Transport of free and peptide-bound pyrraline at intestinal and renal epithelial cells

J Agric Food Chem. 2009 Jul 22;57(14):6474-80. doi: 10.1021/jf901224p.

Abstract

Pyrraline is a quantitatively dominating glycation compound of the advanced Maillard reaction in foods and can be found in urine after consumption of pyrraline-containing food items. The purpose of this study was to investigate the transport of pyrraline and its dipeptide derivatives alanylpyrraline (Ala-Pyrr) and pyrralylalanine (Pyrr-Ala) at intestinal and renal cell lines. Pyrraline inhibited the l-[(3)H]lysine uptake with IC(50) values of 0.3 mM (Caco-2 cells) and 3.5 mM (OK cells), respectively, but not the uptake of [(14)C]Gly-Sar (Caco-2 and SKPT cells). In contrast, Ala-Pyrr strongly inhibited the uptake of [(14)C]Gly-Sar in Caco-2 and SKPT cells with IC(50) values of 0.19 and 0.017 mM, respectively. Pyrr-Ala inhibited the carrier-mediated uptake of [(14)C]Gly-Sar in Caco-2 and SKPT cells by 50% at concentrations of 0.03 and 0.008 mM, respectively. The transepithelial flux of peptide-bound pyrraline across Caco-2 cell monolayers was up to 15-fold higher compared to the flux of free pyrraline. We conclude that free pyrraline is not a substrate for the intestinal lysine transporter and that the absorption of dietary pyrraline occurs most likely in the form of dipeptides rather than as the free amino acid.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alanine / metabolism
  • Amino Acid Transport Systems / metabolism
  • Animals
  • Biological Transport
  • Caco-2 Cells
  • Cell Line
  • Dipeptides / metabolism
  • Epithelial Cells / metabolism
  • Humans
  • Intestinal Mucosa / metabolism*
  • Kidney / metabolism*
  • Kidney Tubules, Proximal
  • Lysine / metabolism
  • Norleucine / analogs & derivatives*
  • Norleucine / metabolism
  • Opossums
  • Peptides / metabolism*
  • Pyrroles / metabolism*
  • Rats

Substances

  • Amino Acid Transport Systems
  • Dipeptides
  • Peptides
  • Pyrroles
  • 2-formyl-5-(hydroxymethyl)pyrrole-1-norleucine
  • Norleucine
  • Lysine
  • Alanine