Molecular Engineering of Technetium and Rhenium Based Radiopharmaceuticals Page: 4 of 21
This report is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
observations drove the elaboration of the coordination chemistry of the Tc-
organohydrazino core and the development of novel coligands. However, the extensive
investigations on the coordination chemistry of the Tc-hydrazino system led us to
conclude that the organohydrazines are inferior chelates and that alternative approaches
to effective labeling should be explored. The preliminary studies on the development of
the single amino acid analog chelators exploiting the {Tc(CO)3 }) core represent a
novel strategy for the development of imaging agents.
II. The Technetium(III)-Bishydrazino core {Tc(H.NNR)2)" in 99mTc-Labeled
Chemotactic Peptide Derivatives. We have developed chemotactic peptides which
incorporated the 9'"Tc binding group HYNIC (hydrazinonicotinamide). This complexing
agent when added to the lysine extended C-terminus of the peptide sequence enabled
robust labeling at high specific activity. Separation of the unlabeled peptide from the
technetium-labeled peptide was easily achievable on HPLC and facilitated by the nature
of the starting technetium complex.
A significant structural feature associated with the [Tc(HYNIC-
peptide)X(coligand)y] reagents is the necessity of a multidentate coligand to bond to the
remaining available coordination sites about the Tc(II)-organohydrazino core. By
varying the identity of the coligand, we have demonstrated that the distribution of 99'Tc-
labeled-HYNIC derivatized chemotactic peptides may be modulated. This study
employed analogs of the polyhydric ligand, glucoheptonate, which was initially
employed to facilitate 9"Tc radiolabeling of the HYNIC moiety of both proteins and
peptides. The compounds used (glucoheptonate, mannitol, glucarate and glucamine)
provided a small series of hydroxyl-backbone ligands which differ in the number and
type of ionizable functional groups. At imaging times of 3 and 18 h, [99"Tc(HYNIC-f-
MLFK)x(mannitol)y] had the lowest levels of accumulation in bowel and the highest level
of accumulation in infected tissue. In addition to influencing biodistribution and
excretion, the choice of coligand significantly affects other chemical and biological
properties of the conjugates, such as the stoichiometry of the complex, chromatographic
separation of labeled and unlabeled peptide and targeting of infection. For infection
imaging, peptide radiolabeled with 99t"Tc-mannitol has the most favorable combination of
concentration in infected tissue, T/B ratio and biodistribution in infected organs.
Upcoming Pages
Here’s what’s next.
Search Inside
This report can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Report.
Zubieta, J. Molecular Engineering of Technetium and Rhenium Based Radiopharmaceuticals, report, June 30, 2003; United States. (https://digital.library.unt.edu/ark:/67531/metadc781378/m1/4/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.