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Marković Z, Komolkin AV, Egorov AV, Milenković D, Jeremić S. Alizarin as a potential protector of proteins against damage caused by hydroperoxyl radical. Chem Biol Interact 2023; 373:110395. [PMID: 36758887 DOI: 10.1016/j.cbi.2023.110395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 01/30/2023] [Accepted: 02/06/2023] [Indexed: 02/10/2023]
Abstract
Alizarin is a natural anthraquinone molecule with moderate antioxidative capacity. Some earlier investigations indicated that it can inhibit osteosarcoma and breast carcinoma cell proliferation by inhibiting of phosphorylation process of ERK protein (extracellular signal-regulated kinases). Several mechanisms of deactivation of one of the most reactive oxygen species, hydroperoxyl radical, by alizarin are estimated: hydrogen atom abstraction (HAA), radical adduct formation (RAF), and single electron transfer (SET). The plausibility of those mechanisms is estimated using density functional theory. The obtained results indicated HAA as the only thermodynamically plausible mechanism. For that purpose, two possible mechanistic pathways for hydrogen atom abstraction are studied in detail: hydrogen atom transfer (HAT) and proton-coupled electron transfer (PCET). Water and benzene are used as models of solvents with opposite polarity. To examine the difference between HAT and PCET is used kinetical approach based on the Transition state theory (TST) and determined rate constants (k). Important data used for a distinction between HAT and PCET mechanisms are obtained by applying the Quantum Theory of Atoms in Molecules (QTAIM), and by the analysis of single occupied molecular orbitals (SOMOs) in transition states for two examined mechanisms. The molecular docking analysis and molecular dynamic are used to predict the most probable positions of binding of alizarin to the sequence of ApoB-100 protein, a protein component of plasma low-density lipoproteins (LDL). It is found that alizarin links the nitrated polypeptide forming the π-π interactions with the amino acids Phenylalanine and Nitrotyrosine. The ability of alizarin to scavenge hydroperoxyl radical when it is in a sandwich structure between the polypeptide and radical species, as the operative reaction mechanism, is not significantly changed concerning its antioxidant capacity in the absence of polypeptide. Therefore, alizarin can protect the polypeptide from harmful hydroperoxyl radical attack, positioning itself between the polypeptide chain and the reactive oxygen species.
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Affiliation(s)
- Zoran Marković
- Institute for Information Technologies, Department of Science, University of Kragujevac, Jovana Cvijića bb, 34000, Kragujevac, Serbia; Department of Natural Science and Mathematics, State University of Novi Pazar, Serbia.
| | - Andrei V Komolkin
- Faculty of Physics, Department of Nuclear-Physics Research Methods, St. Petersburg State University, Saint Petersburg, Russia
| | - Andrei V Egorov
- Faculty of Physics, Department of Nuclear-Physics Research Methods, St. Petersburg State University, Saint Petersburg, Russia
| | - Dejan Milenković
- Institute for Information Technologies, Department of Science, University of Kragujevac, Jovana Cvijića bb, 34000, Kragujevac, Serbia
| | - Svetlana Jeremić
- Department of Natural Science and Mathematics, State University of Novi Pazar, Serbia.
