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InventoryRef 8366515/10/2010

AMIDINOCYSTEINE

2-Guanidino-3-mercaptopropionic acid

AMIDINOCYSTEINE is listed in the EU CosIng inventory, but no direct annex records are linked on this page yet.

Regulatory evidence by market

No rule for this ingredient has been imported for any of the 13 markets tracked here.

That describes this inventory, not the law. No imported rule is not evidence that an ingredient is permitted: a rule may exist under another name or identifier, or in a dataset not yet imported here.

Chemical identity and properties

PubChem 2D chemical structure for CAS 40454-21-5
CAS 40454-21-5PubChem CID 38477

N-(Aminoiminomethyl)-L-cysteine

IUPAC name
(2R)-2-(diaminomethylideneamino)-3-sulfanylpropanoic acid
Molecular formula
C4H9N3O2S
Molecular weight
163.20 g/mol
Exact mass
163.04154771 Da
XLogP3
-1.2
Topological polar surface area
103.0 Ų
Hydrogen-bond donors
4
Hydrogen-bond acceptors
4
Covalent units
1
Defined stereocentres
1

Also known as

IQB-782n-guanylcysteineL-Cysteine, N-(aminoiminomethyl)-N-Guanidine-beta-mercaptoalanine48PVL851IDRefChem:926937N-Amidino-L-cysteineGUANYL-CYS-OH
16 more reported names
N-Guanyl-cysteineamidinocysteineN-AmidinocysteineIqb 782EINECS 254-925-1N-GUANYL-L-CYSTEINEBRN 2087654UNII-48PVL851IDCYSTEINE, N-AMIDINO-, L-CYSTEINE, N-AMIDINO-XWRZKLKALVJDDS-REOHCLBHSA-NN-(Diaminomethylidene)-L-cysteineDA-54366HY-1059402-GUANIDINO-3-MERCAPTOPROPIONIC ACIDCS-0026990
External database identifiers

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

Inventory details for AMIDINOCYSTEINE

INCI name

AMIDINOCYSTEINE

Description

2-Guanidino-3-mercaptopropionic acid

Record provenance

Inventory reference
83665
Imported identity
AMIDINOCYSTEINE
Source update
15/10/2010
European Commission CosIng source notes

Key data

Restriction
Function
HAIR WAVING OR STRAIGHTENING
Modifying the chemical structure of the hair, allowing it to be set in the style required (permanent waves or hair straightening).

Official EU ingredient-name evidence

The ingredient name exactly matches the official 2025 EU glossary of common ingredient names.

Ingredients with overlapping formulation functions

Additional official and scientific sources

11 external databases to check this identity in

How AMIDINOCYSTEINE appears in the CosIng inventory

The CosIng inventory lists AMIDINOCYSTEINE as a cosmetic ingredient and this page links it to 0 annex records. The inventory entry captures names and identifiers, while the annex records show where the substance is prohibited, restricted or positively listed in EU cosmetics law.

AMIDINOCYSTEINE is also tagged with 1 cosmetic function in the official data. Function labels describe intended use, but they do not replace regulatory review of linked annex records before formulation or labelling work.

Frequently asked questions

AMIDINOCYSTEINE is listed in the EU CosIng ingredient inventory with no direct annex restriction records linked at this time. Absence of an annex link does not guarantee unrestricted use — always verify against the current official CosIng database before formulating.

According to the EU CosIng inventory, AMIDINOCYSTEINE carries the following function designation(s):

CAS 40454-21-5 may appear across multiple EU annex records. Viewing the CAS lookup page shows all Annex II–VI entries sharing this identifier, which is useful for identifying cross-annex regulatory status of the same chemical substance.

Use the INCI Checker to screen a full ingredient list across selected markets, or compare this substance across all supported market datasets.

Source note for AMIDINOCYSTEINE

This page reproduces the CosIng inventory entry for AMIDINOCYSTEINE from public European Commission cosmetic ingredient materials and shows linked identifiers even when no direct annex match is currently attached.

Use this inventory page to research AMIDINOCYSTEINE and compare linked records, but verify restrictions and legal status against the current official source text and law before making regulatory decisions.

Tools & next steps

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