ß-catenin axis. HJC0152 treatment efficiently suppressed HNSCC cell proliferation, arrested the cell cycle at the G0-G1 phase, induced apoptosis, and reduced cell invasion in both SCC25 and CAL27 cell lines. Moreover, HJC0152 inhibited nuclear translocation of phosphorylated STAT3 at Tyr705 and decreased VHL/ß-catenin signaling activity via regulation of miR-21. Loss of function of VHL remarkably compromised the antitumor effect of HJC0152 in both cell lines. In our SCC25-derived orthotopic mouse models, HJC0152 treatment significantly abrogated STAT3/ß-catenin expression in vivo, leading to a global decrease of tumor growth and invasion. With its favorable aqueous solubility and oral bioavailability, HJC0152 holds the potential to be translated into the clinic as a promising therapeutic strategy for patients with HNSCC. Mol Cancer Ther; 16(4); 578-90. ©2017 AACR.

Novel salicylanilides from 4,5-dihalogenated salicylic acids: Synthesis, antimicrobial activity and cytotoxicity.

Salicylanilides have proved their activity against tuberculosis (TB). One weak electron-withdrawing substituent is favored at the salicylic part, specially Cl or Br atoms at positions 4 or 5. On the other hand, the antimycobacterial activity of salicylanilides is negatively affected when a strong electron-withdrawing substituent (NO2) is present at the same positions. Herein we describe the synthesis and characterization of novel salicylanilides possessing two weak electron-withdrawing groups (halogen atoms) at their salicylic part and compare their antitubercular activity with their monohalogenated analogues. All dihalogenated derivatives proved to possess antitubercular activity at a very narrow micromolar range (MIC=1-4µM), similar with their most active monohalogenated analogues. More importantly, the most active final molecules were further screened against multidrug resistant strains and found to inhibit their growth at the range of 0.5-4µM.

Reprofiled anthelmintics abate hypervirulent stationary-phase Clostridium difficile.

Prolonged use of broad-spectrum antibiotics disrupts the indigenous gut microbiota, which consequently enables toxigenic Clostridium difficile species to proliferate and cause infection. The burden of C. difficile infections was exacerbated with the outbreak of hypervirulent strains that produce copious amounts of enterotoxins and spores. In recent past, membrane-active agents have generated a surge of interest due to their bactericidal property with a low propensity for resistance. In this study, we capitalized on the antimicrobial property and low oral bioavailability of salicylanilide anthelmintics (closantel, rafoxanide, niclosamide, oxyclozanide) to target the gut pathogen. By broth microdilution techniques, we determined the MIC values of the anthelmintics against 16 C. difficile isolates of defined PCR-ribotype. The anthelmintics broadly inhibited C. difficile growth in vitro via a membrane depolarization mechanism. Interestingly, the salicylanilides were bactericidal against logarithmic- and stationary-phase cultures of the BI/NAP1/027 strain 4118. The salicylanilides were poorly active against select gut commensals (Bacteroides, Bifidobacterium and Lactobacillus species), and were non-hemolytic and non-toxic to mammalian cell lines HepG2 and HEK 293T/17 within the range of their in vitro MICs and MBCs. The salicylanilide anthelmintics exhibit desirable properties for repositioning as anti-C. difficile agents.

Repositioning organohalogen drugs: a case study for identification of potent B-Raf V600E inhibitors via docking and bioassay.

Drug repositioning has been attracting increasingly attention for its advantages of reducing costs and risks. Statistics showed that around one quarter of the marketed drugs are organohalogens. However, no study has been reported, to the best of our knowledge, to aim at efficiently repositioning organohalogen drugs, which may be attributed to the lack of accurate halogen bonding scoring function. Here, we present a study to show that two organohalogen drugs were successfully repositioned as potent B-Raf V600E inhibitors via molecular docking with halogen bonding scoring function, namely D(3)DOCKxb developed in our lab, and bioassay. After virtual screening by D(3)DOCKxb against the database CMC (Comprehensive Medicinal Chemistry), 3 organohalogen drugs that were predicted to form strong halogen bonding with B-Raf V600E were purchased and tested with ELISA-based assay. In the end, 2 of them, rafoxanide and closantel, were identified as potent inhibitors with IC50 values of 0.07 µM and 1.90 µM, respectively, which are comparable to that of vemurafenib (IC50: 0.17 µM), a marketed drug targeting B-Raf V600E. Single point mutagenesis experiments confirmed the conformations predicted by D(3)DOCKxb. And comparison experiment revealed that halogen bonding scoring function is essential for repositioning those drugs with heavy halogen atoms in their molecular structures.