Abstract: Knowledge of the formation of radicals from sulfites, in vivo, is of interest in understanding the allergic and inflammatory responses to environmental sulfur dioxide exposure. Sulfite anion trioxide (SO3-.) radical formation was measured in mice, preloaded with the spin trap, 5-(diethoxy-phosphoryl)-5-methyl-pyrrolidine-N-oxide, (DEPMPO). Based on spin trapping NMR, a surprising quantity of reduced SO3-.-adduct was observed that did not depend on co-administration of oxidizing agents, suggesting a possible nonradical reaction between (bi)sulfite and DEPMPO. The products of the reversible nucleophylic addition of (bi)sulfite to the nitrone functional group were identified using P-31-NMR, H-1-NMR, and C-13-NMR spectroscopy as cis- and trans- stereoisomers of hydroxylamine and confirmed by quantum chemical calculations. Oxidation of the hydroxylamines results in the formation of two corresponding cis- and trans-isomeric nitroxides, only one of which has been earlier described as the paramagnetic adduct of genuinely trapped SO3-. radical. The results demonstrate that SO3-. detection using nitrone spin traps such as DEPMPO and DMPO may involve nonradical addition reactions except in cases when the required controls unambiguously prove a radical mechanism. (C) 2003 Elsevier Science Inc.

Cite: Potapenko D. , Clanton T. , Bagryanskaya E. , Gritsan N. , Reznikov V. , Khramtsov V.
Nonradical mechanism of (bi)sulfite reaction with depmpo: cautionary note for SO3-center dot radical spin trapping
Free Radical Biology and Medicine. 2003. V.34. N2. PII S0891(02)01194-2 . DOI: 10.1016/S0891-5849(02)01194-2 WOS Scopus

Dates:

Published print:

Jan 1, 2003

Identifiers:

Web of science	WOS:000180296000005
Scopus	2-s2.0-84962439021
OpenAlex	W2035022512

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