2880-58-2Relevant articles and documents
Peroxidase versus Peroxygenase Activity: Substrate Substituent Effects as Modulators of Enzyme Function in the Multifunctional Catalytic Globin Dehaloperoxidase
McGuire, Ashlyn H.,Carey, Leiah M.,De Serrano, Vesna,Dali, Safaa,Ghiladi, Reza A.
, p. 4455 - 4468 (2018)
The dehaloperoxidase-hemoglobin (DHP) from the terebellid polychaete Amphitrite ornata is a multifunctional hemoprotein that catalyzes the oxidation of a wide variety of substrates, including halo/nitrophenols, haloindoles, and pyrroles, via peroxidase and/or peroxygenase mechanisms. To probe whether substrate substituent effects can modulate enzyme activity in DHP, we investigated its reactiviy against a panel of o-guaiacol substrates given their presence (from native/halogenated and non-native/anthropogenic sources) in the benthic environment that A. ornata inhabits. Using biochemical assays supported by spectroscopic, spectrometric, and structural studies, DHP was found to catalyze the H2O2-dependent oxidative dehalogenation of 4-haloguaiacols (F, Cl, and Br) to 2-methoxybenzoquinone (2-MeOBQ). 18O labeling studies confirmed that O atom incorporation was derived exclusively from water, consistent with substrate oxidation via a peroxidase-based mechanism. The 2-MeOBQ product further reduced DHP to its oxyferrous state, providing a link between the substrate oxidation and O2 carrier functions of DHP. Nonnative substrates resulted in polymerization of the initial substrate with varying degrees of oxidation, with 2-MeOBQ identified as a minor product. When viewed alongside the reactivity of previously studied phenolic substrates, the results presented here show that simple substituent effects can serve as functional switches between peroxidase and peroxygenase activities in this multifunctional catalytic globin. More broadly, when recent findings on DHP activity with nitrophenols and azoles are included, the results presented here further demonstrate the breadth of heterocyclic compounds of anthropogenic origin that can potentially disrupt marine hemoglobins or function as environmental stressors, findings that may be important when assessing the environmental impact of these pollutants (and their metabolites) on aquatic systems.
Regioselective synthesis of substituted pterocarpans and pterocarpenes. Lewis acid Ti(IV) promoted formal (3 + 2) cycloaddition reactions
Murugesh,Subburaj,Trivedi
, p. 2217 - 2228 (1996)
A synthesis of novel pterocarpans (8a-3, 10a-c and 11a-e) and pterocarpenes (7a-d and 9a-c) has been carried out. This method involves the Lewis acid Ti(IV) promoted formal (3 + 2) cycloaddition reaction of 2-alkoxy-1,4-benzoquinones (6a-c) with appropriately substituted 2H-chromenes (1a-b, 2a-b and 5) at -78°C.
Catalytic conversion of lignin: Studies on oxidation of lignin model phenolic monomer over CoMCM-41 and CoMCM-48 catalysts
Sadual,Sahoo,Badamali
, p. 434 - 442 (2018)
The present study focussed on investigation of the potentiality of cobalt containing mesoporous material (M41S) as a robust heterogeneous catalyst for the oxidation of lignin model phenolic compound. Cobalt containing MCM-41 and MCM-48 were prepared under hydrothermal condition and characterized by various spectroscopic and analytical techniques. Formation of well ordered hexagonal and cubic mesopore structures of MCMs, containing cobalt in the silicate framework was inferred from XRD, TG-DTA and N2 adsorption-desorption studies. DR UV-visible spectral analysis revealed existence of Co(II) and Co(III) in the tetrahedral framework. The oxidative ability of CoMCMs were studied for the lignin model phenolic monomer, 1-(4-hydroxy-3-methoxyphenoxy)-ethanol, under mild conditions using environmentally benign H2O2 as the oxidant. The catalytic results showed that under optimum reaction conditions, apocynol undergoes selective oxidation yielding 2-methoxybenzoquinone and acetovanillone. CoMCM-41 was found to be more selective towards acetovanillone, on the contrary, CoMCM-48 was better catalyst for 2-methoxybenzoquinone yield.
Aerobic Oxidation of Dihydroxyarenes Substrates Catalyzed by Polymer-Supported RuII-Pheox/Silica-Gel: A Beneficial Route for Purification of Industrial Water
Abu-Elfotoh, Abdel-Moneim
supporting information, p. 236 - 243 (2022/04/09)
A broad class of dihydroxyarenes were easily oxidized by aerobic oxygen to quinone products in excellent yields under the catalytic effect of polymer-supported RuII-Pheox/silica-gel catalyst. By using this combined catalyst, hydroquinone and catechol derivatives with electron-donating groups were easily oxidized by molecular oxygen to quinone products in 90% to >99% yield, while in the case of electron-withdrawing group, only 70% was obtained. The biologically useful 1,4-Naphthoqinone products were obtained in 83% to 90%. The catalyst was easily obtained and reused many times without a significant decrease in reactivity. Interestingly, a sample of industrial water contaminated with phenolic compounds was subjected to aerobic oxidation by using this catalyst, and the resultant quinones were detected within one day and the catalyst was removed and reused several times with different contami-nating samples with the same efficiency. Other catalytic oxidations by using this promising catalyst were investigated.
Benzoic acid resin (BAR): a heterogeneous redox organocatalyst for continuous flow synthesis of benzoquinones from β-O-4 lignin models
Dias, Kevin de Aquino,Pereira Junior, Marcus Vinicius Pinto,Andrade, Leandro Helgueira
supporting information, p. 2308 - 2316 (2021/04/07)
A polymer-bound organocatalyst for Baeyer-Villiger reaction and phenol oxidation under continuous flow conditions is described for the first time.BARhas revealed two catalytic activities that enabled the generation of a novel approach for the synthesis of benzoquinones from β-O-4 lignin models in a one-pot protocol. High catalytic activities (yields up to 98%), selectivities, recyclability and productivity were achieved.
