Thermal Induced Homolytic Scissions of Lignin Interunitary Bonds in the Hardwood Lignin Solution. An Esr Study Combined With a Spin Trapping Method

Yoshioka, Aki; Seino, Teruyuki; Takai, Mitsuo; Tabata, Masayoshi

doi:10.1081/wct-100104223

Cited by 4 publications

(5 citation statements)

References 17 publications

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“…The content of these radicals in the wood sample with biodegradation time of 30 days was of 8 9 10 16 spins/g compared to a value of\1 9 10 16 spins/g in the control wood. The evolution of the singlet EPR signal is supportive of the homolytic destruction of lignin during biodegradation and is in line with the aforementioned literature (Yoshioka et al 2001) and personal experience (Dizhbite et al 2004;Telysheva et al 2007).…”

Section: Epr Spectroscopy Resultssupporting

confidence: 74%

“…This line was detected also for the sample in the absence of treatment with DMPO. The literature (Yoshioka et al 2001) and our own experience (Dizhbite et al 2004;Telysheva et al 2007) suggests that the singlet EPR signal can be attributed to the lignin-derived radicals including semiquinone radical-anions. The content of these radicals in the wood sample with biodegradation time of 30 days was of 8 9 10 16 spins/g compared to a value of\1 9 10 16 spins/g in the control wood.…”

Section: Epr Spectroscopy Resultsmentioning

confidence: 92%

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Characterisation of the initial degradation stage of Scots pine (Pinus sylvestris L.) sapwood after attack by brown-rot fungus Coniophora puteana

et al. 2011

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In our study, early period degradation (10 days) of Scots pine (Pinus sylvestris L.) sapwood by the brown-rot fungus Coniophora puteana (Schum.: Fr.) Karst. (BAM Ebw.15) was followed at the wood chemical composition and ultrastructure-level, and highlighted the generation of reactive oxygen species (ROS). An advanced decay period of 50 days was chosen for comparison of the degradation dynamics. Scanning UV microspectrophotometry (UMSP) analyses of lignin distribution in wood cells revealed that the linkages of lignin and polysaccharides were already disrupted in the early period of fungal attack. An increase in the lignin absorption A(280) value from 0.24 (control) to 0.44 in decayed wood was attributed to its oxidative modification which has been proposed to be generated by Fenton reaction derived ROS. The wood weight loss in the initial degradation period was 2%, whilst cellulose and lignin content decreased by 6.7% and 1%, respectively. Lignin methoxyl (-OCH3) content decreased from 15.1% (control) to 14.2% in decayed wood. Diffuse reflectance Fourier-transform infrared (DRIFT) spectroscopy corroborated the moderate loss in the hemicellulose and lignin degradation accompanying degradation. Electron paramagnetic resonance spectra and spin trapping confirmed the generation of ROS, such as hydroxyl radicals (HO∙), in the early wood degradation period. Our results showed that irreversible changes in wood structure started immediately after wood colonisation by fungal hyphae and the results generated here will assist in the understanding of the biochemical mechanisms of wood biodegradation by brown-rot fungi with the ultimate aim of developing novel wood protection methods.

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Section: Epr Spectroscopy Resultssupporting

confidence: 74%

Section: Epr Spectroscopy Resultsmentioning

confidence: 92%

Characterisation of the initial degradation stage of Scots pine (Pinus sylvestris L.) sapwood after attack by brown-rot fungus Coniophora puteana

et al. 2011

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“…The measured EPR spectra displayed the presence of the semiquinone radicals (narrow singlet signal with g~2Á0040) 20,19 and Mn 2+ ions (sextet with g~2Á002) in all chicken tissues under investigation ( Figure 2). The relative concentration of Mn 2+ ions in the tissues samples from the chickens that were fed a high dose of AA was reliably higher compared with date in the control group, in particular for the liver tissue (Table 3).…”

