Toxicity Summary
Identification and Uses: Cysteine forms white or colorless crystals. It is used in biochemical and nutritional studies and as a reducing agent in bread dough (maximum concentration 90 ppm). It is also used as a flavoring agent and in pharmaceuticals, including veterinary drugs. Human Exposure and Toxicity: A 3% cysteine solution is non-irritating to the human eye. Animal Studies: A single instillation of 0.1 g L-cysteine into the eye of a rabbit produced a mild irritant effect, which was completely reversible within 48 hours. A single application of 0.5 g L-cysteine to the skin of three rabbits showed no irritation or corrosive effects. Rats treated with high doses of cysteine experienced reduced litter size, associated with degeneration and/or death of ovulated unfertilized eggs and embryos, accompanied by changes in the zona pellucida, while the zona pellucida in the ovary was affected. Subcutaneous injection of 1.2 mg/g cysteine into the fetus of pregnant mice and rats on the last day of pregnancy resulted in brain degeneration observed in the fetus one day later. Using the Chinese hamster V79 cell line, L-cysteine was considered non-mutagenic at the HPRT locus. L-cysteine did not induce chromosomal structural aberrations in the V79 Chinese hamster cell line. Ecotoxicity Study: This study aimed to determine the effects of cysteine on sperm motility, duration of sperm motility, DNA damage, and fertility in carp (Cyprinus carpio) after thawing. Cysteine supplementation improved fertilization and hatching rates and reduced DNA damage.

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Non-human Toxicity Values
Rats Dermal LD50 >2000 mg/kg body weight
Rats Oral LD50 1890 mg/kg
Rats Intraperitoneal LD50 1620 mg/kg
Rats Subcutaneous LD50 1550 mg/kg
For more complete non-human toxicity data for cysteine (7 items), please visit the HSDB record page.

[1]. Impact of Deuterium Substitution on the Pharmacokinetics of Pharmaceuticals. Ann Pharmacother. 2019;53(2):211-216.

[2]. L-cysteine suppresses ghrelin and reduces appetite in rodents and humans. Int J Obes (Lond). 2015 Mar;39(3):447-55.

Cysteine is a sulfur-containing amino acid, a derivative of propionic acid, with an amino group at position 2 and a thiol group at position 3. It is an important metabolite. It is an α-amino acid, a polar amino acid, and a sulfur-containing amino acid. It contains a thiol methyl group. It is the conjugate base of cysteine. It is the conjugate acid of cysteine (1-). It is the zwitterion tautomer of cysteine. DL-cysteine has been reported in Drosophila melanogaster, white clover, and other organisms with relevant data. See also: Cysteine (note moved to). Therapeutic Uses /EXPL THER/ Acetaminophen-cysteine adduct (APAP-CYS) is a serum biomarker used to detect acetaminophen exposure. APAP-CYS adducts are formed when oxidative metabolites of acetaminophen bind to cysteine residues in liver proteins. In cases of acute liver failure caused by acetaminophen overdose, APAP-CYS adduct levels are elevated and have therefore been proposed as a diagnostic tool to identify acetaminophen-induced acute liver failure when standard test results are inconclusive. Lead is a toxic heavy metal that adversely affects neural tissue; it is commonly found as an environmental pollutant. We investigated histological changes in the cerebral cortex, hippocampus, and cerebellum of adult albino mice after exposure to lead acetate. We also investigated the potential ameliorative effect of the chelating agent L-cysteine on lead-induced neurotoxicity. We divided albino mice into six groups: 1) a control group injected with the solvent only; 2) an L-cysteine control group; 3 and 4) treated with 20 and 40 mg/kg lead acetate, respectively, for 7 days; and 5 and 6) treated with 20 and 40 mg/kg lead acetate, respectively, for 7 days, followed by 50 mg/kg L-cysteine for 7 days. Lead acetate administration resulted in cellular layer structural disorder, neuronal loss and degeneration, and neuropil vacuolation. Brain tissue sections from lead-poisoned mice treated with L-cysteine showed fewer pathological changes; reduced neuronal vacuolation and milder neuronal damage. At the doses we used, L-cysteine only slightly alleviated lead-induced toxicity. In hamster lung cell cultures, the addition of L-cysteine or vitamin C to the culture medium protected against or reversed abnormal growth and malignant transformation in aged controls (1-2 years) or young groups (3-6 months) following repeated exposure to tobacco or cannabis smoke. Oral or intraperitoneal administration of L-cysteine protected rats from acute toxicity of methylmercuric chloride, reduced mercury levels in the kidneys and brain, but had no effect on liver mercury levels. For more complete data on the therapeutic uses of cysteine (7 in total), please visit the HSDB record page. Pharmacodynamics: Due to its ability to undergo redox reactions, cysteine possesses antioxidant properties. Cysteine is an important source of sulfur in human metabolism. Although it is classified as a non-essential amino acid, it may be essential for infants, the elderly, and individuals with certain metabolic diseases or malabsorption syndromes. Cysteine may be recognized as an essential or conditionally essential amino acid in the future.

C3H715NO2S

122.15

122.016

204523-09-1

L-Cysteine;52-90-4

594

White to off-white solid powder

1.3±0.1 g/cm3

220 °C (dec.)(lit.)

1.550

0.028

3

4

2

7

75.3

0

XUJNEKJLAYXESH-UHFFFAOYSA-N

InChI=1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,5,6)

2-amino-3-sulfanylpropanoic acid

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Note: Please store this product in a sealed and protected environment (e.g. under nitrogen), avoid exposure to moisture and light.

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)