title: Pyrimidine and nucleoside gamma-esters of L-Glu-Sar: synthesis, stability and interaction with hPEPT1.
abstract: The aim of the present study was to improve the synthetic pathway of bioreversible dipeptide derivatives as well as evaluate the potential of using l-Glu-Sar as a pro-moiety for delivering three newly synthesised nucleoside and pyrimidine l-Glu-Sar derivatives. l-Glu(trans-2-thymine-1-yl-tetrahydrofuran-3-yl ester)-Sar (I), l-Glu(thymine-1-yl-methyl ester)-Sar (II) and l-Glu(acyclothymidine)-Sar (III) were synthesised and in vitro stability was studied in various aqueous and biological media. Affinity to and translocation via hPEPT1 was investigated in mature Caco-2 cell monolayers, grown on permeable supports. Affinity was estimated in a competition assay, using [14C] labelled Gly-Sar (glycylsarcosine). Translocation was measured as pHi-changes induced by the substrates using the fluorescent probe BCECF and an epifluorescence microscope setup. All dipeptide derivatives released the model drugs quantitatively by specific base-catalysed hydrolysis at pH>6.0. II was labile in aqueous buffer solution, whereas I and III showed appropriate stability for oral administration. In 10% porcine intestinal homogenate, the half-lives of the dipeptide derivatives indicated limited enzyme catalyzed degradation. All compounds showed good affinity to hPEPT1, but the Compounds I and III showed not to be translocated by hPEPT1. The translocation of the l-Glu-Sar derivative of acyclovir, l-Glu(acyclovir)-Sar was also investigated and showed not to take place. Consequently, l-Glu-Sar seems to be a poor pro-moiety for hPEPT1-mediated transport.
authors.affiliation: Department of Pharmaceutics, The Danish University of Pharmaceutical Sciences, Universitetsparken 2, DK-2100 Copenhagen, Denmark.
authors.forename: André H
authors.initials: AH
authors.lastname: Eriksson
authors.forename: Peter L
authors.initials: PL
authors.lastname: Elm
authors.forename: Mikael
authors.initials: M
authors.lastname: Begtrup
authors.forename: Birger
authors.initials: B
authors.lastname: Brodin
authors.forename: Robert
authors.initials: R
authors.lastname: Nielsen
authors.forename: Bente
authors.initials: B
authors.lastname: Steffansen
mesh_terms: D001692:Biological Transport; D018938:Caco-2 Cells; D004151:Dipeptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D004355:Drug Stability; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009705:Nucleosides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D000074011:Peptide Transporter 1; D011355:Prodrugs / Q000138:chemical synthesis* / Q000378:metabolism; D011743:Pyrimidines / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D027981:Symporters / Q000502:physiology*
chemical_list: D004151:Dipeptides; D009705:Nucleosides; D000074011:Peptide Transporter 1; D011355:Prodrugs; D011743:Pyrimidines; C082186:SLC15A1 protein, human; D027981:Symporters