title: Biotinylated heptapeptides substituted with a D-amino acid as platelet-activating factor inhibitors.
abstract: Platelet-activating factor (PAF), a potent lipid mediator, is implicated in many inflammatory diseases, and therefore may serve as a direct target for anti-inflammatory drugs. We previously reported that synthetic biotinylated peptides having a Tyr-Lys-Asp-Gly sequence markedly inhibit PAF-induced inflammation by direct binding, and that two synthetic fluorescence-labelled heptapeptides (Lys-Trp-Tyr-Lys-Asp-Gly-Asp and D-Lys-Trp-Tyr-Lys-Asp-Gly-Asp) with high stability in plasma specifically bind to PAF-like lipids (oxidized- and lyso-phosphatidylchoine). In this study, synthetic heptapeptides (Lys-Trp-Tyr-Lys-Asp-Gly-Asp) coupled to a biotin molecule through the N-terminal amino group and ε-amino group of N-terminus Lys, (Btn)KP6 and K(Btn)P6, respectively, and their biotinylated peptides substituted with D-Lys at the N-terminus, (Btn)dKP6 and dK(Btn)P6, respectively, were investigated for their effects on PAF-induced inflammation. In the experiments using a rat model of hind paw oedema, (Btn)KP6, K(Btn)P6, (Btn)dKP6, and dK(Btn)P6 significantly inhibited PAF-induced paw oedema, with the highest inhibitory effect exhibited by dK(Btn)P6. The inhibitory effect of D-Tyr-D-Lys-D-Asp-Gly tetrapeptide on PAF-induced paw oedema was much lower than that of Tyr-Lys-Asp-Gly tetrapeptide. In the experiments using tryptophan fluorescence spectroscopy, (Btn)KP6, K(Btn)P6, (Btn)dKP6, and dK(Btn)P6 bound to PAF dose-dependently, with dK(Btn)P6 showing the strongest binding affinity, indicating that its affinity appears to be closely correlated with its inhibitory effect on PAF-induced inflammation. These results suggest that direct binding of (Btn)KP6, K(Btn)P6, (Btn)dKP6, and dK(Btn)P6 to PAF can lead to marked inhibition of PAF-induced inflammation, and these agents, particularly dK(Btn)P6, may be useful as anti-inflammatory drugs targeting PAF with high stability in plasma.
authors.affiliation: Faculty of Pharmacy, Iwaki Meisei University, 5-5-1, Chuodai-Iino, Iwaki, Fukushima 970-8551, Japan. Electronic address: a-sato@iwakimu.ac.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Sato
authors.affiliation: Faculty of Pharmacy, Iwaki Meisei University, 5-5-1, Chuodai-Iino, Iwaki, Fukushima 970-8551, Japan.
authors.forename: Izumi
authors.initials: I
authors.lastname: Yokoyama
authors.affiliation: Faculty of Pharmacy, Iwaki Meisei University, 5-5-1, Chuodai-Iino, Iwaki, Fukushima 970-8551, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Ebina
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D000893:Anti-Inflammatory Agents / Q000737:chemistry / Q000627:therapeutic use*; D019921:Biotinylation; D004487:Edema / Q000139:chemically induced / Q000188:drug therapy*; D008297:Male; D009842:Oligopeptides / Q000737:chemistry / Q000627:therapeutic use*; D010972:Platelet Activating Factor / Q000037:antagonists & inhibitors*; D017208:Rats, Wistar
chemical_list: D000596:Amino Acids; D000893:Anti-Inflammatory Agents; D009842:Oligopeptides; D010972:Platelet Activating Factor
keywords: Anti-inflammatory drug; Biotinylated peptide; D-Amino acid; Inflammation; Platelet-activating factor