Estimation of heterogeneous rate constants of reaction of electrochemically generated <i>o</i>‐benzoquinones with various nucleophiles containing thiol group

Fotouhi, Lida; Tammari, Esmail; Asadi, Samaneh; Heravi, Majid M.; Nematollahi, Davood

doi:10.1002/kin.20402

Cited by 13 publications

(8 citation statements)

References 23 publications

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“…The same results obtained in electrochemical oxidation of catechols (1) in the presence of pyrimidine-2-thiol derivatives (85) as nucleophiles (Scheme 25) [93][94][95][96].…”

Section: C-s C-s Bond Formationsupporting

confidence: 58%

Mechanistic study of homogeneous reactions coupled with electrochemical oxidation of catechols

Nematollahi

Rafiee

Fotouhi

2009

JICS

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The electrochemical oxidation of catechols was described and has shown that these compounds can be oxidized to related obenzoquinones. The electrochemically generated o-benzoquinones are quite reactive and can be attacked by a variety of nucleophiles under various mechanistic disciplines such as CE, EC, EC ' , ECE, ECEC, ECEC 2 , ECECE, ECECEC, ECECECE and trimerization, in which E represents an electron transfer at the electrode surface, and C represents a homogeneous chemical reaction. The mechanistic pathways and final products are depending on some parameters such as electron withdrawing or donating properties of nucleophile, electrolysis medium (solvent, acidity or pH) and nature of catechol.

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“…The same results obtained in electrochemical oxidation of catechols (1) in the presence of pyrimidine-2-thiol derivatives (85) as nucleophiles (Scheme 25) [93][94][95][96].…”

Section: C-s C-s Bond Formationsupporting

confidence: 58%

Mechanistic study of homogeneous reactions coupled with electrochemical oxidation of catechols

Nematollahi

Rafiee

Fotouhi

2009

JICS

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“…In all cases, the slopes are in good agreement with the theoretical slope (2.303mRT/nF) of 59 mV/pH with m ≈ 2 and n = 2, where n and m are number of electron and proton respectively [12]. On increasing the pH of supporting electrolyte both the anodic and cathodic peak potentials shifted towards more negative potential [13] as shown in the Figure 1. This is expected because of the participation of proton in the oxidation reactions and these shifts of potential indicate that the electron transfer process from catechol to o-benzoquinone occurs at glassy carbon electrode easily at higher pH than at lower pH.…”

Section: Cyclic Voltammetry Of Catecholsupporting

confidence: 83%

Cyclic Voltammetric and Electrochemical Simulation Studies on the Electro-Oxidation of Catechol in the Presence of 4, 4-bipyridine

Kasa¹,

Solomon²

2016

AJPC

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The studies were made using cyclic voltammetry on a glassy carbon electrode in aqueous solution containing phosphate buffer solution as supporting electrolyte. The purpose of the investigation was to carry out a quantitative detailed study of the electrochemical oxidation of catechol in the presence of 4, 4-bipyridine in aqueous solution. The electrooxidation of catechol produces a very reactive intermediate, o-benzoquinone, which subsequently reacts with 4, 4-bipyridine in 1, 4-Michael addition reaction to form the corresponding catechol derivative product. The kinetic data were extracted from cyclic voltammograms with the help of digital simulation. The results of the study show that catechol is oxidized in aqueous phosphate buffer solution to a very reactive intermediate o-benzoquinone.

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“…Voltammetry performed on L-DOPA solutions with glyphosate showed dose-dependent shifts towards a negative potential (Fig 7E and 7H) in peaks that corresponded to L-DOPA oxidation [103] (Peak 1). We validated these as L-DOPA oxidation peaks by performing voltammetry on various L-DOPA concentrations (S8A Fig) . The peak shift towards negative potentials indicates the L-DOPA was oxidized more easily and had less ability to be an oxidant, similar to the negative potential shifts associated with alkaline pH and increased oxidation [104]. We controlled for any pH-dependent peak shifts by adjusting each solution to pH 6.00 prior to measurement.…”

Section: Plos Biologymentioning

confidence: 99%

Glyphosate inhibits melanization and increases susceptibility to infection in insects

et al. 2021

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Melanin, a black-brown pigment found throughout all kingdoms of life, has diverse biological functions including UV protection, thermoregulation, oxidant scavenging, arthropod immunity, and microbial virulence. Given melanin’s broad roles in the biosphere, particularly in insect immune defenses, it is important to understand how exposure to ubiquitous environmental contaminants affects melanization. Glyphosate—the most widely used herbicide globally—inhibits melanin production, which could have wide-ranging implications in the health of many organisms, including insects. Here, we demonstrate that glyphosate has deleterious effects on insect health in 2 evolutionary distant species, Galleria mellonella (Lepidoptera: Pyralidae) and Anopheles gambiae (Diptera: Culicidae), suggesting a broad effect in insects. Glyphosate reduced survival of G. mellonella caterpillars following infection with the fungus Cryptococcus neoformans and decreased the size of melanized nodules formed in hemolymph, which normally help eliminate infection. Glyphosate also increased the burden of the malaria-causing parasite Plasmodium falciparum in A. gambiae mosquitoes, altered uninfected mosquito survival, and perturbed the microbial composition of adult mosquito midguts. Our results show that glyphosate’s mechanism of melanin inhibition involves antioxidant synergy and disruption of the reaction oxidation–reduction balance. Overall, these findings suggest that glyphosate’s environmental accumulation could render insects more susceptible to microbial pathogens due to melanin inhibition, immune impairment, and perturbations in microbiota composition, potentially contributing to declines in insect populations.

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Estimation of heterogeneous rate constants of reaction of electrochemically generated o‐benzoquinones with various nucleophiles containing thiol group

Cited by 13 publications

References 23 publications

Mechanistic study of homogeneous reactions coupled with electrochemical oxidation of catechols

Mechanistic study of homogeneous reactions coupled with electrochemical oxidation of catechols

Cyclic Voltammetric and Electrochemical Simulation Studies on the Electro-Oxidation of Catechol in the Presence of 4, 4-bipyridine

Glyphosate inhibits melanization and increases susceptibility to infection in insects

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