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Methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus (VRSA) are primary causes of skin and soft tissue infections worldwide. To address the emergency caused due to increasing multidrug-resistant (MDR) bacterial infections, a series of novel fluoro and trifluoromethyl-substituted salicylanilide derivatives were synthesized and their antimicrobial activity was investigated. MIC data reveal that the compounds inhibited S. aureus specifically (MIC 0.25–64 µg/mL). The in vitro cytotoxicity of compounds with MIC

Hypertension is an important target for drug discovery. We have focused on the with-no-lysine kinase (WNK)-oxidative stress-responsive 1 (OSR1) and STE20/SPS1-related proline-alanine-rich protein kinase (SPAK)-NaCl cotransporter (NCC) signal cascade as a potential target, and we previously developed a screening system for inhibitors of WNK-OSR1/SPAK-NCC signaling. Herein we used this system to examine the structure-activity relationship (SAR) of salicylanilide derivatives as SPAK kinase inhibitors. Structural design and development based on our previous hit compound, aryloxybenzanilide derivative 2, and the veterinary anthelmintic closantel (3) led to the discovery of compound 10 a as a potent SPAK inhibitor with reduced toxicity. Compound 10 a decreased the phosphorylation level of NCC in mouse kidney in vivo, and appears to be a promising lead compound for a new class of antihypertensive drugs.

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.

The Wnt signaling pathway is critical for normal tissue development and is an underlying mechanism of disease when dysregulated. Previously, we reported that the drug Niclosamide inhibits Wnt/β-catenin signaling by decreasing the cytosolic levels of Dishevelled and β-catenin, and inhibits the growth of colon cancers both in vitro and in vivo. Since the discovery of Niclosamide’s anthelmintic activity, a growing body of literature indicates that Niclosamide is a multifunctional drug. In an effort to identify derivatives of Niclosamide with improved pharmacokinetic properties that maintain the multifunctional drug activity of Niclosamide for clinical evaluation, we designed DK419, a derivative containing a 1H-benzo[d]imidazole-4-carboxamide substructure, using the structure-activity relationships (SAR) of the Niclosamide salicylanilide chemotype. Similar to Niclosamide, we found DK419 inhibited Wnt/β-catenin signaling, altered cellular oxygen consumption rate and induced production of pAMPK. Moreover, we found DK419 inhibited the growth of CRC tumor cells in vitro, had good plasma exposure when dosed orally, and inhibited the growth of patient derived CRC240 tumor explants in mice dosed orally. DK419, a derivative of Niclosamide with multifunctional activity and improved pharmacokinetic properties, is a promising agent to treat colorectal cancer, Wnt-related diseases and other diseases in which Niclosamide has demonstrated functional activity.

Based on the presence of carbamate moiety, twenty salicylanilide N-monosubstituted carbamates concomitantly with their parent salicylanilides and five newly prepared 4-chlorophenyl carbamates obtained from isocyanates were investigated using Ellman’s method for their in vitro inhibitory activity against acetylcholinesterase (AChE) from electric eel and butyrylcholinesterase (BChE) from equine serum. The carbamates and salicylanilides exhibited mostly a moderate inhibition of both cholinesterase enzymes with IC50 values ranging from 5 to 235 µM. IC50 values for AChE were in a narrower concentration range when compared to BChE, but many of the compounds produced a balanced inhibition of both cholinesterases. The derivatives were comparable or superior to rivastigmine for AChE inhibition, but only a few of carbamates also for BChE. Several structure-activity relationships were identified, e.g., N-phenethylcarbamates produce clearly favourable BChE inhibition. The compounds also share convenient physicochemical properties for CNS penetration.

Palladium(II)-Salicylanilide complexes of the type [Pd(κ2-Saln)2] (1), [Pd(κ2-Saln)2(diphos)] (2-6) (diphos = dppe, dppp, dppb, dppf, and dppmS2) and [Pd(κ2-Saln)2(μ-dppm)] (7) were synthesized and characterized. The salicylanidate ligand (Saln−) was bonded as bidentate chelating through the O atoms of hydroxyl and carbonyl groups in complex (1), whereas coordinated as monodentate through the O atom of hydroxyl group in complexes (2-7), and the all diphosphine ligands except dppm bonded as bidentate chelating to afford a square planner geometry around the Pd(II) ion. The dppm ligand was coordinated as bidentate bridging to afford binuclear complex. The prepared complexes displayed respectable activity against the pathogen bacteria species. Complex (5) showed the highest inhibition value against all types of bacteria, compared to the other complexes and the free ligand. On the other hand, the complex [Pd(Saln)2], showed the lowest inhibition against all types of bacteria. And the inhibition sequence of complexes is as following: (5) > (4) > (2) > (3) > HSaln > (1) Calculations of density function theory (DFT) were performed at the B3LYP/6-311G(d,p) level involved in the Gaussian 09 program to inspect the optimized structures of the chelating agent and its complexes. Docking study of the ligand was performed against the proteins of bacterial strains Pseudomonas aeruginosa (ID: 3P3E), Escherichia coli (ID: 1C14), Staphylococcus aureus (ID: 3BL6), and Salmonella typhimurium (ID: 3V7F) by Auto-Dock tools to portend the best binding mode.

