Methionine is a sulfur-containing amino acids. Methionine has lipotropic action as choline, because the methyl need be supplied by methionine when synthesize choline in vivo, and choline is a component for lecithin which is essential for transporting fatty out of liver and removing the depositional fatty of the liver. In addition, methionine supply sulfur to synthesize non-exogenous amino acid in vivo, while the latter has a detoxifying effect. Therefore this drug is used for the liver lipotropic in clinical medicine. This medicine applies with fatty liver and chronic hepatitis, cirrhosis accompanied with fatty infiltration of the liver. It still be clinically used as a poisoning adjuvant therapy of alcohol and sulfa.
The scientific name is methylthio butyric acid, one of the essential amino acids. It is a white flaky crystal or crystalline powder with a specific odor. The molecular weight is 149.21. The melting point of DL- methionine (racemic) is 281 ℃ (decomposition). The relative density is 1.340. DL- methionine is soluble in water, dilute acid and alkali, slightly soluble in 95% ethanol, and insoluble in ether. The melting point of L- methionine (L-body) is 280 ~ 281 ℃ (decomposition). L- methionine is soluble in hot water and dilute alcohol, insoluble in absolute ethanol, ethyl ether, petroleum ether, benzene and acetone. The melting point of D- methionine (D-body) is 273 ℃ (decomposition).D- methionine is soluble in water, dilute acid and alkali; very slightly soluble in alcohol, and insoluble in ether. Usually right-handed amino acids in biochemistry have low biological effects while methionine is an exception. D- methionine and L- methionine are effective accelerator which is due to the D- methionine can be converted into L- methionine in vivo. Therefore synthetic DL- methionine does not require separation and can be used directly. Methionine is an essential amino acid in animal body and a component for proteins. It can maintain the body's growth and nitrogen balance. It can not be synthesized in the body of animals and must be acquired in the form of amino acids or proteins from in vitro supply. It is an important feed additive (nutritional supplements).In the food sector, Methionine mainly make a complex flavor with glycine alanine valine glutamic acid and other amino acids. In medicine, it is a main component of amino acid infusion liquid and amino acid complex preparation. It is also used for prevention and treatment of liver disease and arsenic, benzene poisoning. It also act as a protein nutritional supplements for the patients who are lack of protein or absorb protein inadequately. These protein is derived from acrolein and methyl mercaptan synthesis. It may also be acquired by casein hydrolysis and purification.