Role of hydroxyl radicals and trapped holes in photocatalysis. A pulse radiolysis study

1991 ◽  
Vol 95 (13) ◽  
pp. 5166-5170 ◽  
Author(s):  
D. Lawless ◽  
N. Serpone ◽  
D. Meisel
Keyword(s):  
Hydroxyl Radicals ◽  
Pulse Radiolysis

scholarly journals Cisplatin-induced hydroxyl radicals mediate pro-survival autophagy in human lung cancer H460 cells

2021 ◽  
Vol 54 (1) ◽  
Author(s):  
Somruethai Sumkhemthong ◽  
Eakachai Prompetchara ◽  
Pithi Chanvorachote ◽  
Chatchai Chaotham
Keyword(s):  
Lung Cancer ◽  
Hydroxyl Radicals ◽  
Human Lung ◽  
Human Lung Cancer ◽  
Radical Scavenger ◽  
Apoptosis Resistance ◽  
Lung Cancer Patients ◽  
Human Lung Cancer Cells ◽  
H460 Cells

Abstract Background Accumulated evidence demonstrates cisplatin, a recommended chemotherapy, modulating pro-survival autophagic response that contributes to treatment failure in lung cancer patients. However, distinct mechanisms involved in cisplatin-induced autophagy in human lung cancer cells are still unclear. Results Herein, role of autophagy in cisplatin resistance was indicated by a decreased cell viability and increased apoptosis in lung cancer H460 cells pre-incubated with wortmannin, an autophagy inhibitor, prior to treatment with 50 µM cisplatin for 24 h. The elevated level of hydroxyl radicals detected via flow-cytometry corresponded to autophagic response, as evidenced by the formation of autophagosomes and autolysosomes in cisplatin-treated cells. Interestingly, apoptosis resistance, autophagosome formation, and the alteration of the autophagic markers, LC3-II/LC3-I and p62, as well as autophagy-regulating proteins Atg7 and Atg3, induced by cisplatin was abrogated by pretreatment of H460 cells with deferoxamine, a specific hydroxyl radical scavenger. The modulations in autophagic response were also indicated in the cells treated with hydroxyl radicals generated via Fenton reaction, and likewise inhibited by pretreatment with deferoxamine. Conclusions In summary, the possible role of hydroxyl radicals as a key mediator in the autophagic response to cisplatin treatment, which was firstly revealed in this study would benefit for the further development of novel therapies for lung cancer.

ChemInform Abstract: Palladium Catalyzed Csp2-H Activation for Direct Aryl Hydroxylation: The Unprecedented Role of 1,4-Dioxane as a Source of Hydroxyl Radicals.

ChemInform ◽  
2015 ◽  
Vol 46 (22) ◽  
pp. no-no
Author(s):  
Kapileswar Seth ◽  
Manesh Nautiyal ◽  
Priyank Purohit ◽  
Naisargee Parikh ◽  
Asit K. Chakraborti
Keyword(s):  
Hydroxyl Radicals ◽  
Palladium Catalyzed

Key Role of Equilibrium HONO Concentration over the Soil 

2021 ◽  
Author(s):  
Fengxia Bao ◽  
Hang Su ◽  
Uwe Kuhn ◽  
Yafang Cheng
Keyword(s):  
Gas Phase ◽  
Hydroxyl Radicals ◽  
Nitrous Acid ◽  
Measurement Method ◽  
Oxidative Capacity ◽  
Sources And Sinks ◽  
Dynamic Chamber ◽  
Open Question ◽  
Actinic Radiation

<p>Nitrous acid (HONO) is an important component of the nitrogen cycle. HONO can also be rapidly photolyzed by actinic radiation to form hydroxyl radicals (OH) and exerts a primary influence on the oxidative capacity of the atmosphere. The sources and sinks of HONO, however, are not fully understood. Soil nitrite, produced via nitrification or denitrification, is an important source for the atmospheric HONO production. [HONO]*, the equilibrium gas phase HONO concentration over the soil, has been suggested as key to understanding the environmental effects of soil fluxes of HONO (Su et al., 2011). But if and how [HONO]* may exist and vary remains an open question. In this project, a measurement method using a dynamic chamber has been developed to derive [HONO]* and the atmospheric soil fluxes of HONO can accordingly be quantified. We demonstrate the existence of [HONO]* and determine its variation in the course of soil drying processes. We show that when [HONO]* is higher than the atmospheric HONO concentration, HONO will be released from soil; otherwise, HONO will be deposited on soil. This work advances the understanding of soil HONO emissions, and the evaluation of its impact on the atmospheric oxidizing capacity and the nitrogen cycling.</p>