Tuberculosis is caused by Mycobacterium tuberculosis, an intracellular pathogen that can survive in host cells, mainly in macrophages. An increase of multidrug-resistant tuberculosis qualifies this infectious disease as a major public health problem worldwide. The cellular uptake of the antimycobacterial agents by infected host cells is limited. Our approach is to enhance the cellular uptake of the antituberculars by target cell-directed delivery using drug-peptide conjugates to achieve an increased intracellular efficacy. In this study, salicylanilide derivatives (2-hydroxy-N-phenylbenzamides) with remarkable antimycobacterial activity were conjugated to macrophage receptor specific tuftsin based peptide carriers through oxime bond directly or by insertion of a GFLG tetrapeptide spacer. We have found that the in vitro antimycobacterial activity of the salicylanilides against M. tuberculosis H37Rv is preserved in the conjugates. While the free drug was ineffective on infected macrophage model, the conjugates were active against the intracellular bacteria. The fluorescently labelled peptide carriers that were modified with different fatty acid side chains showed outstanding cellular uptake rate to the macrophage model cells. The conjugation of the salicylanilides to tuftsin based carriers reduced or abolished the in vitro cytostatic activity of the free drugs with the exception of the palmitoylated conjugates. The conjugates degraded in the presence of rat liver lysosomal homogenate leading to the formation of an oxime bond-linked salicylanilide-amino acid fragment as the smallest active metabolite.

Graphical abstract, Zika virus has emerged as a potential threat to human health globally. A previous drug repurposing screen identified the approved anthelminthic drug niclosamide as a small molecule inhibitor of Zika virus infection. However, as antihelminthic drugs are generally designed to have low absorption when dosed orally, the very limited bioavailability of niclosamide will likely hinder its potential direct repurposing as an antiviral medication. Here, we conducted SAR studies focusing on the anilide and salicylic acid regions of niclosamide to improve physicochemical properties such as microsomal metabolic stability, permeability and solubility. We found that the 5-bromo substitution in the salicylic acid region retains potency while providing better drug-like properties. Other modifications in the anilide region with 2’-OMe and 2’-H substitutions were also advantageous. We found that the 4’-NO2 substituent can be replaced with a 4’-CN or 4’-CF3 substituents. Together, these modifications provide a basis for optimizing the structure of niclosamide to improve systemic exposure for application of niclosamide analogs as drug lead candidates for treating Zika and other viral infections. Indeed, key analogs were also able to rescue cells from the cytopathic effect of SARS-CoV-2 infection, indicating relevance for therapeutic strategies targeting the COVID-19 pandemic.

Two series of novel salicylanilide analogues (4a-4 g) and (4h-4t) were designed, synthesized, and characterized, especially the structure of compound 4q was further confirmed by single X-ray diffraction. The inhibitory activity on polyphenoloxidase (PPO) from the cephalothorax of Chinese white shrimp (Fenneropenaeus chinensis) was evaluated. The result indicated that all the synthesized derivatives (except 4 g and 4t) exhibited moderate PPO inhibitory properties having IC50 values in the range of 0.21 ± 0.19 to 4.32 ± 0.53 mM, whereas reference inhibitor salicylic acid and 3a have IC50 values 3.93 ± 0.43 mM and 12.83 ± 0.51 mM, respectively. Specifically, 4-nitro-benzoic acid 3-(2‑hydroxy‑benzoylamino)- propyl ester (4q) exhibited the most potent PPO inhibitory activity with an IC50 value of 0.21 ± 0.19 mM. The kinetic studies of the compound (4q) demonstrated that the inhibitory effects of the compound on the PPO were belonging to competitive inhibitors. Meanwhile, the structure-activity relationship was discussed. Therefore, compound 4q could act as a PPO inhibitor with anti-browning and antimicrobial properties to be applied in the food industry.

Inhibiting osteoclastogenesis is a promising therapeutic target for treating osteoclast-related diseases. Herein, we synthesized a series of modified salicylanilides and their corresponding 3-phenyl-2H-benzo[e][1,3]oxazine-2,4(3H)-dione and 10-phenyldibenzo[b,f][1,4]oxazepin-11(10H)-one derivatives, and investigated the effects of such compounds on RANKL-induced osteoclast formation. Among them, a salicylanilide derivative (A04) and its 3-phenyl-2H-benzo[e][1,3]oxazine-2,4(3H)-dione derivative (B04) markedly suppressed RANKL-induced osteoclast differentiation and showed no significant cytotoxic effects at doses higher than that required to inhibit osteoclast formation. Both compounds reduced osteoclast formation and bone resorptive activity of osteoclasts in a dose-dependent manner. Further, the anti-osteoclastogenic effects of A04 and B04 may operate through reducing the RANKL-induced nuclear translocation of NFATc1. Accordingly, we present the potent anti-osteoclastogenic compounds A04 and B04 as promising candidates for further optimization as anti-resorptive agents.

