<i>In Vitro</i> Antimycobacterial Activity Evaluation of a New Lead Compound (LQFM326) against Clinical Strains of <i>Mycobacterium</i> sp.

Tuberculosis (TB) remains a significant global public health challenge. The novel compound LQFM326 was evaluated for its antimycobacterial activity against seven Mycobacterium species. Minimum inhibitory concentrations (MICs) were determined, revealing values of 15.6 μg/mL against <i>Mycobacterium tuberculosis</i> H37Ra and 12.5 μg/mL against clinical strains. The MIC values observed for these reference antimicrobials against <i>M. tuberculosis</i> H37Ra were 0.25 μg/mL for rifampicin and 0.125 μg/mL for isoniazid. Surface damage to <i>Mycobacterium abscessus</i> cells was observed <i>via</i> scanning electron microscopy (SEM), confirming morphological alterations induced by LQFM326. Cellular viability was assessed using the Live/Dead assay, with a CC₅₀ of 126.68 ± 42.66 μg/mL. The selectivity index (SI), calculated from MIC and CC₅₀ values, ranged from 2.03 to 10.13, with values above 10 indicating favorable selectivity. Additionally, synergistic effects were observed when LQFM326 was combined with other antibiotics. These findings highlight LQFM326 as a promising antimycobacterial agent with potential efflux-inhibitory and synergistic properties. Further studies are needed to validate its efficacy across diverse clinical strains and to elucidate its mechanism of action.