Kinetics of Free Radical Reactions of Some Biologically Important Compounds as Studied by Pulse Radiolysis

Adhikari, Soumyakanti; Mukherjee, Tulsi

doi:10.3184/007967401103165307

Cited by 7 publications

(4 citation statements)

References 90 publications

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“…Formation of the Cβ-radical product complex is weakly exothermic by 3.5 kJ mol −1 and is associated with a slightly higher barrier than for HAT from Cα, suggesting that this pathway should be only a minor contributor. While Trp is readily oxidizable (Trp: E ° = 1.02 V vs. NHE at pH 7), 8 the spin densities and Mulliken charges for the thermodynamically feasible reactions at Cα and Cβ did not reveal accumulation of negative charge on the MeOO fragment (see Fig. S8†), suggesting a HAT process without ET contributions.…”

Section: Resultsmentioning

confidence: 99%

“…6 Thus, alkyl peroxyl radicals should therefore be principally able to remove an electron from amino acids with readily oxidizable side chains, for example tyrosine ( E ° = 0.93 V vs. NHE at pH 7). 7 However, since ‘plain’ alkyl peroxyl radicals lack a characteristic UV absorption band that would enable direct absorption measurements, 8 kinetic studies have most commonly been performed by either monitoring the decay of ROO˙ using EPR spectroscopy or through observing the appearance of reaction transients using optical spectroscopy. 9 Thus, for the reaction of MeOO˙ with the water-soluble antioxidant ascorbate a rate coefficient of 1–2 × 10 6 M −1 s −1 has been determined at pH = 7.4, 10 which is about one order of magnitude faster than the value obtained for the reaction with α-tocopherol (9.4 × 10 4 M −1 s −1 for HOCH 2 CH 2 OO˙).…”

Section: Introductionmentioning

confidence: 99%

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Damage of amino acids by aliphatic peroxyl radicals: a kinetic and computational study

et al. 2023

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Damage of amino acids by aliphatic peroxyl radicals: a kinetic and computational study

et al. 2023

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“…The pulse radiolysis system with 7 MeV electrons was used in the present study (Adhikari & Mukherjee, 2002). The dosimetry was carried out using an air-saturated aqueous solution containing 5 × 10 −2 mol dm −3 KSCN (Gε = 23,889 dm 3 mol −1 cm −1 per 100 eV at 500 nm) (Buxton & Stuart, 1995).…”

Section: Abts Radical Scavenging Assay By Pulse Radiolysismentioning

confidence: 99%

Evaluation of free radical scavenging activity of morel mushroom,Morchella esculentamycelia: A potential source of therapeutically useful antioxidants

Nitha

Adhikari

et al. 2010

Pharmaceutical Biology

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“…A variety of studies in the past have made noteworthy contributions to the understanding of the electron processes in reverse micelles and microemulsions. Kinetic evidence had shown earlier that the location of the probes in reverse micelles plays an important role in their reactivities .…”

Section: Introductionmentioning

confidence: 99%

Generation of Counter Ion Radical (Br₂^•–) and Its Reactions in Water-in-Oil (CTAB or CPB)/n-Butanol/Cyclohexane/Water) Microemulsion

et al. 2011

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Herein we report the generation of counterion radicals and their reactions in quaternary water-in-oil microemulsion. Hydrated electrons in the microemulsion CTAB/H(2)O/n-butanol/cyclohexane have a remarkably short half-life (∼1 μs) and lower yield as compared to that in the pure water system. Electrons are solvated in two regions: one is the water core and other the interface; however, the electrons in the water core have a shorter half-life than those in the interface. The decay of the solvated electrons in the interface is found to be water content dependent and it has been interpreted in terms of increased interfacial fluidity with the increase in water content of the microemulsion. Interestingly another species, dibromide radical anion (Br(2)(•-)) in CTAB and CPB microemulsions have been observed after the electron beam irradiation. Assuming that the extinction coefficient of the radicals is the same as that in the aqueous solution, the yields of the radicals per 100 eV are 0.29 and 0.48 for the Br(2)(•-) radical in CTAB and CPB containing microemulsions (W(0) = 40), respectively, under N(2)O saturated conditions. Further, we intended to study electron transfer reactions, which occur at and through the interface. The reaction of the Br(2)(•-) radical anion with ABTS [2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)] has been studied to generate the ABTS radical in the water core, and further, its reaction has been investigated with the water-insoluble molecule vitamin E (tocopherol) and water-soluble vitamin C (ascorbic acid). In the present study, we were able to show that, even for molecules which are completely insoluble in water, ABTS scavenging assay is possible by pulse radiolysis technique. Furthermore, these results show that it is possible to follow the reaction of the hydrated inorganic radical with solutes dissolved in the organic phase in a microemulsion without use of a phase transfer catalyst.

show abstract

Kinetics of Free Radical Reactions of Some Biologically Important Compounds as Studied by Pulse Radiolysis

Cited by 7 publications

References 90 publications

Damage of amino acids by aliphatic peroxyl radicals: a kinetic and computational study

Damage of amino acids by aliphatic peroxyl radicals: a kinetic and computational study

Evaluation of free radical scavenging activity of morel mushroom,Morchella esculentamycelia: A potential source of therapeutically useful antioxidants

Generation of Counter Ion Radical (Br₂^•–) and Its Reactions in Water-in-Oil (CTAB or CPB)/n-Butanol/Cyclohexane/Water) Microemulsion

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Kinetics of Free Radical Reactions of Some Biologically Important Compounds as Studied by Pulse Radiolysis

Cited by 7 publications

References 90 publications

Damage of amino acids by aliphatic peroxyl radicals: a kinetic and computational study

Damage of amino acids by aliphatic peroxyl radicals: a kinetic and computational study

Evaluation of free radical scavenging activity of morel mushroom,Morchella esculentamycelia: A potential source of therapeutically useful antioxidants

Generation of Counter Ion Radical (Br2•–) and Its Reactions in Water-in-Oil (CTAB or CPB)/n-Butanol/Cyclohexane/Water) Microemulsion

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Generation of Counter Ion Radical (Br₂^•–) and Its Reactions in Water-in-Oil (CTAB or CPB)/n-Butanol/Cyclohexane/Water) Microemulsion