A new series of 27 diethyl 2-(phenylcarbamoyl)phenyl phosphorothioates (thiophosphates) was synthesized, characterized by NMR, IR and CHN analyses and evaluated against Mycobacterium tuberculosis H37Rv, Mycobacterium avium and two strains of Mycobacterium kansasii. The best activity against M. tuberculosis was found for O-{4-bromo-2-[(3,4-dichlorophenyl)carbamoyl]phenyl} O,O-diethyl phosphorothioate (minimum inhibitory concentration of 4 µM). The highest activity against nontuberculous mycobacteria was exhibited by O-(5-chloro-2-{[4-(trifluoromethyl)phenyl]carbamoyl}-phenyl) O,O-diethyl phosphorothioate with MIC values from 16 µM. Prepared thiophosphates were also evaluated against acetylcholinesterase from electric eel and butyrylcholinesterase from equine serum. Their inhibitory activity was compared to that of the known cholinesterases inhibitors galanthamine and rivastigmine. All tested compounds showed a higher (for AChE inhibition) and comparable (for BChE inhibition) activity to that of rivastigmine, with IC50s within the 8.04 to 20.2 µM range.

A series of 27 salicylanilide diethyl phosphates was prepared as a part of our on-going search for new antimicrobial active drugs. All compounds exhibited in vitro activity against Mycobacterium tuberculosis, Mycobacterium kansasii and Mycobacterium avium strains, with minimum inhibitory concentration (MIC) values of 0.5-62.5μmol/L. Selected salicylanilide diethyl phosphates also inhibit multidrug-resistant tuberculous strains at the concentration of 1μmol/L. Salicylanilide diethyl phosphates also exhibited mostly the activity against Gram-positive bacteria (MICs ≥1.95μmol/L), whereas their antifungal activity is significantly lower. The IC50 values for Hep G2 cells were within the range of 1.56-33.82μmol/L, but there is no direct correlation with MICs for mycobacteria.

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.

The development of novel antimicrobial agents represents a timely research topic. Eighteen salicylanilide 4-(trifluoromethyl)benzoates were evaluated against Mycobacterium tuberculosis, M. avium and M. kansasii, eight bacterial strains including methicillin-resistant Staphylococcus aureus (MRSA) and for the inhibition of mycobacterial isocitrate lyase. Some compounds were further screened against drug-resistant M. tuberculosis and for their cytotoxicity. Minimum inhibitory concentrations (MICs) for all mycobacterial strains were within 0.5–32 μmol/L, with 4-chloro-2-[4-(trifluoromethyl)phenylcarbamoyl]phenyl 4-(trifluoromethyl)benzoate superiority. Gram-positive bacteria including MRSA were inhibited with MICs ³ 0.49 μmol/L, while Gram-negative ones were much less susceptible. Salicylanilide 4-(trifluoromethyl)benzoates showed significant antibacterial properties, for many strains being comparable to standard drugs (isoniazid, benzylpenicillin) with no cross-resistance. All esters showed mild inhibition of mycobacterial isocitrate lyase and four compounds were comparable to 3-nitropropionic acid without a direct correlation between in vitro MICs and enzyme inhibition.

The Wnt signaling pathway plays a key role in organ and tissue homeostasis, and when dysregulated, can become a major underlying mechanism of disease, particularly cancer. We reported previously that the anthelmintic drug Niclosamide inhibits Wnt/β-catenin signaling and suppresses colon cancer cell growth in vitro and in vivo. To define Niclosamide's mechanism of Wnt/β-catenin inhibition, and to improve its selectivity and pharmacokinetic properties as an anticancer treatment, we designed a novel class of benzimidazole inhibitors of Wnt/β-catenin signaling based on SAR studies of the Niclosamide salicylanilide chemotype. Niclosamide has multiple biological activities. To address selectivity in our design, we interrogated a protonophore SAR model and used the principle of conformational restriction to identify novel Wnt/β-catenin inhibitors with less effect on ATP cellular homeostasis. These studies led to the identification of 4-chloro-2-(5-(trifluoromethyl)-1H-benzo[d]imidazol-2-yl) phenol (4) and related derivatives with greater selectivity for Wnt/β-catenin signaling inhibition vs. differential effects on cellular ATP homeostasis. This is the first report that the Wnt signaling inhibitory activity of Niclosamide can be translated into a new chemical class and to show that its effects on ATP homeostasis can be separated from its inhibitory effects on Wnt signaling. These compounds could be useful tools to elucidate the mechanism of Niclosamide's inhibition of Wnt signaling, and aid the discovery of inhibitors with improved pharmacologic properties to treat cancer and diseases in which Niclosamide has important biological activity.

The increasing emergence especially of drug-resistant tuberculosis has led to a strong demand for new anti-tuberculosis drugs. Eighteen salicylanilide benzoates were evaluated for their inhibition potential against Mycobacterium tuberculosis, Mycobacterium avium and two strains of Mycobacterium kansasii; minimum inhibitory concentration values ranged from 0.5 to 16 μmol/L. The most active esters underwent additional biological assays. Four benzoates inhibited effectively the growth of five multidrug-resistant strains and one extensively drug-resistant strain of M. tuberculosis at low concentrations (0.25–2 μmol/L) regardless of the resistance patterns. The highest rate of multidrug-resistant mycobacteria inhibition expressed 4-chloro-2-[4-(trifluoromethyl)-phenylcarbamoyl]phenyl benzoate (0.25–1 μmol/L). Unfortunately, the most potent esters were still considerably cytotoxic, although mostly less than their parent salicylanilides.

