Free Radicals and Inhalation Pathology

Schiller, Erich

doi:10.1007/978-3-642-18619-6

Cited by 7 publications

(4 citation statements)

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“…4) revealed some oxidative potential for both, although more for Fe 2ϩ , supported by a carbonylation assessment that indicated more ROS-based oxidative damage (42) in bulk enzyme extracts in T. reesei than in P. placenta (Table 1). This might reflect some potential for Fe 2ϩ to auto-oxidize in the presence of molecular oxygen, leading to the production of HO˙in the absence of H 2 O 2 (43). Collectively, these analyses imply that our treatments generated oxidative stress when Fenton reactants were present and that P. placenta enzyme activities were more robustly tolerant to this stress than those of T. reesei.…”

Section: Resultsmentioning

confidence: 79%

Oxidative Damage Control during Decay of Wood by Brown Rot Fungus Using Oxygen Radicals

Castaño

Zhang

Anderson

et al. 2018

Appl Environ Microbiol

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Brown rot wood-degrading fungi deploy reactive oxygen species (ROS) to loosen plant cell walls and enable selective polysaccharide extraction. These ROS, including Fenton-generated hydroxyl radicals (HO˙), react with little specificity and risk damaging hyphae and secreted enzymes. Recently, it was shown that brown rot fungi reduce this risk, in part, by differentially expressing genes involved in HO˙ generation ahead of those coding carbohydrate-active enzymes (CAZYs). However, there are notable exceptions to this pattern, and we hypothesized that brown rot fungi would require additional extracellular mechanisms to limit ROS damage. To assess this, we grew directionally on wood wafers to spatially segregate early from later decay stages. Extracellular HO˙ production (avoidance) and quenching (suppression) capacities among the stages were analyzed, along with the ability of secreted CAZYs to maintain activity postoxidation (tolerance). First, we found that HO and Fe concentrations in the extracellular environment were conducive to HO˙ production in early (HO:Fe ratio 2:1) but not later (ratio 1:131) stages of decay. Second, we found that ABTS radical cation quenching (antioxidant capacity) was higher in later decay stages, coincident with higher fungal phenolic concentrations. Third, by surveying enzyme activities before/after exposure to Fenton-generated HO˙, we found that CAZYs secreted early, amid HO˙, were more tolerant of oxidative stress than those expressed later and were more tolerant than homologs in the model CAZY producer Collectively, this indicates that uses avoidance, suppression, and tolerance mechanisms, extracellularly, to complement intracellular differential expression, enabling this brown rot fungus to use ROS to degrade wood. Wood is one of the largest pools of carbon on Earth, and its decomposition is dominated in most systems by fungi. Wood-degrading fungi specialize in extracting sugars bound within lignin, either by removing lignin first (white rot) or by using Fenton-generated reactive oxygen species (ROS) to "loosen" wood cell walls, enabling selective sugar extraction (brown rot). Although white rot lignin-degrading pathways are well characterized, there are many uncertainties in brown rot fungal mechanisms. Our study addressed a key uncertainty in how brown rot fungi deploy ROS without damaging themselves or the enzymes they secrete. In addition to revealing differentially expressed genes to promote ROS generation only in early decay, our study revealed three spatial control mechanisms to avoid/tolerate ROS: (i) constraining Fenton reactant concentrations (HO, Fe), (ii) quenching ROS via antioxidants, and (iii) secreting ROS-tolerant enzymes. These results not only offer insight into natural decomposition pathways but also generate targets for biotechnological development.

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Section: Resultsmentioning

confidence: 79%

Oxidative Damage Control during Decay of Wood by Brown Rot Fungus Using Oxygen Radicals

Castaño

Zhang

Anderson

et al. 2018

Appl Environ Microbiol

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“…The second order rate constant is 2.1 (±0.34) × 10 7 M –1 s –1 at pH 8.0 (SI) for the reaction between 1 O 2 and APAP, and it is 6.3(±1.0) × 10 7 M –1 s –1 for the reaction between 1 O 2 and TMP at pH 8.0 . Combined with the low steady-state concentration of 1 O 2 , it was expected that the transformations of both APAP and TMP would be only slightly inhibited by NaN 3 , which is normally used to quench 1 O 2 and •OH with high rate constants (2.2 × 10 9 and 1.0 × 10 10 M –1 s –1 for 1 O 2 and •OH). , As the contribution of •OH to the transformation of PhOH was small, the results indicated that 1 O 2 contributed little to the photosensitized transformation of phenol in aerated HA solution. Li et al also observed that 1 O 2 contributed little to the transformation of APAP in other NOM solutions.…”

Section: Resultsmentioning

confidence: 99%

Contribution of the Excited Triplet State of Humic Acid and Superoxide Radical Anion to Generation and Elimination of Phenoxyl Radical

Chen

Zhang

2018

Environ. Sci. Technol.

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Contributions of excited triplet state of humic acid (HA*) and superoxide radical anion (O), which is mainly generated via the reaction of O with HA-derived reducing intermediates (HA), to phenol transformation were revealed using acetaminophen, 2,4,6-trimethylphenol and tyrosine as probe molecules. Phenol transformation was initiated by HA*, leading to the formation of the phenoxyl radical (PhO•), but the distribution of transformation intermediates was codetermined byHA* and HA. The influence of HA essentially resulted from the production of O, which affected the fate of PhO•. PhO• could undergo dimerization, or react with O, leading to either phenol peroxide formation (radical addition) or phenol regeneration (electron transfer). In addition, PhO• could bind to HA or react with HA radicals, particularly in the absence of O and O. These PhO• reactions were dependent on the reduction potential and structure of PhO•. This study also proved that the reaction of phenol with O and the reaction of PhO• with O lead to the same oxidation product. The contributions of HA* and its generatedO, HA and its generated O to phenol transformation were pH-dependent.

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“…Recent discoveries on non-neuronal cholinergic system as a regulator of skin (patho)physiology have drawn attention to the importance of acetylcholinesterase (AChE) in the human skin 57 , 58 . Apart from the extensively known role of AChE in the termination of nerve impulse transmission at the cholinergic synapses by rapid hydrolysis of the neurotransmitter acethylcholine, the rationale underlying the use of AChE inhibitors in the symptomatic treatment of Alzheimer’s disease 59 , 60 .…”

Section: Discussionmentioning

confidence: 99%

Screening the dermatological potential of Plectranthus species components: antioxidant and inhibitory capacities over elastase, collagenase and tyrosinase

Andrade

Domínguez-Martín

Nicolai

et al. 2020

Journal of Enzyme Inhibition and Medicinal Chemistry

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Free Radicals and Inhalation Pathology

Cited by 7 publications

References 0 publications

Oxidative Damage Control during Decay of Wood by Brown Rot Fungus Using Oxygen Radicals

Oxidative Damage Control during Decay of Wood by Brown Rot Fungus Using Oxygen Radicals

Contribution of the Excited Triplet State of Humic Acid and Superoxide Radical Anion to Generation and Elimination of Phenoxyl Radical

Screening the dermatological potential of Plectranthus species components: antioxidant and inhibitory capacities over elastase, collagenase and tyrosinase

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