Direct labeling of chemotactic peptide ForNleLFNleYK radioiodine-in vivo- stability evaluation

Abstract

Some peptides are naturally occuring inflammatory mediators which specifically bind to receptors abundantly present in the area of inflammation, and owing to their small size, they rapidly clear from all non­target tissues. ForNleLFNleYK is a synthetic chemotactic peptide with high affinity to receptors on the white blood cell membranes. This hexapeptide contains a tyrosine residue susceptible to iodination by oxidative eletrophilic substitution ­ direct labeling. The aim of this study was the radioiodination of ForNleLFNleYK using the direct method (chloramine T) and its in vivo stability evaluation. The labeled compound was obtained in a short reaction time with high radiochemical purity (96.8 ± 0.84%) and remained stable over 48 hours when stored at low temperature. Biological distribution studies showed an uptake in inflammated tight significantly greater than the normal tight (p < 0.05, Student t test), and some in vivo dehalogenation of the compound.