Dynamic Aspects of Enzymatic O-Methylation and -Demethylation of Catechols in Vitro and in Vivo

The importance of 0-methylation of catecholamines and other catechols as a metabolic pathway has been amply shown (l-4).The isolation of "Substanz Y," a p-O-methylcatechol derivative from beef adrenal glands (5), and the occurrence of p-o-methylcatechol derivatives in urine ( 6) are suggestive of p-o-methylation in viva.Previous studies ( 7) have shown that in vitro the enzyme 0-methyltransferase effects both pura and meta O-methylation.The following study demonstrates that (nor)epinephrine is converted to p-O-methyl-(nor)epinephrine in vitro and that 3,4dihydroxyacetophenone, arterenone, and adrenalone undergo p-O-methylation in the intact rat.The para and meta 0-methylated derivatives of 3,4-dihydroxyacetophenone (acetoisovanillone and acetovanillone) have been shown to undergo a novel interconversion in vivo.