BACKGROUND AND PURPOSE: New compounds and innovative therapeutic approaches are trying to prevent antimicrobial resistance, which has become a global health challenge. EXPERIMENTAL APPROACH: This study includes a series of twelve mono-, di- and trichlorinated 1-hydroxynaphthalene-2-carboxanilides designed as multitarget agents. All compounds were evaluated for their antistaphylococcal activity. Furthermore, MTT assay and chemoproteomic analysis of selected compounds were performed. Cytotoxicity in human cells was also tested. KEY RESULTS: N-(3,5-Dichlorophenyl)-1-hydroxynaphthalene-2-carboxamide (10) demonstrated activity comparable to or higher than clinically used drugs, with minimum inhibitory concentrations (MICs) of 0.37 μM. The compound was equally effective against clinical isolates of methicillin-resistant S. aureus. On the other hand, compound 10 showed 96 % inhibition of S. aureus respiration only at a concentration of 16× MIC. Chemoproteomic analysis revealed that the effect of agent 10 on staphylococci resulted in the downregulation of four proteins. This compound expressed no in vitro cytotoxicity up to a concentration of 30 μM. CONCLUSION: From the set of tested mono-, di- and trisubstituted derivatives, it is evident that the position of chlorine atoms is decisive for significant antistaphylococcal activity. Inhibition of energy metabolism does not appear to be one of the main mechanisms of action of compound 10; on the contrary, the antibacterial effect may likely be contributed by downregulation of proteins (especially ATP-dependent protease ATPase subunit HslU) involved in processes essential for bacterial survival and growth, such as protein, nucleotide/nucleic acid synthesis and efficient protein repair/degradation.

• Keywords
• Lipophilicity, MTT assay, antistaphylococcal activity, chemoproteomic analysis, cytotoxicity,
• Publication type
• Journal Article MeSH

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/β-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.

• Keywords
• STAT3, TK EGFR, anticancer properties, drug repurposing, mitochondrial uncoupling, niclosamide, salicylanilides,
• MeSH
• Anthelmintics * pharmacology   MeSH
• Humans MeSH
• Niclosamide pharmacology   MeSH
• Salicylanilides * pharmacology   chemistry   MeSH
• Signal Transduction MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Review MeSH
• Names of Substances
• Anthelmintics * MeSH
• Niclosamide MeSH
• Salicylanilides * MeSH

A series of twenty-two novel N-(disubstituted-phenyl)-3-hydroxynaphthalene- 2-carboxamide derivatives was synthesized and characterized as potential antimicrobial agents. N-[3,5-bis(trifluoromethyl)phenyl]- and N-[2-chloro-5-(trifluoromethyl)phenyl]-3-hydroxy- naphthalene-2-carboxamide showed submicromolar (MICs 0.16-0.68 µM) activity against methicillin-resistant Staphylococcus aureus isolates. N-[3,5-bis(trifluoromethyl)phenyl]- and N-[4-bromo-3-(trifluoromethyl)phenyl]-3-hydroxynaphthalene-2-carboxamide revealed activity against M. tuberculosis (both MICs 10 µM) comparable with that of rifampicin. Synergistic activity was observed for the combinations of ciprofloxacin with N-[4-bromo-3-(trifluoromethyl)phenyl]- and N-(4-bromo-3-fluorophenyl)-3-hydroxynaphthalene-2-carboxamides against MRSA SA 630 isolate. The similarity-related property space assessment for the congeneric series of structurally related carboxamide derivatives was performed using the principal component analysis. Interestingly, different distribution of mono-halogenated carboxamide derivatives with the -CF3 substituent is accompanied by the increased activity profile. A symmetric matrix of Tanimoto coefficients indicated the structural dissimilarities of dichloro- and dimetoxy-substituted isomers from the remaining ones. Moreover, the quantitative sampling of similarity-related activity landscape provided a subtle picture of favorable and disallowed structural modifications that are valid for determining activity cliffs. Finally, the advanced method of neural network quantitative SAR was engaged to illustrate the key 3D steric/electronic/lipophilic features of the ligand-site composition by the systematic probing of the functional group.

• Keywords
• CoMSA, IVE-PLS, MIC, MTT assay, antistaphylococcal activity, antitubercular activity, hydroxynaphthalenecarboxamides, lipophilicity, similarity-activity landscape index,
• MeSH
• Anti-Infective Agents chemical synthesis   MeSH
• Methicillin-Resistant Staphylococcus aureus * MeSH
• Microbial Sensitivity Tests MeSH
• Mycobacterium tuberculosis * MeSH
• Naphthalenes chemistry   MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Infective Agents MeSH
• Naphthalenes MeSH
• naphthalene-2-carboxamide MeSH Browser

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.

