Discovery of quinolone derivatives as antimycobacterial agents

Abstract

Tuberculosis (TB), an infectious disease caused byMycobacterium tuberculosis(M. tuberculosis), is an important public health issue. Current first-line drugs administered to TB patients have been in use for over 40 years, whereas second-line drugs display strong side effects and poor compliance. Additionally, designing effective regimens to treat patients infected with multi- and extremely-drug-resistant (MDR and XDR) strains of TB is challenging. In this report, we screened our compound library and identified compound1with antituberculosis activity and a minimal inhibitory concentration (MIC) againstM. tuberculosisof 20 μg mL−1. Structure optimization and the structure-activity relationship of1as the lead compound enabled the design and synthesis of a series of quinolone derivatives,6a1-6a2,6b1-6b36,6c1,6d1-6d14,7a1-7a2,7b1-7b2,7c1,8a1-8a5,9a1-9a4and10a1-10a6. These compounds were evaluatedin vitrofor anti-tubercular activity against theM. tuberculosisH37Rv strain. Among them, compounds6b6,6b12and6b21exhibited MIC values in the range of 1.2-3 μg mL−1and showed excellent activity against the tested MDR-TB strain (MIC: 3, 2.9 and 0.9 μg mL−1, respectively). All three compounds were non-toxic toward A549 and Vero cells (>100 and >50 μg mL−1, respectively). In addition, an antibacterial spectrum test carried out using compound6b21showed that this compound specifically inhibitsM. tuberculosis. These can serve as a new starting point for the development of anti-TB agents with therapeutic potential.