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Start Over Author "AMORATI, RICCARDO" Journal chemistry - a european journal
20 results on '"AMORATI, RICCARDO"'

1. Pro‐aromatic Natural Terpenes as Unusual "Slingshot" Antioxidants with Promising Ferroptosis Inhibition Activity.

Author

Jin, Zongxin, Mollica, Fabio, Huang, Yeqin, Guernelli, Susanna, Baschieri, Andrea, Diquigiovanni, Chiara, Rizzardi, Nicola, Valenti, Francesca, Pincigher, Luca, Bergamini, Christian, and Amorati, Riccardo

Abstract

Ferroptosis is a cell death mechanism based on extensive cellular membrane peroxidation, implicated in neurodegenerative and other diseases. The essential oil component γ‐terpinene, a natural monoterpene with a unique highly oxidizable pro‐aromatic 1,4‐cyclohexadiene skeleton, inhibits peroxidation of polyunsaturated lipid in model heterogeneous systems (micelles and liposomes). Upon H‐atom abstraction, an unstable γ‐terpinene‐derived peroxyl radical is formed, that aromatizes to p‐cymene generating HOO⋅ radicals. As HOO⋅ are small and hydrophilic radicals, they quickly diffuse outside the lipid core, blocking the radical chain propagation of polyunsaturated lipids. This unprecedented antioxidant "slingshot" mechanism explains why γ‐terpinene shows a protective activity against ferroptosis, being effective at submicromolar concentrations in human neuroblastoma (SH‐SY5Y) cells. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Hydroperoxyl Radicals (HOO.): Vitamin E Regeneration and H-Bond Effects on the Hydrogen Atom Transfer.

Author

Cedrowski, Jakub, Litwinienko, Grzegorz, Baschieri, Andrea, and Amorati, Riccardo

Subjects
POLAR solvent analysis, TRANSITION state theory (Chemistry), RADICALS (Chemistry), PHOTOCATALYSIS, ENZYME analysis, ANTIOXIDANT analysis
Abstract

Hydroperoxyl (HOO.) and alkylperoxyl (ROO.) radicals show a different behavior in H-atom-transfer processes. Both radicals react with an analogue of α-tocopherol (TOH), but HOO., unlike ROO., is able to regenerate TOH by a fast H-atom transfer: TO.+HOO.→TOH+O2. The kinetic solvent effect on the H-atom transfer from TOH to HOO. is much stronger than that observed for ROO. because noncovalent interactions with polar solvents (Solv⋅⋅⋅HOO.) destabilize the transition state. [ABSTRACT FROM AUTHOR]

Published
2016
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16. A Straightforward Route to Potent Phenolic Chain-Breaking Antioxidants by Acid-Promoted Transposition of 1,4-Benzo[ b]oxathiines to Dihydrobenzo[ b]thiophenes.

Author

Viglianisi, Caterina, Amorati, Riccardo, Di Pietro, Leonardo, and Menichetti, Stefano

Subjects
*ANTIOXIDANTS, *CHEMICAL synthesis, *STRUCTURE-activity relationships, *PHENOL synthesis, *HETEROCYCLIC compounds, *ELECTROPHILIC substitution reactions
Abstract

The transformation of simple phenols with limited antioxidant activity into potent chain-breaking antioxidants was achieved by a three-step protocol, consisting of the conversion of phenols into 1,4-benzo[ b]oxathiines followed by an unprecedented acid-promoted transposition to o-hydroxydihydrobenzo[ b]thiophenes, or dihydrobenzo[ de]thiochromenes, starting from phenols or naphthols, respectively. These derivatives, bearing a benzo-fused heterocycle with a sulfide sulfur ortho to the phenolic OH, have a rate constant of reaction with alkylperoxyl radicals ( kinh) comparable to that of α-tocopherol. A solid rationale for the transposition mechanism as well as for the structure-antioxidant activity relationship is presented. [ABSTRACT FROM AUTHOR]

Published
2015
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19. Hydroperoxyl Radicals (HOO. ): Vitamin E Regeneration and H-Bond Effects on the Hydrogen Atom Transfer

Author

Andrea Baschieri, Riccardo Amorati, Jakub Cedrowski, Grzegorz Litwinienko, Cedrowski, Jakub, Litwinienko, Grzegorz, Baschieri, Andrea, Amorati, Riccardo, DIPARTIMENTO DI CHIMICA 'GIACOMO CIAMICIAN', Da definire, and AREA MIN. 03 - Scienze chimiche

