title: Esterase activity in excised and reconstructed human skin--biotransformation of prednicarbate and the model dye fluorescein diacetate.
abstract: Reconstructed human epidermis (RHE) is used in non-animal testing for hazard analysis and reconstructed human skin (RHS) gains growing interest in preclinical drug development. RHE and RHS have been characterised regarding their barrier function, but knowledge about biotransformation capacity in these constructs and in human skin remains rather poor. However, metabolising enzymes can be highly relevant for the efficacy of topical dermatics as well as genotoxicity and sensitisation. We have compared the esteratic cleavage of the prednisolone diester prednicarbate and the enzyme kinetic parameters (Vmax and S0.5) of the model substrate fluorescein diacetate (FDA) in commercially available RHS and RHE with excised human skin and monolayer cultures of normal and immortalised human keratinocytes and of fibroblasts. Formation of the main metabolite prednisolone and of fluorescein ranked as: RHS~RHE>excised human skin and keratinocytes>fibroblasts, respectively. Because of the aromatic probe, however, Vmax of FDA cleavage did not show a linear relationship with prednicarbate metabolism. In conclusion, RHE and RHS may be useful to quantitatively address esterase activity of human skin in drug development and hazard analysis, although an increased activity compared to native human skin has to be taken into account.
authors.affiliation: Institut für Pharmazie (Pharmakologie und Toxikologie), Freie Universität Berlin (FU), Berlin, Germany.
authors.forename: Franzisca Marie
authors.initials: FM
authors.lastname: Bätz
authors.forename: Wiebke
authors.initials: W
authors.lastname: Klipper
authors.forename: Hans Christian
authors.initials: HC
authors.lastname: Korting
authors.forename: Frank
authors.initials: F
authors.lastname: Henkler
authors.forename: Robert
authors.initials: R
authors.lastname: Landsiedel
authors.forename: Andreas
authors.initials: A
authors.lastname: Luch
authors.forename: Uwe
authors.initials: U
authors.lastname: von Fritschen
authors.forename: Günther
authors.initials: G
authors.lastname: Weindl
authors.forename: Monika
authors.initials: M
authors.lastname: Schäfer-Korting
mesh_terms: D001711:Biotransformation; D002460:Cell Line; D015925:Cryopreservation; D004305:Dose-Response Relationship, Drug; D004817:Epidermis / Q000187:drug effects* / Q000201:enzymology*; D004950:Esterases / Q000737:chemistry*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects*; D005452:Fluoresceins / Q000008:administration & dosage* / Q000493:pharmacokinetics; D006801:Humans; D066298:In Vitro Techniques; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects*; D011239:Prednisolone / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000737:chemistry / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D012869:Skin Absorption / Q000187:drug effects; D013997:Time Factors
chemical_list: D005452:Fluoresceins; D011239:Prednisolone; D004950:Esterases; C035287:prednicarbate; C018506:diacetylfluorescein