Isolation and characterization of phenylethylamine and phenylethanolamine from human brain

Abstract

T he P resence of endogenous 2‐phenylethylamine in mammalian tissues has long been suspected, in view of the fact that L‐phenylanine, a substrate for L‐aromatic amino acid decarboxylase (L ovenberg , W eissbach and U denfriend , 1962), is found in substantial amounts in many neural and non‐neural tissues. It has been difficult to demonstrate the presence of phenylethylamine in tissues of untreated animals because this amine is an excellent substrate for monoamine oxidase (M antegazza and R iva , 1963). Using paper chromatography and electrophoresis, N akajima , K akimoto and S ano (1964) tentatively identified phenylethylamine in many organs of animals pretreated with monoamine oxidase inhibitors. Phenylethylamine exerts, in animals pretreated with such inhibitors, behavioural stimulant effects similar to those induced by amphetamine (M antegazza and R iva , 1963). These effects may in part be attributable to catecholamine release (F uxe , G robecker and J onsson , 1967) and partly to a direct effect exerted by phenylethylamine itself (F ischer , L udmer and S abelli , 1967; G iardina , P edemonte and S abelli , 1972). The brain content of phenylethylamine in mice (M osnaim and S abelli , 1971), rabbits (S abelli , G iardina , M osnaim and I nwang , 1972) and rats (F ischer , S patz , H eller and R eggiani , 1972) is increased by antidepressive treatments (imipramine, monoamine oxidase inhibitors, electroshock) and reduced by reserpine. The urinary excretion of phenylethylamine is decreased in depressed patients (F ischer , H eller and M iró , 1968; B oulton and M ilward , 1971; I nwang , S ugerman , M osnaim and S abelli , 1972; F ischer et al. , 1972). However, the presence of phenylethylamine in brain has not yet been conclusively demonstrated because the analytical procedures used in the above‐mentioned investigations were not sufficiently specific. In the present study we isolated and identified, by a number of analytical procedures, phenylethylamine and its metabolite 2‐hydroxy‐2‐phenylethylamine (phenylethanolamine) from human brain. M olinoff , L andsberg and A xelrod (1969) have shown by enzymatic methods the formation of phenylethanolamine following the administration of phenylethylamine.