Reactions of Alkoxy Radicals in Aqueous Solutions

Bors, Wolf; Tait, David S.; Michel, Christa; Sarán, Manfred; Erben‐Russ, Michael

doi:10.1002/ijch.198400003

Cited by 39 publications

(19 citation statements)

References 114 publications

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“…H + /-BuOOH CH2C(CH3)2OOH + H2 (17) OH + /-BuOOH -» t-BuOO + H 20 (18) OH + /-BuOOH -* CH2C(CH3)2OOH + H20 (19) The form ation of the /-butoxyl radical /-BuO can be m onitored by product analysis since it de composes very rapidly (/1/2 ~ 1 //s [21,22]) into acetone, the key product for this study, and a methyl radical (reaction (21)). These radicals are also produced in a bimolecular decay (reaction (20)) o f the /-butylperoxyl radicals.…”

Section: Resultsmentioning

confidence: 99%

“…The term ination rate constants of C H 2C (C H 3)2OOH and t-BuOO were assumed to represent diffusion control (reac- tions (32) and (33)) except for the self-termination of /-BuOO' which was taken at 2.5 * 104 dm 3 m ol-1 s"1 [33]. The situation to be modeled is com plicat ed; upon term ination o f peroxyl radicals with each other, some oxygen is formed that reacts with C H 2C (C H 3)2OOH; methyl radicals from reac tion (21) are also present.…”

Section: Chain Reaction Upon O H Radical Attackmentioning

confidence: 99%

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Radiolysis of Tertiary Butyl Hydroperoxide in Aqueous Solution. Reductive Cleavage by the Solvated Electron, the Hydrogen Atom, and, in Particular, the Superoxide Radical Anion

Phulkar

Rao

Schuchmann

et al. 1990

Zeitschrift Für Naturforschung B

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The reactions o f the solvated electron, the H atom, the OH radical and the superoxide radi cal anion with /-butylhydroperoxide (/-BuOOH) have been studied in aqueous solutions using y-radiolysis and pulse radiolysis to generate these radicals.The solvated electron reacts rapidly with r-BuOOH (k = 5 x 109 dm 3 m ol" 1 s~') yielding /-BuO ' and OH in a ratio o f 4:1. The yield o f r-BuO' has been determined by measuring its fragmentation product, acetone.The H atom reacts more slowly with r-BuOOH (k = 5x 107 dm 3 m o l-1 s"1). There is very little H-abstraction from the methyl and the hydroperoxyl groups (about 3%), the main reac tion again being the scission o f the hydroperoxyl function with a branching ratio /-BuO'/'OH o f about unity.The OH radical reacts with /-BuOOH considerably more slowly (k = 8 x 107 dm3 m o l" 1 s ' 1) than with /-butanol (k = 5 X 108 dm3 m o l-1 s"1) with an approximate preference o f 8:1 o f ab stracting a methyl hydrogen over a hydroperoxyl hydrogen atom. The carbon-centered radical undergoes y-cleavage (k ~ 102 s"1) thereby reforming an OH radical. The resulting chain reac tion is rather short (maximum yield G (2-methyl-1,2-epoxypropane), 26 x 10"7 mol / ' at low dose rate) due to H-abstraction at the hydroperoxyl function o f r-BuOOH by the OH radical.The superoxide radical anion also reacts with /-BuOOH by cleaving the hydroperoxyl func tion. Its reactivity is, however, rather low (k = 5 dm3 m ol" 1 s"1).

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Section: Resultsmentioning

confidence: 99%

Section: Chain Reaction Upon O H Radical Attackmentioning

confidence: 99%

Radiolysis of Tertiary Butyl Hydroperoxide in Aqueous Solution. Reductive Cleavage by the Solvated Electron, the Hydrogen Atom, and, in Particular, the Superoxide Radical Anion

Phulkar

Rao

Schuchmann

et al. 1990

Zeitschrift Für Naturforschung B

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“…130 The chemical reactivity of ROO and RO is determined by their a-substituents. 130,142,143 The reaction of O 2 À with NO yields the strong oxidant peroxynitrite, ONOO À (Scheme 1, reaction 8), which can react with wide array of biological entities, including DNA and proteins. 144,145 Protonation of ONOO À forms peroxynitrous acid, which can undergo homolytic cleavage to form OH and nitrogen dioxide (Scheme 1, reaction 9b).…”

