Stereoselective and manganese-dependent sulfation and urinary excretion of d-form and l-form meta-tyrosine O-sulfate by Sprague–Dawley rats

In our previous studies, we have demonstrated the stereoselective and manganese-dependent sulfation of tyrosine and Dopa isomers by human monoamine (M)-form phenol sulfotransferase (PST). In the present study, we investigated the occurrence of these phenomena in vivo using Sprague–Dawley rats as an experimental model. Three groups of six male rats were orally introduced with 1 ml of, respectively, 3 mM, 10 mM and 30 mM MnCl2 with a constant level of 0.2 mM dl-m-tyrosine per day for 7 days. Their urine was collected and analyzed for the presence of sulfated dl-m-tyrosine (dl-m-TyrS) by ion-pair HPLC using a C18 reversed-phase column. The level of urinary dl-m-TyrS, which was detected in the urine of the MnCl2-treated rats but not control rats, appeared to increase proportionally to the amount of MnCl2 administered. Chiral HPLC was employed to differentiate the d-form and l-form m-TyrS present in the urine sample of MnCl2-treated rats. Both d-m-TyrS and l-m-TyrS were detected, with the d-form being present at significantly higher level than the l-form.