Fluorine-18-labeled [Nle 4, d-Phe 7]-α-MSH, an α-melanocyte stimulating hormone analogue

• Published in: Nuclear medicine and biology 1997-02, Vol.24 (2), p.171-178
• Main Authors: Vaidyanathan, Ganesan, Zalutsky, Michael R.
• Format: Article
• Language: English
• Subjects: alpha-MSH - analogs & derivatives; alpha-MSH - pharmacokinetics; Animals; Binding, Competitive; Biological and medical sciences; Contrast media. Radiopharmaceuticals; Fluorine Radioisotopes - pharmacokinetics; Fluorine-18; Iodine Radioisotopes - pharmacokinetics; Kinetics; Medical sciences; Melanocyte; Melanocyte-Stimulating Hormones - chemical synthesis; Melanocyte-Stimulating Hormones - pharmacokinetics; Melanoma, Experimental - metabolism; Metabolic Clearance Rate; Mice; Mice, Inbred BALB C; MSH; Pharmacology. Drug treatments; Receptors, Pituitary Hormone - metabolism; Specific Activity; Tissue Distribution
• ISSN: 0969-8051; 1872-9614
• DOI: 10.1016/S0969-8051(96)00211-9

The α-melanocyte stimulating hormone (α-MSH) analogue [Nle 4, d-Phe 7]-α-MSH was labeled with 18F using N-succinimidyl 4-[ 18F]fluorobenzoate ([ 18F]SFB) in >80% radiochemical yield. The IC 50 values of [Nle 4, d-Phe 7]-α-MSH and para-fluorobenzoyl-[Nle 4, d-Phe 7]-α-MSH ([Nle 4, d-Phe 7, Lys 11-( 18F)PFB]-α-MSH) for inhibiting the binding of meta-[ 131I]iodobenzoyl-[Nle 4, d-Phe 7]-α-MSH ([NIe 4, d-Phe 7, Lys 11- 131I)MIB]-α-MSH) to B16-F1 murine melanoma cells were 89 ± 9 pM and 112 ± 22 pM, respectively, suggesting that addition of 4-fluorobenzoate did not compromise α-MSH receptor binding affinity. Binding of [Nle 4, d-Phe 7,Lys 11-( 18F)PFB]-α-MSH was influenced by the specific activity of the preparation (400–1000 Ci/mmol). The normal tissue clearance of [Nle 4, d-Phe 7,Lys 11-( 18F)PFB]-α-MSH in mice was quite rapid, with little evidence for defluorination.