Sulfation of phenylephrine by the human cytosolic sulfotransferases.

Previous studies had demonstrated that sulfation constituted a major pathway for the metabolism of phenylephrine in vivo. The current study was designed to identify the major human SULT(s) responsible for the sulfation of phenylephrine. Of the twelve human SULTs analyzed, SULT1A3 displayed the strongest sulfating activity toward phenylephrine. The enzyme exhibited a pH optimum spanning 7 - 10.5. Kinetic analysis revealed that SULT1A3- mediated sulfation of phenylephrine occurred in the same order of magnitude compared with that previously reported for SULT1A3-mediated sulfation of dopamine. Moreover, sulfation of phenylephrine was shown to occur in HepG2 cells under metabolic setting. Collectively, these results provided useful information concerning the biochemical basis underlying the metabolism of phenylephrine in vivo as previously reported.