1Department of Radiopharmacy, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran
2Radiation Application Research School, Nuclear Science and Technology Research Institute (NSTRI), Tehran, Iran
3Research Center for Nuclear Medicine, Tehran University of Medical Sciences, Tehran, Iran
4Department of Radiopharmacy, School of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.
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.