Reaction pathways involved in the production of hydroxyl radicals in thylakoid membrane: EPR spin-trapping study

2006 ◽  
Vol 5 (5) ◽  
pp. 472-476 ◽  
Author(s):  
Iva Šnyrychová ◽  
Pavel Pospíšil ◽  
Jan Nauš
Keyword(s):  
Hydroxyl Radicals ◽  
Thylakoid Membrane ◽  
Spin Trapping ◽  
Reaction Pathways ◽  
Epr Spin Trapping

The photodegradation of model quinolone carboxylates in aqueous media

2014 ◽  
Vol 7 (1) ◽  
pp. 1-8
Author(s):  
Miroslava Bobeničová ◽  
Andrea Čaklóšová ◽  
Dana Dvoranová
Keyword(s):  
Titanium Dioxide ◽  
Hydroxyl Radicals ◽  
Aqueous Media ◽  
Spin Trapping ◽  
Alkaline Media ◽  
Uva Irradiation ◽  
Epr Spin Trapping ◽  
Photoinduced Processes

Abstract This work was focused on the study of photoinduced processes of quinolone carboxylates in the presence of titanium dioxide in an alkaline media. UVA irradiation without/with titanium dioxide caused the decomposition of molecules, with higher efficiency of degradation in the presence of titanium dioxide. EPR spin trapping experiments proved that investigated quinolone carboxylates behave as the efficient scavengers of hydroxyl radicals produced upon irradiation of aerated alkaline titanium dioxide systems.

Enhancement of hydroxyl radical generation by phenols and their reaction intermediates during ozonation

1998 ◽  
Vol 38 (6) ◽  
pp. 147-154 ◽  
Author(s):  
Hideo Utsumi ◽  
Sang-Kuk Han ◽  
Kazuhiro Ichikawa
Keyword(s):  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Spin Trapping ◽  
Active Species ◽  
Generation Rate ◽  
Peak Height Ratio ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Phenol Derivatives ◽  
Semiquinone Radicals

Generation of hydroxyl radicals, one of the major active species in ozonation of water was directly observed with a spin-trapping/electron spin resonance (ESR) technique using 5,5-dimethyl-1-pyrrolineN-oxide (DMPO) as a spin-trapping reagent. Hydroxyl radical were trapped with DMPO as a stable radical, DMPO-OH. Eighty μM of ozone produced 1.08 X 10-6M of DMPO-OH, indicating that 1.4% of •OH is trapped with DMPO. Generation rate of DMPO-OH was determined by ESR/stopped-flow measurement. Phenol derivatives increased the amount and generation rate of DMPO-OH, indicating that phenol derivatives enhance •OH generation during ozonation of water. Ozonation of 2,3-, 2,5-, 2,6-dichlorophenol gave an ESR spectra of triplet lines whose peak height ratio were 1:2:1. ESR parameters of the triplet lines agreed with those of the corresponding dichloro-psemiquinone radical. Ozonation of 2,4,5- and 2,4,6-trichlorophenol gave the same spectra as those of 2,5- and 2,6-dichlorophenol, respectively, indicating that a chlorine group in p-position is substituted with a hydroxy group during ozonation. Amounts of the radical increased in an ozone-concentration dependent manner and were inhibited by addition of hydroxyl radical scavengers. These results suggest that p-semiquinone radicals are generated from the chlorophenols by hydroxyl radicals during ozonation. The p-semiquinone radicals were at least partly responsible for enhancements of DMPO-OH generation.

Photoredox Reactions of Iodo Iron(III) Complexes Containing Tetradentate Ligands

2001 ◽  
Vol 66 (1) ◽  
pp. 109-118 ◽  
Author(s):  
Jozef Šima ◽  
Dáša Lauková ◽  
Vlasta Brezová
Keyword(s):  
Schiff Bases ◽  
Spin Trapping ◽  
Molar Ratio ◽  
Oh Radicals ◽  
Solvated Electrons ◽  
Open Chain ◽  
Tetradentate Ligands ◽  
Visible Irradiation ◽  
Epr Spin Trapping ◽  
Spin Trapping Technique

Photoredox reactions occurring in irradiated methanolic solutions of trans-[FeIII(R,R'-salen)(CH3OH)I], where R,R'-salen2- are N,N'-ethylenebis(R,R'-salicylideneiminato), tetradentate open-chain N2O2-Schiff bases with R,R' = H, 5-Cl, 5-Br, 3,5-di-Br, 3,5-di-(CH3), 3-OCH3, 5-OCH3, have been investigated and their mechanism proposed. The complexes are redox-stable in the dark. Ultraviolet and/or visible irradiation of methanolic solution of the complexes induces photoreduction of Fe(III) to Fe(II). Depending on the composition of the irradiated solutions, •CH2OH radicals or solvated electrons were identified by the EPR spin trapping technique. The final product of the photooxidation coupled with the photoreduction of Fe(III) is formaldehyde and the molar ratio of Fe(II) and CH2O is close to 2 : 1. The efficiency of the photoredox process is strongly wavelength-dependent and influenced by the peripheral groups R,R' of the tetradentate ligands.

Microwave Induced Free Radicals Production in Red Wine and Model Wine by EPR Spin Trapping

2021 ◽  
Author(s):  
Jiangfeng Yuan ◽  
Zhuoyao Chen ◽  
Dahong Wang ◽  
Minggui Gong ◽  
Zhijun Qiu
Keyword(s):  
Free Radicals ◽  
Red Wine ◽  
Spin Trapping ◽  
Epr Spin Trapping
Sign in / Sign up

Export Citation Format

Share Document