• Keywords
• antiproliferative effect, apoptosis, cell cycle, hydroxynaphthalene carboxamides, salicylanilides,
• MeSH
• Anilides chemistry   pharmacology   MeSH
• Apoptosis drug effects   MeSH
• Cell Cycle drug effects   MeSH
• Humans MeSH
• Membrane Potential, Mitochondrial drug effects   MeSH
• MCF-7 Cells MeSH
• Mitochondria drug effects   metabolism   MeSH
• Molecular Structure MeSH
• Naphthols chemistry   MeSH
• Cell Proliferation drug effects   MeSH
• Antineoplastic Agents chemistry   pharmacology   MeSH
• Reactive Oxygen Species metabolism   MeSH
• Salicylanilides chemistry   pharmacology   MeSH
• Superoxides metabolism   MeSH
• THP-1 Cells MeSH
• Cell Survival drug effects   MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anilides MeSH
• Naphthols MeSH
• Antineoplastic Agents MeSH
• Reactive Oxygen Species MeSH
• salicylanilide MeSH Browser
• Salicylanilides MeSH
• Superoxides MeSH

A series of twenty-six methoxylated and methylated N-aryl-1-hydroxynaphthalene- 2-carboxanilides was prepared and characterized as potential anti-invasive agents. The molecular structure of N-(2,5-dimethylphenyl)-1-hydroxynaphthalene-2-carboxamide as a model compound was determined by single-crystal X-ray diffraction. All the analysed compounds were tested against the reference strain Staphylococcus aureus and three clinical isolates of methicillin-resistant S. aureus as well as against Mycobacterium tuberculosis and M. kansasii. In addition, the inhibitory profile of photosynthetic electron transport in spinach (Spinacia oleracea L.) chloroplasts was specified. In vitro cytotoxicity of the most effective compounds was tested on the human monocytic leukaemia THP-1 cell line. The activities of N-(3,5-dimethylphenyl)-, N-(3-fluoro-5-methoxy-phenyl)- and N-(3,5-dimethoxyphenyl)-1-hydroxynaphthalene-2-carbox- amide were comparable with or even better than the commonly used standards ampicillin and isoniazid. All promising compounds did not show any cytotoxic effect at the concentration >30 µM. Moreover, an in silico evaluation of clogP features was performed for the entire set of the carboxamides using a range of software lipophilicity predictors, and cross-comparison with the experimentally determined lipophilicity (log k), in consensus lipophilicity estimation, was conducted as well. Principal component analysis was employed to illustrate noticeable variations with respect to the molecular lipophilicity (theoretical/experimental) and rule-of-five violations. Additionally, ligand-oriented studies for the assessment of the three-dimensional quantitative structure-activity relationship profile were carried out with the comparative molecular surface analysis to determine electron and/or steric factors that potentially contribute to the biological activities of the investigated compounds.

• Keywords
• 3D-QSAR, CoMSA, MTT assay, PET inhibition, X-Ray structure, antimycobacterial activity, antistaphylococcal activity, cytotoxicity, hydroxynaphthalenecarboxamides, lipophilicity,
• MeSH
• Ampicillin pharmacology   MeSH
• Principal Component Analysis MeSH
• Anilides chemical synthesis   chemistry   pharmacology   MeSH
• Anti-Bacterial Agents chemical synthesis   chemistry   pharmacology   MeSH
• Chloroplasts drug effects   physiology   MeSH
• Photosynthesis drug effects   MeSH
• Isoniazid pharmacology   MeSH
• Humans MeSH
• Methicillin-Resistant Staphylococcus aureus drug effects   growth & development   MeSH
• Methylation MeSH
• Microbial Sensitivity Tests MeSH
• Mycobacterium kansasii drug effects   growth & development   MeSH
• Mycobacterium tuberculosis drug effects   growth & development   MeSH
• Naphthols chemical synthesis   chemistry   pharmacology   MeSH
• Spinacia oleracea chemistry   drug effects   metabolism   MeSH
• THP-1 Cells MeSH
• Electron Transport drug effects   MeSH
• Structure-Activity Relationship MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Comparative Study MeSH
• Names of Substances
• Ampicillin MeSH
• Anilides MeSH
• Anti-Bacterial Agents MeSH
• Isoniazid MeSH
• Naphthols MeSH