A series of unsubstituted and substituted cyclic amino derivatives at 7-position of 1-aryl-6-Huoro-4-quinolone-3-carboxylic acid (aryl=4-fluoro-, 2, 4-difluoro-, 4-fluoro-2-hydroxy-and 4-hydroxyphenyl) has been, prepared and their antibacterial activity was evaluated. The compounds 6b and 7b, 1-(4-Huorophenyl) and 1-(2, 4-difluorophenyl) variants of norfloxacin (NF), respectively, showed better in vitro activity than NF and good urinary recovery. 7-(3-Methyl-1-piperaziny1) and 7-(3-amino-1-pyrrolidiny1) derivatives of 1-(2, 4-difluoropheny1)-6-fluoro-4-quinolone-3-carboxylicacids (7c, f) exhibited comparable in vitro activity and excellent in vivo efficacy on systemic infections and practically no toxicity [ED 50 (mg/mouse, p. o.): vs.S.aureus SA-57, 7c=0.020, 7f=0.023;vs.S.marcescens IID 620, 7c=0.013, 7f=0.012].Structure-activity relationship focused on 7-substituents is also discussed.
