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Ju CW, Shen Y, French EJ, Yi J, Bi H, Tian A, Lin Z. Accurate Electronic and Optical Properties of Organic Doublet Radicals Using Machine Learned Range-Separated Functionals. J Phys Chem A 2024. [PMID: 38382058 DOI: 10.1021/acs.jpca.3c07437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
Luminescent organic semiconducting doublet-spin radicals are unique and emergent optical materials because their fluorescent quantum yields (Φfl) are not compromised by the spin-flipping intersystem crossing (ISC) into a dark high-spin state. The multiconfigurational nature of these radicals challenges their electronic structure calculations in the framework of single-reference density functional theory (DFT) and introduces room for method improvement. In the present study, we extended our earlier development of ML-ωPBE [J. Phys. Chem. Lett., 2021, 12, 9516-9524], a range-separated hybrid (RSH) exchange-correlation (XC) functional constructed using the stacked ensemble machine learning (SEML) algorithm, from closed-shell organic semiconducting molecules to doublet-spin organic semiconducting radicals. We assessed its performance for a new test set of 64 doublet-spin radicals from five categories while placing all previously compiled 3926 closed-shell molecules in the new training set. Interestingly, ML-ωPBE agrees with the nonempirical OT-ωPBE functional regarding the prediction of the molecule-dependent range-separation parameter (ω), with a small mean absolute error (MAE) of 0.0197 a0-1, but saves the computational cost by 2.46 orders of magnitude. This result demonstrates an outstanding domain adaptation capacity of ML-ωPBE for diverse organic semiconducting species. To further assess the predictive power of ML-ωPBE in experimental observables, we also applied it to evaluate absorption and fluorescence energies (Eabs and Efl) using linear-response time-dependent DFT (TDDFT), and we compared its behavior with nine popular XC functionals. For most radicals, ML-ωPBE reproduces experimental measurements of Eabs and Efl with small MAEs of 0.299 and 0.254 eV, only marginally different from those of OT-ωPBE. Our work illustrates a successful extension of the SEML framework from closed-shell molecules to doublet-spin radicals and will open the venue for calculating optical properties for organic semiconductors using single-reference TDDFT.
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Affiliation(s)
- Cheng-Wei Ju
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Pritzker School of Molecular Engineering, The University of Chicago, Chicago, Illinois 60637, United States
| | - Yili Shen
- Manning College of Information and Computer Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Computer Science and Engineering, University of Notre Dame, Notre Dame, Indiana 46556, United States
| | - Ethan J French
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Charlestown, Massachusetts 02129, United States
| | - Jun Yi
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Chemistry, Wake Forest University, Winston-Salem, North Carolina 27109, United States
| | - Hongshan Bi
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Aaron Tian
- Manning College of Information and Computer Sciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
- Department of Mathematics and Statistics, University of Massachusetts, Amherst, Massachusetts 01003, United States
| | - Zhou Lin
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, United States
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2
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Singh G, Kesharwani P, Kumar Singh G, Kumar S, Putta A, Modi G. Ferroptosis and its modulators: A raising target for cancer and Alzheimer's disease. Bioorg Med Chem 2024; 98:117564. [PMID: 38171251 DOI: 10.1016/j.bmc.2023.117564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Revised: 12/01/2023] [Accepted: 12/18/2023] [Indexed: 01/05/2024]
Abstract
The process of ferroptosis, a recently identified form of regulated cell death (RCD) is associated with the overloading of iron species and lipid-derived ROS accumulation. Ferroptosis is induced by various mechanisms such as inhibiting system Xc, glutathione depletion, targeting excess iron, and directly inhibiting GPX4 enzyme. Also, ferroptosis inhibition is achieved by blocking excessive lipid peroxidation by targeting different pathways. These mechanisms are often related to the pathophysiology and pathogenesis of diseases like cancer and Alzheimer's. Fundamentally distinct from other forms of cell death, such as necrosis and apoptosis, ferroptosis differs in terms of biochemistry, functions, and morphology. The mechanism by which ferroptosis acts as a regulatory factor in many diseases remains elusive. Studying the activation and inhibition of ferroptosis as a means to mitigate the progression of various diseases is a highly intriguing and actively researched topic. It has emerged as a focal point in etiological research and treatment strategies. This review systematically summarizes the different mechanisms involved in the inhibition and induction of ferroptosis. We have extensively explored different agents that can induce or inhibit ferroptosis. This review offers current perspectives on recent developments in ferroptosis research, highlighting the disease's etiology and presenting references to enhance its understanding. It also explores new targets for the treatment of cancer and Alzheimer's disease.
