Design, synthesis and 2D QSAR study of novel pyridine and quinolone hydrazone derivatives as potential antimicrobial and antitubercular agents.

The increased development of highly resistant bacterial strains and tuberculosis, constitute a serious public health threat, highlighting the urgent need of novel antibacterial agents. In this work, two novel series of nicotinic acid hydrazone derivatives (6a-r) and quinolone hydrazide derivatives (12a-l) were synthesized and evaluated as antimicrobial and antitubercular agents. The synthesized compounds were evaluated in vitro for their antibacterial, antifungal and antimycobacterial activities. Compounds 6f and 6p bearing the 3,4,5- (OCH3)3 and 2,5-(OCH3)2 benzylidene motifs were the most potent and as antibacterial, antifungal (MIC: 0.49-1.95 μg/mL) and (MIC: 0.49-0.98 μg/mL) respectively and antimycobacterial activity (MIC = 0.76 and 0.39 μg/mL) respectively. Besides, several derivatives, 6e, 6h, 6l-6o, 6q, 6r, 12a, 12b, 12e, 12h, 12k and 12l, exhibited significant antibacterial and antifungal activities with MIC values ranging from 1.95 to 7.81 μg/mL, they also displayed excellent to good activity against Mycobacterium tuberculosis with MIC range from 0.39 to 3.12 μg/mL. In addition, some of the most active compounds were tested for cytotoxic activities against human lung fibroblast normal cells (WI-38) and displayed low toxicity. Moreover, 2D-QSAR models to characterize the descriptors controlling the observed activities, were generated and validated.