L-Cysteine monohydrochloride
52-89-1 · (1R)-1-carboxy-2-sulfanylethan-1-aminium chloride · (2R)-2-amino-3-mercapto-propionic acid · (2R)-2-amino-3-sulfanyl-propanoic acid;hydrochloride · (2R)-2-Amino-3-sulfanylpropanoic acid hydron chloride hydrate · (2R)-2-amino-3-sulfanylpropanoic acid;hydrochloride · (R)-2-Amino-3-mercaptopropanoic acid hydrochloride · (R)-2-Amino-3-mercaptopropanoicacidhydrochloride · (R)-Cysteine hydrochloride · 3-Mercaptoalanine hydrochloride · CAS-52-89-1 · CCRIS 3613 · Cystein chloride · Cysteine (as hydrochloride) · Cysteine chlorhydrate · Cysteine HCl · Cysteine HCl (anhydrous) · CYSTEINE HYDROCHLORIDE · Cysteine hydrochloride (anhydrous) · CYSTEINE HYDROCHLORIDE (II) · CYSTEINE HYDROCHLORIDE (USP MONOGRAPH) · CYSTEINE HYDROCHLORIDE ANHYDROUS (II) · CYSTEINE HYDROCHLORIDE MONOHYDRATE · CYSTEINE HYDROCHLORIDE MONOHYDRATE (EP IMPURITY) · CYSTEINE HYDROCHLORIDE MONOHYDRATE (EP MONOGRAPH) · Cysteine monohydrochloride · Cysteine, L-, hydrochloride · Cysteine, L-, monohydrochloride · cysteine-hcl · cysteine-hydrochloride · ELCYS · H-Cys-OH inverted exclamation mark currencyHCl · H-Cys-OH.HCl · L-(+)-Cysteine hydrochloride · L-2-Amino-3-mercaptopropanoic acid monohydrochloride · l-cysteine chlorhydrate · L-CYSTEINE HCl anhydrous · L-Cysteine hydro-chloride · L-Cysteine hydrochloride · L-Cysteine hydrochloride anhydrous · L-Cysteine hydrochloride, 98.0-102.0% · L-Cysteine hydrochloride, anhydrous, >=98% (TLC) · L-Cysteine hydrochloride, anhydrous, >=99.0% (RT) · L-Cysteine hydrochloride, anhydrous, from non-animal source, BioReagent, suitable for cell culture, >=98.0% · L-Cysteine hydrochloride, Vetec(TM) reagent grade, >=98% · L-Cysteine monohydrochloride · L-Cysteine, hydrochloride (1:1) · L-Cysteine--hydrogen chloride (1/1) · l-Cysteine.HCl · L-cysteinium chloride · NOURESS · (2R)-2-amino-3-sulfanylpropanoic acid hydrochloride · (R)-Cysteine HCl; (R)-1-carboxy-2-mercaptoethanaminium chloride; L-(+)-Cysteine hydrochloride · L-Cysteine monohydrochlorideCAS 52-89-1
L-Cysteine monohydrochloride is the stable salt form of L-cysteine, used as a dough conditioner and a nutrient. The same source question applies to it.
Where it is and isn’t permitted
| Jurisdiction | Status | Scope and limits | Citation |
|---|---|---|---|
| United States | Permitted | 21 CFR 184.1272retrieved 2026-09-07 | |
| Codex Alimentarius | Not listedDoes not appear on this jurisdiction’s permitted list. That is not the same as being prohibited. |
What it is made from
Made from L-cysteine, which may be produced by fermentation or by hydrolysing keratin from feathers or hair.
- Vegan status depends on the source
- Vegetarian status depends on the source
- May raise a halal question
- May raise a kosher question
This is not an omission. What this additive is made from is not fixed — depending on the manufacturer it may be plant, animal or microbial in origin, nobody is required to say which, and the same product can change source between production runs. Ask the manufacturer if it matters to you; a label cannot answer it.
- CAS registry number
- 52-89-1
- InChIKey
- IFQSXNOEEPCSLW-DKWTVANSSA-N
- PubChem
- CID 60960
Every name it appears under
54 recorded names. A label may use any of them.
CAS registry number
- 52-89-1
As it appears in regulation
- L-Cysteine monohydrochloride
Other names
- (1R)-1-carboxy-2-sulfanylethan-1-aminium chloride
- (2R)-2-amino-3-mercapto-propionic acid
- (2R)-2-amino-3-sulfanyl-propanoic acid;hydrochloride
- (2R)-2-Amino-3-sulfanylpropanoic acid hydron chloride hydrate
- (2R)-2-amino-3-sulfanylpropanoic acid;hydrochloride
- (R)-2-Amino-3-mercaptopropanoic acid hydrochloride
- (R)-2-Amino-3-mercaptopropanoicacidhydrochloride
- (R)-Cysteine hydrochloride
- 3-Mercaptoalanine hydrochloride
- CAS-52-89-1
- CCRIS 3613
- Cystein chloride
- Cysteine (as hydrochloride)
- Cysteine chlorhydrate
- Cysteine HCl
- Cysteine HCl (anhydrous)
- CYSTEINE HYDROCHLORIDE
- Cysteine hydrochloride (anhydrous)
- CYSTEINE HYDROCHLORIDE (II)
- CYSTEINE HYDROCHLORIDE (USP MONOGRAPH)
- CYSTEINE HYDROCHLORIDE ANHYDROUS (II)
- CYSTEINE HYDROCHLORIDE MONOHYDRATE
- CYSTEINE HYDROCHLORIDE MONOHYDRATE (EP IMPURITY)
- CYSTEINE HYDROCHLORIDE MONOHYDRATE (EP MONOGRAPH)
- Cysteine monohydrochloride
- Cysteine, L-, hydrochloride
- Cysteine, L-, monohydrochloride
- cysteine-hcl
- cysteine-hydrochloride
- ELCYS
- H-Cys-OH inverted exclamation mark currencyHCl
- H-Cys-OH.HCl
- L-(+)-Cysteine hydrochloride
- L-2-Amino-3-mercaptopropanoic acid monohydrochloride
- l-cysteine chlorhydrate
- L-CYSTEINE HCl anhydrous
- L-Cysteine hydro-chloride
- L-Cysteine hydrochloride
- L-Cysteine hydrochloride anhydrous
- L-Cysteine hydrochloride, 98.0-102.0%
- L-Cysteine hydrochloride, anhydrous, >=98% (TLC)
- L-Cysteine hydrochloride, anhydrous, >=99.0% (RT)
- L-Cysteine hydrochloride, anhydrous, from non-animal source, BioReagent, suitable for cell culture, >=98.0%
- L-Cysteine hydrochloride, Vetec(TM) reagent grade, >=98%
- L-Cysteine monohydrochloride
- L-Cysteine, hydrochloride (1:1)
- L-Cysteine--hydrogen chloride (1/1)
- l-Cysteine.HCl
- L-cysteinium chloride
- NOURESS
Systematic names
- (2R)-2-amino-3-sulfanylpropanoic acid hydrochloride
- (R)-Cysteine HCl; (R)-1-carboxy-2-mercaptoethanaminium chloride; L-(+)-Cysteine hydrochloride
Hazard reference values
No reference value for this substance in the sources we hold.
Evidence and how bodies read it
Studies, and the differing conclusions regulators drew from them, are curated by hand rather than machine-read, and none has been written for this substance yet.
Sources for this page
- ecfr retrieved 2026-09-07
Full licence terms and publisher details on Sources. How this page is built and updated: Method.
Machine-readable:/api/v1/additives/l-cysteine-monohydrochloride.json