Section: Nature and Properties Of Rosmentioning

confidence: 99%

Proteolysis and Oxidation of Therapeutic Proteins After Intradermal or Subcutaneous Administration

Varkhede

Bommana

Schöneich

et al. 2020

Journal of Pharmaceutical Sciences

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Keywords:intradermal subcutaneous therapeutic proteins PBPK modeling reactive oxygen species proteolysis oxidation lymphatic system a b s t r a c tThe intradermal (ID) and subcutaneous (SC) routes are commonly used for therapeutic proteins (TPs) and vaccines; however, the bioavailability of TPs is typically less than small molecule drugs given via the same routes. Proteolytic enzymes in the dermal, SC, and lymphatic tissues may be responsible for the loss of TPs. In addition, the TPs may be exposed to reactive oxygen species generated in the SC tissue and the lymphatic system in response to injection-related trauma and impurities within the formulation. The reactive oxygen species can oxidize TPs to alter their efficacy and immunogenicity potential. Mechanistic understandings of the dominant proteolysis and oxidative routes are useful in the drug discovery process, formulation development, and to assess the potential for immunogenicity and altered pharmacokinetics (PK). Furthermore, in vitro tools representing the ID or SC and lymphatic system can be used to evaluate the extent of proteolysis of the TPs after the injection and before systemic entry. The in vitro clearance data may be included in physiologically based pharmacokinetic models for improved PK predictions. In this review, we have summarized various physiological factors responsible for proteolysis and oxidation of TPs after ID and SC administration.

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“…The spin trapping of secondary alkoxyl radicals in aqueous systems has proven difficult, apparently because of their rapid cyclization. However, product analysis and spin-trapping investigations have demonstrated that fatty acid alkoxyl radicals undergo intramolecular epoxidation [10,14,15,18], β-scission [15,18,19] and intermolecular reactions [20].…”

Section: Introductionmentioning

confidence: 99%

Detection of free radicals produced from the reaction of cytochrome P-450 with linoleic acid hydroperoxide

Rota

Barr

Martin

et al. 1997

Biochemical Journal

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The ESR spin-trapping technique was employed to investigate the reaction of rabbit cytochrome P-450 1A2 (P450) with linoleic acid hydroperoxide. This system was compared with chemical systems where FeSO4 or FeCl3 was used in place of P450. The spin trap 5, 5'-dimethyl-1-pyrroline N-oxide (DMPO) was employed to detect and identify radical species. The DMPO adducts of hydroxyl, O2-., peroxyl, methyl and acyl radicals were detected in the P450 system. The reaction did not require NADPH-cytochrome P-450 reductase or NADPH. The same DMPO-radical adducts were detected in the FeSO4 system. Only DMPO-.OH radical adduct and carbon-centred radical adducts were detected in the FeCl3 system. Peroxyl radical production was completely O2-dependent. We propose that polyunsaturated fatty acids are initially reduced to form alkoxyl radicals, which then undergo intramolecular rearrangement to form epoxyalkyl radicals. Each epoxyalkyl radical reacts with O2, forming a peroxyl radical. Subsequent unimolecular decomposition of this peroxyl radical eliminates O2-. radical.

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Reactions of Alkoxy Radicals in Aqueous Solutions

Cited by 39 publications

References 114 publications

Radiolysis of Tertiary Butyl Hydroperoxide in Aqueous Solution. Reductive Cleavage by the Solvated Electron, the Hydrogen Atom, and, in Particular, the Superoxide Radical Anion

Radiolysis of Tertiary Butyl Hydroperoxide in Aqueous Solution. Reductive Cleavage by the Solvated Electron, the Hydrogen Atom, and, in Particular, the Superoxide Radical Anion

Proteolysis and Oxidation of Therapeutic Proteins After Intradermal or Subcutaneous Administration

Detection of free radicals produced from the reaction of cytochrome P-450 with linoleic acid hydroperoxide

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