Cysteamine

Description

Cysteamine, also known as 2-aminoethanethiol, is a chemical compound with the formula HSCH₂CH₂NH₂. It is the simplest stable aminothiol and a degradation product of the amino acid cysteine. It is often used as the hydrochloride salt, HSCH2CH2NH3Cl. The comparatively high melting point of cysteamine (95-97 °C), indicates that exists in a salt form.

Chemical Properties

2-Aminoethanethiol is a white to pale yellow solid powder with a melting point of 99–100°C. It is readily soluble in water and alcohols, exhibits an alkaline reaction, and readily oxidises to form disulphides in air. The free base is highly unstable and is generally formulated as the hydrochloride salt [156-57-0].

Uses

2-Aminoethanethiol is used in preparation method of fluorescence quenching array sensor based on cadmium telluride quantum dots and application in qualitative discrimination and quantitative analysis of organic acids.

Application

Cysteamine is suitable for use:

• in the preparation of cysteamine modified gold nanoparticles (AuNP)
• in the fabrication of SU-8 microrods, where in, the amine group of cysteamine reacts with the unreacted epoxide rings present on the surface of the particles, thereby opening it and forming a covalent bond
• to enhance in vitro development of porcine oocytes matured and fertilized in vitro
• in a study to demonstrate the depletion effect of cysteamine on cystinotic leucocyte granular fractions of cystine by disulphide interchange
• as a radioprotector
• to administer subcutaneously in rats to study its blocking effect on somatostatin secretion without modifying the pancreatic insulin or glucagon content
• as a scavenger in electrophoretic gels (acetic acid/urea gels)
• Scavenges benzyl and allyl halides and ketones.

Definition

2-AMINOETHANETHIOL is an amine that consists of an ethane skeleton substituted with a thiol group at C-1 and an amino group at C-2. It is an antihyperlipidemic and HMG-CoA reductase inhibitor.

Preparation

Cysteamine can also be prepared by the reaction of ethylenimine with hydrogen sulfide.
(NHCH₂CH₂) + H₂S → HSCH₂CH₂NH₂.

Reactions

2-AMINOETHANETHIOL is used as the hydrochloride salt, as it readily oxidizes to the corresponding disulfide, in the presence of air. The amine portion of the molecule serves as a catalyst for this reaction.
4 HSCH₂CH₂NH₂ + O₂ → 2 NH₂CH₂CH₂SSCH₂CH₂NH₂ + 2 H₂O.

benefits

Cysteamine is a potent inhibitor of dopamine-β-hydroxylase, leading to dopamine accumulation. Within the hypothalamus, dopamine strongly promotes the synthesis and secretion of growth hormone (GH). The active ingredient contained within exerts physiological regulatory effects, including improving the body's nutrient absorption and conversion, accelerating the growth rate of livestock and poultry, reducing body fat deposition, inhibiting protein degradation, and promoting protein synthesis.

reaction suitability

reaction type: solution phase peptide synthesis
reagent type: catalyst
reagent type: chelator

Pharmaceutical Applications

Under the trade name Cystagon, cysteamine is used in the treatment of disorders of cystine excretion. Cysteamine cleaves the disulfide bond with cystine to produce molecules that can escape the metabolic defect in cystinosis and cystinuria.
It is also used for treatment of radiation sickness.
Cysteamine is used in the body to form the essential biochemical coenzyme A by combining with pantothenate and adenosine triphosphate.
In 2008, Raptor Pharmaceuticals started phase II clinical trials testing a delayed release (DR) preparation of cysteamine bitartrate for Huntington's disease. DR Cysteamine is also being investigated as a treatment for cystinosis, Batten disease, and non-alcoholic steatohepatitis.

Biochem/physiol Actions

Cysteamine (β-mercaptoethylamine) depletes cystine from patient′s cells and there by regulates renal glomerular function and increases growth in them. Therefore, cysteamine is considered to be a potential therapeutic for nephropathic cystinosis.

Safety Profile

Poison by intravenous, subcutaneous, and intraperitoneal routesModerately toxic by ingestion. Experimental reproductive effects. Mutation data reported. When heated to decomposition it emits very toxic fumes of SO, and NOx,.

Purification Methods

It is soluble in H2O giving an alkaline reaction, and it has a disagreeable odour. A likely impurity is the disulfide cystamine which is not soluble in alkaline solution. Under a N2 atmosphere dissolve it in EtOH, evaporate to dryness and wash the white residue with dry pet ether, then sublime it at 0.1mm and store it under N2 at 0-10o in the dark. Its HgCl2 (2:3) complex has m 181-182o (from H2O), and its picrate has m 125-126o. [Mills & Bogert J Am Chem Soc 57 2328 1935, 62 1173 1940, Baddiley & Thain J Chem Soc 800 1952, Shirley Preparation of Organic Intermediates (J. Wiley) Vol 3 189 1951, Barkowski & Hedberg J Am Chem Soc 109 6989 1987, Beilstein 4 IV 1570.]