Free-radical chemistry of sulfite.

Neta, P.; Huie, Robert E.

doi:10.1289/ehp.8564209

Cited by 274 publications

(162 citation statements)

References 80 publications

(70 reference statements)

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“…Sulfur dioxide, one of the major atmospheric pollutants, is water-soluble and, in aqueous solution at neutral pH, exists primarily as sulfite (SO 3 2− ) and (bi)sulfite (HSO 3 − ) (pKa = 7.2) [1–5]. Due to its antioxidant and antimicrobial properties, (bi)sulfite is used extensively as a preservative in beverages and foods [6], but it has also been reported that (bi)sulfite is toxic at high concentrations [7].…”

Section: Introductionmentioning

confidence: 99%

“…This metal-catalyzed autoxidation generates sulfur trioxide anion radical ( • SO 3 − ) in an initiating one-electron oxidation step through an oxygen-consuming chain reaction [3,5,10,11]. It has also been shown that the one-electron oxidation of (bi)sulfite to sulfate is catalyzed enzymatically by prostaglandin H synthase (hydroperoxide) [12], horseradish peroxidase [13,14] and xanthine oxidase [15–17] with formation of • SO 3 − .…”

Section: Introductionmentioning

confidence: 99%

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New insights into the detection of sulfur trioxide anion radical by spin trapping: radical trapping versus nucleophilic addition

Ranguelova

Mason

2009

Free Radical Biology and Medicine

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It has recently been proposed that (bi)sulfite (hydrated sulfur dioxide) reacts with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) in biological systems via a nonradical, nucleophilic reaction, implying that the radical adduct (DMPO/•SO3−) formation in these systems is an artifact and not the result of spin trapping of sulfur trioxide anion radical (•SO3−). Here, the one-electron oxidation of (bi)sulfite catalyzed by horseradish peroxidase/H2O2 has been re-investigated by ESR spin trapping with DMPO and oxygen uptake studies in order to obtain further evidence for the radical reaction mechanism. In the case of ESR experiments, the signal of DMPO/•SO3− radical adduct was detected, and the initial rate of its formation was calculated. Support for the radical pathway via •SO3− was obtained from the stoichiometry between the amount of consumed molecular oxygen and the amount of (bi)sulfite oxidized to sulfate (SO42−). When DMPO was incubated with (bi)sulfite, oxygen consumption was completely inhibited due to the efficiency of DMPO trapping. In the absence of DMPO, the initial rate of oxygen and H2O2 consumption was determined to be half of the initial rate of DMPO/•SO3− radical adduct formation as determined by ESR, demonstrating that DMPO forms the radical adduct by trapping the •SO3− exclusively. We conclude that DMPO is not susceptible to artifacts arising from nonradical chemistry (nucleophilic addition) except when both (bi)sulfite and DMPO concentrations are at nonphysiological levels of at least 0.1 M and the incubations are for longer time periods.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

New insights into the detection of sulfur trioxide anion radical by spin trapping: radical trapping versus nucleophilic addition

Ranguelova

Mason

2009

Free Radical Biology and Medicine

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“…SO 5 -radicals. Direct evidence of the radicals' presence during the course of the reaction has been often described, e.g., in [14,15]. A more detailed overview of possible reactions taking part in the mechanism and covering almost all sulfur-oxygen compounds was given by Ermakov and Purmal [8].…”

Section: Reaction Mechanismmentioning

confidence: 99%

Kinetics of Catalytic Oxidation of Sulfite in Diluted Aqueous Solutions

et al. 2015

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The reaction kinetics for low concentrations of sulfite close to the stoichiometric ration of oxygen was investigated in a rapid-mixing apparatus. Air-or pure oxygen-saturated solution containing the catalyst was mixed with aqueous sulfite solution. Mixing ratios with stoichiometric excess of dissolved oxygen were tested. Reaction orders for sulfite, oxygen, and a Co(II) catalyst from literature were confirmed in the tested concentration range. The apparent kinetic constant and activation energy data are presented. The high importance of proper mixing of the two reacting solutions is reported, which was revealed during the development of the precise experimental technique providing reliable kinetic data.

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“…In healthy individuals beside enzymatic transformation other processes to control the level of sulfite must be involved: for instance, chemical pathways. In fact, the sulfite reacts with disulfide proteins bond such as oxidized glutathione and cystine leading to the formation of the corresponding sulfidryl derivative, or is oxidized to sulfate [4] [5]. But, the mechanism of both the negative and positive actions in which the sulfite could be involved is not clear; for example, it has been suggested that the sulfite might affect some mediators such as the nitric oxide and/or its carriers [6]- [8].…”

Section: Introductionmentioning

confidence: 99%

Nitric Oxide: Probably the <i>in Vivo</i> Mediator of the Bisulfite’s Effects

Grossi¹

2014

JBM

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The use of bisulfite in food and beverage preservation, as well as in commercial goods and pharmaceuticals as antimicrobial agents is well known, but not very much is reported on its action in vivo. It has been stressed that its action is connected to the presence of NO, and the only reported/ hypothesized evidence concerns the possible interaction with GSNO (S-nitrosoglutathione), an NO releaser. In this light, we investigated the interaction between GSNO and the bisulfite in an aqueous medium at pH = 6.4; actually, a positive effect of the sulfite was evidenced. i.e., the S-nitrosoglutathione becomes a more efficient NO-releaser. But, the nitrite is the real pool of NO in vivo, therefore we investigate its interaction with the bisulfite in an aqueous acidic solution at pH = 6.4; this time, a definitely efficient and abundant NO release, 3.61 times higher compared to the GSNO, has been evidenced. Therefore, these results allow hypothesizing a fundamental role of NO in the bisulfite's action in vivo, or most probably the bisulfite acts simply as cofactor of NO-releasers.

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Free-radical chemistry of sulfite.

Cited by 274 publications

References 80 publications

New insights into the detection of sulfur trioxide anion radical by spin trapping: radical trapping versus nucleophilic addition

New insights into the detection of sulfur trioxide anion radical by spin trapping: radical trapping versus nucleophilic addition

Kinetics of Catalytic Oxidation of Sulfite in Diluted Aqueous Solutions

Nitric Oxide: Probably the <i>in Vivo</i> Mediator of the Bisulfite’s Effects

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Free-radical chemistry of sulfite.

Cited by 274 publications

References 80 publications

New insights into the detection of sulfur trioxide anion radical by spin trapping: radical trapping versus nucleophilic addition

New insights into the detection of sulfur trioxide anion radical by spin trapping: radical trapping versus nucleophilic addition

Kinetics of Catalytic Oxidation of Sulfite in Diluted Aqueous Solutions

Nitric Oxide: Probably the &lt;i&gt;in Vivo&lt;/i&gt; Mediator of the Bisulfite’s Effects

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Nitric Oxide: Probably the <i>in Vivo</i> Mediator of the Bisulfite’s Effects