A series of novel sulfonamides containing 5-chloro-2-hydroxybenzaldehyde or 5-chloro-2-hydroxybenzoic acid scaffolds were designed, synthesized and characterized by IR, 1 H NMR and 13 C NMR. All ten target synthesized derivatives and starting sulfonamides were evaluated in vitro for the activity against Gram-positive and Gram-negative bacteria, fungi, Mycobacterium tuberculosis , Mycobacterium avium and Mycobacterium kansasii . The most active compound against methicillin-sensitive and methicillin-resistant Staphyloccoccus aureus was 5-chloro- N -{4-[ N -(4,6-dimethylpyrimidin-2-yl)sulfamoyl]phenyl}-2-hydroxybenzamide with MIC 15.62–31.25 μmol/L. 4-Amino- N -(thiazol-2-yl)benzenesulfonamide and 4-(5-chloro-2-hydroxybenzylideneamino)- N -(thiazol-2-yl)benzenesulfonamide have shown the best activity against M. kansasii at the concentrations of 1–4 μmol/L. The efficacy against other strains was weaker and the studied derivatives exhibited almost none antifungal potency.

A series of eighteen novel esters of salicylanilides with benzenesulfonic acid were designed, synthesized and characterized by IR, 1H-NMR and 13C-NMR. They were evaluated in vitro as potential antimycobacterial agents towards Mycobacterium tuberculosis, Mycobacterium avium and two strains of Mycobacterium kansasii. In general, the minimum inhibitory concentrations range from 1 to 500 µmol/L. The most active compound against M. tuberculosis was 4-chloro-2-(4-(trifluoromethyl)phenylcarbamoyl)-phenyl benzenesulfonate, with MIC of 1 µmol/L and towards M. kansasii its isomer 5-chloro-2-(4-(trifluoromethyl)phenylcarbamoyl)phenyl benzenesulfonate (MIC of 2–4 µmol/L). M. avium was the less susceptible strain. However, generally, salicylanilide benzenesulfonates did not surpass the activity of other salicylanilide esters with carboxylic acids.

Salicylanilides are a well-known family of pharmacological compounds, which are under renewed investigation because of the discovery of novel interesting biological activities and mechanisms of action over the last decade. This comprehensive mini-review de-scribes the biological and pharmacological properties of salicylanilides, their activity against atypical and multi-drug resist ant mycobacte-rial strains, and synthetic routes for their preparation. In particular, this review focuses on the synthesis and biological properties of sali-cylanilides and O -substituted derivates reported between 2000 and 2010, which have displayed the highest antituberculosis or antifungal activity. Keywords: Anti-MDR tuberculotics, anti-tuberculotic agents, hydroxybenzamides, salicylan ilides, salicylanilide derivates. 1. INTRODUCTION Salicylanilides ( N -substituted hydroxy benzamides) are well-known organic pharmacological compounds with numerous bio-logical activities, which were initially investigated for their antimi-crobial [1] and antifungal activities [2], as well as their usefulness as topical antimycotics and antiplaque agents [3]. Salicylanilides have also found use as molluscicidal [4] or anthelmintic agents [5] in human and veterinary practise. The most successful of these, 5,2´-dichloro-4´-nitrosalicylanilide (Niclosamide), is a member of a group of common molluscicides [6] with anthelmintic properties, and is also effective in the treatment of diphyllobothriasis and hy-menolepiasis [7]. Closantel is another broad-spectrum anthelmintic salicylanilide, which has been used as an anti-trematode, anti-nematode and anti-arthropod, in combination with benzimidazole anthelmintics such as Mebendazole [8]. Rafoxanide is highly active against

A highly efficient protocol for the preparation of aromatic amides is described by the direct reactions between salicyclic acid and aromatic amines in the presence of phosphorous trichloride under microwave irradiation. The method has several advantages over the conventional methods, including operational simplicity, good yield, and reduced reaction time.

Eleven halogenated ( S )-2-(phenylcarbamoyl)phenyl 2-acetamido-3-phenylpropanoates ( 3a – 3k ) were designed and synthesized as potential antimicrobial agents. They were evaluated in vitro against some mycobacterial, bacterial and fungal strains. These compounds were active against drug-sensitive and atypical mycobacterial strains with general MIC values from 0.25 to 16 μmol/L. The most active compounds were ( S )-4-chloro-2-(4-(trifluoromethyl)phenylcarbamoyl)phenyl 2-acetamido-3-phenylpropanoate ( 3i ) and ( S )-4-bromo-2-(4-(trifluoromethyl)phenylcarbamoyl)phenyl 2-acetamido-3-phenylpropanoate ( 3k ) which exhibited activity against MDR and XDR-TB strains with MICs from 1 to 2 μmol/L. 3k was shown to be less cytotoxic with higher IC 50 . Some compounds exhibited low MICs on Gram-positive bacteria (MICs ≥ 0.98 μmol/L) and on fungi (MICs ≥ 3.9 μmol/L).

To identify new transglycosylase inhibitors with potent anti-methicillin-resistant Staphylococcus aureus (MRSA) activities, a high-throughput screening against Staphylococcus aureus was conducted to look for antibacterial cores in our 2M compound library that consists of natural products, proprietary collection, and synthetic molecules. About 3600 hits were identified from the primary screening and the subsequent confirmation resulted in a total of 252 compounds in 84 clusters which showed anti-MRSA activities with MIC values as low as 0.1 μg/ml. Subsequent screening targeting bacterial transglycosylase identified a salicylanilide-based core that inhibited the lipid II polymerization and the moenomycin-binding activities of transglycosylase. Among the collected analogues, potent inhibitors with the IC(50) values below 10 μM against transglycosylase were identified. The non-carbonhydrate scaffold reported in this study suggests a new direction for development of bacterial transglycosylase inhibitors.

