title: 6-Aminoquinolones: a new class of quinolone antibacterials?
abstract: A series of quinolone- and 1,8-naphthyridone-3-carboxylic acids, designed by previous QSAR studies and characterized by an amino group at the C-6 position instead of the usual fluorine atom, were synthesized for the first time and evaluated for in vitro antibacterial activity. All of the synthesized compounds maintain good activity against Gram-negative bacteria (Pseudomonas aeruginosa excluded), and those compounds having a thiomorpholine group as the C-7 substituent also have good activity against Gram-positive bacteria. Some aspects of structure-activity relationships associated with the C-1, C-5, C-7, and C-8 substituents are also discussed. Derivatives 18g and 38g displayed the best activity with geometric mean MICs of 0.45 and 0.66-0.76 micrograms/mL against Gram-negative and Gram-positive bacteria, respectively. This antimicrobial activity reflects their ability to inhibit bacterial DNA-gyrase. The results of this study show that, while the C-6 fluorine is still the preferred substituent, good activity can still be obtained by replacing it with an amino group.
authors.affiliation: Istituto di Chimica Farmaceutica e Tecnica Farmaceutica, Università di Perugia, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Cecchetti
authors.forename: S
authors.initials: S
authors.lastname: Clementi
authors.forename: G
authors.initials: G
authors.lastname: Cruciani
authors.forename: A
authors.initials: A
authors.lastname: Fravolini
authors.forename: P G
authors.initials: PG
authors.lastname: Pagella
authors.forename: A
authors.initials: A
authors.lastname: Savino
authors.forename: O
authors.initials: O
authors.lastname: Tabarrini
mesh_terms: D042462:4-Quinolones; D000634:Aminoquinolines / Q000138:chemical synthesis* / Q000494:pharmacology*; D000890:Anti-Infective Agents / Q000138:chemical synthesis* / Q000494:pharmacology*; D004269:DNA, Bacterial / Q000187:drug effects / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D013329:Structure-Activity Relationship
chemical_list: D042462:4-Quinolones; D000634:Aminoquinolines; D000890:Anti-Infective Agents; D004269:DNA, Bacterial