Syntheses of the sulfoconjugated isomers of norepinephrine and dopamine, controlled by HPLC with ultraviolet detection.

The physiological significance of sulfoconjugated catecholamines and their involvement in clinical disorders, e.g. hypertension and Parkinsonism, is poorly investigated. For this reason, the sulfoconjugated isomers of dopamine as well as of norepinephrine were synthesized by modified methods. All isomers and their intermediates could be detected by a reversed-phase high-performance liquid chromatography with ultraviolet detection (HPLC-UV) with short retention times and a good reproducibility. Ion-exchange chromatography with an extended column length improved the separation of the reaction products, and the immediate control by HPLC-UV enabled precise cutting of the fractions. The selection of the fractions with the optimum ratios of product/by-product resulted in improved yields and highest purity. All by-products, e.g. dopamine sulfonic acids, were less than 0.04%, as detected by HPLC-UV and, in addition, the contamination by free catecholamines was only 41 x 10(-4)-87 x 10(-4)%, as measured by HPLC with electrochemical detection (HPLC-ED). The purity was further demonstrated in two highly sensitive biological assays: cAMP production in human mononuclear leukocytes and aggregation of human platelets. The sulfoconjugated catecholamines were characterized by melting point, thin-layer chromatography, infrared spectrum, HPLC-UV, elemental analysis, and unequivocally identified by 1H-NMR.