The thiation properties of the dimer of p-methoxyphenylthionophosphine sulfide, 1, has been investigated by performing reactions with a representative series of aliphatic and aromatic primary, secondary, and tertiary carboxamides in the temperature range 80-100 °C using HMPA as solvent. This new method seems to be superior to all others as in most cases quantitative yields are found. Salicylanilide, when reacted with 1, in HMPA, yields salicylthioanilide and a new type of phosphorus heterocycle, 3, whose structure has been determined by NMR-and X-ray analyses. 13C NMR data are tabulated for a series of thioamide carbons.

The preparation of new prodrug forms of anti-tuberculosis active salicylanilide esters with amino acids led to an unexpected rearrangement. The isolation and the structure determination of 2-(5-chloro-2-hydroxyphenyl)-3-(3-chlorophenyl)-5-substituted-3,5-dihydro-4H-imidazol-4-ones unambiguously confirm one of the two proposed reaction mechanisms.

A series of novel, highly antimicrobial salicylanilide esters of N -protected amino acids were synthesized and characterized. Their in vitro antimicrobial activity against eight fungal strains and Mycobacterium tuberculosis was determined. The compounds had the highest level of activity against Aspergillus fumigatus , Absidia corymbifera and Trichophyton mentagrophytes , and these levels were higher than that of the standard drug fluconazole. In addition, three compounds showed interesting antituberculosis activity, with inhibition ranging from 89% to 99%. ( S )-4-Chloro-2-(4-trifluoromethylphenylcarbamoyl)-phenyl 2-benzyloxy-carbonylamino-propionate had the highest level of both antifungal and antimycobacterial activity. The structure–activity relationships of the new compounds are discussed.

Interleukin (IL)-12p40, a subunit component of both IL-12 and IL-23, is being widely studied for its role in inflammatory disease. As part of an effort to profile cellular signaling pathways across different cell types, we report salicylanilide inhibitors of IL-12p40 production in stimulated dendritic cells. Based on a hypothesis that a desirable therapeutic profile is one that could block IL-12p40 but not IL-6 production, we engaged in directed analoging. This resulted in salicylanilides with similar IL-12p40 related potency but enhanced selectivity relative to IL-6 production.

A series of salicylanilides (1a-h) bearing varied substituents at the 3'- or 4'-position of the anilino moiety (substituent = p-OCH3, p-CH3, m-CH3, H, p-Cl, m-Cl, p-CO2CH3, and p-CN) were synthesized. In acetonitrile all of the substituted salicylanilides 1a-h predominantly adopt the "closed-ring" conformation facilitated by a strong intramolecular OH...O=C hydrogen bond. In the presence of H2PO4-, the conformation of 1a-h was found to be modulated by the substituent. With our proposed proton-transfer fluorescence probing method, we were able to show that the conformation of 1a-f bearing a not highly electron-withdrawing substituent was switched to the "open-ring" form by H2PO4-, whereas 1h bearing a highly electron-withdrawing substituent, p-CN, remained in the "closed-ring" conformation. The significance of these findings for understanding, from a molecular structural point of view, the mechanism of salicylanilide-based inhibitors for inhibiting the protein tyrosine kinase epidermal growth factor receptor was discussed.

Discovery of novel topological agents against Oncomelania hupensis snails and cercariae remains a significant challenge in current Schistosomiasis control. A pseudo-ring formed from salicylanilide by an intramolecular hydrogen bond led to the discovery of 3-substituted quinazolinone derivatives which showed a potent molluscicidal and cercaricidal activities.

The research of innovative antimicrobial agents represents a cutting edge topic. Hence, we synthesized and characterised novel salicylanilide N-monosubstituted carbamates. Twenty compounds were evaluated in vitro against eight bacterial strains and eight fungal species. The lowest minimum inhibitory concentrations (MICs) were found to be ⩽0.49 μM. Genus Staphylococcus, including methicillin-resistant Staphylococcus aureus, and fungus Trichophyton mentagrophytes showed uniformly the highest rate of susceptibility, whilst Gram-negative bacteria and most of the fungi were less susceptible. A wide range of carbamates provided comparable or superior in vitro antimicrobial activity in comparison to established drugs. Interestingly, extended-spectrum β-lactamase producing strain of Klebsiella pneumoniae was inhibited with MICs starting from 31.25 μM. With respect to Staphylococci, 2-[(4-bromophenyl)carbamoyl]-4-chlorophenyl phenylcarbamate exhibited the lowest MIC values (⩽0.98 μM). 2-[(4-Bromophenyl)carbamoyl]-4-chlorophenyl benzylcarbamate showed the widest spectrum of antifungal action. The results indicate that some salicylanilide carbamates can be considered to be promising candidates for future investigation.

