title: Metabolism of prednisolone by the isolated perfused human placental lobule.
abstract: Previous studies of the metabolism of 11 beta-hydroxy corticosteroids by placental tissue have indicated that the only product is the C11-oxidized metabolite. In the present study we have re-examined the metabolism of prednisolone in the isolated, perfused, dual recirculating human placental lobule, using a perfusate based on tissue culture medium 199. Four metabolites were identified in both the maternal and fetal compartments in 6 h perfusions by comparison of relative retention times measured by HPLC and capillary gas chromatography (GC) and of mass spectra recorded by capillary gas chromatography-mass spectrometry (GC-MS) with those of authentic reference standards. The steroids were derivatized as the MO-TMS ethers for mass spectral measurements. Analysis of samples from five perfusion experiments resulted in the following percentage conversions after 6 h perfusion (mean +/- SD, maternal and fetal perfusate, respectively): prednisone (49.1 +/- 7.8, 49.1 +/- 6.6), 20 alpha-dihydroprednisone (0.84 +/- 0.29, 0.81 +/- 0.35), 20 beta-dihydroprednisone (39.1 +/- 6.7, 39.2 +/- 5.9), 20 beta-dihydroprednisolone (6.8 +/- 2.7, 6.3 +/- 1.6) and unmetabolized prednisolone (4.1 +/- 1.8, 4.6 +/- 2.1). No evidence was found for metabolites formed by 6 beta-hydroxylation or cleavage of the C17-C20 bond.
authors.affiliation: Conjoint Internal Medicine Laboratory, Royal Brisbane Hospital, Australia.
authors.forename: R S
authors.initials: RS
authors.lastname: Addison
authors.forename: D J
authors.initials: DJ
authors.lastname: Maguire
authors.forename: R H
authors.initials: RH
authors.lastname: Mortimer
authors.forename: G R
authors.initials: GR
authors.lastname: Cannell
mesh_terms: D002849:Chromatography, Gas; D002851:Chromatography, High Pressure Liquid; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D066298:In Vitro Techniques; D008431:Maternal-Fetal Exchange; D010477:Perfusion; D010920:Placenta / Q000378:metabolism*; D011239:Prednisolone / Q000378:metabolism*; D011247:Pregnancy
chemical_list: D011239:Prednisolone