Dopamine 3-O-sulphate, an end product of L-dopa metabolism in Parkinson patients

PREVIOUS studies from these laboratories 1 have shown that L-3,4-dihydroxyphenylalanine (L-dopa) does not undergo sulphoconjugation in vitro in the cytosol sulphating system of rat tissues whereas dopamine very readily yields a mixture of the 3- and 4-O-sulphates. These observations might therefore serve to explain earlier claims 2 that sulphoconjugated dopamine constituted a significant proportion of the amine fraction extractable from rat tissues following the administration of 14 C-labelled L-dopa and raises the question of the role of sulphoconjugation in dopamine metabolism. In man this may be of significance in L -dopa therapy in the treatment of Parkinson's disease since such conjugates might represent either intermediates or end products of metabolism.