In the Mycobacterium genus over one hundred species are already described and new ones are periodically reported. Species that form colonies in a week are classified as rapid growers, those requiring longer periods (up to three months) are the mostly pathogenic slow growers. More recently, new emerging species have been identified to lengthen the list, all rapid growers. Of these, Mycobacterium abscessus is also an intracellular pathogen and it is the most chemotherapy-resistant rapid-growing mycobacterium. In addition, the cases of multidrug-resistant Mycobacterium tuberculosis infection are also increasing. Therefore there is an urgent need to find new active molecules against these threatening strains. Based on previous results, a series of salicylanilides, salicylanilide 5-chloropyrazinoates and carbamates was designed, synthesized and characterised. The compounds were evaluated for their in vitro activity on M. abscessus, susceptible M. tuberculosis H37Rv, multidrug-resistant (MDR) M. tuberculosis MDR A8, M. tuberculosis MDR 9449/2006 and on the extremely-resistant Praha 131 (XDR) strains. All derivatives exhibited a significant activity with minimum inhibitory concentrations (MICs) in the low micromolar range. Eight salicylanilide carbamates and two salicylanilide esters exhibited an excellent in vitro activity on M. abscessus with MICs from 0.2 to 2.1 μM, thus being more effective than ciprofloxacin and gentamicin. This finding is potentially promising, particularly, as M. abscessus is a threateningly chemotherapy-resistant species. M. tuberculosis H37Rv was inhibited with MICs from 0.2 μM, and eleven compounds have lower MICs than isoniazid. Salicylanilide esters and carbamates were found that they were effective also on MDR and XDR M. tuberculosis strains with MICs ≥1.0 μM. The in vitro cytotoxicity (IC50) was also determined on human MonoMac-6 cells, and selectivity index (SI) of the compounds was established. In general, salicylanilide derivatives substituted by halogens on both salicyl and aniline rings showed better activity, than 4-benzoylaniline derivatives. The ester or carbamate bond formation of parent salicylanilides mostly retained or improved antimycobacterial potency with moderate selectivity.

Novel benzoxazepines were prepared upon esterification of biologically active salicylanilides with some N-protected amino acids. While the desired conjugates of the salicylanilides with the amino acids were obtained when sterically more demanding amino acids were used, benzoxazepines were formed as a result of a seven-exo-trig cyclization in the case of N-protected glycine and alanine. The structures of the products were confirmed by 2D NMR methods, and further transformations of the acyclic conjugates provided additional support for the proposed mechanism of cyclization.

A facile synthesis and studies on the stereochemistry and biochemical aspects of some organosilicon(IV), organotin(IV), and manganese(II) complexes derived from imine having N∪N∪O donor system is reported. The imine was prepared by the condensation of salicylanilide with sulphathiazole. This imine reacts with organosilicon(IV)chloride, organotin(IV)chloride, and hydrated manganese(II) chloride to yield compounds having M─O and M←N bonds. The structures of the compounds have been elucidated by physicochemical and spectral (IR, 1H NMR, 13C NMR, 29Si NMR, 119Sn NMR, and ESR) studies, which clearly point to a trigonal bipyramidal geometry around silicon(IV) and tin(IV), and tetrahedral geometry around manganese(II), as the active lone pair of the nitrogen is also included in the coordination sphere. In the search for better fungicides and bactericides, studies were conducted to assess the growth-inhibiting potential of the synthesized complexes against various pathogenic fungal and bacterial strains. These co...

Based on the previously described antimicrobial activity of salicylanilide derivatives, we designed and synthesized novel 2-(phenylcarbamoyl)phenyl 4-substituted benzoates. The most active salicylanilides were selected for esterification by various 4-substituted benzoic acids. These compounds were evaluated in vitro against Mycobacterium tuberculosis , including multidrug-resistant strains, nontuberculous mycobacteria ( Mycobacterium avium and Mycobacterium kansasii ), and eight bacterial and fungal strains. We also investigated the cytostatic and cytotoxic actions of the esters. The minimum inhibitory concentrations (MICs) against mycobacteria ranged from 0.125 to 8 μM. Interestingly, the drug-resistant strains exhibited the highest susceptibility without any cross-resistance with established drugs. 4-Bromo-2-[4-(trifluoromethyl)phenylcarbamoyl]phenyl 4-nitrobenzoate showed the most potent inhibition with MIC values ranging from 0.25 to 2 μM. Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus , were inhibited by two derivatives with MIC values of at least 0.49 μM, whereas Gram-negative bacteria and most of the tested fungi did not display any marked susceptibility. Benzoates exhibited no cytotoxicity at concentrations up to 50 μM but most caused significant cytostasis with IC 50 values lower than 10 μM. Some cytotoxicity-based selectivity indexes for drug-susceptible and drug-resistant M. tuberculosis as well as Staphylococci were higher than 100. These values indicate that some of these derivatives are promising candidates for future research.

