Inhibition of catechol-O-methyltransferase by hydroxybenzenes and related compounds.

The inhibitory action of 1, 2, 3-trihydroxybenzene (pyrogallol) on the activity of catechol-O-methyltransferase (COMT) is well known (1-4). Recently, 1, 3, 5,-trihydroxy benezene (phloroglucinol) and 2, 4, 6-trihydroxy-l-propiophenom~ (THPP) have been shown to exert spasmolytic action in experimental animals and to relieve spastic disorders of the urinary tract and biliary ducts in patients (5-10). Comparing the relative effects of trihydroxybenzenes on the smooth muscle organs, Inoue and associates (11-13) have found that these compounds possess catecholamine-like actions and potentiate the effect of catecholamines. Therefore, it is expected that phloroglucinol and THPP also inhibit the COMT activity. In the present experiments, the effects of phenol, phenolic ethanol amines, dihydroxybenzenes, trihydroxybenzenes and related compounds on the COMT activity of rat liver were studied in vitro.