Section: Resultsmentioning

confidence: 96%

“…The integral intensities of the EPR spectra were obtained by evaluating their double integrals (DI EPR ) using the WIN EPR software (BRU). The relative concentration (c rel ) of paramagnetic species were calculated as c rel = DI EPR /DI EPR ref , where DI EPR and D IEPR ref represent double integrals found for chicken tissue samples and the reference sample supplied by BRUKER (a weak pitch sample for semiquinone radicals and Mn 2+ in MgO for Mn 2+ ions), respectively …”

Section: Methodsmentioning

confidence: 99%

“…The integral intensities of the EPR spectra were obtained by evaluating their double integrals (DI EPR ) using the WIN EPR software (BRU). The relative concentration (c rel ) of paramagnetic species were calculated as c rel = DI EPR 19,20 Morphological study For histological examination, 1-cm segments of intestinal samples (duodenum was taken 0Á5 cm distal to the ampulla of Vater and ileum 10 cm proximal to the ileocecal junction) were isolated from ten animals from each group and fixed in 10% neutral buffered formalin. Paraffin-embedded tissue was cut into 4-mm-thick sections and stained with haematoxylin-eosin and the periodic acid-Schiff (PAS) reagent.…”

Section: Electron Paramagnetic Resonance (Epr) Spectroscopymentioning

confidence: 99%

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Oxidative stress and innate immunity status in chickens exposed to high dose of ascorbic acid

Berzina

Markovs

Dizhbite

et al. 2013

Cell Biochemistry & Function

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The effects of high dose ascorbic acid (10 000 mg·kg(-1) in the diet) and the transition metal on the presence of oxidative stress in the internal organs of growing chicks, as well as on the innate immune system status, were investigated. Supplementation with a high dose of ascorbic acid had pro-inflammatory effects on the intestinal mucosa, and lysozyme levels were decreased significantly in all organs studied. High-dose ascorbic acid caused an imbalance between prooxidative and antioxidative activities and was associated with the generation of semiquinone radicals. We observed that ascorbic acid increased iron and cadmium absorption. When a high dose of ascorbic acid was applied, elevated kidney and intestinal mucosa iron concentrations were observed. The amount of free malondialdehyde in the above organs has increased as well. These data have important implications for the mechanism of the oxidative stress development under the influence of high dose of ascorbic acid, indicating the importance of the side reactions of the mitochondrial electron transport chain with the formation of semiquinone radicals and the role of transition metals in this process.

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Breaking Strong Alkynyl-Phenyl Bonds: Poly(para-phenylene ethynylene)s under Mechanical Stress

Elter,

Brosz,

Sucerquia

et al. 2024

J. Am. Chem. Soc.

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Stronger chemical bonds withstand higher mechanical forces; thus, the rupture of single bonds is preferred over the rupture of double or triple bonds or aromatic rings. We investigated bond scission in poly(dialkylp-phenylene ethynylene)s (PPEs), a fully conjugated polymer. In a scalebridging approach using electron-paramagnetic resonance spectroscopy and gel permeation chromatography of cryomilled samples, in combination with density functional theory calculations and coarse-grained simulations, we conclude that mechanical force cleaves the sp−sp 2 bond of PPEs (bond dissociation energy as high as 600 kJ mol −1 ). Bond scission primarily occurs in shear bands with locally increased shear stresses. The scission occurs in the middle of the PPE chains. Breaking sp−sp 2 bonds into free radicals thus is feasible but requires significant mechanical force and an efficient stress concentration.

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Thermal Induced Homolytic Scissions of Lignin Interunitary Bonds in the Hardwood Lignin Solution. An Esr Study Combined With a Spin Trapping Method

Cited by 4 publications

References 17 publications

Characterisation of the initial degradation stage of Scots pine (Pinus sylvestris L.) sapwood after attack by brown-rot fungus Coniophora puteana

Characterisation of the initial degradation stage of Scots pine (Pinus sylvestris L.) sapwood after attack by brown-rot fungus Coniophora puteana

Oxidative stress and innate immunity status in chickens exposed to high dose of ascorbic acid

Breaking Strong Alkynyl-Phenyl Bonds: Poly(para-phenylene ethynylene)s under Mechanical Stress

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