Antimicrobial Activity of Novel Nitro-substituted Benzazolo[3,2 a]quinolinium Chloride Salts (NBQs) Against Bacterial Strains

Benzazoloquinolinium salts (BQs) have shown previously cytotoxic effect in a variety of cancer cell lines specifically in the human epidermoid A431 cells. Members of this novel category of unnatural alkaloids includes the nitro-substituted benzazolo[3,2-a]quinolinium chlorides (NBQs) that has demonstrated activity as an anticancer agents. Preliminary studies with gram-positive and gram-negative bacterial types treated with fluorescent members of this family of compounds have also shown the capacity of these BQS to bind to bacteria. In this study, the antimicrobial potential of several NBQs against different bacterial genera of both gram-positive and gram-negative types are presented and compared to penicillin as the positive control. Determination of the minimum inhibitory concentration (MIC) of the drugs was performed using different concentrations. Susceptibility tests were examined using the disk-diffusion (Kirby-Bauer) method. NBQ-95 and NBQ-106 exhibited significant action against all strains of the gram-positive cultures at a 3mM concentration. However NBQ-48 and NBQ-51 also showed little inhibitory capacity in comparison with penicillin. Results of this study indicate the potential use of these novel compounds as antimicrobial agents. Further analysis of the synergistic effect of NBQs with additional chemical compounds will elucidate the clinical aspect of these drugs.