HomeSearch by AntimicrobialNalidixic acid (NegGam)
Antimicrobial Name: Nalidixic acid (NegGam)
CAS Number: 389-08-2
Type of Antibiotic: Quinolones->First Generation
Origin: Chemical/Synthetic
Functional Category: Antibiotic
Molecular Weight: 232.235
Chemical Formula:



35 mg/ml at 23°C in chloroform

1.6 mg/ml at 23°C in toluene

1.3 mg/ml at 23°C in methanol

0.9 mg/ml at 23°C in ethanol

0.1 mg/ml at 23°C in water

0.1 mg/ml at 23°C in ether

Melting point:

229 - 230 °C


Nalidixic acid (NegGam) is the first of the synthetic quinolone antibiotics.Technically, it is a naphthyridone, not a quinolone: its ring structure is a 1,8-naphthyridines nucleus that contains two nitrogen atoms, not quinoline, which has a single nitrogen atom. Nalidixic acid is effective against both gram-positive and gram-negative bacteria. In lower concentrations, it acts in a bacteriostatic manner; that is, it inhibits growth and reproduction. In higher concentrations, it is bactericidal, meaning that it kills bacteria instead of merely inhibiting their growth. It is especially used in treating urinary tract infection.It is also a tool in studies as a regulation of bacterial division. It selectively and reversibly blocks DNA replication in susceptible bacteria. Nalidixic acid and related antibiotics inhibit a subunit of DNA gyrase and induce formation of relaxation complex analogue. It also inhibits the nicking dosing activity on the subunit of DNA gyrase that release the positive binding stress on the supercoiled DNA.