STRUCTURE-ANTIBACTERIAL ACTIVITY AND CYTOTOXICITY RELATIONSHIPS OF THIAZOLO AND THIAZETOQUINOLONE DERIVATIVES

In the course of our search for derivatives with potent antibacterial activity and low cytotoxicity, we have studied the relationships among the structure, antibacterial activity and cytotoxicity of thiazoloqui nolone and thiazetoquinolone derivatives (the term quinolone as used i n this paper includes the quinolone, 1,8-naphthyridine and pyridopyrim idine nuclei), The antibacterial activities and cytotoxicity of these derivatives mere compared,vith those of norfloxacin, ofloxacin, enoxac in and ciprofloxacin. The antibacterial activities of the thiazoloquin olone derivatives were more potent than those of the dihyrothiazoloqui nolone derivatives, and comparable to that of ciprofloxacin. All of th e thiazoloquinolone derivatives were highly cytotoxic against mammalia n cells, but some of the dihyrothiazoloquinolone derivatives were less cytotoxic, being comparable in cytotoxicity to the reference drugs. T he thiazetoquinolone derivatives were less cytotoxic than the thiazolo quinolone derivatives, and one of them, nyl)-4H-[1,3]thiazeto[3,2-a]qu inoline-3-carboxylic acid, showed the most potent antibacterial activi ty of all compounds tested in this study, as well as a very low cytoto xicity. The antibacterial activity and cytotoxicity of this compound w ere similar to that of ciprofloxacin.