title: Chemistry of bifunctional photoprobes. 6. Synthesis and characterization of high specific activity metalated photochemical probes: development of novel rhenium photoconjugates of human serum albumin and fab fragments.
abstract: Functionalization of perfluoro aryl azides by bifunctional chelating agents (BFCAs) capable of forming high specific activity complexes with (99m)Tc (for gamma-imaging) and (188)Re (for radiotherapy) is described. The synthesis of multidonor BFCAs containing N(2)S(2), N(4), and N(3)S donor groups containing imidazole, pyridine, and pyrazine functionalities that may be important for tuning the pharmacokinetic parameters is also described. Functionalization of perfluoro aryl azides at various sites on BFCAs yields novel bifunctional photolabile chelating agents (BFPCAs) that are useful for covalent attachment to biomolecules. A representative Re-BFPCA 8a in a model solvent, diethylamine, proceeded to give a high yield of intermolecular NH insertion product without the decomplexation of the metal ion from 8a. All products originated from the photolysis of 8a in diethylamine are characterized by analytical techniques, and a plausible mechanism of formation of different photolytic products is suggested. The high yield of intermolecular NH insertion of Re-BFPCA 8a is extended to labeling of human serum albumin (HSA) and Fab fragments under aqueous conditions. The photolabeling technology developed here offers a new way to attach diagnostically and therapeutically useful radiotracers (e.g., (99m)Tc, (188)Re) to Fab fragments for potential noninvasive imaging and therapy of cancer.
authors.affiliation: Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA.
authors.forename: Raghavan
authors.initials: R
authors.lastname: Rajagopalan
authors.forename: Robert R
authors.initials: RR
authors.lastname: Kuntz
authors.forename: Uday
authors.initials: U
authors.lastname: Sharma
authors.forename: Wynn A
authors.initials: WA
authors.lastname: Volkert
authors.forename: Raghoottama S
authors.initials: RS
authors.lastname: Pandurangi
mesh_terms: D002384:Catalysis; D002614:Chelating Agents / Q000138:chemical synthesis*; D006801:Humans; D007140:Immunoglobulin Fab Fragments / Q000378:metabolism; D007128:Immunoglobulin Fragments / Q000378:metabolism*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis*; D015609:Organotechnetium Compounds; D010777:Photochemistry / Q000379:methods; D010782:Photolysis; D011868:Radioisotopes / Q000737:chemistry; D012211:Rhenium / Q000737:chemistry*; D012709:Serum Albumin / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D002614:Chelating Agents; D007140:Immunoglobulin Fab Fragments; D007128:Immunoglobulin Fragments; D008024:Ligands; D009942:Organometallic Compounds; D015609:Organotechnetium Compounds; D011868:Radioisotopes; D012709:Serum Albumin; D012211:Rhenium