L-Cysteine hydrochloride hydrate (L-Cysteine hydrochloride monohydrate) is a conditionally essential amino acid, which acts as a precursor for biologically active molecules such as hydrogen sulphide (H2S), taurine and glutathione. L-Cysteine hydrochloride hydrate suppresses ghrelin and reduces appetite in rodents and humans.

L-Cysteine (L-(+)-Cysteine) is a non-essential sulfur-containing amino acid in humans. L-Cysteine is important for protein synthesis, detoxification, and diverse metabolic functions. Found in beta-keratin, the main protein in nails, skin, and hair, L-Cysteine is important in collagen production, as well as skin elasticity and texture. Also required in the manufacture of amino acid taurine, L-Cysteine is a component of the antioxidant glutathione, and plays a role in the metabolism of essential biochemicals such as coenzyme A, heparin, and biotin.

L-Cysteine S-sulfate (S-Sulfo-L-cysteine) is an effective N-methyl-d-aspartate (NMDA) glutamatergic receptors agonist. L-Cysteine S-sulfate is the substrate for cystine lyase [1].

Acetylcysteine (NAC) is an N-acetyl derivative of cysteine, a ROS inhibitor and mucolytic agent. Acetylcysteine induces apoptosis, can be used to reduce mucus thickness, and has anti-influenza viral activity.

S-allyl-L-cysteine (S-Allylcysteine), a natural constituent of fresh garlic, has antioxidant and anticancer properties in animals.

γ-L-Glutamyl-S-allyl-L-cysteine is an organosulfur compound naturally present in garlic [1].

L-Deoxyalliin , also known as S-allyl-L-cysteine, is a water soluble organosulfur compound derived from garlic that has neuroprotective and antioxidative activities. N-Acetyl-S-allyl-L-cysteine is a principal metabolite of L-deoxyalliin in humans, mice, rats, and dogs. It is readily detected in plasma and urine. The conversion of L-deoxyalliin to N-acetyl-S-allyl-L-cysteine appears to be mediated by a family of flavin-containing monooxygenases.

Penicillamine (Artamine), possessing antineoplastic properties, induces apoptosis by a p53-mediated mechanism and inhibits angiogenesis by chelating with copper, a cofactor for angiogenesis. Artamine is a beta dimethyl analog of the amino acid cysteine. As a degradation product of penicillin antibiotics, Artamine chelates with heavy metals and increases their urinary excretion.

S-(2-Carboxypropyl)cysteine is a urinary metabolite of S-(2-Carboxypropyl)glutathione.

1-PeCSO is isolated from onion or garlic bulbs. It acts as a key compound in garlic greening and reacts with lachrymatory factor synthase.

L-Cysteine hydrochloride (L-Cysteine HCl) is a conditionally essential amino acid,L-Cysteine hydrochloride suppresses ghrelin and reduces appetite in rodents and humans

S-1-Propenyl-L-cysteine, a stereoisomer of S-allyl-l-cysteine, exhibits immunomodulatory effects and has been shown to decrease blood pressure in hypertensive animal models.

γ-Glutamyl-S-1-propenyl cysteine is a compound isolated from garlic.

D-Cysteine is the D-isomer of cysteine and a powerful inhibitor of the growth of E. coli. D-cysteine is mediated by D-amino acid oxidase to produce H2S, and is a neuroprotective agent against cerebellar ataxia. D-cysteine can inhibit the growth and cariog

γ-Glutamyl-S-allylcysteine (L-γ-Glutamyl-(S)-Allyl-Cysteine) is a γ-glutamyl peptide extracted from Allium sativum L. γ-Glutamyl-S-allylcysteine possesses anti-glycation and antioxidant activities, and can inhibit the cholesterol biosynthesis.

S-Methyl-L-cysteine (S-Methylcysteine) is a natural product that acts as a substrate in the catalytic antioxidant system mediated by methionine sulfoxide reductase A (MSRA), with neuroprotective, antioxidative, and anti-obesity activities.

(R)-1-PeCSO, also known as trans-(+)-S-1-Propenyl-L-cysteine sulfoxide, constitutes the primary flavor precursor in onions [1].

Papain is a cysteine protease of the peptidase C1 family. Papain is used in food, pharmaceutical, textile, and cosmetic industries.

DL-Homocysteine thiolactone hydrochloride (DL-Homocysteinethiolactone hydrochloride) is a cysteine derivative that binds to and induces conformational changes in various plasma proteins, slowing coagulation and inducing oxidative stress. It decreases left ventricular systolic blood pressure and cardiac force and induces seizures in vivo.

Levomefolic Acid (5-MTHF) is a natural, active form of folic acid used at the cellular level for DNA reproduction, the cysteine cycle and the regulation of homocysteine among other functions. Levomefolinic acid is used as a treatment and to prevent Folate Deficiency

L-Cystine (Cystine Acid) is not considered one of the 20 amino acids, L-Cystine (Cystine Acid) is a sulfur-containing derivative obtained from oxidation of cysteine amino acid thiol side chains. It functions as an antioxidant and protects tissues against radiation and pollution, slowing the aging process. It also aids protein synthesis. L-Cystine (Cystine Acid) is abundant in many proteins of skeletal tissues and skin, and found in insulin and digestive enzymes chromotrypsinogen A, papain, and trypsinogen.

N-acetyl-L-methionine is nutritionally and metabolically equivalent to L-methionine. Methionine is a dietary indispensable amino acid required for normal growth and development of humans, other mammals, and avian species. In addition to being a substrate

DL-Homocysteine (2-Amino-4-mercaptobutyric acid) is a potential marker for tumor cell growth. increased plasma homocysteine is a risk factor for coronary heart disease and carcinogenesis.

