79494-16-9Relevant academic research and scientific papers
Synthesis of nitroxyl radicals for overhauser-enhanced magnetic resonance imaging
Yamada, Ken-Ichi,Kinoshita, Yuichi,Yamasaki, Toshihide,Sadasue, Hiromi,Mito, Fumiya,Nagai, Mika,Matsumoto, Shingo,Aso, Mariko,Suemune, Hiroshi,Sakai, Kiyoshi,Utsumi, Hideo
experimental part, p. 548 - 553 (2009/04/11)
Non-invasive measurement and visualization of free radicals in vivo would be important to clarify their roles in the pathogenesis of free radical-associated diseases. Nitroxyl radicals can react with free radicals and be derivatized to achieve specific cellular / subcellular localizing capabilities while retaining the simple spectral features useful in imaging. Overhauser-enhanced magnetic resonance imaging (OMRI), which is a double resonance technique, creates images of free radical distributions in small animals by enhancing the water proton signal intensity via the Overhauser Effect. In this study, we synthesized various nitroxyl probes having 15N nuclei and deuterium, and measured the enhancement factor for Overhauser-enhanced magnetic resonance imaging experiments. 15N-D-4- Oxo-2,2,6,6-tetramethylpiperidine-1-oxyl (15N-D-oxo-TEMPO) has the highest enhancement factor compared with other nitroxyl probes. The proton signal enhancement was higher for 15N-labeled nitroxyl probes when compared to the 14N-labeled analogues because of the reduced spectral multiplicity of the I = 1/2 nucleus. Furthermore, this enhancement is proportional to the line width and number of electron spin resonance lines of nitroxyl radicals. Finally, we compared the Overhauser-enhanced magnetic resonance image of 15N-labeled, deuterated 4-Oxo-2,2,6,6- tetramethylpiperidine-1-oxyl with that of 14N-H-TEMPOL. These results suggested that the selective deuteration of the nitroxyl probes enhanced the signal-to-noise ratio and thereby improved spatial and temporal resolutions.
A time-resolved electron paramagnetic resonance investigation of the spin exchange and chemical interactions of reactive free radicals with isotopically symmetric (14N-X-14N) and isotopically asymmetric ( 14N-X-15
Sartori, Elena,Khudyakov, Igor V.,Lei, Xuegong,Turro, Nicholas J.
, p. 7785 - 7792 (2008/02/09)
Interactions between reactive free radicals (r) with stable mononitroxyl radicals (N) and bisnitroxyl radicals (N-X-N) were studied by time-resolved electron paramagnetic resonance (TR-EPR). Reactive spin-polarized free radicals (r#), with non-
15N NMR spectroscopy of labeled alkoxyamines. 15N-labeled model compounds for nitroxide-trapping studies in free-radical (Co)polymerization
Kelemen, Peter,Lugtenburg, Johan,Klumperman, Bert
, p. 7322 - 7328 (2007/10/03)
Eight 15N-labeled derivatives of 1-ethoxy-2,2,6,6-tetramethylpiperidine were synthesized in order to investigate the effects of their structural units on 15N NMR spectra. A single peak is found for each alkoxyamine. The chemical shift depends extensively on the nature of the α carbon atom of the alkoxy group. The remote functional group attached to position 4 of the piperidine ring has a smaller but still significant effect. The results of the 15N NMR measurements are supported by the detection of the N-H and N-C spin-spin coupling from the 1H and 13C NMR. The investigated alkoxyamines are model compounds for the radical-trapping products of styryl, methyl methacryloyl, α-methylstyryl, and methyl acryloyl radicals by 15N-labeled nitroxides. The potential of 15N NMR spectroscopy to analyze such products is discussed. In addition, it is shown that the 13C chemical shifts of the α carbon atom of the alkoxy group fall in an empty part of the 13C NMR spectrum, which allows the identification of trapped (macro)radicals via natural abundance 13C NMR.
