a 99mtc-tricine-hynic-labeled peptide targeting the melanocortin-1 receptor for melanoma imaging

melanocortin-1 (mc1) receptor is an attractive melanoma-specific target for the development of α-msh peptide based imaging and therapeutic agents. in this work a new lactam bridge α-msh analogue was synthesized and radiolabeled with 99mtc via hynic chelator and tricine as co-ligand. also, stability in human serum, receptor bound internalization and tissue biodistribution in tumor bearing nude mice were thoroughly investigated. radiolabeling with 99mtc was performed at high specific activities (163mbq/nmol) with an acceptable labeling yield (>98%). the radioligand showed specific internalization into b16/f10 cells (13.35 ± 0.9% at 4 hours). in biodistribution studies, a receptor-specific uptake was observed in mc1 receptor positive organ so that after 4 hours the tumor uptake was 4.51±0.11 % id/g. predominant renal excretion pathway with a highest accumulation of activity in tumor was observed for this radiopeptide. obtained results show that the new designed labeled peptide conjugate can be a suitable candidate for diagnosis of metastatic melanomas.