Based on the presence of dialkyl phosphate moiety, we evaluated twenty-seven salicylanilide diethyl phosphates (diethyl [2-(phenylcarbamoyl)phenyl] phosphates) for the inhibition of acetylcholinesterase (AChE) from electric eel ( Electrophorus electricus L.) and butyrylcholinesterase (BChE) from equine serum. Ellman’s spectrophotometric method was used. The inhibitory activity (expressed as IC 50 values) was compared with that of the established drugs galantamine and rivastigmine. Salicylanilide diethyl phosphates showed significant activity against both cholinesterases with IC 50 values from 0.903 to 86.3 μM. IC 50 s for BChE were comparatively lower than those obtained for AChE. All of the investigated compounds showed higher inhibition of AChE than rivastigmine, and six of them inhibited BChE more effectively than both rivastigmine and galantamine. In general, derivatives of 4-chlorosalicylic acid showed enhanced activity when compared to derivatives of 5-halogenated salicylic acids, especially against BChE. The most effective inhibitor of AChE was O -{5-chloro-2-[(3-bromophenyl)carbamoyl]phenyl} O , O -diethyl phosphate with IC 50 of 35.4 μM, which is also one of the most potent inhibitors of BChE. O -{5-Chloro-2-[(3,4-dichlorophenyl)carbamoyl]phenyl} O , O -diethyl phosphate exhibited in vitro the strongest inhibition of BChE (0.90 μM). Salicylanilide diethyl phosphates act as pseudo-irreversible cholinesterases inhibitors.

Novel cercaricides of PEG-N-salicylanilide derivatives that could self-spread and float on the water surface were designed and synthesized according to the particular habit of cercariae larvae of Schistosome japonicum. The structures of the cercaricides were characterized by the infrared spectra (IR), magnetic resonance ((1) H NMR), and mass spectrum (MS). The images of the floating cercaricides on the water surface were investigated by the Brewster angle microscopy (BAM). When the cercaricides were dropped on the water surface, they could spread along the air-water interface automatically and form thin membranes floating on the water surface immediately. The lethality rate of cercariae for 5a and 6a was more than 90% in 120 min at a surface concentration of 0.008 mg/cm(2) . The non-ionic surfactant-cercaricides not only showed strong cercaricidal activities against the cercariae larvae but also exhibited low toxicities, which offered an effective and environment-friendly approach for the reduction of population infection rate and the realization of schistosome control.

The development of novel antimicrobial drugs represents a cutting edge research topic. In this study, 20 salicylanilide N , N -disubstituted carbamates and thiocarbamates were designed, synthesised and characterised by IR, 1 H NMR and 13 C NMR. The compounds were evaluated in vitro as potential antimicrobial agents against Mycobacterium tuberculosis and nontuberculous mycobacteria ( Mycobacterium avium and Mycobacterium kansasii ) as well as against eight bacterial and fungal strains. Additionally, we investigated the inhibitory effect of these compounds on mycobacterial isocitrate lyase and cellular toxicity. The minimum inhibitory concentrations (MICs) against mycobacteria were from 4 μM for thiocarbamates and from 16 μM for carbamates. Gram-positive bacteria, including methicillin-resistant Staphylococcus aureus , were inhibited with MICs from 0.49 μM by thiocarbamates, whilst Gram-negative bacteria and most of the fungi did not display any significant susceptibility. All (thio)carbamates mildly inhibited isocitrate lyase (up to 22%) at a concentration of 10 μM. The (thio)carbamoylation of the parent salicylanilides led to considerably decreased cytotoxicity and thus improved the selectivity indices (up to 175). These values indicate that some derivatives are attractive candidates for future research.

Two series of novel salicylanilide were synthesized as potential epidermal growth factor receptor (EGFR) inhibitors. The enzyme inhibitory activity against EGFR of all compounds was carried out, and their antiproliferative activities against the A549 and A431 cell lines were also evaluated. Of the compounds studied, majority of them exhibited high antiproliferative activities compared with gefitinib; especially, 12a and 12b exhibited stronger inhibitory activity against EGFR with IC50 values of 10.4 ± 2.25 and 15.4 ± 2.33 nm, respectively, which were comparable to the positive control of gefitinib (IC50 = 12.1 ± 2.21 nm). Compound 12b also showed outstanding inhibitory activity against A431 and A549 cell lines with the IC50 values of 0.42 ± 0.43 μm and 0.57 ± 0.43 μm, which was better than the positive controls. In the molecular modeling study, compound 12b was bound into the active pocket of EGFR with two hydrogen bond and with minimum binding free energy ▵Gb = -25.1125 kcal/mol. The result also suggested that compound 12b could bind the EGFR kinase well.

An analytical method for the determination of nitroxynil, oxyclozanide, closantel and rafoxanide in liquid milk by high performance liquid chromatography (HPLC) has been established. The milk sample was extracted with acetonitrile containing 1% (v/v) triethylamine. The supernatant was purified by an anion exchange solid phase extraction column. The analyte was detected by ultraviolet detector after the HPLC separation on a C18 RP column. The mobile phase was composed of acetonitrile-0.02 mol/L ammonium acetate solution with pH 4.0. The linear ranges of the four drugs in the spiked blank milk samples were 5-500 microg/kg, and the correlation coefficients were higher than 0.99. The limits of detection (LOD) were 3 microg/kg, and the limits of quantification (LOQ) were 5 microg/kg. The average recoveries and relative standard deviations (RSDs) of nitroxynil, oxyclozanide, closantel and rafoxanide at the spiked levels of 1/2MRL (maximum residue limit), MRL and 2MRL ranged from 92.20% to 96.13%, 5.55% to 16.30%; 87.40% to 94.74%, 5.40% to 12.21%; 86.97% to 91.09%, 2.67% to 8.17%; and 77.86% to 95.36%, 5.02% to 13.15% respectively. The method is simple and sensitive for the quantification of phenolic and salicylanilide anthelmintics in liquid milk.

