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Abiotic Stress-Mediated Oxidative Damage in Plants
Published in Hasanuzzaman Mirza, Nahar Kamrun, Fujita Masayuki, Oku Hirosuke, Tofazzal M. Islam, Approaches for Enhancing Abiotic Stress Tolerance in Plants, 2019
Ruchi Rai, Shilpi Singh, Shweta Rai, Alka Shankar, Antra Chatterjee, L.C. Rai
Glutathione also helps in the elimination of reactive oxygen as it is oxidized directly by oxidants such as hydroxyl radical (•OH) (Gardner and Aust, 2009; Sagone et al., 1984). Direct oxidation leads to the production of thiyl radicals (GS•). The thiyl radicals formed from these reactions can also combine with different molecules, as well as with other thiyl radicals, leading to the formation of oxidized glutathione (glutathione disulfide, GSSG) (Lushchak, 2012). GSSG is also produced in reactions catalyzed by GPx and glutaredoxins (GR). GSH is extensively used as a cosubstrate by GPx, reducing H2O2 or organic peroxides (generally abbreviated as ROOH or LOOH in the case of lipid peroxides) with the production of GSSG, water or alcohols. Hydroxyl radical may interact directly with GSH, leading to GSSG formation. Hydrogen peroxide may be removed by catalase or by GPx. The latter requires GSH to reduce peroxide. However, enhanced ROS levels may require not only enhanced GSH action to maintain redox status but also enhanced energy and material consumption to transport consumed GSH to the places where it is needed.
UV Radiation Processes (with Ruben Rivera)
Published in Jiri George Drobny, Radiation Technology for Polymers, 2020
This reaction is based on a stoichiometric reaction of multifunctional olefins (enes) with thiols. The addition reaction can be initiated thermally, photochemically, and by electron beam and radical or ionic mechanism.55 Thiyl radicals can be generated by the reaction of an excited carbonyl compound (usually in its triplet state) with a thiol or via radicals, such as benzoyl radicals from a Type I photoinitiator, reacting with the thiol. The thiyl radicals add to olefins, and this is the basis of the polymerization process.56 The addition of a dithiol to a diolefin yields linear polymer, higher-functionality thiols, and alkenes form cross-linked systems.
Recent developments in the greener approaches for the dithioacetalization of carbonyl compounds
Published in Journal of Sulfur Chemistry, 2023
K. Du et al. [106] disclosed a metal-free and solvent-free visible-light photoredox-catalyzed dithioacetalization of aldehydes using different aliphatic thiols and dithiols (Scheme 21). Eosin Y(0.1 mol%) was employed as the organic photocatalyst for the reactions under 10W blue LED irradiation. A wide range of aromatic aldehydes having electronically diverse functional groups have been explored for the dithioacetalization with 1-dodecanethiol in the presence of eosin Y at room temperature. The corresponding dithioacetals were obtained in excellent yields. However, aromatic aldehydes with electron-withdrawing groups like − NO2 and − CN yielded poor yields. Heteroaryl and α, β-unsaturated aromatic aldehydes were also compatible with the present reaction conditions. Cyclic dithioacetals of aromatic aldehydes were also formed in moderate yields (35 − 81%). The yield is diminished using thiophenol, while cyclohexanethiol and 2-butanethiol resulted in the formation of desired dithioacetals with aromatic aldehydes in excellent yields (99%). The reactions followed a radical mechanism in the presence of blue LED irradiation (Scheme 21). Initially, a reactive thiyl radical was formed via single-electron oxidation of thiol. Afterward, the thiyl radical reacted with the aldehyde to produce an acyloxy radical intermediate. This intermediate then reacted with the thiol to finally yield the dithioacetal. The solvent-free conditions of this photoinduced dithioacetalization elevate this method to be more eco-friendly and more viable compared to the methods described by Chaiseeda et al. [102], Xing et al. [103] and K. Choudhary et al. [104].