Isoniazid-N-acylhydrazones as promising compounds for the anti-tuberculosis treatment

Tuberculosis (TB), a disease caused by Mycobacterium tuberculosis complex, still presents significant numbers of incidence and mortality, in addition to several cases of drug resistance. Resistance, especially to isoniazid, which is one of the main drugs used in the treatment, has increased. In this context, N-acylhydrazones derived from isoniazid have shown important anti-Mycobacterium tuberculosis activity. Hence, this work aimed to determine the anti-TB potential of 11 isoniazid-N-acylhydrazones (INH-acylhydrazones). For this purpose, the determination of minimum inhibitory concentration (MIC) against M. tuberculosis H37Rv and clinical isolates was carried out. Drug combination, minimum bactericidal concentration, cytotoxicity, and in silico parameters were also performed. INH-acylhydrazones (2), (8), and (9) had MIC for M. tuberculosis H37Rv similar to or lower than isoniazid, and bactericidal activity was observed. In addition, these compounds showed low cytotoxicity, with a selectivity index greater than 3,000. Interesting results were also obtained in the drug combination assay, with synergistic combinations with isoniazid, ethambutol, and rifampicin. In the in silico study, INH-acylhydrazones behaved similarly to INH, but with improvements in some aspects. Based on these findings, it is concluded that compounds (2), (8), and (9) are considered promising scaffolds and warrant further investigation for designing future antimicrobial drugs.

In Vitro and In Silico Evaluations of Anti-Mycobacterium tuberculosis Activity of Benzohydrazones Compounds

Tuberculosis is a disease caused by Mycobacterium tuberculosis, with high mortality rates and an extended treatment that causes severe adverse effects, besides the emergence of resistant bacteria. Therefore, the search for new compounds with anti-M. tuberculosis activity has considerably increased in recent years. In this context, benzohydrazones are significant compounds that have antifungal and antibacterial action. This study aimed at evaluating the in vitro activity of 18 benzohydrazones against M. tuberculosis. Compounds' cytotoxicity, inhibition of M. tuberculosis efflux pumps, and in silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) assays were also performed. In general, the minimum inhibitory concentration values for the standard M. tuberculosis H₃₇Rv strain ranged from 7.8 to 250 μg/mL, and some compounds were not toxic to any of the cells tested (IC₅₀ ranged from 18.0 to 302.5 μg/mL). In addition, compounds (4) and (7) showed to be possible efflux pump inhibitors. In ADMET assays, all benzohydrazones had high gastrointestinal absorption. Most of the compounds were able to overcome the blood-brain barrier, and no compounds had irritant or tumorigenic effects. Compounds (1), (3), (9), (12), and (15) stood out for showing good activities, both in vitro and in silico assays.