FIG. 2.

Inhibition of precursor incorporation into macromolecules by naphthyridones differs in H. influenzae and S. pneumoniae. Inhibition of synthesis was measured for protein (leucine [□]), valine (▪), RNA (uridine [•]), and DNA (methylthymidine [○]) in H. influenzae (left) and S. pneumoniae (right); for clarity, precursors for incorporation into fatty acid (acetic acid) and peptidoglycan/cell wall (N-acetylglucosamine), which were inhibited to much lower extents, have been omitted. Results obtained with compound 1 (top) are typical for all four naphthyridone compounds; ciprofloxacin (bottom) served as a control for inhibition of DNA synthesis in both S. pneumoniae and H. influenzae. Results with additional control compounds (erythromycin, triclosan, carbonyl cyanide m-chlorophenylhydrazone, rifampin, and penicillin G) are not shown.