Influence of the Bifunctional Chelator on the Pharmacokinetic Properties of <sup>99m</sup>Tc(CO)<sub>3</sub>-Labeled Cyclic α-Melanocyte Stimulating Hormone Analog
作者:Maurício Morais、Bruno L. Oliveira、João D. G. Correia、Maria Cristina Oliveira、Maria Angeles Jiménez、Isabel Santos、Paula D. Raposinho
DOI:10.1021/jm301647t
日期:2013.3.14
Aiming at the design of specific melanocortin-1 receptor (MC1R) targeted imaging probes, we report on the effect of different azolyl-ring substitution patterns (carboxylate at the 4-position and/or methyl groups at the 3,5 positions) of pyrazolyldiamine bifunctional chelators (Pz(2)-Pz(4)) on the pharmacokinetic profile of the Tc-99m(CO)(3)-labeled lactam bridge-cyclized alpha-melanocyte stimulating hormone derivative, beta AlaNleCycMSH(hex). Three pyrazolyl-diamine-containing chelators were conjugated to beta AlaNleCycMSH(hex), with the resulting peptide conjugates displaying subnanomolar MC1R binding affinity. Biodistribution studies in B16F1 melanoma-bearing mice show that all radiopeptides present a good melanoma uptake. The introduction of a carboxylate group in the azolyl-ring leads to a remarkable reduction of the kidney (>89%) and liver (>91%) accumulation for Tc-99m(CO)(3)-Pz(3)-beta AlaNleCycMSH(hex) and Tc-99m(CO)(3)-Pz(4)-beta AlaNleCycMSH(hex) when compared to the radiopeptide Tc-99m(CO)(3)-Pz(1)-beta AlaNleCycMSH(hex), where that group is absent. The good tumor uptake and favorable tumor-to-nontarget-organs ratios of Tc-99m(CO)(3)-Pz(3)-beta AlaNleCycMSH(hex) and Tc-99m(CO)(3)-Pz(4)-beta AlaNleCycMSH(hex) highlights the potential of both compounds as melanoma imaging agents.