Figure 1.

The bicyclic core structure of fluoroquinolones. X and Y are carbon or nitrogen atoms. A carbon atom at Y defines the quinolones. Fluoroquinolones have a fluorine (F) atom at C6. Different substitutions at positions R1, R5, R7 and R8 can improve the activity of the drug. Adapted from Pham et al and Rusu et al ^{42 44}