title: Evaluation of a thiodipeptide, L-phenylalanyl-Ψ[CS-N]-L-alanine, as a novel probe for peptide transporter 1.
abstract: L-Phenylalanyl-Ψ[CS-N]-l-alanine (Phe-Ψ-Ala), a thiourea dipeptide, was evaluated as a probe for peptide transporter 1 (PEPT1). Uptake of Phe-Ψ-Ala in PEPT1-overexpressing HeLa cells was significantly higher than that in vector-transfected HeLa cells and the Km value was 275 ± 32 µM. The uptake was pH-dependent, being highest at pH 6.0, and was significantly decreased in the presence of PEPT1 inhibitors [glycylsarcosine (Gly-Sar), cephalexin, valaciclovir, glycylglycine, and glycylproline]. In metabolism assay using rat intestinal mucosa, rat hepatic microsomes, and human hepatocytes, the amount of Phe-Ψ-Ala was unchanged, whereas phenylalanylalanine was extensively decomposed. The clearance, distribution volume, and half-life of intravenously administered Phe-Ψ-Ala in rats were 0.151 ± 0.008 L/h/kg, 0.235 ± 0.012 L/kg, and 1.14 ± 0.07 h, respectively. The maximum plasma concentration of orally administered Phe-Ψ-Ala (2.31 ± 0.60 µg/mL) in the presence of Gly-Sar was significantly decreased compared with that in the absence of glycylsarcosine (3.74 ± 0.44 µg/mL), suggesting that the intestinal absorption of Phe-Ψ-Ala is mediated by intestinal PEPT1. In conclusion, our results indicate that Phe-Ψ-Ala is a high-affinity, metabolically stable, non-radioactive probe for PEPT1, and it should prove useful in studies of PEPT1, e.g., for predicting drug-drug interactions mediated by PEPT1 in vitro and in vivo.
authors.affiliation: Faculty of Pharmacy, Takasaki University of Health and Welfare.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Arakawa
authors.forename: Sachi
authors.initials: S
authors.lastname: Saito
authors.forename: Masahiko
authors.initials: M
authors.lastname: Kanagawa
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kamioka
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yano
authors.forename: Kaori
authors.initials: K
authors.lastname: Morimoto
authors.forename: Takuo
authors.initials: T
authors.lastname: Ogihara
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001692:Biological Transport; D004151:Dipeptides / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism* / Q000493:pharmacokinetics / Q000494:pharmacology; D006207:Half-Life; D006367:HeLa Cells; D022781:Hepatocytes / Q000378:metabolism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007275:Injections, Intravenous; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D049990:Membrane Transport Modulators / Q000494:pharmacology; D008862:Microsomes, Liver / Q000378:metabolism; D000074011:Peptide Transporter 1; D017208:Rats, Wistar; D027981:Symporters / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D004151:Dipeptides; D049990:Membrane Transport Modulators; D000074011:Peptide Transporter 1; C082186:SLC15A1 protein, human; C489940:Slc15a1 protein, rat; D027981:Symporters; C004194:glycylsarcosine; C039552:phenylalanylalanine