Redox Status of Main Urinary Sulfur Amino Acids Evaluation by Liquid Chromatography

Abstract

Thiol redox status, defined as reduced-to-oxidized ratio, of main urinary aminothiols has been measured. Both forms of thiols were determined by liquid chromatography with ultraviolet detection. The analytes were derivatized with thiol-specific ultraviolet labeling reagent, 2-chloro-1-methylquinolinium tetrafluoroborate, separated chromatographically and detected at 355 nm. Oxidized forms were converted to their thiol counterparts by reductive cleavage with tris(2-carboxyethyl)phosphine hydrochloride prior to derivatization step. Redox status of cysteine and cysteinylglycine was determined in urine of 45 healthy volunteers distributed for age. There were no significant differences in cysteine redox status depending on the age (P > 0.05), whereas cysteinylglycine redox status was significantly lower in children than in adults (P < 0.01). Total cysteine and cysteinylglycine in urine, normalized on creatinine, were also studied. Excretion of these thiols showed a wide range of variation, however mean values were not significantly different (P > 0.05) between age groups.