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Affiliation(s)
- Gourav Singh
- Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India
| | - Prashant Kesharwani
- Department of Pharmaceutics, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, 110062, India
| | - Gireesh Kumar Singh
- Department of Pharmacy, School of Health Science, Central University of South Bihar Gaya, 824236, India
| | - Saroj Kumar
- Department of Biophysics, All India Institute of Medical Sciences, New Delhi 110029, India
| | - Anjaneyulu Putta
- Department of Chemistry, University of South Dakota, Churchill Haines, Vermillion SD-57069, United States
| | - Gyan Modi
- Department of Pharmaceutical Engineering & Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005, India.
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3
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Barragan AM, Soudackov AV, Luthey-Schulten Z, Hammes-Schiffer S, Schulten K, Solov'yov IA. Theoretical Description of the Primary Proton-Coupled Electron Transfer Reaction in the Cytochrome bc1 Complex. J Am Chem Soc 2021; 143:715-723. [PMID: 33397104 DOI: 10.1021/jacs.0c07799] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The cytochrome bc1 complex is a transmembrane enzymatic protein complex that plays a central role in cellular energy production and is present in both photosynthetic and respiratory chain organelles. Its reaction mechanism is initiated by the binding of a quinol molecule to an active site, followed by a series of charge transfer reactions between the quinol and protein subunits. Previous work hypothesized that the primary reaction was a concerted proton-coupled electron transfer (PCET) reaction because of the apparent absence of intermediate states associated with single proton or electron transfer reactions. In the present study, the kinetics of the primary bc1 complex PCET reaction is investigated with a vibronically nonadiabatic PCET theory in conjunction with all-atom molecular dynamics simulations and electronic structure calculations. The computed rate constants and relatively high kinetic isotope effects are consistent with experimental measurements on related biomimetic systems. The analysis implicates a concerted PCET mechanism with significant hydrogen tunneling and nonadiabatic effects in the bc1 complex. Moreover, the employed theoretical framework is shown to serve as a general strategy for describing PCET reactions in bioenergetic systems.
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Affiliation(s)
- Angela M Barragan
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, United States.,Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801, United States
| | - Alexander V Soudackov
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Zaida Luthey-Schulten
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, United States.,Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801, United States.,Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06520, United States
| | - Klaus Schulten
- NIH Center for Macromolecular Modeling and Bioinformatics, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, 405 North Mathews Avenue, Urbana, Illinois 61801, United States.,Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois 61801, United States
| | - Ilia A Solov'yov
- Department of Physics, Carl von Ossietzky University, Carl-von-Ossietzky-Strasse 9-11, Oldenburg 26111, Germany
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4
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Arenas‐Jal M, Suñé‐Negre JM, García‐Montoya E. Coenzyme Q10 supplementation: Efficacy, safety, and formulation challenges. Compr Rev Food Sci Food Saf 2020; 19:574-594. [DOI: 10.1111/1541-4337.12539] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Revised: 11/26/2019] [Accepted: 01/03/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Marta Arenas‐Jal
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy and Food SciencesUniversity of Barcelona Barcelona Spain
| | - J. M. Suñé‐Negre
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy and Food SciencesUniversity of Barcelona Barcelona Spain
| | - Encarna García‐Montoya
- Pharmacy and Pharmaceutical Technology Department, Faculty of Pharmacy and Food SciencesUniversity of Barcelona Barcelona Spain
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5
