Isolation and characterization of phenylethylamine and phenylethanolamine from human brain

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Abstract
The Presence 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 (Lovenberg, Weissbach and Udenfriend, 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 (Mantegazza and Riva, 1963). Using paper chromatography and electrophoresis, Nakajima, Kakimoto and Sano (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 (Mantegazza and Riva, 1963). These effects may in part be attributable to catecholamine release (Fuxe, Grobecker and Jonsson, 1967) and partly to a direct effect exerted by phenylethylamine itself (Fischer, Ludmer and Sabelli, 1967; Giardina, Pedemonte and Sabelli, 1972). The brain content of phenylethylamine in mice (Mosnaim and Sabelli, 1971), rabbits (Sabelli, Giardina, Mosnaim and Inwang, 1972) and rats (Fischer, Spatz, Heller and Reggiani, 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 (Fischer, Heller and Miró, 1968; Boulton and Milward, 1971; Inwang, Sugerman, Mosnaim and Sabelli, 1972; Fischeret 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. Molinoff, Landsberg and Axelrod (1969) have shown by enzymatic methods the formation of phenylethanolamine following the administration of phenylethylamine.