3.4- Dihydroxyphenylethylamin

Dopamine (3 4 dihydroxyphenylethylamine), like noradrenaline and adrenaline, is a eateeholamine and in addition to its independent neurotransmitter role in the CNS it is a preeursor to noradrenaline (NA) in all central and peripheral noradrenegic neurons. 

This enzyme rapidly deaminates certain primary and secondary unsubstituted p-hy-droxy- and 3,4-dihydroxyphenylethylamines wherein the amino group is on the terminal carbon atom of the side chain (4,18, 22,40,128). 

Westerink BH, Tuinte MH (1986) Chronic use of intracerebral dialysis for the in vivo measurement of 3,4-dihydroxyphenylethylamine and its metabolite 3,4-dihydroxy-phenylacetic acid. J Neurochem 46 181-185. 

The conversion of tyrosine to 3,4-dihydroxyphenylalanine occurs both in vivo in man (590) and in vitro by the action of tissue tyrosinase (205, 688). Mammals can decarboxylate both tyrosine (402,407) and dihydroxyphenyl-alanine (406), tyrosine decarboxylase and dihydroxyphenylalanine (dopa) decarboxylases being quite distinct and separable (405), though both are dependent on pyridoxal phosphate (73, 758, and review 72). In mammals dihydroxyphenylalanine is the most readily decarboxylated of all amino acids, and it is therefore not unreasonable to assume that this is the substrate normally decarboxylated in adrenaline biosynthesis cf. 74, 75). Support for this concept derives from the fact that both the substrate and the product of the reaction (3,4-dihydroxyphenylethylamine diagram 11) can or do occur in the adrenal (298, 299, 802), and the amine is moreover, like adrenaline and noradrenaline, a normal urinary excretion product (245, 404). 

The relation of many of the simpler alkaloids to the aromatic amino acids is obvious. For example, germinating barley contains (241), besides tyrosine and tyramine, A -methyltyramine, JViV -dimethyltyramine (hordenine), and the trimethylammonium derivative (candicine). In this simple case the. AT-methylated derivatives are known to be derivable from isotopically labeled tyramine (538) and the methyl groups are known to arise from methionine by transmethylation (540, 586). Similarly AT-methyl derivatives of phenylethylamine, 3,4-dihydroxyphenylethylamine, and 3,4,5-trihy-droxyphenylethylamine are well known alkaloids (cf. review, 701). N-Methylated derivatives of tryptamine and hydroxytryptamine equally occur for example, eserine has an obvious relation to 5-hydroxy tryptamine. Methylated derivatives of metabolites of the aromatic amino acids also occur, for example, trigonelline (67), which is the betaine of nicotinic acid, and damascenine is probably similarly related to hydroxyanthranilic acid. 

DA (3,4-dihydroxyphenylethylamine Table 10-1) is the metabolic precursor of NE and Epi it is a central neurotransmitter particularly important in the regulation of movement see Chapters 12, 18, and 20). In the periphery, DA is synthesized in epithelial cells of the proximal tubule and is thought to exert local diuretic and natriuretic effects. DA is a substrate for both MAO and COMT and thus is ineffective when administered orally. Classification of DA receptors is described in Chapters 12 and 20. 

Biomimetic Syntheses of 5,6-Dihydroxyindoles 1 and 2, and Related Derivatives Based on Oxidative Cyclization of 3,4-Dihydroxyphenylethylamines... 

Biomimetic-type syntheses of indoles 1 and 2 are analogous to the early stages of melanogenesis in which a 3,4-dihydroxyphenylethylamine is oxidized to the corresponding ort/zo-quinone. The latter undergoes intramolecular cyclization to give an aminochrome intermediate which is converted into the indole product (Scheme 14). 

Friedman S, Kaufman S (1965) 3,4-Dihydroxyphenylethylamine /3-Hydroxylase. Physical Properties, Copper Content, and Role of Copper in the Catalytic Activity. J Biol Chem 240 4763... 

Alkaloids possessing the 1-benzylisoquinoline skeleton are biosynthesized from two molecules of tyrosine, which are differentiated at the beginning of the biosynthetic pathway. Namely, the isoquinoline moiety, except for one carbon, originates from 3, 4 -dihydroxyphenylethylamine (dopamine), which is formed from tyramine following the decarboxylation of tyrosine. The other part of the alkaloid is derived from 4 -hydroxyphenylac-etaldehyde, which is formed from tyrosine via 4 -hydroxyphenyl pyruvic acid. These two compounds are coupled stereoselectively to give (S)-norcoclaurine. (S)-Norcoclaurine is transformed into (S)-coclaurine by 6-O-methylation, and further N-methylation, hydroxylation at the... 

A third major group, including emetine and a series of structurally related alkaloids, involves condensation of the same amine precursor (3,4-dihydroxyphenylethylamine or dopamine) with a carbonyl group from secologanin—an iri-doid monoterpene precursor. Most of these compounds have been isolated from two families, the Rubiaceae and the Alan-giaceae. 

Isoquinoline alkaloids are derived from tyrosine through the intermediacy of 3,4-dihydroxyphenylethylamine (dopamine) and a carbonyl unit of various origins. The genesis of tyramine, and dopamine from tyrosine has been described previously (see Chapter 28). In contrast to benzylisoquinoline alkaloids (see below), the formation of isoquinoline alkaloids usually involves the amine and an a-ketoacid instead of an amine and aldehyde. However, several compounds can... 

The order of methoxylation and oxidation steps varies. In some instances, the 3,4-dihydroxyphenylethylamine (dopamine) precursor may be modified before condensation occurs. Despite their structural similarity, pellotine (2) and anhalamine (1) are probably synthesized along distinct pathways from mescaline (4). All three alkaloids co-occur in Lophophora williamsii. 

The similar treatment in the presence of chlorogenic acid produced the modified chitosan soluble imder both acidic and basic conditions (311). On the other hand, the tyrosinase-catalyzed reaction of 3,4-dihydroxyphenylethylamine (dopamine) provided water-resistant adhesive properties to chitosan (312). A chitosan derivative modified with hydroxy or dihydroxybenzaldehyde was cross-linked by tyrosinase to give stable and self-sustaining gels (313). Phenolic moiety of a synthetic polymer, poly(p-hydroxystyrene), was also subjected to tyrosinase-catalyzed oxidation (314). 

Cervantes Cianca RC, Faro LR, Duran BR, Alfonso PM (2011) Alterations of 3,4-dihydroxyphenylethylamine and its metabolite 3,4-dihydroxyphenylacetic produced in rat brain tissues after systemic administration of saxitoxin. Neurochem Int 59 643-647. doi 10.1016/j.neuint.2011.06.005... 

Similar rheomelanins are formed in human plasma [319] and whole blood [320] from 3,4-dihydroxyphenylethylamines other than adrenaline. Haemolysis was also associated with the formation of these rheomelanins [320]. Once again erythrocytes from schizophrenic patients were more susceptible to the haemolytic effects of these rheomelanins [320a]. Recently, Altschule and Nayak have described the presence of an adrenaline-cyclising enzyme in human serum [300], but they reported, however, that its activity was not increased in serum from schizophrenic patients [3(X)]. 

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