Official EU label nameGlossary entry 7979

CYSTEINE

This record confirms an official common ingredient name for EU cosmetic product labelling. It does not by itself confirm that the substance is permitted, unrestricted or safe.

Global evidence snapshot

The resolved identity has matching regulatory evidence in 0 of 13 indexed market datasets: 0 country records and 0 EU Annex records. Every result and evidence gap is listed below.

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Evidence gaps

Resolved identifiers

Resolved substance identity

CAS:52-90-43374-22-9

EC:200-158-2222-160-2

Ingredient index records:

CYSTEINE

Cosmetic functions: ANTIOXIDANT, ANTISTATIC, FRAGRANCE, HAIR CONDITIONING, HAIR WAVING OR STRAIGHTENING, REDUCING

L-Cysteine

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2 matched or reported names

CYSTEINEcysteine

Regulatory evidence across markets

None of the 13 markets tracked here holds an imported rule under the name CYSTEINE.

That is a statement about this inventory, not about the law: no imported rule is not evidence that a substance is permitted. A rule may exist under a different name, under a CAS or EC number this glossary entry does not carry, or in a dataset not yet imported.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 3374-22-9

CAS 3374-22-9PubChem CID 594

DL-cysteine

Cysteine is a sulfur-containing amino acid that is propanoic acid with an amino group at position 2 and a sulfanyl group at position 3. It has a role as a fundamental metabolite. It is a polar amino acid, a sulfur-containing amino acid and an alpha-amino acid. It contains a sulfanylmethyl group. It is a conjugate base of a cysteinium. It is a conjugate acid of a cysteinate(1-). It is a tautomer of a cysteine zwitterion. — ChEBI

IUPAC name: 2-amino-3-sulfanylpropanoic acid

Molecular formula: C3H7NO2S
Molecular weight: 121.16 g/mol
Exact mass: 121.01974964 Da
XLogP3: -2.5
Topological polar surface area: 64.3 Å²
Hydrogen-bond donors: 3
Hydrogen-bond acceptors: 4
Covalent units: 1
Defined stereocentres: 0

Also known as

CYSTEINE, DL-5CM45Q5YAFNSC-63864RefChem:1083896222-160-2DL-Cystein(+/-)-2-Amino-3-mercaptopropionic acidNSC 63864

16 more reported names

ZysteinHcysd,l-cysteineUNII-5CM45Q5YAF[35s]cysteineCCRIS 85982-amino-3-sulfanyl-propanoic acidL-HSCH2CH(NH2)COOHCAS_5862DL-2-Amino-3-mercaptopropionic acidCS-W013566Tox21_111766_1H-Cys-OH HCl HOCAS-3374-22-9C3H7NO2SSR-01000944791

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External database identifiers

ChEBI:CHEBI:15356
ChEMBL:CHEMBL54943
EPA DTXSID:DTXSID5046988
PubMed:23024785
PubMed:22867025
PubMed:22813754
PubMed:22769850
PubMed:22572786
PubMed:22539321
PubMed:22533155
PubMed:22524145
PubMed:22523489
PubMed:22427952
PubMed:22405311
PubMed:22365687

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

PubChem 2D chemical structure for CAS 52-90-4

CAS 52-90-4PubChem CID 5862

L-(+)-Cysteine

L-cysteine is an optically active form of cysteine having L-configuration. It has a role as a flour treatment agent, an EC 4.3.1.3 (histidine ammonia-lyase) inhibitor and a human metabolite. It is a cysteine, a L-alpha-amino acid, a serine family amino acid and a proteinogenic amino acid. It is a conjugate base of a L-cysteinium. It is a conjugate acid of a L-cysteinate(1-). It is an enantiomer of a D-cysteine. It is a tautomer of a L-cysteine zwitterion. — ChEBI

IUPAC name: (2R)-2-amino-3-sulfanylpropanoic acid

Molecular formula: C3H7NO2S
Molecular weight: 121.16 g/mol
Exact mass: 121.01974964 Da
XLogP3: -2.5
Topological polar surface area: 64.3 Å²
Hydrogen-bond donors: 3
Hydrogen-bond acceptors: 4
Covalent units: 1
Defined stereocentres: 1

Also known as

L-cysteinecysteineCystein(R)-2-Amino-3-mercaptopropanoic acidThioserineHalf-cystinebeta-MercaptoalanineL-Cystein

16 more reported names

CysteinumL-CyscisteinaHalf cystine2-Amino-3-mercaptopropionic acidL-Alanine, 3-mercapto-FREE CYSTEINECisteinumFEMA No. 3263Cisteinum [Latin]NSC-8746alpha-Amino-beta-thiolpropionic acidL-2-Amino-3-mercaptopropionic acidbeta-Mercaptoalanine, L-(2R)-2-amino-3-mercaptopropanoic acidL Cysteine

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External database identifiers

ChEBI:CHEBI:17561
ChEBI:CHEBI:47915
ChEMBL:CHEMBL863
EPA DTXSID:DTXSID8022876
PubMed:23125019
PubMed:23124343
PubMed:23122078
PubMed:23118898
PubMed:23118886
PubMed:23114088
PubMed:23113344
PubMed:23113039
PubMed:23111743
PubMed:23109897
PubMed:23109729
PubMed:23107541

Retrieved from NIH PubChem on 2026-09-02 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Additional authoritative substance research

Each link searches that source for this identity. A link is a research route, not a claim that the source holds an exact record. What each source is, and its legal weight

Cosmetic Ingredient Review safety assessments FDA Global Substance Registration System ILO/WHO International Chemical Safety Cards Japan NITE-CHRIP NIOSH Pocket Guide to Chemical Hazards OECD eChemPortal US EPA CompTox CTX APIs

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Official source and scope

Imported from Commission Implementing Decision (EU) 2025/1175 (dataset version EU 2025/1175). The glossary supplies common ingredient names for the ingredient list required by Article 19(1)(g); it is not an approval or safety list.

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