EFFECTS OF 1,3,5-TRIHYDROXYBENZENE AND 2,4,6-TRIHYDROXY-1-PROPIOPHENONE ON THE SMOOTH MUSCLE ORGANS

Abstract

Although 1, 2, 3-trihydroxybenzene (pyrogallol) is known to inhibit the activity of catechol-o-methyltransferase (COMT) (1, 2), its clinical application is limited because of toxic effects such as formation of methemoglobin and degeneration of the kidney and liver (3). Pyrogallol has been useful only as an experimental tool to modify the metabolic process of exogenous as well as endogenous catecholamines. The present experiments were facilitated by the facts that 1, 3, 5-trihydroxybenzene (phloroglucinol, THB) and 2, 4, 6-trihydroxy-l-propiophenone (THPP) showed the definite spasmolytic action in experimental animals (4, 5) and that these compounds relieved the spastic disorders of the urinary tract, bile duct and uterus in patients (6). Based on the experimental findings that the mode of spasmolytic action is neither atropine-like, anti-histamine-like, nor papaverine-like, Cahen (4) has suggested a direct musculotropic action of these compounds. Hattori et al. (7) have shown that trihydroxybenzenes inhibit slightly to markedly COMT activity in vitro. The acute, subacute and chronic toxicity tests of THB in experimental animals confirmed that it is of low toxicity and wide margin of safety (8). In the present experiments the pharmacodynamic effects of THB and THPP on the smooth muscle organs were tested taking into consideration whether the spasmolytic actions of trihydroxybenzenes are correlated with COMT inhibition and subsequent potentiation of the action of catecholamines.