Fluoroquinolones belong to a group of synthetic antibiotics that are derived from basic structure of nalidixic acid and have substituents at N-1, C-5, C-7, position 8 and a fluorine atom at position 6. There are also polycyclic derivatives. Quinolone antibiotics have a ketone at position 4 and a carboxylic group at position 3. Fluoroquinolones inhibit the bacterial DNA gyrase or the topoisomerase IV enzyme, resulting the inhibition of DNA replication and transcription. Fluorine at position 6 enhances gyrase inhibition and cell penetration. Piperaziny substituents provide activity against Gram-negative bacteria and pyrrolidinyl moiety is active against Gram-positive cocci. They improve water solubility needed oral application. The function substituted at position 8 IS to control anaerobe activity.

Fluoroquinolone	Substituent
Substituted at N-1
Norfloxacin	Ethyl
Enoxacin	Ethyl
Lomefloxacin	Ethyl
Fleroxacin	Fluoro ethyl
Difloxacin	Fluorophenyl
Temafloxacin	Difluorophenyl
Trovafloxacin	Difluorophenyl
Amifloxacin	Methyl amino
Ciprofloxacin	Cyclopropyl
Grepafloxacin	Cyclopropyl
Alumofloxacin	Cyclopropyl
Gemifloxacin	Cyclopropyl
Moxifloxacin	Cyclopropyl
Ecenofloxacin	Cyclopropyl
Balofloxacin	Cyclopropyl
Substituted at C-5
Sparfloxacin	Amine
Grepafloxacin	Methyl
Substituted at C-7
Trovafloxacin	Bicyclic
Moxifloxacin	Bicyclic
Danafloxacin	Bicyclic
Garenoxacin	Bicyclic
Ciprofloxacin	Piperazinyl
Lomefloxacin	Piperazinyl
Norfloxacin	Piperazinyl
Fleroxacin	Piperazinyl
Ofloxacin	Piperazinyl
Sparfloxacin	Piperazinyl
Grepafloxacin	Piperazinyl
Gatafloxacin	Piperazinyl
Levofloxacin	Piperazinyl
Clinafloxacin	Pyrrolidinyl
Nadifloxacin	Pyrrolidinyl
Sitafloxacin	Pyrrolidinyl
Irloxacin	Pyrryl
Balofloxacin	Piperidinyl
Substituted at position 8
Sparfloxacin	F
Lomefloxacin	F
Fleroxacin	F
Ciprofloxacin	CH₂
Temafloxacin	CH₂
Pefloxacin	CH₂
Norfloxacin	CH₂
Grepafloxacin	CH₂
Clinafloxacin	Cl
Sitafloxacin	Cl
Enoxacin	N
Tosufloxacin	N
Gemifloxacin	N
Trovafloxacin	N
Ecenofloxacin	N
Alatrofloxacin	N
Gatifloxacin	Methoxy
Pazufloxacin	Methoxy
Balofloxacin	Methoxy
Moxifloxacin	Methoxy
Garenoxacin	Methoxy
Tricyclic derivatives
Abufloxacin
Droxacin
Flumequine
Levofloxacin
Marbofloxacin
Miloxacin
Ofloxacin
Oxolinic acid
Pazufloxacin
Prulifloxacin
Rufloxacin
Verbafloxacin