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Nakanishi I, Ohkubo K, Ogawa Y, Matsumoto KI, Ozawa T, Fukuzumi S. Aluminium ion-promoted radical-scavenging reaction of methylated hydroquinone derivatives. Org Biomol Chem 2018; 14:7956-61. [PMID: 27492849 DOI: 10.1039/c6ob01470d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The effect of the aluminium ion (Al(3+)) on the scavenging reaction of a 2,2-diphenyl-1-picrylhydrazyl radical (DPPH˙), as a reactivity model of reactive oxygen species, with hydroquinone (QH2) and its methylated derivatives (MenQH2, n = 1-4) was investigated using stopped-flow and electrochemical techniques in a hydroalcoholic medium. The second-order rate constants (k) for the DPPH˙-scavenging reaction of the hydroquinones increased with the increasing number of methyl substituents. Upon addition of Al(3+), the k values significantly increased depending on the concentration of Al(3+). Such an accelerating effect of Al(3+) on the DPPH˙-scavenging rates of the hydroquinones results from the remarkable positive shift of the one-electron reduction potential (Ered) of DPPH˙ in the presence of Al(3+). These results demonstrate that Al(3+), a strong Lewis acid, can act as a radical-scavenging promoter by stabilising the one-electron reduced species of the radical, although Al(3+) is reported not only to act as a pro-oxidant but also to strongly interact with biomolecules, showing toxicities.
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Affiliation(s)
- Ikuo Nakanishi
- Quantitative RedOx Sensing Team (QRST), Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Inage-ku, Chiba 263-8555, Japan.
| | - Kei Ohkubo
- Quantitative RedOx Sensing Team (QRST), Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Inage-ku, Chiba 263-8555, Japan. and Division of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan and Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea
| | - Yukihiro Ogawa
- Quantitative RedOx Sensing Team (QRST), Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Inage-ku, Chiba 263-8555, Japan. and Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba 263-8522, Japan
| | - Ken-Ichiro Matsumoto
- Quantitative RedOx Sensing Team (QRST), Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Inage-ku, Chiba 263-8555, Japan. and Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba 263-8522, Japan
| | - Toshihiko Ozawa
- Division of Oxidative Stress Research, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan
| | - Shunichi Fukuzumi
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea and Faculty of Science and Technology, Meijo University, SENTAN, Japan Science and Technology Agency (JST), Nagoya, Aichi 468-8502, Japan
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6
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Greene LE, Godin R, Cosa G. Fluorogenic Ubiquinone Analogue for Monitoring Chemical and Biological Redox Processes. J Am Chem Soc 2016; 138:11327-34. [DOI: 10.1021/jacs.6b06899] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Lana E. Greene
- Department of Chemistry and
Center for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3G 0B8, Canada
| | - Robert Godin
- Department of Chemistry and
Center for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3G 0B8, Canada
| | - Gonzalo Cosa
- Department of Chemistry and
Center for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University, 801 Sherbrooke Street West, Montreal, Quebec H3G 0B8, Canada
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7
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Mukai K, Nagai K, Egawa Y, Ouchi A, Nagaoka SI. Kinetic Study of Aroxyl-Radical-Scavenging and α-Tocopherol-Regeneration Rates of Five Catecholamines in Solution: Synergistic Effect of α-Tocopherol and Catecholamines. J Phys Chem B 2016; 120:7088-97. [PMID: 27346174 DOI: 10.1021/acs.jpcb.6b04285] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Detailed kinetic studies have been performed for reactions of aroxyl (ArO(•)) and α-tocopheroxyl (α-Toc(•)) radicals with five catecholamines (CAs) (dopamine (DA), norepinephrine (NE), epinephrine (EN), and 5- and 6-hydroxydopamine (5- and 6-OHDA)) and two catechins (epicatechin (EC) and epigallocatechin gallate (EGCG)) to clarify the free-radical-scavenging activity of CAs. Second-order rate constants (ks and kr) for reactions of ArO(•) and α-Toc(•) radicals with the above antioxidants were measured in 2-propanol/water (5:1, v/v) solution at 25.0 °C, using single- and double-mixing stopped-flow spectrophotometries, respectively. Both the rate constants (ks and kr) increased in the order NE < EN < DA < EC < 5-OHDA < EGCG < 6-OHDA. The ks and kr values of 6-OHDA are large and comparable to the corresponding values of ubiquinol-10 and sodium ascorbate, which show high free-radical-scavenging activity. The ultraviolet-visible absorption of α-Toc(•) (λmax = 428 nm), which was produced by the reaction of α-tocopherol (α-TocH) with ArO(•), disappeared under the coexistence of CAs due to the α-TocH-regeneration reaction. The results suggest that the CAs may contribute to the protection from oxidative damage in nervous systems, by scavenging free radicals (such as lipid peroxyl radical) and regenerating α-TocH from the α-Toc(•) radical.
