Biogenic amines catechol

Catecholamines are biogenic amines with a catechol (o-dihydroxy-benzol) structure. They are synthesized in nerve endings from tyrosine and include dopamine, noradrenaline (norepinephrine) and adrenaline (epinephrine). 

The use of HPLC to analyze biogenic amines and their acid metabolites is well documented. HPLC assays for classical biogenic amines such as norepinephrine (NE), epinephrine (E), dopamine (DA), and 5-hydroxytryptamine (5-HT, serotonin) and their acid metabolites are based on several physicochemical properties that include a catechol moiety (aryl 1,2-dihydroxy), basicity, easily oxidized nature, and/or native fluorescence characteristics (Anderson, 1985). Based on these characteristics, various types of detector systems can be employed to assay low concentrations of these analytes in various matrices such as plasma, urine, cerebrospinal fluid (CSE), tissue, and dialysate. 

The catecholamines are biogenic amines that have a catechol group. Their biosynthesis in the adrenal cortex and CNS starts from tyrosine. 

Epinephrine (see Figure 1) is synthesized in several steps from either phenylalanine or tyrosine (both amino acids). Two adjacent hydroxyl groups are placed on the aromatic ring, leading to the ring structure called catechol. These hydroxylations form the intermediate L-dopa, which in turn is converted to dopamine (a neurotransmitter), norepinephrine (also a neurotransmitter), and finally epinephrine. Epinephrine together with norepinephrine and dopamine make up the family of biogenic amines called catecholamines. 

Takadate, A., and Fishman, J., 6-Aminoalkyl catechol estrogens. Models of steroidal biogenic amines, J. Org. Chem., 44, 67, 1979. 

Figure 2-2 illustrates the irreversible inhibition of the flavine-enzyme monamine oxidase (MAO) by the antihypertensive agent pargyline. This enzyme is important in the catabolism of catechol- and other biogenic amines, including epinephrine and norepinephrine to their corresponding aldehydes. Equation 2.8 illustrates the oxidation of monamines by way of an imino intermediate while the oxidized flavine prosthetic group FAD is simultaneously reduced. 

The adrenal medulla forms part of the sympathetic nervous system and is the primary site for the production of the catecholamines—epinephrine (adrenaline) and norepinephrine (noradrenaline), which are primary hormones (also called biogenic amines). The cells of the medulla are arranged in lobules and the medulla contains chromaffin cells, which are modified postganglionic cells of the sympathetic nervous system. The medulla produces catecholamines from tyrosine and their structures contain catechol and amine groups (Figure 10.3.3). 

The enzyme catechol-0-methyl transferase (COMT, E.C. 2.1.1.6) catalyzes the transfer of an intact methyl group from S-adenosyl-methionine (SAM) to a catecholamine as shown in below. This is representative of a group of enzymes which methylate small molecules such as the biogenic amines, norepinephrine, histamine and 5-hydroxytryptamine (4). We have previously shown (5) by steady-... 

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