Viruses use a limited set of host pathways for infection. These pathways represent bona fide antiviral targets with low likelihood of viral resistance. We identified the salicylanilide niclosamide as a broad range antiviral agent targeting acidified endosomes. Niclosamide is approved for human use against helminthic infections, and has anti-neoplastic and antiviral effects. Its mode of action is unknown. Here, we show that niclosamide, which is a weak lipophilic acid inhibited infection with pH-dependent human rhinoviruses (HRV) and influenza virus. Structure-activity studies showed that antiviral efficacy and endolysosomal pH neutralization co-tracked, and acidification of the extracellular medium bypassed the virus entry block. Niclosamide did not affect the vacuolar H+-ATPase, but neutralized coated vesicles or synthetic liposomes, indicating a proton carrier mode-of-action independent of any protein target. This report demonstrates that physico-chemical interference with host pathways has broad range antiviral effects, and provides a proof of concept for the development of host-directed antivirals., Author Summary Current antiviral approaches are directed against specific viral targets but are limited in their broad-spectrum potential. Targeting host pathways, on the other hand can have broad antiviral effects, albeit with possible side effects. Here, we report the mode of antiviral action of a small chemical compound, niclosamide. Niclosamide belongs to the salicylanilides, and has been FDA approved to treat parasitic helminthic infestations in humans since decades. In recent years, niclosamide was shown to have anti-neoplastic and antiviral effects. We screened a library of FDA-approved chemicals, and found that niclosamide is an entry inhibitor for a number of pH-dependent respiratory viruses, including influenza virus and human rhinoviruses. Cell biological and biochemical analyses and intracellular pH measurements showed that niclosamide neutralizes acidic membrane-bounded compartments. Niclosamide did not affect the vacuolar ATPase but acted as a protonophore, both in vesicles isolated from cells, and protein-free liposome assays. It blocked rhinovirus infections synergistically with the proton ATPase inhibitor bafilomycin A1. Niclosamide targets endosomes by a mode of action distinct from that of endosomal pH neutralizing agents, such as chloroquine, which accumulates in acidic endosomes.

A series of twenty-five novel salicylanilide N-alkylcarbamates were investigated as potential acetylcholinesterase inhibitors. The compounds were tested for their ability to inhibit acetylcholinesterase (AChE) from electric eel (Electrophorus electricus L.). Experimental lipophilicity was determined, and the structure-activity relationships are discussed. The mode of binding in the active site of AChE was investigated by molecular docking. All the discussed compounds expressed significantly higher AChE inhibitory activity than rivastigmine and slightly lower than galanthamine. Disubstitution by chlorine in C'(3,4) of the aniline ring and the optimal length of hexyl-undecyl alkyl chains in the carbamate moiety provided the most active AChE inhibitors. Monochlorination in C'(4) exhibited slightly more effective AChE inhibitors than in C'(3). Generally it can be stated that compounds with higher lipophilicity showed higher inhibition, and the activity of the compounds is strongly dependent on the length of the N-alkyl chain.

A new series of N-(3/4-substituted phenyl) 4/5-chloro-2-methoxybenzamides and their thioxo analogues have been synthesised and evaluated for in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv, as well as the two atypical strains Mycobacterium kansasii and Mycobacterium avium. Five of the most active compounds were evaluated for cytotoxicity and their ability to inhibit mycobacterial isocitrate lyase, which is responsible for latent survival of Mycobacterium. The results showed that benzthioanilides were more active than the corresponding benzanilides. The most active compound, 4-chloro-2-methoxy-N-(3,4-dichlorophenyl)benzothioamide (4e), had a minimal inhibition concentration (MIC) against M. tuberculosis of 2 μmol L(-1), which was better than the activity of the previously published corresponding salicylanilide.

The resistance to antimicrobial agents brings a need of novel antimicrobial agents. We have synthesized and found thein vitroantibacterial activity of salicylanilide esters with benzoic acid (2-(phenylcarbamoyl)phenyl benzoates) in micromolar range. They were evaluatedin vitrofor the activity against eight fungal and eight bacterial species. All derivatives showed a significant antibacterial activity against Gram-positive strains with minimum inhibitory concentrations ≥0.98 μmol/L including methicillin-resistantStaphylococcus aureusstrain. The most active compounds were 5-chloro-2-(3,4-dichlorophenylcarbamoyl)phenyl benzoate and 4-chloro-2-(4-(trifluoromethyl)phenylcarbamoyl)phenyl benzoate. The antifungal activity is significantly lower.

In the present study salicylanilide was reacted with 2,4,6-trichloro-1,3,5-triazine producing reactive salicylanilide at a yield of 45% according to reaction conditions set. The reactive salicylanilide was confirmed structurally through FT-IR analysis. Pristine viscose fabric was treated with active salicylanilide to impart permanent antibacterial and antifungus properties to the fabric. Covalently attached reactive salicylanilide, as revealed, was quantitatively assessed through spectrophotometric and nitrogen elemental analysis. The antibacterial and antifungus capability of reactive salicylanilide treated viscose fabric; fastness and washing reproduction were examined and evaluated.