flucytosine

CHEBI:5100 ·resolve ·ANTIFUNGAL ·EXACT SEEDED

An organofluorine compound that is cytosine that is substituted at position 5 by a fluorine. A prodrug for the antifungal 5-fluorouracil, it is used for the treatment of systemic fungal infections. — 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

nucleoside antibioticARO:3000034

Strictly broader compounds or drug classes this molecule belongs to.

CHEBI:37143 CHEBI:37143
CHEBI:38337 CHEBI:38337
CHEBI:38338 CHEBI:38338
CHEBI:60783 CHEBI:60783
CHEBI:87205 CHEBI:87205
ARO:3000034 ARO:3000034
ARO:3007560 ARO:3007560

Chemical structure

Computed structure properties
Molecular formula	C4H4FN3O
Charge	0
Average mass	129.094 Da
Monoisotopic mass	129.03384 Da
Source	ChEBI
InChIKey	XRECTZIEBJDKEO-UHFFFAOYSA-N

SMILES

Nc1nc(=O)ncc1F

InChI

InChI=1S/C4H4FN3O/c5-2-1-7-4(9)8-3(2)6/h1H,(H3,6,7,8,9)

Also called

Ancotil (BRAND_NAME)— chebi
flucytosina (INN)— chebi
flucytosinum (INN)— chebi
4-amino-5-fluoropyrimidin-2(1H)-one (EXACT_SYNONYM)— chebi
5-FC (EXACT_SYNONYM)— chebi
5-Fluorocystosine (EXACT_SYNONYM)— chebi
5-Fluorocytosine (EXACT_SYNONYM)— chebi
Ancobon (TN) (EXACT_SYNONYM)— chebi

Cross-references

Equivalent identifiers for this same structure in other resources.

ARO:3007558
ARO:3009160
cas:2022-85-7
drugbank:DB01099
drugcentral:1188
hmdb:HMDB0015231
kegg.drug:D00323
lincs.smallmolecule:LSM-5878
patent:US2802005
patent:US2945038
patent:US3040026
pdb-ccd:1LD
wikipedia.en:Flucytosine
chembl:CHEMBL1463
pubchem.compound:3366

Activity roles

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

CHEBI:35718 CHEBI:35718
CHEBI:86327 CHEBI:86327

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:3007558`	5-flucytosine	`antibioticmech:aro-39cd22b2c6`	2026-08-30
ARO	`ARO:3009160`	5-fluorocytosine	`antibioticmech:aro-0e2ad8e0aa`	2026-08-30
CHEBI	`CHEBI:5100`	flucytosine	`antibioticmech:chebi-e46c25078c`	2026-08-30

Mechanism summary

Clinical status: APPROVED

Resistance mechanisms

8 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 5

ANTIBIOTIC_TARGET_ALTERATION
Determinant	ARO ID	Organism	Gene families	Evidence
Candida spp. FUR1 with mutations conferring resistance to 5-flucytosine	ARO:3007557	not organism-specific	—	ARO:3007557 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3007558 (5-flucytosine); database assertion, not a primary citation.)
Cryptococcus neoformans USX1 UDP-xylose synthase with mutations conferring resistance to 5-fluorocytosine	ARO:3009629	not organism-specific	—	ARO:3009629 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3007558 (5-flucytosine); database assertion, not a primary citation.)
Cryptococcus neoformans Ura6 uridylate kinase with mutations conferring resistance to 5-fluorocytosine	ARO:3009633	not organism-specific	—	ARO:3009633 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3009160 (5-fluorocytosine); database assertion, not a primary citation.)
Nakaseomyces glabratus Fur1 with mutations associated with resistance to 5-fluorocytosine	ARO:3009286	not organism-specific	—	ARO:3009286 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3009160 (5-fluorocytosine); database assertion, not a primary citation.)
Saccharomyces spp. FUR1 with mutations conferring resistance to 5-flucytosine	ARO:3007559	not organism-specific	—	ARO:3007559 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3007558 (5-flucytosine); database assertion, not a primary citation.)

REDUCED_PERMEABILITY 2

REDUCED_PERMEABILITY
Determinant	ARO ID	Organism	Gene families	Evidence
Aspergillus spp. fcyB conferring resistance to 5-flucytosine via reduced permeability	ARO:3007642	not organism-specific	—	ARO:3007642 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3007558 (5-flucytosine); database assertion, not a primary citation.)
Candida spp. FCY2 conferring resistance to 5-flucytosine via reduced permeability	ARO:3007665	not organism-specific	—	ARO:3007665 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3007558 (5-flucytosine); database assertion, not a primary citation.)

UNKNOWN 1

UNKNOWN
Determinant	ARO ID	Organism	Gene families	Evidence
Cryptococcus spp. UXS1 conferring resistance to 5-flucytosine via absence	ARO:3007568	not organism-specific	—	ARO:3007568 (CARD/ARO asserts confers_resistance_to_antibiotic ARO:3007558 (5-flucytosine); database assertion, not a primary citation.)

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

Provenance

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