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S-adenosylmethionine (SAMe)

S-adenosylmethionine (SAMe, or SAM) is a naturally occurring molecule found in all living organisms including yeast, vegetable and all animal species. SAMe is a significant physiologic compound that is present throughout body tissue and that takes part in a number of biologic reactions as a methyl group donor or an enzymatic activator during the synthesis and metabolism of hormones, neurotransmitters, nucleic acids, phospholipids, and proteins. It is naturally formed in the body from ATP and methionine. SAMe is synthesized in the body from methionine and adenosine triphosphate (ATP) in a reaction catalyzed by ATP-methionine S-adenosyl transferase. SAMe is distributed throughout virtually all body tissues where it acts as a substrate in many biological reactions involving enzymatic transmethylation. S-adenosylmethionine is active in more than forty biological reactions in vivo. S-adenosylmethionine also operates in association with folic acid and vitamin B-12 as a methylating agent, and is essential for the formation of many sulfur-containing compounds in the body, including glutathione and various components of cartilaginous connective tissue. SAMe is an extremely important reactant in many biochemical reactions including transmethylation, transsulfation, and synthesis of amines. S-Adenosyl-L-methionine plays a pivotal role in the physiology of all cells, both as methyl donor in myriad of biological and biochemical events and as a precursor of polyamines. In higher organisms, SAMe plays a significant role in transmethylation processes in more than 40 anabolic or catabolic reactions involving the transfer of the methyl group of S-adenosylmethionine to substrates such as nucleic acids, proteins and lipids, among others. The SAMe molecule is a carrier of methyl groups and provides a sulfur molecule as well. The liver is a site of methylation and sulfation reactions necessary for detoxification, and can use SAMe to assist in these processes. SAMe is also a cofactor in several metabolic reactions. By donating its methyl group, SAMe is converted to adenosylhomocysteine which, in turn, is rapidly hydrolysed to adenosine and homocysteine and eventually to the amino acid, cysteine. S-adenosylmethionine is known to show a variety of actions, i.e. inhibition of neuronal death following ischemia, improvement of cerebral glucose utility, inhibition of brain edema, improvement of EEG, improvement of evoked potential, ameliorative action on motor function, and therefore reported to be important as a cure for stroke. S-adenosylmethionine participates in a great number of metabolic processes of fundamental importance for human organism, and consequently its deficiency lies at the basis of many organic malfunctions. SAM has been used to treat various disorders. In various forms of liver disease, SAM acts as an anticholestatic agent. S-adenosylmethionine is necessary for the production of Glutathione, the primary antioxidant found in the liver. SAMe and its products, including glutathione, are of great importance in the prevention of liver damage. The changes produced by ethanol (EtOH) in the liver provide examples of injuries that can occur in the liver on the cellular level and help explain the mechanism of action by which SAMe counteracts these injuries. SAMe also protects liver cells indirectly via its antioxidant products cysteine and glutathione, which help prevent damage by the excessive free radicals produced during alcohol intoxication. SAM has also been administered as an antidepressant for use in the management of psychiatric disorders, and as an anti-inflammatory compound in the management of osteoarthritis. S-adenosylmethionine is now widely distributed as an over-the-counter dietary supplement.

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