Catechol 3-methyltransferase inhibition mechanism

Adrenaline and noradrenaline are unstable in aqueous solution where they are subjected to spontaneous oxidation. In vivo this mechanism is only relevant under pathophysiological conditions of an catecholamine excess, since two enzymes, the catechol-O-methyltransferase (COMT) and the monoamineoxidase (MAO), inactivate physiological amounts of the transmitters. There are at least two subtypes of the enzyme MAO, A and B, which can be inhibited selectively for therapeutic purposes, for example by moclobemide and selegiline. 

Mechanism of Action An antiparkinson agent that inhibits the enzyme catechol-O-methyltransferase (COMT), potentiating dopamine activity and increasing the duration of action of levodopa. Therapeutic Effect Relieves signs and symptoms of Parkinson s disease. 

Garner, C. E. Matthews, H. B. Burka, L. T. Rhenolphthalein metabohte inhibits catechol-O-methyltransferase-mediated metabohsm of catechol estrogens a possible mechanism for carcinogenicity. Toxicol. Appl. Pharmacol. 2000,162,124—131. 

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