Enantio-selective occurrence of (S)-tetrahydropapaveroline in human brain

Tetrahydropapaveroline is an endogenous complex alkaloid derived from dopamine through the oxidation by monoamine oxidase. This alkaloid is considered to be involved in the pathogenesis of alcoholism and to act as a false neurotransmitter. Recently the (S) enantiomer was proposed to be a precursor of morphine biosynthesis in the opium poppy. In this paper stereo-chemical characteristic of tetrahydropapaveroline in human brains was examined. In all four control human brains examined, only the (S)-tetrahydropapaveroline was detected. The concentrations were 0.12-0.22 pmol/g wet weight of brain tissue, and the presence of alcohol in blood did not affect the concentration. The results suggest that (S)-tetrahydropapaveroline may be enantio-selectively synthesized in human brain and it may be an intermediate of the de novo synthesis of morphine analogues.