title: Synthesis, characterization, and in vitro evaluation of nitroimidazole--BATO complexes: new technetium compounds designed for imaging hypoxic tissue.
abstract: Several technetium-99 BATO (boronic acid adduct of technetium dioximes) complexes TcX(dioxime)3BR (X = Cl) that contain a boron cap R which bears a 2- or 4-nitroimidazole moiety have been prepared from either TcCl(dioxime)3 or from Tc(dioxime)3(mu-OH)SnCl3 [dioxime = dimethyl glyoxime (DMG) or cyclohexanedione dioxime (CDO)]. Two hydroxy analogs (X = OH) were isolated by treatment of the corresponding chloro complexes with aqueous NaOH. The complexes have been characterized by elemental analysis, mass spectrometry, NMR, UV/vis spectroscopy, and high-performance liquid chromatography. These complexes have the potential for selective retention in hypoxic tissue, by a mechanism believed to be the result of nitro reduction. The electrochemistry and enzymatic reduction of these complexes was studied to assess the potential for reduction in vivo. The nitroreductase enzyme xanthine oxidase was shown to reduce the nitroimidazole group on the complexes 99TcOH(DMG)3BBNO2 and 99TcOH(DMG)3BprenNO2 under anaerobic conditions in the presence of hypoxanthine. However, the results indicated that the rate of reduction might be slow in vivo, limiting the suitability of these compounds for imaging of regions of hypoxia.
authors.affiliation: Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, New Jersey 08543-4000.
authors.forename: K E
authors.initials: KE
authors.lastname: Linder
authors.forename: Y W
authors.initials: YW
authors.lastname: Chan
authors.forename: J E
authors.initials: JE
authors.lastname: Cyr
authors.forename: D P
authors.initials: DP
authors.lastname: Nowotnik
authors.forename: W C
authors.initials: WC
authors.lastname: Eckelman
authors.forename: A D
authors.initials: AD
authors.lastname: Nunn
mesh_terms: D000693:Anaerobiosis; D001897:Boronic Acids / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D000860:Hypoxia / Q000000981:diagnostic imaging*; D007202:Indicators and Reagents; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D009593:Nitroimidazoles / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D011877:Radionuclide Imaging; D013056:Spectrophotometry, Ultraviolet; D017556:Technetium Compounds / Q000138:chemical synthesis*; D014969:Xanthine Oxidase / Q000378:metabolism
chemical_list: D001897:Boronic Acids; D007202:Indicators and Reagents; D009593:Nitroimidazoles; D017556:Technetium Compounds; D014969:Xanthine Oxidase