Esters of 5-carboxyl-5-methyl-1-pyrroline N-oxide: A family of spin traps for superoxide

Pei Tsai, Kazuhiro Ichikawa, Colin Mailer, Sovitj Pou, Howard J. Halpern, Bruce H. Robinson, Robert Nielsen, Gerald M. Rosen

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Abstract

Apparent rate constants, at acidic pH and neutral pH for the reaction of a family of ester-containing 5-carboxyl-5-methyl-1-pyrroline N-oxides with superoxide (O2.-) were estimated, using ferricytochrome c as a competitive inhibitor. It was of interest to note that the rate constants were similar among the different nitrones and not that significantly different from that found for 5-(diethoxyphosphoryl)-5-dimethyl-1-pyrroline N-oxide. At acidic pH, the rate constant for spin trapping O2.- 3-fold greater than that at physiological pH. Subsequent experiments determined the half-life of aminoxyls, derived from the reaction of these nitrones with O2.-. The EPR spectra were modeled by using a global analysis method. The results clearly demonstrated that EPR spectra of all the aminoxyls were inconsistent with a model that included a single γ-hydrogen splitting. A better interpretation modeled them as two diastereomers with identical nitrogen splittings and slightly different β-hydrogen splittings. Detailed line width analyses slightly favored an equal line width-unequal population ratio for the two diastereomers.

Original languageEnglish
Pages (from-to)7811-7817
Number of pages7
JournalJournal of Organic Chemistry
Volume68
Issue number20
DOIs
Publication statusPublished - Oct 3 2003

All Science Journal Classification (ASJC) codes

  • Organic Chemistry

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    Tsai, P., Ichikawa, K., Mailer, C., Pou, S., Halpern, H. J., Robinson, B. H., Nielsen, R., & Rosen, G. M. (2003). Esters of 5-carboxyl-5-methyl-1-pyrroline N-oxide: A family of spin traps for superoxide. Journal of Organic Chemistry, 68(20), 7811-7817. https://doi.org/10.1021/jo0350413