Abstract

A method is described for the isolation and measurement of dopamine 3-O-sulfate and dopamine 4-O-sulfate. The sulfate isomers of dopamine were synthesized chemically by the reaction of dopamine with sulfuric acid. The isomers were isolated by anion-exchange column chromatography and the identities of the two isomers were confirmed by gas chromatography coupled with mass spectrometry. A method is described for the assay of the two isomers by high-pressure liquid chromatography. When Parkinsonian patients were treated with 4.0 g/day of L-dopa, the amount of dopamine 3-O-sulfate excreted in the urine was 19.6 times that of dopamine 4-O-sulfate. When untreated Parkinsonian patients received tracer quantities of 3H-L-dopa either intravenously or orally, 3H-dopamine 3-O-sulfate was the predominant isomer but the amounts were only 3 times those of the 4-isomer. Greater quantities of both isomers were excreted when 3H-L-dopa was given orally as compared to intravenous administration. Since dopamine 3-O-sulfate is the predominant sulfate isomer, it is concluded that sulfate conjugation of dopamine could possibly compete with 3-O-methylation in determining the resultant conjugated product.