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Affiliation(s)
- Kazuo Mukai
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
| | - Kanae Nagai
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
| | - Yoshifumi Egawa
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
| | - Aya Ouchi
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
| | - Shin-Ichi Nagaoka
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
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8
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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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9
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Mukai K, Nakamura A, Nagaoka SI, Ouchi A, Azuma N. Notable Effects of the Metal Salts on the Quenching Reaction of Singlet Oxygen by α-Tocopherol in Ethanol Solution. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2015. [DOI: 10.1246/bcsj.20150182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Kazuo Mukai
- Department of Chemistry, Faculty of Science, Ehime University
| | - Asuka Nakamura
- Department of Chemistry, Faculty of Science, Ehime University
| | | | - Aya Ouchi
- Department of Chemistry, Faculty of Science, Ehime University
- Quality Control Division, Osaka Delika Foods Co., Ltd
| | - Nagao Azuma
- Department of Chemistry, Faculty of Science, Ehime University
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10
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Roginskii VA. Kinetic isotope effect in the oxidation of unsaturated fatty acids. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY B 2015. [DOI: 10.1134/s1990793115030094] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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11
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Muchalski H, Xu L, Porter NA. Tunneling in tocopherol-mediated peroxidation of 7-dehydrocholesterol. Org Biomol Chem 2014; 13:1249-53. [PMID: 25435103 DOI: 10.1039/c4ob02377c] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The peroxidation of 7-dehydrocholesterol (7-DHC), a biosynthetic precursor to vitamin D3 and cholesterol, has been linked to the pathophysiology of Smith-Lemli-Optiz syndrome (SLOS), a devastating human disorder. In SLOS, 7-DHC plasma and tissue levels are elevated because of defects in the enzyme that convert it to cholesterol. α-Tocopherol can mediate the peroxidation of 7-DHC under certain circumstances and this prompted us to investigate the kinetic isotope effect (KIE) during this process. Thus, 9,14-d2-7-DHC was synthesized using a photochemical cyclization of deuterium-reinforced previtamin D3 (retro to its biosynthesis). Subsequently, we carried out co-oxidation of 9,14-h2-25,26,26,26,27,27,27-d7- and 9,14-d2-7-DHC in the presence of α-tocopherol under conditions that favor TMP. By monitoring the products formed from each precursor using mass spectrometry, the KIE for the hydrogen (deuterium) atom removal at C9 was found to be 21 ± 1. This large KIE value indicates that tunneling plays a role in the hydrogen atom transfer step in the tocopherol-mediated peroxidation of 7-DHC.
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Affiliation(s)
- H Muchalski
- Department of Chemistry, Vanderbilt University, 7330 Stevenson Center, Station B 351822, Nashville, TN 37235, USA.
