L-Cysteine Hydrochloride
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L-Cysteine Hydrochloride

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L-cysteine hydrochloride is the salt form of L-cysteine, which acts as a histidine ammonia-lyase inhibitor.
Protein supplement in health care products.

L-Amino Acids
Catalog number
CAS number
Molecular Formula
Molecular Weight
L-Cysteine Hydrochloride
(2R)-2-amino-3-sulfanylpropanoic acid;hydrochloride
(r)-cysteinehydrochloride; (R)-Cysteine-hydrochloride; 3-Mercaptoalanine hydrochloride; Cystein chloride; Cysteine chlorhydrate; Cysteine chlorohydrate; Cysteine, hydrochloride, L-; cysteinechlorhydrate
White crystalline powder
Melting Point
Boiling Point
293.9°C at 760 mmHg
Store at RT
Soluble in Aqueous Acid, DMSO, Water, Methanol
InChI Key
Canonical SMILES
Ingredient of health care products.
1. Derivatives of S-9-fluorenylmethyl-L-cysteine
M Bodanszky, M A Bednarek Int J Pept Protein Res. 1982 Nov;20(5):434-7. doi: 10.1111/j.1399-3011.1982.tb03064.x.
The 9-fluorenylmethyl (Fm) group was examined with respect to its potential for blocking the sulfhydryl function. The S-Fm group is resistant to acids and to catalytic hydrogenation but is cleaved by ammonia in methanol or by organic bases, such as a 20% solution of piperidine in dimethylformamide. Synthesis of N-tert.-butyloxycarbonyl-S-9-fluorenylmethyl-L-cysteine p-nitrophenyl ester and of cysteinyl peptides protected with the S-Fm group are described.
2. Far-infrared terahertz properties of L-cysteine and its hydrochloride monohydrate
Guanhua Ren, Siqi Zong, Zhongjie Zhu, Chao Cheng, Ligang Chen, Lu Zhou, Jianbing Zhang, Liyuan Liu, Jiaguang Han, Hongwei Zhao Spectrochim Acta A Mol Biomol Spectrosc. 2020 Jan 15;225:117476. doi: 10.1016/j.saa.2019.117476. Epub 2019 Aug 19.
As the building blocks of proteins, amino acids serve vital metabolic functions in addition to protein synthesis and thus attract enormous interest. Here we reported the far-infrared optical properties of L-cysteine (Lcys) and its hydrochloride monohydrate (LCHM) characterized by terahertz time-domain spectroscopy. The Lcys and LCHM exhibit quite distinct characteristics in the terahertz region due to diverse collective vibrations of the molecules, which is further confirmed by the solid-state density functional theory (DFT) calculations. The presented studies indicate that the intermolecular hydrogen bonds play a critical role in the far-infrared terahertz response of Lcys and LCHM.
3. Chemical and Biological Properties of S-1-Propenyl-l-Cysteine in Aged Garlic Extract
Yukihioro Kodera, Mitsuyasu Ushijima, Hirotaka Amano, Jun-Ichiro Suzuki, Toshiaki Matsutomo Molecules. 2017 Mar 31;22(4):570. doi: 10.3390/molecules22040570.
S-1-Propenyl-l-cysteine (S1PC) is a stereoisomer of S-1-Propenyl-l-cysteine (SAC), an important sulfur-containing amino acid that plays a role for the beneficial pharmacological effects of aged garlic extract (AGE). The existence of S1PC in garlic preparations has been known since the 1960's. However, there was no report regarding the biological and/or pharmacological activity of S1PC until 2016. Recently, we performed a series of studies to examine the chemical, biological, pharmacological and pharmacokinetic properties of S1PC, and obtained some interesting results. S1PC existed only in trace amounts in raw garlic, but its concentration increased almost up to the level similar of SAC through aging process of AGE. S1PC showed immunomodulatory effects in vitro and in vivo, and reduced blood pressure in a hypertensive animal model. A pharmacokinetic study revealed that S1PC was readily absorbed after oral administration in rats and dogs with bioavailability of 88-100%. Additionally, S1PC had little inhibitory influence on human cytochrome P450 activities, even at a concentration of 1 mM. Based on these findings, S1PC was suggested to be another important, pharmacologically active and safe component of AGE similar to SAC. In this review, we highlight some results from recent studies on S1PC and discuss the potential medicinal value of S1PC.
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