Gamma-glutamylcysteine is a natural product for research related to life sciences. The catalog number is T38024 and the CAS number is 636-58-8.

L-Cysteinesulfinic acid is a potent agonist at several rat metabotropic glutamate receptors (mGluRs, pEC50s of 3.92±0.03, 4.6±0.2, 3.9±0.2, 2.7±0.2, 4.0±0.2, and 3.94±0.08 for mGluR1, mGluR5, mGluR2, mGluR4, mGluR6, and mGluR8, respectively).

Se-Methylselenocysteine (Se-MSC) is a potent chemopreventive agent in many test systems and has been shown to inhibit tumor promotion and induce apoptosis.

L-Homocysteine, an L-configured homocysteine metabolite, induces the upregulation of cathepsin V, which mediates vascular endothelial inflammation in hyperhomocysteinaemia.

Vitedoin A shows stronger antioxidative activity than alpha-tocopherol using the ferric thiocyanate method, it also shows higher radical-scavenging effect on the stable free radical, 1,1-diphenyl-2-picrylhydrazyl, than L-cysteine.

Helenalin is a selective inhibitor of transcription factor NF-κB by direct targeting of p65. It is an anti-inflammatory sesquiterpene lactone compound with alkylating activity. Through its ability to target the cysteine sulfhydryl groups in the p65 subunit of NF-κB, helenalin effectively inhibits its DNA binding.

L-Cysteic acid monohydrate (3-Sulfo-L-alanine Monohydrate) is an oxidation product of L-cysteine that may be used as a competitive inhibitor of the bacterial aspartate: alanine antiporter (AspT) exchange of aspartate and in other aspartate biological systems. L-Cysteic acid monohydrate is used in monomeric surfactant development. L-Cysteic acid monohydrate may be used in studies of excitatory amino acids in the brain, such as those that bind to cysteine sulfinic acid receptors. It is a useful agonist at several rat metabotropic glutamate receptors (mGluRs).

4,4'-Disulfanediylbis(2-aminobutanoic acid) (DL-Homocystine) is the double-bonded form of homocysteine, but it occurs only transiently before being converted to the harmless cystathionine via a vitamin B6-dependent enzyme. Homocystine and homocysteine-cysteine mixed disulfide account for >98% of total homocysteine in plasma from healthy individuals.

6,6′-Dihydroxythiobinupharidine, a cysteine proteases inhibitor, amplifies DNA cleavage facilitated by human topoisomerase IIα and IIβ by approximately 8-fold and 3-fold, respectively [1] [2].

Saikosaponin A has a variety of pharmacological benefits, including antiepileptic, anti-osteoporosis, antioxidant, anti-in ammatory, immunomodulatory, and anti-bacterial activities. It can effectively attenuate neuropathic pain in CCI rats by inhibiting the activation of p38 MAPK and NF-κB signaling pathways in spinal cord. It can inhibit NMDA receptor current and persistent sodium current, and inhibit the TNF-α level, the IL-1β production, and cysteine-aspartic acid protease (caspase)-1 activity.

SAH (SAH (S-Adenosylhomocysteine)) is an inhibitor for the METTL3-METTL14 heterodimer complex (METTL3-14, IC50: 0.9 μM).

Hypotaurine (2-Aminoethanesulfinic acid), functioning as an intermediate in the biosynthesis of taurine from cysteine within astrocytes, acts as an endogenous inhibitory amino acid targeting the glycine receptor.

O-Acetylserine (O-Acetyl-L-serine) (O-Acetyl-L-serine) is an intermediate in the biosynthesis of the cysteine in bacteria and plants.

Coenzyme A is an obligatory cofactor in all living cells synthesized from pantothenate (Vitamin B5), adenosine triphosphate (ATP), and cysteine.

Diaminopimelic acid or DAPA is a lysine-like amino acid derivative that is a key component of the bacterial cell wall. DAPA is incorporated or integrated into peptidoglycan of gram negative bacteria and is the attachment point for Braun's lipoprotein (BLP or Murein Lipoprotein). BLP is found in gram-negative cell walls and is one of the most abundant membrane proteins. BLP is bound at its C-terminal end (a lysine) by a covalent bond to the peptidoglycan layer (specifically to diaminopimelic acid molecules) and is embedded in the outer membrane by its hydrophobic head (a cysteine with lipids attached). BLP tightly links the two layers and provides structural integrity to the bacterial outer membrane. Diaminopimelic acid can be found in human urine or feces due to the lysis or enzymatic breakdown of gram negative gut microbes.

Pyridoxal 5'-phosphate hydrate (PLP)(1:x), the active form of vitamin B6, is a cofactor for many different enzymes involved in transamination reactions, including mitochondrial cysteine desulfurase, cystathionine γ-synthase, various aminotransferases, and a d-serine dehydratase.

Indolokine A5, a catabolite of L-cysteine, is a potent AhR agonist .

3-Methylhistidine belongs to the class of organic compounds known as histidine and derivatives. Histidine and derivatives are compounds containing cysteine or a derivative thereof resulting from reaction of cysteine at the amino group or the carboxy group

O-Acetylserine (OASS) is an acylated amino acid derivative. It is an intermediate in the biosynthesis of the common amino acid cysteine in bacteria and plants. Its presence in humans arises from either microbial metabolism in the gut or through consumptio