Biogenic Amines and Their Metabolites as Substrates for Phenol Sulphotransferase (Ec 2.8.2.1) of Brain and Liver

Phenol sulphotransferase activity in homogenates of rat liver and brain was determined spectrophotometrically. Rat liver had about 100‐fold more phenol sulphotransferase activity than brain; however, both tissues showed about the same spectrum of activity towards the phenolic compounds tested. Dopamine and its acidic and neutral metabolites and the neutral metabolites of norepinephrine were the compounds most readily sulphury‐lated in vitro . They were also the compounds most readily sulphurylated in vivo when they were injected intraventricularly together with labelled Na 2 SO 4 . When labelled Na 2 SO 4 was injected alone, we detected conjugation of endogenous phenols. One of the compounds formed was identified by its chromatographic characteristics as 3‐methoxy‐4‐hydroxy‐phenylethyleneglycol sulphate. We detected other conjugates which appeared to be the sulphate esters of 3,4‐dihydroxyphenylethyleneglycol; 3,4‐dihydroxyphenylacetic acid; and homovanillic acid. In brain, sulphate conjugation may be a major route of metabolism for many of the phenolic compounds related to the biogenic amines and possibly for phenolic drugs which enter the brain.