# Insight into antistaphylococcal effect of chlorinated 1-hydroxynaphthalene-2-carboxanilides

## TL;DR

This study explores new chlorinated compounds that show strong antistaphylococcal activity, potentially offering a new approach to combat antibiotic-resistant bacteria.

## Contribution

The study introduces chlorinated 1-hydroxynaphthalene-2-carboxanilides as multitarget agents with potent antistaphylococcal activity and identifies key proteins affected by these compounds.

## Key findings

- Compound 10 showed antistaphylococcal activity comparable to or better than existing drugs with MICs of 0.37 μM.
- Compound 10 downregulated four proteins in staphylococci, including ATP-dependent protease ATPase subunit HslU.
- The position of chlorine atoms in the compounds significantly influences their antistaphylococcal activity.

## Abstract

New compounds and innovative therapeutic approaches are trying to prevent antimicrobial resistance, which has become a global health challenge.

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.

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.

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.