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|Section2= |Section3= }} ''N''-Methyltyramine (NMT), also known as 4-hydroxy-''N''-methylphenethylamine, is a human trace amine neurotransmitter and natural phenethylamine alkaloid found in a variety of plants.〔T. A. Smith (1977). "Phenethylamine and related compounds in plants." ''Phytochem.'' 16 9 – 18.〕 As the name implies, it is the N-methyl analog or derivative of the well-known biogenic amine, tyramine, with which it shares many pharmacological properties (see below). Biosynthetically, NMT is produced by the N-methylation of tyramine via the action of the enzyme tyramine ''N''-methyltransferase.〔(Tyrosine metabolism - Reference pathway ), Kyoto Encyclopedia of Genes and Genomes (KEGG)〕 ==Occurrence== N-methyltyramine seems to be quite widely distributed in plants.〔〔T. A. Stewart and I. Stewart (1970) ''Lloydia'' 33 244-254.〕 NMT was isolated as a natural product for the first time, from germinating barley roots, by Kirkwood and Marion in 1950. These chemists found that 600 g of barley, after germination and 10-day growth, yielded 168 mg of N-methyltyramine.〔S. Kirkwood and L. Marion (1950) ''J. Am. Chem. Soc.'' 72 2522-2524.〕 Since barley, via its conversion to malt, is used extensively in the production of beer, beer and malt have been examined by several groups of investigators for the presence of NMT. Citing a 1965 study by McFarlane,〔W. D. McFarlane (1965). "Tyrosine derived amines and phenols in wort and beer." ''Proc. Europ. Brew. Conv.'' 387.〕 Poocharoen reported that beer contained ~ 5–8 mg/L of NMT.〔B. Poocharoen (1983), Ph. D. Thesis, Oregon State University. http://ir.library.oregonstate.edu/xmlui/handle/1957/27227〕 The NMT content of various malts and malt fractions was extensively studied by Poocharoen himself, who also provided a good coverage of related literature up to 1983. This researcher found a mean concentration of NMT in raw barley〔The level of NMT in ungerminated barley is generally negligible, but rises as germination (the first part of the "malting" process) proceeds.〕 of ~ 5 μg/g; in green malts (i.e. barley that had been soaked in water for 2 days then germinated for 4 days), the mean concentration was ~ 21 μg/g, and in kilned malts (i.e. green malts that had been heated in a kiln for 1–2 days) the mean concentration was ~ 27 μg/g. When only green malt roots were examined, their mean content of NMT was ~ 1530 μg/g, whereas the mean level in kilned malt roots was ~ 1960 μg/g.〔 Studies of ''Acacia'' species have shown the presence of significant levels of NMT in their leaves: ~ 240-1240 ppm (or μg/g) in ''A. rigidula''〔B. A. Clement, C. M. Goff and T. D. A. Forbes (1998). "Toxic amines and alkaloids from ''Acacia rigidula''." ''Phytochem.'' 49 1377-1380.〕 and ~ 190-750 ppm in ''A. berlandieri''.〔B. A. Clement, C. M. Goff and T. D. A. Forbes (1997) ''Phytochem.'' 46 249-254.〕 The seeds of ''A. schweinfurthii'' yielded 440 μg/g of NMT.〔C. S. Evans, E. A. Bell and E. S. Johnson (1979) ''Phytochem.'' 18 2022-2023.〕 NMT is found in bitter orange, ''Citrus aurantium'', and a concentration of ~ 180 μg/g has been reported from an extract made from the ripe fruit, although the method by which this extract was prepared is not very clearly described.〔B. C. Nelson et al. (2007) ''J. Agric. Fd. Chem.'' 55 9769-9775.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「N-Methyltyramine」の詳細全文を読む スポンサード リンク
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