Topic
Hydrogen peroxide
About: Hydrogen peroxide is a research topic. Over the lifetime, 42583 publications have been published within this topic receiving 1043732 citations. The topic is also known as: H2O2 & dioxidane.
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TL;DR: Electron paramagnetic resonance (EPR) coupled with a salicylic acid trapping method were used to detect free radicals in biochar and verify OH generation from biochar suspensions, providing new insights into the physicochemical properties and environmental implications of biochar.
264 citations
TL;DR: Results suggest that drug-induced hydrogen peroxide and hydroxyl radical production may play a role in the antineoplastic action of redox active anticancer quinones.
Abstract: The cytotoxicity of the clinically important antineoplastic quinones doxorubicin, mitomycin C, and diaziridinylbenzoquinone for the Ehrlich ascites carcinoma was significantly reduced or abolished by the antioxidant enzymes catalase and superoxide dismutase, the hydroxyl radical scavengers dimethyl sulfoxide, diethylurea, and thiourea, and the iron chelators deferoxamine, 2,2-bipyridine, and diethylenetriaminepentaacetic acid. However, tumor cell killing by 5-iminodaunorubicin, a doxorubicin analog with a modified quinone function that prohibits oxidation-reduction cycling, was not ameliorated by any of the free radical scavengers tested. Furthermore, treatment of intact tumor cells with doxorubicin, mitomycin C, and diaziridinylbenzoquinone but not 5-iminodaunorubicin generated the hydroxyl radical, or a related chemical oxidant, in vitro in a process that required hydrogen peroxide, iron, and intact tumor cells. These results suggest that drug-induced hydrogen peroxide and hydroxyl radical production may play a role in the antineoplastic action of redox active anticancer quinones.
263 citations
TL;DR: During the course of the delignification reaction, O2 is evolved from the reaction mixture indicating active H2O2 decomposition, and the total amount of O2 evolved is inversely proportional to the amount of substrate present, indicating that some of the peroxide oxygen becomes incorporated into lignin degradation products.
Abstract: Alkaline solutions of hydrogen peroxide partially delignify wheat straw and other lignocellulosic materials, leaving a cellulosic residue that is highly susceptible to enzymatic digestion by cellulase. The delignification reaction is strongly dependent upon the pH of the reaction mixture, with an optimum at pH 11.5-11.6, pKa for the dissociation H(2)O(2) right harpoon over left harpoon H(+) + HOO(-). The data are consistent with a mechanism in which H(2)O(2) decomposition products such as .OH and O(2) (-)., rather than H(2)O(2) or HOO(-), are the primary lignin oxidizing species. During the course of the delignification reaction, O(2) is evolved from the reaction mixture indicating active H(2)O(2) decomposition. At a given concentration of H(2)O(2), the rate of O(2) evolution is proportional to the amount of lignocellulosic substrate present in the reaction mixture. However, the total amount of O(2) evolved is inversely proportional to the amount of substrate present, indicating that some of the peroxide oxygen becomes incorporated into lignin degradation products. The amount of peroxide oxygen incorporated can range as high as 2 O(2) per lignin C(9) unit, depending upon the initial concentration of lignocellulosic substrate.
263 citations
TL;DR: It is shown that both catalase and urease enzyme molecules spread toward areas of higher substrate concentration, a form of chemotaxis at the molecular scale, showing that chemically interconnected enzymes can be drawn together.
Abstract: Using fluorescence correlation spectroscopy, we show that the diffusive movements of catalase enzyme molecules increase in the presence of the substrate, hydrogen peroxide, in a concentration-dependent manner. Employing a microfluidic device to generate a substrate concentration gradient, we show that both catalase and urease enzyme molecules spread toward areas of higher substrate concentration, a form of chemotaxis at the molecular scale. Using glucose oxidase and glucose to generate a hydrogen peroxide gradient, we induce the migration of catalase toward glucose oxidase, thereby showing that chemically interconnected enzymes can be drawn together.
262 citations
TL;DR: A highly enantioselective epoxidation of cyclic enones with hydrogen peroxide has been developed that is catalyzed by chiral primary amine salts.
Abstract: A highly enantioselective epoxidation of cyclic enones with hydrogen peroxide has been developed that is catalyzed by chiral primary amine salts.
262 citations