FIG. 2.

Lethal activity of N-1 cyclopropyl, 8-methoxy fluoroquinolones and N-1/C-8 fused-ring analogs in the presence or absence of chloramphenicol. Survival of E. coli was measured as a function of the fluoroquinolone concentration expressed as a multiple of the MIC in the presence (filled symbols) or absence (open symbols) of chloramphenicol, an inhibitor of protein synthesis. Data for the 8-methoxy compounds are in the left column, and data for fused-ring compounds are in the right column. The names of the compounds are indicated in each panel (Et, ethyl; Me, methyl), as are the C-7 ring structures (lower left). The error bars represent standard deviations of the means shown; similar results were observed with 2 additional, replicate experiments.