Subjects
medicine.medical_treatment, Radical, solvent effects, 010402 general chemistry, Photochemistry, 01 natural sciences, hydrogen atom transfer, Catalysis, chemistry.chemical_compound, medicine, Non-covalent interactions, reactive oxygen species, chemistry.chemical_classification, reactive oxygen specie, solvent effect, hydroperoxyl radical, 010405 organic chemistry, Hydrogen bond, Vitamin E, hydroperoxyl radicals, tocopherol, Chemistry (all), Organic Chemistry, General Chemistry, Hydrogen atom, 0104 chemical sciences, Hydroperoxyl, chemistry, Solvent effects
Abstract

none 4 si Hydroperoxyl (HOO.) and alkylperoxyl (ROO.) radicals show a different behavior in H-atom-transfer processes. Both radicals react with an analogue of α-tocopherol (TOH), but HOO., unlike ROO., is able to regenerate TOH by a fast H-atom transfer: TO.+HOO.→TOH+O2. The kinetic solvent effect on the H-atom transfer from TOH to HOO.is much stronger than that observed for ROO.because noncovalent interactions with polar solvents (Solv⋅⋅⋅HOO.) destabilize the transition state. Cedrowski, Jakub; Litwinienko, Grzegorz; Baschieri, Andrea; Amorati, Riccardo Cedrowski, Jakub; Litwinienko, Grzegorz; Baschieri, Andrea; Amorati, Riccardo

Published
2016
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20. Peroxyl Radical Reactions in Water Solution: A Gym for Proton-Coupled Electron-Transfer Theories

Author

Gloria Morroni, Riccardo Amorati, Andrea Baschieri, Rossana Gambino, Luca Valgimigli, DIPARTIMENTO DI CHIMICA 'GIACOMO CIAMICIAN', AREA MIN. 03 - Scienze chimiche, Da definire, Amorati, Riccardo, Baschieri, Andrea, Morroni, Gloria, Gambino, Rossana, and Valgimigli, Luca

Subjects
radical reactions, Reaction mechanism, antioxidant, antioxidants, kinetics, proton inventory, reaction mechanisms, Chemistry (all), radical reaction, Radical, kinetic, 010402 general chemistry, Photochemistry, 01 natural sciences, Catalysis, chemistry.chemical_compound, Electron transfer, Autoxidation, 010405 organic chemistry, Organic Chemistry, General Chemistry, 0104 chemical sciences, chemistry, Radiolysis, reaction mechanism, Trolox, Proton-coupled electron transfer, Solvent effects
Abstract

none 5 no The reactions of alkylperoxyl radicals with phenols have remained difficult to investigate in water. We describe herein a simple and reliable method based on the inhibited autoxidation of water/THF mixtures, which we calibrated against pulse radiolysis. With this method we measured the rate constants kinh for the reactions of 2-tetrahydrofuranylperoxyl radicals with reference compounds: urate, ascorbate, ferrocenes, 2,2,5,7,8-pentamethyl-6-chromanol, Trolox, 6-hydroxy-2,5,7,8-tetramethylchroman-2-acetic acid, 2,6-di-tert-butyl-4-methoxyphenol, 4-methoxyphenol, catechol and 3,5-di-tert-butylcatechol. The role of pH was investigated: the value of kinh for Trolox and 4-methoxyphenol increased 11- and 50-fold from pH 2.1 to 12, respectively, which indicate the occurrence of a SPLET-like mechanism. H(D) kinetic isotope effects combined with pH and solvent effects suggest that different types of proton-coupled electron transfer (PCET) mechanisms are involved in water: less electron-rich phenols react at low pH by concerted electron-proton transfer (EPT) to the peroxyl radical, whereas more electron-rich phenols and phenoxide anions react by multi-site EPT in which water acts as proton relay. Radical kinetics: A simple and reliable method to measure the kinetics of peroxyl radical reactions in water is described (see figure). The proton-coupled electron transfer from a variety of compounds was investigated. Electron-poorer phenols react by concerted electron-proton transfer (EPT or CPET), whereas electron-richer phenols and phenoxide anions react by multi-site EPT (separated CPET) in which water acts as proton relay, similarly to the chemistry of radical enzymes. Amorati, Riccardo; Baschieri, Andrea; Morroni, Gloria; Gambino, Rossana; Valgimigli, Luca Amorati, Riccardo; Baschieri, Andrea; Morroni, Gloria; Gambino, Rossana; Valgimigli, Luca

Published
2016
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