STUDIES ON 6-AMINOQUINOLONES - SYNTHESIS AND ANTIBACTERIAL EVALUATIONOF 6-AMINO-8-METHYLQUINOLONES

The 6-aminoquinolone had previously been identified as a new class of quinolone antibacterial agents. To continue our structure-activity rel ationship (SAR) study in this series, novel 6-amino-8-methylquinolone derivatives have now been synthesized and evaluated for in vitro antib acterial activity. We have shown that the coupled presence of a methyl group at the C-8 position with an amino group at C-6 is effective for enhancing antibacterial activity, particularly against Gram-positive bacteria. The SARs associated with the N-1, C-6, and C-7 are discussed . The 1,2,3,4-tetrahydroisoquinolinyl derivative 19v showed the highes t antibacterial activity with MIC values on Gram-positive bacteria sup erior to that of ciprofloxacin, especially against Staphylococcus aure us strains, including those strains which are methicillin- and ciprofl oxacin-resistant.