Screening of compounds containing aminobutanol and camphane moieties against Mycobacterium tuberculosis clinical isolates of different genotypes

Abstract

Aim and objectives: Despite the availability of sufficiently effective treatment regimens, prevention and control, the widespread transmission and prevalence of resistant variants of Mycobacterium tuberculosis, which do not respond to any of the commercial drugs, remains a serious health problem for both developed and developing countries. Multidrug-resistant (MDR) strains present new threat to health security. This situation is of global concern due to increased human mobility, partly illegal and spontaneous. Patients infected with drug resistant strains are hard or impossible to be cured, and their treatment is more toxic and expensive. The urgent need of new antimycobacterial agents and development pathways is becoming more and more apparent. Methods: In this study, we synthesized new compounds containing 2-aminobutanol and camphane moieties and evaluated them with the reference strain and clinical M. tuberculosis isolates from a high-burden country, Russian Federation. All four compounds were obtained by simple synthetic procedures as pure diastereoisomeres and characterized by mass spectrometry, nuclear magnetic resonance, melting points and elemental analysis. The cell lines HEP-G2, HaCaT, HEK293 and CCL-1 were used to study the cytotoxicity and metabolism of tested compounds. The MTT colorimetric test was used to determine the average inhibitory concentrations of 50% (IC50). The CFU test was used to assess the long-term antiproliferative effect of the compounds. In vitro antimycobacterial activity of all compounds was tested by resazurin microtiter assay (REMA). All compounds were tested against reference strain H37Rv and 11 clinical isolates. Results: The isolates represented different clusters within clinically/epidemiologically important Beijing genotype (B0/W148, 94-32, Central Asian Outbreak, ancestral sublineage) and differed in phenotypic drug resistance (one extensively drug resistant, six multidrug resistant, two polyresistant, and two susceptible to all tested drugs). The most efficient compound showed a wide range of MIC that varied from 3.1 μg/ml (H37Rv, ancestral Beijing, most of B0/W148 isolates) to 100 μg/ml (other isolates). Conclusions: To conclude, this study highlighted a key importance of testing new anti-TB compounds not only with reference laboratory strain H37Rv that belongs to the phylogenetically marginal branch of M. tuberculosis, but on the clinical drug-resistant isolates circulating in the countries with high burden of MDR-TB. Acknowledgements. This study was supported by the Russian Science Foundation (grant 19-15-00028). Partial support was received from the Bulgarian National Science Fund (grant KP-06-H39-7).