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Liu Y, Li X, Hua Y, Zhang W, Zhou X, He J, Chen D. Tannic Acid as a Natural Ferroptosis Inhibitor: Mechanisms and Beneficial Role of 3’‐
O
‐Galloylation. ChemistrySelect 2021. [DOI: 10.1002/slct.202004392] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Yangping Liu
- The Fourth Clinical Medical College Guangzhou University of Chinese Medicine Waihuan East Road No. 232, Guangzhou Higher Education Mega Center Guangzhou China 510006
| | - Xican Li
- School of Chinese Herbal Medicine Guangzhou University of Chinese Medicine Waihuan East Road No. 232, Guangzhou Higher Education Mega Center Guangzhou China 510006
| | - Yujie Hua
- School of Chinese Herbal Medicine Guangzhou University of Chinese Medicine Waihuan East Road No. 232, Guangzhou Higher Education Mega Center Guangzhou China 510006
| | - Wenhui Zhang
- School of Chinese Herbal Medicine Guangzhou University of Chinese Medicine Waihuan East Road No. 232, Guangzhou Higher Education Mega Center Guangzhou China 510006
| | - Xianxi Zhou
- School of Basic Medical Science Guangzhou University of Chinese Medicine Guangzhou China 510006
| | - Jianfeng He
- School of Chinese Herbal Medicine Guangzhou University of Chinese Medicine Waihuan East Road No. 232, Guangzhou Higher Education Mega Center Guangzhou China 510006
| | - Dongfeng Chen
- School of Basic Medical Science Guangzhou University of Chinese Medicine Guangzhou China 510006
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3
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Jaglan R, Mandal D. The role of potential energy surface in quantum mechanical tunneling: A computational perspective. COMPUT THEOR CHEM 2020. [DOI: 10.1016/j.comptc.2020.112920] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Kosugi K, Nakano H, Sato H. SCC-DFTB-PIMD Method To Evaluate a Multidimensional Quantum Free-Energy Surface for a Proton-Transfer Reaction. J Chem Theory Comput 2019; 15:4965-4973. [PMID: 31419131 DOI: 10.1021/acs.jctc.9b00355] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The self-consistent charge density functional tight binding method was combined with the path-integral molecular dynamics method for the first time to evaluate the two-dimensional free-energy surface including nuclear quantum effects of a proton-transfer reaction in a 2,4-dichlorophenol-trimethylamine complex. A statistically converged two-dimensional quantum free-energy surface was evaluated by the multidimensional blue moon ensemble method. The accuracy was guaranteed by optimizing the repulsive potential between the sp3-hybridized nitrogen and hydrogen atoms in a SCC-DFTB3 parameter set for the system to reproduce high-level quantum chemical calculations. The present study illustrates the usefulness of this new approach to investigate nuclear quantum effects in various realistic proton-transfer reactions.
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Affiliation(s)
- Kento Kosugi
- Department of Molecular Engineering , Kyoto University , Kyoto Daigaku Katsura, Kyoto 615-8510 , Japan
| | - Hiroshi Nakano
- Department of Molecular Engineering , Kyoto University , Kyoto Daigaku Katsura, Kyoto 615-8510 , Japan.,Elements Strategy Initiative for Catalysts and Batteries , Kyoto University , Kyoto 615-8520 , Japan
| | - Hirofumi Sato
- Department of Molecular Engineering , Kyoto University , Kyoto Daigaku Katsura, Kyoto 615-8510 , Japan.,Elements Strategy Initiative for Catalysts and Batteries , Kyoto University , Kyoto 615-8520 , Japan
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Otukile KP, Kabanda MM. A DFT mechanistic, thermodynamic and kinetic study on the reaction of 1, 3, 5-trihydroxybenzene and 2, 4, 6-trihydroxyacetophenone with •OOH in different media. JOURNAL OF THEORETICAL & COMPUTATIONAL CHEMISTRY 2019. [DOI: 10.1142/s0219633619500238] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A theoretical investigation on the reactions of 1, 3, 5-trihydroxybenzene (PG) and 2, 4, 6-trihydroxyacetophenone (ACPG) with •OOH has been performed with the aim of elucidating the peroxyl radical scavenging properties of PG and its acylated derivative. The study has considered the hydrogen atom transfer (HAT), the single electron transfer-proton transfer and the sequential proton loss-electron transfer mechanisms and determined the geometric, energetic and electronic properties of the reaction species as well as the kinetic parameters for the HAT mechanism. DFT/M06-2X, DFT/MPW1K and DFT/BHHLYP calculation methods have been utilized in combination with the 6-311++G(3df, 2p) basis set. The DFT methods were benchmarked using the CBS-QB3 method. Thermodynamic parameters such as bond dissociation enthalpy (BDE) and ionization energy suggest that the thermodynamically preferred mechanism is the HAT mechanism. The geometric, electronic and energetic parameters suggest that the preferred site for the abstraction of the free phenolic H atom in ACPG is the ortho position. Spin density and branching ratio values indicate that the most stable and preferable product formed is for the reaction of ACPG [Formula: see text] •OOH at the ortho position. The estimated rate constants obtained indicate that the reaction of ACPG [Formula: see text] •OOH is kinetically preferred to the reaction of PG [Formula: see text] •OOH, which is in agreement with experimental findings.
