High-performance liquid chromatographic analysis of the sulfation of 4-hydroxypropranolol enantiomers by monkey liver cytosol

We developed a new high-performance liquid chromatographic method using an ODS column and a chiral column for the assay of racemic 4-OH-PL sulfate and enantiomeric 4-OH-PL sulfates, respectively. The method was successfully a pplied to measure phenolsulfotransferase (PST) activities for 4-OH-PL in cy tosolic fractions from livers of Japanese monkeys (Macaca fuscata) and for comparison with its activity of cytosolic fractions from rat, rabbit, dog, and human livers and Hep G2 cells. The activity was ranked as Hep G2 cells > monkeys = humans = dogs = rats > rabbits. To evaluate the Japanese monkey as a nonhuman animal model in drug metabolism studies, we further characte rized sulfation of 4-OH-PL as a further metabolic pathway in monkey livers to compare that with human livers. Inhibition studies in which cytosolic fr actions were preincubated at 43 degreesC or 2,6-dichloro-4-nitrophenol (DCN P) used as a PST inhibitor indicated that two kinds of PSTs, thermolabile, low-Km and DCNP-resistant PST and thermostable, high-Km and DCNP-sensitive PST were involved in 4-OH-PL sulfation by monkey liver cytosol, which is ve ry similar to the reported profile of COH-PL sulfation by human liver cytos ol. Sulfation kinetics in a low concentration range of 4-OH-PL enantiomers demonstrated that apparent Km values were similar between human and monkey liver cytosolic fractions, but the Vmax values were different, so that intr insic clearance values (Vmax/Km, CLint) were higher in monkeys than in huma ns. Furthermore, enantiomer selectivity of [R(+)-4-OH-PL > S(-)-4-OH-PL] wa s observed in the Vmax and CLint values of monkey liver cytosol. These resu lts indicate that the profile of sulfation of 4-OH-PL by liver cytosolic fr actions is similar in humans and Japanese monkeys. Chirality 13:140-147, 20 01. (C) 2001 Wiley-Liss, Inc.