Dynamic Aspects of Enzymatic 0-Methylation and -Demethylation of Catechols in Vitro and in Viva

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.