norfloxacin

CHEBI:100246 ·resolve ·ANTIBACTERIAL ·EXACT SEEDED

A quinolinemonocarboxylic acid with broad-spectrum antibacterial activity against most gram-negative and gram-positive bacteria. Norfloxacin is bactericidal and its mode of action depends on blocking of bacterial DNA replication by binding itself to an enzyme called DNA gyrase. — ChEBI

Machine-generated and unreviewed. Identity, structure and cross-references come straight from ChEBI's and CARD's own data; no curator has signed off on this record yet.

Classification

fluoroquinolone antibioticARO:0000001

Strictly broader compounds or drug classes this molecule belongs to.

CHEBI:23765 CHEBI:23765
CHEBI:26512 CHEBI:26512
CHEBI:46848 CHEBI:46848
CHEBI:86324 CHEBI:86324
CHEBI:87211 CHEBI:87211
ARO:0000001 ARO:0000001

Chemical structure

Computed structure properties
Molecular formula	C16H18FN3O3
Charge	0
Average mass	319.336 Da
Monoisotopic mass	319.13322 Da
Source	ChEBI
InChIKey	OGJPXUAPXNRGGI-UHFFFAOYSA-N

SMILES

CCn1cc(C(=O)O)c(=O)c2cc(F)c(N3CCNCC3)cc21

InChI

InChI=1S/C16H18FN3O3/c1-2-19-9-11(16(22)23)15(21)10-7-12(17)14(8-13(10)19)20-5-3-18-4-6-20/h7-9,18H,2-6H2,1H3,(H,22,23)

Also called

norfloxacine (INN)— chebi
norfloxacino (INN)— chebi
norfloxacinum (INN)— chebi
1-ethyl-6-fluoro-4-oxo-7-(piperazin-1-yl)-1,4-dihydroquinoline-3-carboxylic acid (EXACT_SYNONYM)— chebi
1,4-Dihydro-1-ethyl-6-fluoro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid (EXACT_SYNONYM)— chebi
1-Ethyl-6-fluor-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-chinolincarbonsäure (EXACT_SYNONYM)— chebi
1-Ethyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-3-quinolinecarboxylic acid (EXACT_SYNONYM)— chebi
NFLX (EXACT_SYNONYM)— chebi

Cross-references

Equivalent identifiers for this same structure in other resources.

ARO:3000662
cas:70458-96-7
drugbank:DB01059
drugcentral:1967
gmelin:1576626
hmdb:HMDB0015192
kegg.compound:C06687
kegg.drug:D00210
lincs.smallmolecule:LSM-5286
patent:BE863429
patent:DE2840910
patent:US4146719
patent:US4292317
reaxys:567897
vsdb:1831
wikipedia.en:Norfloxacin
chembl:CHEMBL9
pubchem.compound:4539

Activity roles

Every antimicrobial role a source asserts for this compound — the unreduced evidence behind its antimicrobial_class.

CHEBI:33281 CHEBI:33281
CHEBI:36047 CHEBI:36047

Source concepts

Every upstream concept that resolved to this record. The merge is the product: this is what shows ChEBI and CARD are describing the same structure.

Upstream concepts merged into this record
Source	Native ID	Label	Minted CURIE	Version
ARO	`ARO:3000662`	norfloxacin	`antibioticmech:aro-920bf40494`	2026-08-30
CHEBI	`CHEBI:100246`	norfloxacin	`antibioticmech:chebi-bb2c1d2f77`	2026-08-30

Molecular targets

The molecular entity or process this compound acts on. Each target carries evidence — this is a mechanistic claim, not a classification.

fluoroquinolone sensitive gyrA PROTEIN DIRECT_BINDING_TARGET

ARO:3000733

CARD/ARO database assertion; target organism, strain, and assay are not specified. ARO explicitly describes ligand binding to gyrase subunit A. Evidence status: PRIMARY_EVIDENCE_NEEDED. Source: CARD_ARO 2026-08-30 (retrieved 2026-08-30).

ARO:3000733 (CARD/ARO asserts targeted_by_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)

Fluoroquinolone sensitive parC PROTEIN DIRECT_BINDING_TARGET

ARO:3000735

CARD/ARO database assertion; target organism, strain, and assay are not specified. ParC is asserted as the fluoroquinolone-sensitive subunit. Evidence status: PRIMARY_EVIDENCE_NEEDED. Source: CARD_ARO 2026-08-30 (retrieved 2026-08-30).

ARO:3000735 (CARD/ARO asserts targeted_by_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)

Mechanism summary

Mode of action: NUCLEIC_ACID_SYNTHESIS_INHIBITION microbial target — CURATOR: Confirmed as bacterial DNA gyrase inhibition after primary norfloxacin mechanism review. PMID:2536729; PMID:2982149; PMID:3010848.
Clinical status: APPROVED

Resistance mechanisms

48 known routes by which microbes resist this compound, grounded in ARO where CARD models them. Grouped by mechanism type — expand a group to see its determinants.