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Affiliation(s)
- Kgalaletso P. Otukile
- Department of Chemistry, Faculty of Natural and Agriculture Sciences, North-West University, Private Bag X2046, Mmabatho 2735, South Africa
- Material Science Innovation and Modelling (MaSIM), Research Focus Area, Faculty of Natural and Agriculture Sciences, North-West University, Private Bag X 2046, Mmabatho 2735, South Africa
| | - Mwadham M. Kabanda
- Department of Chemistry, Faculty of Natural and Agriculture Sciences, North-West University, Private Bag X2046, Mmabatho 2735, South Africa
- Material Science Innovation and Modelling (MaSIM), Research Focus Area, Faculty of Natural and Agriculture Sciences, North-West University, Private Bag X 2046, Mmabatho 2735, South Africa
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Quintero-Saumeth J, Rincón DA, Doerr M, Daza MC. Concerted double proton-transfer electron-transfer between catechol and superoxide radical anion. Phys Chem Chem Phys 2018; 19:26179-26190. [PMID: 28930314 DOI: 10.1039/c7cp03930a] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We have carried out a computational study on the reactivity of catechol (1,2-dihydroxybenzene) towards superoxide radical anion (O2˙-) in water, N,N-dimethylformamide (DMF), pentyl ethanoate (PEA) and vacuum using density functional theory and the coupled cluster method. Five reaction mechanisms were studied: (i) sequential proton transfer followed by hydrogen atom transfer (PT-HT), (ii) sequential hydrogen atom transfer followed by proton transfer (HT-PT), (iii) single electron transfer (SET), (iv) radical adduct formation (RAF) and (v) concerted double proton-transfer electron-transfer (denoted as global reaction, GR). Our results show that catechol and superoxide do not react via a sequential reaction mechanism (initial PT, initial HAT or SET). Instead, the reaction proceeds via a concerted double proton-transfer electron-transfer mechanism yielding hydrogen peroxide and catechol radical anion. The protons are transferred asynchronously between the σ orbitals of the catechol oxygen atoms to superoxide, while the electron is transferred between oxygen π orbitals in the same direction. The calculated rate constants in aqueous media agree with the experimental values reported in the literature. This suggests that the mechanism proposed in this work is adequate to describe this reaction. In addition, our results show that the reaction exhibits a large tunneling effect.
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Affiliation(s)
- Jorge Quintero-Saumeth
- Grupo de Bioquímica Teórica, Universidad Industrial de Santander, Carrera 27, Calle 9, Bucaramanga, Colombia.
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Rafatijo H, Thompson DL. General application of Tolman’s concept of activation energy. J Chem Phys 2017; 147:224111. [DOI: 10.1063/1.5009751] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Homayoon Rafatijo
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600, USA
| | - Donald L. Thompson
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211-7600, USA
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8
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Hydrogen atom transfer versus proton coupled electron transfer mechanism of gallic acid with different peroxy radicals. REACTION KINETICS MECHANISMS AND CATALYSIS 2017. [DOI: 10.1007/s11144-017-1286-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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9
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Sheng X, Shan C, Liu J, Yang J, Sun B, Chen D. Theoretical insights into the mechanism of ferroptosis suppression via inactivation of a lipid peroxide radical by liproxstatin-1. Phys Chem Chem Phys 2017; 19:13153-13159. [DOI: 10.1039/c7cp00804j] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Ferroptosis is a recently discovered iron-dependent form of non-apoptotic cell death caused by the accumulation of membrane lipid peroxidation products, which is involved in various pathological conditions of the brain, kidneys, liver and heart.
