Exploring efflux pump inhibition through oxytetracycline analogues: In silico approaches to tackle tetracycline resistance

The inappropriate administration of antibiotics results in the emergence of antibiotic resistance, threatening public health, food safety and sustainability. A key resistance mechanism involves the export of antimicrobial agents through multidrug efflux pumps. Although efflux pump inhibitors, small molecules, can restore the effectiveness of existing antibiotics but their poor stability, poor selectivity and severe cytotoxicity have limited them for clinical use. This study aimed to identify potential analogues of oxytetracycline that inhibit efflux pump-mediated resistance employing in silico approaches. A high quality 3D structure of tetA protein was predicted and validated, revealing 96.8% residues in the favourable region. The protein and ligands were prepared for docking and employed for blind docking, protein-ligand interactions analyses and ADMET profiling. Docking analysis revealed binding affinities in the range of -7.0 ̶ -8.3 kcal/mol, with the highest binding affinities for omadacycline (-8.3 kcal/mol), TP-271 (-8.1 kcal/mol), doxycycline (-8.0 kcal/mol) and tetracycline (-8.0 kcal/mol). The interaction analyses revealed an abundance of hydrophobic and hydrogen interactions in top complexes, omadacycline and TP-271. However, ADMET profiling highlighted implications such as low solubility, a shorter life-span and significant nephrotoxicity and hepatotoxicity in modern analogues. In conclusion, these findings suggest that omadacycline and TP-271 are promising candidates for the inhibition of efflux pumps and AMR mitigation, though structural modifications without compromising binding affinities are necessary to improve safety. This study provides a foundation for integrated wet-lab and dry-lab experiments to identify effective yet safer oxytetracycline alternatives.