ANTIBIOTIC_TARGET_ALTERATION 24

ANTIBIOTIC_TARGET_ALTERATION
Determinant	ARO ID	Organism	Gene families	Evidence
Acinetobacter baumannii gyrA conferring resistance to fluoroquinolones	ARO:3003817	not organism-specific	—	ARO:3003817 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Acinetobacter baumannii parC conferring resistance to fluoroquinolones	ARO:3003818	not organism-specific	—	ARO:3003818 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Bartonella bacilliformis gyrA conferring resistance to fluoroquinolones	ARO:3003297	not organism-specific	—	ARO:3003297 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Capnocytophaga gingivalis gyrA conferring resistance to fluoroquinolones	ARO:3003931	not organism-specific	—	ARO:3003931 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Escherichia coli gyrA conferring resistance to fluoroquinolones	ARO:3003294	not organism-specific	—	ARO:3003294 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Escherichia coli parC conferring resistance to fluoroquinolones	ARO:3003308	not organism-specific	—	ARO:3003308 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Escherichia coli parE conferring resistance to fluoroquinolones	ARO:3003316	not organism-specific	—	ARO:3003316 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Helicobacter pylori gyrB conferring resistance to fluoroquinolones	ARO:3007053	not organism-specific	—	ARO:3007053 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Morganella morganii gyrB conferring resistance to fluoroquinolones	ARO:3003306	not organism-specific	—	ARO:3003306 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Mycobacterium leprae gyrA conferring resistance to fluoroquinolones	ARO:3003298	not organism-specific	—	ARO:3003298 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Mycobacterium leprae gyrB conferring resistance to fluoroquinolones	ARO:3003304	not organism-specific	—	ARO:3003304 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Mycobacterium tuberculosis gyrA conferring resistance to fluoroquinolones	ARO:3003295	not organism-specific	—	ARO:3003295 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Mycobacterium tuberculosis gyrB with mutation conferring resistance to fluoroquinolones	ARO:3003459	not organism-specific	—	ARO:3003459 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Mycoplasma hominis parC conferring resistance to fluoroquinolones	ARO:3003310	not organism-specific	—	ARO:3003310 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Salmonella serovars gyrB conferring resistance to fluoroquinolones	ARO:3003307	not organism-specific	—	ARO:3003307 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Salmonella serovars parE conferring resistance to fluoroquinolones	ARO:3003317	not organism-specific	—	ARO:3003317 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Shigella flexneri gyrA conferring resistance to fluoroquinolones	ARO:3003940	not organism-specific	—	ARO:3003940 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Shigella flexneri parC conferring resistance to fluoroquinolones	ARO:3003941	not organism-specific	—	ARO:3003941 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Staphylococcus aureus gyrA conferring resistance to fluoroquinolones	ARO:3003296	not organism-specific	—	ARO:3003296 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Staphylococcus aureus parC conferring resistance to fluoroquinolones	ARO:3003312	not organism-specific	—	ARO:3003312 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Staphylococcus aureus parE conferring resistance to fluoroquinolones	ARO:3003315	not organism-specific	—	ARO:3003315 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Streptococcus pneumoniae parC conferring resistance to fluoroquinolones	ARO:3003311	not organism-specific	—	ARO:3003311 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Ureaplasma urealyticum gyrB conferring resistance to fluoroquinolones	ARO:3003305	not organism-specific	—	ARO:3003305 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Ureaplasma urealyticum parC conferring resistance to fluoroquinolones	ARO:3003309	not organism-specific	—	ARO:3003309 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)