The role of alkoxy radicals in the heterogeneous reaction of two structural isomers of dimethylsuccinic acid

2015 ◽  
Vol 17 (38) ◽  
pp. 25309-25321 ◽  
Author(s):  
Chiu Tung Cheng ◽  
Man Nin Chan ◽  
Kevin R. Wilson
Keyword(s):  
Molecular Weight ◽  
Hydroxyl Radicals ◽  
Heterogeneous Reaction ◽  
Methyl Groups ◽  
Structural Isomers ◽  
Alkoxy Radicals ◽  
Weight Growth ◽  
Bond Scission

The heterogeneous reaction of hydroxyl radicals with two isomers of dimethylsuccinic acid is used to explore how the location of branched methyl groups controls C–C bond scission and molecular weight growth reactions.

Deamination of β-alanine induced by hydroxyl radicals and monovalent copper ions. A pulse radiolysis study

1992 ◽  
Vol 192 (1) ◽  
pp. 87-93 ◽  
Author(s):  
Sara Goldstein ◽  
Gidon Czapski ◽  
Haim Cohen ◽  
Dan Meyerstein
Keyword(s):  
Hydroxyl Radicals ◽  
Pulse Radiolysis ◽  
Copper Ions

Effects of free radical generation on mouse pial arterioles: probable role of hydroxyl radicals

1983 ◽  
Vol 245 (1) ◽  
pp. H139-H142 ◽  
Author(s):  
W. I. Rosenblum
Keyword(s):  
Free Radical ◽  
Xanthine Oxidase ◽  
Hydroxyl Radicals ◽  
Free Radical Scavengers ◽  
Radical Scavengers ◽  
Pial Arterioles ◽  
Probable Role ◽  
Radical Generation ◽  
Superoxide Scavenger

Mouse pial arterioles were exposed to the free radical-generating reactants acetaldehyde and xanthine oxidase. Concentrations of 0.5 mM acetaldehyde and 0.1 U/ml xanthine oxidase caused reversible dilations, whereas higher concentrations produced initial constrictions followed by reversible dilations. The following free radical scavengers inhibited the dilation when added to the lower concentrations of reactants: superoxide dismutase, a superoxide scavenger; catalase, an H2O2 scavenger; and mannitol, a hydroxyl scavenger. In addition, pretreatment of the animal with dimethyl sulfoxide, a hydroxyl scavenger, also inhibited the response. The scavengers were also tested against either the dilation produced by increased inspired CO2 or against the dilation produced by local application of 10(-3) M papaverine. No significant effect was observed. The data support the hypothesis that hydroxyl radicals can dilate pial arterioles, since all the scavengers can ultimately reduce levels of hydroxyl generated by acetaldehyde plus xanthine oxidase.

Ischemia-induced vascular changes: role of xanthine oxidase and hydroxyl radicals

1983 ◽  
Vol 245 (2) ◽  
pp. G285-G289 ◽  
Author(s):  
D. A. Parks ◽  
D. N. Granger
Keyword(s):  
Hydroxyl Radical ◽  
Dimethyl Sulfoxide ◽  
Xanthine Oxidase ◽  
Vascular Permeability ◽  
Hydroxyl Radicals ◽  
Vascular Injury ◽  
Oxygen Radicals ◽  
Intestinal Ischemia ◽  
Xanthine Oxidase Inhibitor

The results of previous studies indicate that oxygen-derived free radicals are responsible for the increased vascular permeability produced by 1 h of intestinal ischemia. The aims of this study were 1) to test the hypothesis that the enzyme xanthine oxidase is the source of oxygen radicals in the ischemic bowel and 2) to assess the role of the hydroxyl radical in the ischemia-induced vascular injury. The capillary osmotic reflection coefficient was estimated from lymphatic protein flux data in the cat ileum for the following conditions: ischemia, ischemia plus pretreatment with allopurinol (a xanthine oxidase inhibitor), and ischemia plus pretreatment with dimethyl sulfoxide (a hydroxyl radical scavenger). The increased vascular permeability produced by ischemia was largely prevented by pretreatment with either allopurinol or dimethyl sulfoxide. These findings support the hypothesis that xanthine oxidase is the source of oxygen radicals produced during ischemia. The results also indicate that hydroxyl radicals, derived from the superoxide anion, are primarily responsible for the vascular injury associated with intestinal ischemia.

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