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Affiliation(s)
- Xiehuang Sheng
- College of Chemistry
- Chemical Engineering and Materials Science
- Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong
- Key Laboratory of Molecular and Nano Probes
- Ministry of Education
| | - Chao Shan
- College of Chemistry
- Chemical Engineering and Materials Science
- Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong
- Key Laboratory of Molecular and Nano Probes
- Ministry of Education
| | - Jianbiao Liu
- College of Chemistry
- Chemical Engineering and Materials Science
- Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong
- Key Laboratory of Molecular and Nano Probes
- Ministry of Education
| | - Jintong Yang
- College of Chemistry
- Chemical Engineering and Materials Science
- Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong
- Key Laboratory of Molecular and Nano Probes
- Ministry of Education
| | - Bin Sun
- College of Chemistry
- Chemical Engineering and Materials Science
- Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong
- Key Laboratory of Molecular and Nano Probes
- Ministry of Education
| | - Dezhan Chen
- College of Chemistry
- Chemical Engineering and Materials Science
- Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong
- Key Laboratory of Molecular and Nano Probes
- Ministry of Education
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10
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Phenolic Melatonin-Related Compounds: Their Role as Chemical Protectors against Oxidative Stress. Molecules 2016; 21:molecules21111442. [PMID: 27801875 PMCID: PMC6274579 DOI: 10.3390/molecules21111442] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Revised: 10/17/2016] [Accepted: 10/24/2016] [Indexed: 12/22/2022] Open
Abstract
There is currently no doubt about the serious threat that oxidative stress (OS) poses to human health. Therefore, a crucial strategy to maintain a good health status is to identify molecules capable of offering protection against OS through chemical routes. Based on the known efficiency of the phenolic and melatonin (MLT) families of compounds as antioxidants, it is logical to assume that phenolic MLT-related compounds should be (at least) equally efficient. Unfortunately, they have been less investigated than phenols, MLT and its non-phenolic metabolites in this context. The evidence reviewed here strongly suggests that MLT phenolic derivatives can act as both primary and secondary antioxidants, exerting their protection through diverse chemical routes. They all seem to be better free radical scavengers than MLT and Trolox, while some of them also surpass ascorbic acid and resveratrol. However, there are still many aspects that deserve further investigations for this kind of compounds.
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11
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Meisner J, Kästner J. Atom Tunneling in Chemistry. Angew Chem Int Ed Engl 2016; 55:5400-13. [DOI: 10.1002/anie.201511028] [Citation(s) in RCA: 140] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Revised: 01/08/2016] [Indexed: 01/01/2023]
Affiliation(s)
- Jan Meisner
- Institut für Theoretische Chemie Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
| | - Johannes Kästner
- Institut für Theoretische Chemie Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Germany
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12
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Affiliation(s)
- Jan Meisner
- Institut für Theoretische Chemie Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Deutschland
| | - Johannes Kästner
- Institut für Theoretische Chemie Universität Stuttgart Pfaffenwaldring 55 70569 Stuttgart Deutschland
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13
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Shen GB, Xia K, Li XT, Li JL, Fu YH, Yuan L, Zhu XQ. Prediction of Kinetic Isotope Effects for Various Hydride Transfer Reactions Using a New Kinetic Model. J Phys Chem A 2016; 120:1779-99. [DOI: 10.1021/acs.jpca.5b10135] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Guang-Bin Shen
- Department of Chemistry, The State Key Laboratory
of Elemento-Organic Chemistry and the ‡Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Ke Xia
- Department of Chemistry, The State Key Laboratory
of Elemento-Organic Chemistry and the ‡Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Xiu-Tao Li
- Department of Chemistry, The State Key Laboratory
of Elemento-Organic Chemistry and the ‡Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Jun-Ling Li
- Department of Chemistry, The State Key Laboratory
of Elemento-Organic Chemistry and the ‡Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Yan-Hua Fu
- Department of Chemistry, The State Key Laboratory
of Elemento-Organic Chemistry and the ‡Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Lin Yuan
- Department of Chemistry, The State Key Laboratory
of Elemento-Organic Chemistry and the ‡Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
| | - Xiao-Qing Zhu
- Department of Chemistry, The State Key Laboratory
of Elemento-Organic Chemistry and the ‡Collaborative Innovation Center
of Chemical Science and Engineering, Nankai University, Tianjin 300071, China
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14
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Nagaoka SI, Nitta A, Suemitsu A, Mukai K. Tunneling effect in vitamin E recycling by green tea. RSC Adv 2016. [DOI: 10.1039/c6ra05986d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
A tunneling effect was found to play an important role in vitamin E recycling reactions by catechins contained in green tea.