ANTIBIOTIC_EFFLUX 23

ANTIBIOTIC_EFFLUX
Determinant	ARO ID	Organism	Gene families	Evidence
Enterobacter aerogenes acrR with mutation conferring multidrug antibiotic resistance	ARO:3003374	not organism-specific	—	ARO:3003374 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Klebsiella pneumoniae KpnGH-TolC	ARO:3004598	not organism-specific	—	ARO:3004598 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
MdtEF-TolC	ARO:3000788	not organism-specific	—	ARO:3000788 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
MexEF-OprN with MvaT deletion conferring resistance to chloramphenicol and norfloxacin	ARO:3004070	not organism-specific	—	ARO:3004070 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
MexGHI-OpmD	ARO:3000799	not organism-specific	—	ARO:3000799 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
MexHI-OpmD	ARO:3009153	not organism-specific	—	ARO:3009153 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
MexXY-OprA	ARO:3003038	not organism-specific	—	ARO:3003038 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
MexXY-OprM	ARO:3003032	not organism-specific	—	ARO:3003032 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
PatA-PatB	ARO:3000769	not organism-specific	—	ARO:3000769 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
QepA1	ARO:3000448	not organism-specific	—	ARO:3000448 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
QepA2	ARO:3004103	not organism-specific	—	ARO:3004103 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
QepA4	ARO:3004379	not organism-specific	—	ARO:3004379 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
Staphylococcus aureus norA	ARO:3004667	not organism-specific	—	ARO:3004667 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
abeM	ARO:3000753	not organism-specific	—	ARO:3000753 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
hmrM	ARO:3003953	not organism-specific	—	ARO:3003953 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
lfrA	ARO:3003967	not organism-specific	—	ARO:3003967 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
mdtH	ARO:3001216	not organism-specific	—	ARO:3001216 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
mdtM	ARO:3001214	not organism-specific	—	ARO:3001214 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
norA	ARO:3000391	not organism-specific	—	ARO:3000391 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
norB	ARO:3000421	not organism-specific	—	ARO:3000421 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
pmrA	ARO:3000822	not organism-specific	—	ARO:3000822 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
putative nickel/cobalt transporter	ARO:3007659	not organism-specific	—	ARO:3007659 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)
sdrM	ARO:3007013	not organism-specific	—	ARO:3007013 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)

ANTIBIOTIC_TARGET_PROTECTION 1

ANTIBIOTIC_TARGET_PROTECTION
Determinant	ARO ID	Organism	Gene families	Evidence
quinolone resistance protein (qnr)	ARO:3000419	not organism-specific	—	ARO:3000419 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3000662 (norfloxacin); database assertion, not a primary citation.)

Causal graphs

Evidence-backed mechanism graphs: how the compound reaches its target, what the target does, and how the effect propagates to growth inhibition or death.

Norfloxacin inhibits bacterial DNA gyrase supercoiling MECHANISTIC

Norfloxacin binds the DNA-DNA gyrase reaction complex and inhibits DNA gyrase-catalyzed supercoiling, disrupting bacterial chromosome topology control.

Nodes — norfloxacin_dna_gyrase_supercoiling_inhibition
Node	Label	Type	Grounding
`norfloxacin`	norfloxacin	COMPOUND	`CHEBI:100246`
`dna_gyrase`	bacterial DNA gyrase	GENE_OR_PROTEIN	`ARO:3000733`
`dna_supercoiling`	ATP-dependent DNA supercoiling	BIOLOGICAL_PROCESS	REVIEWED_LABEL_ONLY
`dna_topology_control`	bacterial DNA topology control	BIOLOGICAL_PROCESS	REVIEWED_LABEL_ONLY

Edges — norfloxacin_dna_gyrase_supercoiling_inhibition
Subject	Predicate	Object	Evidence
`norfloxacin`	binds	`dna_gyrase`	PMID:2536729 (Shen and colleagues characterized norfloxacin binding sites that appear in DNA gyrase-DNA complexes.)
`norfloxacin`	inhibits	`dna_supercoiling`	PMID:2982149 (Shen and Pernet assayed tritiated norfloxacin to probe quinolone inhibition of DNA gyrase.) PMID:3010848 (Zweerink and Edison compared norfloxacin and other quinolones in Micrococcus luteus DNA gyrase supercoiling assays.)
`dna_gyrase`	enables	`dna_supercoiling`	PMID:3010848 (The purified-enzyme assay measured quinolone inhibition of supercoiling by Micrococcus luteus DNA gyrase.)
`dna_supercoiling`	supports	`dna_topology_control`	PMID:3010848 (The in vitro comparison links quinolone-sensitive DNA gyrase activity to DNA supercoiling.)

Curation history

SEEDED_FROM_SOURCES 2026-08-30 · seed_from_sources
Seeded from data/raw/ inventories (ARO, CHEBI)
RESEEDED_FROM_SOURCES 2026-08-30 · seed_from_sources
Re-seeded from updated data/raw/ inventories
RESEEDED_FROM_SOURCES 2026-08-30 · seed_from_sources
Re-seeded from updated data/raw/ inventories
RESEEDED_FROM_SOURCES 2026-08-31 · seed_from_sources
Re-seeded from updated data/raw/ inventories
RESEEDED_FROM_SOURCES 2026-08-31 · seed_from_sources
Re-seeded from updated data/raw/ inventories
RESEEDED_FROM_SOURCES 2026-08-31 · seed_from_sources
Re-seeded from updated data/raw/ inventories
CURATED_CAUSAL_GRAPH 2026-09-04 · codex · LLM-assisted
Added a PMID-supported causal graph for norfloxacin inhibition of bacterial DNA gyrase supercoiling and marked the coarse target scope as curator-reviewed.

Provenance

Seeded by scripts/seed_from_sources.py from the committed inventories in data/raw/. View the record.