Past work has shown that the extracellular manganese-dependent peroxidases (MnPs) of ligninolytic fungi degrade the principal non-phenolic structures of lignin when they peroxidize unsaturated fatty acids. This reaction is likely to be relevant to ligninolysis in sound wood, where enzymes cannot penetrate, only if it employs a small, diffusible lipid radical as the proximal oxidant of lignin. Here we show that a non-phenolic beta-O-4-linked lignin model dimer was oxidized to products indicative of hydrogen abstraction and electron transfer by three different peroxyl radical-generating systems: (a) MnP/Mn(II)/linoleic acid, (b) arachidonic acid in which peroxidation was initiated by a small amount of H(2)O(2)/Fe(II), and (c) the thermolysis in air of either 4,4'-azobis(4-cyanovaleric acid) or 2,2'-azobis(2-methylpropionamidine) dihydrochloride. Some quantitative differences in the product distributions were found, but these were attributable to the presence of electron-withdrawing substituents on the peroxyl radicals derived from azo precursors. Our results introduce a new hypothesis: that biogenic peroxyl radicals may be agents of lignin biodegradation.
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http://dx.doi.org/10.1016/s0014-5793(99)01432-5 | DOI Listing |
Microvasc Res
January 2025
University of South Florida, Morsani College of Medicine, James A Haley Veterans' Hospital, United States of America. Electronic address:
Intestinal ischemia-reperfusion (I/R) injury occurs under various surgical or disease conditions, where tissue hypoxia followed by reoxygenation results in the production of oxygen radicals and inflammatory mediators. These substances can target the endothelial barrier, leading to microvascular leakage. In this study, we induced intestinal I/R injury in mice by occluding the superior mesenteric artery, followed by removing the clamp to resume blood circulation.
View Article and Find Full Text PDFRedox Biol
January 2025
Free Radical and Radiation Biology Program, Department of Radiation Oncology, Holden Comprehensive Cancer Center, The University of Iowa College of Medicine, Iowa City, IA 52242, USA; Interdisciplinary Graduate Program in Human Toxicology, The University of Iowa, Iowa City, IA, 52242, USA.
Differences in cancer and normal cell oxidative metabolism provide a unique therapeutic opportunity for developing combined modality approaches with redox-active small molecules as radio-chemosensitizers that are well-tolerated by normal tissues. Pentaazamacrocyclic Mn (II)-containing (MnPAM) superoxide dismutase (SOD) mimetics and pharmacological ascorbate given IV to achieve [mM] plasma levels (pharmacological ascorbate: P-AscH‾) have been shown to act individually as cancer cell radio- and chemosensitizers via the generation of HOin vivo. The current study shows that the combination of newly developed MnPAM dismutase mimetic, rucosopasem manganese (RUC) with P-AscH‾ radio-sensitizes non-small cell lung cancer cells (NSCLC) and increases steady state levels of intracellular HO with no additional toxicity to normal human bronchial epithelial cells (HBECs).
View Article and Find Full Text PDFChem Sci
January 2025
Instituto de Carboquímica (ICB-CSIC) C/Miguel Luesma Castán 4 E-50018 Zaragoza Spain
Fluorescent nitrogen-doped carbon dots (N-GQDs) with long-wavelength emission properties are of increased interest for technological applications. They are widely synthesized through the solvothermal treatment of graphene oxide (GO) using ,-dimethylformamide (DMF) as a cleaving and doping agent. However, this process simultaneously generates undesired interfering blue-emissive by-products.
View Article and Find Full Text PDFInt J Pharm
January 2025
The Comprehensive Breast Care Center, The Second Affiliated Hospital of Xi'an Jiaotong University, No.157 Xiwu Road, Xi'an, Shaanxi 710004, China. Electronic address:
Both photothermal therapy (PTT) and chemodynamic therapy (CDT) are designed to focus their antitumor effect on only the tumor site, thereby minimizing unwanted severe damage to healthy tissue outside the tumor. However, each monotherapy is limited in achieving complete tumor eradication, resulting in tumor recurrence. The combination of multiple therapies may help to overcome the limitations of single therapy, improve the chances of complete tumor eradication, and reduce the risk of recurrence.
View Article and Find Full Text PDFBackground: The photothermal sensitivity of tobacco refers to how tobacco plants respond to variations in the photothermal conditions of their growth environment. The degree of this sensitivity is crucial for determining the optimal planting regions for specific varieties, as well as for improving the quality and yield of tobacco leaves. However, the precise mechanisms underlying the development of photothermal sensitivity in tobacco remain unclear.
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