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Affiliation(s)
- Shin-ichi Nagaoka
- Department of Chemistry
- Faculty of Science and Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
| | - Akiko Nitta
- Department of Chemistry
- Faculty of Science and Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
| | - Ai Suemitsu
- Department of Chemistry
- Faculty of Science and Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
| | - Kazuo Mukai
- Department of Chemistry
- Faculty of Science and Graduate School of Science and Engineering
- Ehime University
- Matsuyama 790-8577
- Japan
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15
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Fabijanić I, Jakobušić Brala C, Pilepić V. The DFT local reactivity descriptors of α-tocopherol. J Mol Model 2015; 21:99. [DOI: 10.1007/s00894-015-2644-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/09/2015] [Indexed: 12/26/2022]
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Mandal D, Ramanan R, Usharani D, Janardanan D, Wang B, Shaik S. How does tunneling contribute to counterintuitive H-abstraction reactivity of nonheme Fe(IV)O oxidants with alkanes? J Am Chem Soc 2015; 137:722-33. [PMID: 25513834 DOI: 10.1021/ja509465w] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
This article addresses the intriguing hydrogen-abstraction (H-abstraction) and oxygen-transfer (O-transfer) reactivity of a series of nonheme [Fe(IV)(O)(TMC)(Lax)](z+) complexes, with a tetramethyl cyclam ligand and a variable axial ligand (Lax), toward three substrates: 1,4-cyclohexadiene, 9,10-dihydroanthracene, and triphenyl phosphine. Experimentally, O-transfer-reactivity follows the relative electrophilicity of the complexes, whereas the corresponding H-abstraction-reactivity generally increases as the axial ligand becomes a better electron donor, hence exhibiting an antielectrophilic trend. Our theoretical results show that the antielectrophilic trend in H-abstraction is affected by tunneling contributions. Room-temperature tunneling increases with increase of the electron donation power of the axial-ligand, and this reverses the natural electrophilic trend, as revealed through calculations without tunneling, and leads to the observed antielectrophilic trend. By contrast, O-transfer-reactivity, not being subject to tunneling, retains an electrophilic-dependent reactivity trend, as revealed experimentally and computationally. Tunneling-corrected kinetic-isotope effect (KIE) calculations matched the experimental KIE values only if all of the H-abstraction reactions proceeded on the quintet state (S = 2) surface. As such, the present results corroborate the initially predicted two-state reactivity (TSR) scenario for these reactions. The increase of tunneling with the electron-releasing power of the axial ligand, and the reversal of the "natural" reactivity pattern, support the "tunneling control" hypothesis (Schreiner et al., ref 19). Should these predictions be corroborated, the entire field of C-H bond activation in bioinorganic chemistry would lay open to reinvestigation.
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Affiliation(s)
- Debasish Mandal
- Institute of Chemistry and the Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem , 91904 Jerusalem, Israel
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Castañeda-Arriaga R, Alvarez-Idaboy JR. Lipoic acid and dihydrolipoic acid. A comprehensive theoretical study of their antioxidant activity supported by available experimental kinetic data. J Chem Inf Model 2014; 54:1642-52. [PMID: 24881907 DOI: 10.1021/ci500213p] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The free radical scavenging activity of lipoic acid (LA) and dihydrolipoic acid (DHLA) has been studied in nonpolar and aqueous solutions, using the density functional theory and several oxygen centered radicals. It was found that lipoic acid is capable of scavenging only very reactive radicals, while the dehydrogenated form is an excellent scavenger via a hydrogen transfer mechanism. The environment plays an important role in the free radical scavenging activity of DHLA because in water it is deprotonated, and this enhances its activity. In particular, the reaction rate constant of DHLA in water with an HOO(•) radical is close to the diffusion limit. This has been explained on the basis of the strong H-bonding interactions found in the transition state, which involve the carboxylate moiety, and it might have implications for other biological systems in which this group is present.
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Affiliation(s)
- Romina Castañeda-Arriaga
- Departamento de Física y Química Teórica, Facultad de Química, Universidad Nacional Autonoma de Mexico , Av Universidad 3000, Copilco Universidad, Coyoacán, Ciudad de Mexico DF 04510, Mexico
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