Synthesis, characterization and biological studies of rhenium, technetium-99m and rhenium-188 pentapeptides Journal Article


Authors: Sanders, V. A.; Iskhakov, D.; Abdel-Atti, D.; Devany, M.; Neary, M. C.; Czerwinski, K. R.; Francesconi, L. C.
Article Title: Synthesis, characterization and biological studies of rhenium, technetium-99m and rhenium-188 pentapeptides
Abstract: A pentapeptide macrocyclic ligand, KYCAR (lysyl-tyrosyl-cystyl-alanyl-arginine), has been designed as a potential chelating ligand for SPECT imaging and therapeutic in vivo agents. This study shows the synthesis and characterization of KYCAR complexes containing nonradioactive rhenium, 99m Tc, or 188 Re. The metal complexes were also biologically evaluated to determine in vivo distribution in healthy mice. The overall goals of this project were (1) to synthesize the Tc/Re pentapeptide complexes, (2) to identify spectroscopic methods for characterization of syn versus anti rhenium peptide complexes, (3) to analyze the ex vivo stability, and (4) to assess the biological properties of the [ 99m Tc]TcO-KYCAR and [ 188 Re]ReO-KYCAR complexes in vivo. Details on these efforts are provided below. Methods: Nat Re/ 99m Tc/ 188 ReO-KYCAR complexes were synthesized, and macroscopic species were characterized via HPLC, IR, NMR, and CD. These characterization data were compared to the crystallographic data of ReO-KYC to assist in the assignment of diastereomers and to aid in the determination of the structure of the complex. Results: The radiometal complexes were synthesized with high purity (>95%). HPLC, IR, NMR and CD data on the macroscopic nat ReO-KYCAR complexes confirm the successful complexation as well as the presence of two diastereomers in syn and anticonformations. Tracer level complexes show favorable stabilities ex vivo for 2+ h. Conclusion: Macroscopic metal complexes form diastereomers with the KYCAR ligand; however, this phenomenon is not readily observed on the tracer level due to the rapid interconversion. It was determined through pK a measurements that the macroscopic nat ReO-KYCAR complex is 0 at physiological pH. The [ 99m Tc]TcO-KYCAR is stable in vitro while the [ 188 Re]ReO-KYCAR shows 50% decomposition in PBS and serum. Biologically, the tracer level complexes clear through the hepatobiliary pathway. Some decomposition of both tracers is evident by uptake in the thyroid and stomach. © 2018 Elsevier Inc.
Keywords: controlled study; unclassified drug; nonhuman; methodology; technetium 99m; mouse; complex formation; animal experiment; ph; in vivo study; in vitro study; drug uptake; isotope labeling; radioactivity; radiopharmaceutical agent; drug clearance; crystal structure; drug purity; high performance liquid chromatography; ex vivo study; spectroscopy; infrared spectroscopy; synthesis; drug stability; chelation; proton nuclear magnetic resonance; crystallography; spect; circular dichroism; pka; rhenium; rhenium 188; article; drug decomposition; radiometals; 188 re; 99m tc; kycar; metal peptide complex; lysyl tyrosyl cystyl alanyl arginine tc 99m; lysyl tyrosyl cystyl alanyl rhenium 188; biological study
Journal Title: Nuclear Medicine and Biology
Volume: 68-69
ISSN: 0969-8051
Publisher: Elsevier Science Inc.  
Date Published: 2019-01-01
Start Page: 1
End Page: 13
Language: English
DOI: 10.1016/j.nucmedbio.2018.11.001
PUBMED: 30578134
PROVIDER: scopus
PMCID: PMC6451878
DOI/URL:
Notes: Article -- Export Date: 1 May 2019 -- Source: Scopus
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