Pyrimidine and nucleoside γ-esters of l-Glu-Sar: Synthesis, stability and interaction with hPEPT1
作者:André H. Eriksson、Peter L. Elm、Mikael Begtrup、Birger Brodin、Robert Nielsen、Bente Steffansen
DOI:10.1016/j.ejps.2005.02.007
日期:2005.5
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 [C-14] 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 1 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. (c) 2005 Elsevier B.V. All rights reserved.