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12
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Ouchi A, Nagaoka SI, Suzuki T, Izumisawa K, Koike T, Mukai K. Finding of synergistic and cancel effects on the aroxyl radical-scavenging rate and suppression of prooxidant effect for coexistence of α-tocopherol with β-, γ-, and δ-tocopherols (or -tocotrienols). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2014; 62:8101-8113. [PMID: 25052002 DOI: 10.1021/jf502049k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Measurements of aroxyl radical (ArO•)-scavenging rate constants (k(s)(AOH)) of antioxidants (AOHs) [α-, β-, γ-, and δ-tocopherols (TocHs) and -tocotrienols (Toc-3Hs)] were performed in ethanol solution via stopped-flow spectrophotometry. k(s)(AOH) values of α-, β-, γ-, and δ-Toc-3Hs showed good agreement with those of the corresponding α-, β-, γ-, and δ- TocHs. k(s)(AOH) values were measured not only for each antioxidant but also for mixtures of two antioxidants: (i) α-TocH with β-, γ-, or δ-TocH and (ii) α-TocH with α-, β-, γ-, or δ-Toc-3H. A synergistic effect in which the k(s)(AOH) value increases by 12% for γ-TocH (or by 12% for γ-Toc-3H) was observed for solutions including α-TocH and γ-TocH (or γ-Toc-3H). On the other hand, a cancel effect in which the k(s)(AOH) value decreases (a) by 7% for β-TocH (or 11% for β-Toc-3H) and (b) by 24% for δ-TocH (or 25% for δ-Toc-3H) was observed for solutions including two kinds of antioxidants. However, only a synergistic effect may function in edible oils, because contents of β- and δ-TocHs (and β- and δ-Toc-3Hs) are much less than those of α- and γ-TocHs (and α- and γ-Toc-3Hs) in many edible oils. UV-vis absorption of α-Toc•, which was produced by reaction of α-TocH with ArO•, decreased remarkably for coexistence of α-TocH with β-, γ-, or δ-TocH (or β-, γ-, or δ-Toc-3H), indicating that the prooxidant effect of α-Toc• is suppressed by the coexistence of other TocHs and Toc-3Hs.
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Affiliation(s)
- Aya Ouchi
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
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13
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Inagaki T, Yamamoto T. Critical Role of Deep Hydrogen Tunneling to Accelerate the Antioxidant Reaction of Ubiquinol and Vitamin E. J Phys Chem B 2014; 118:937-50. [DOI: 10.1021/jp410263f] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Taichi Inagaki
- Department of
Chemistry, Graduate School of
Science, Kyoto University, Kyoto 606-8502, Japan
| | - Takeshi Yamamoto
- Department of
Chemistry, Graduate School of
Science, Kyoto University, Kyoto 606-8502, Japan
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14
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Ouchi A, Ikemoto K, Nakano M, Nagaoka SI, Mukai K. Kinetic study of aroxyl radical scavenging and α-tocopheroxyl regeneration rates of pyrroloquinolinequinol (PQQH2, a reduced form of pyrroloquinolinequinone) in dimethyl sulfoxide solution: finding of synergistic effect on the reaction rate due to the coexistence of α-tocopherol and PQQH2. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:11048-11060. [PMID: 24175624 DOI: 10.1021/jf4040496] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Measurements of aroxyl radical (ArO•)-scavenging rate constants (ks AOH) of antioxidants (AOHs: pyrroloquinolinequinol (PQQH2), α-tocopherol (α-TocH), ubiquinol-10 (UQ10H2), epicatechin, epigallocatechin, epigallocatechin gallate, and caffeic acid) were performed in dimethyl sulfoxide (DMSO) solution, using stopped-flow spectrophotometry. The ks AOH values were measured not only for each AOH but also for the mixtures of two AOHs ((i) α-TocH and PQQH2 and (ii) α-TocH and UQ10H2). A notable synergistic effect that the ks AOH values increase 1.72, 2.42, and 2.50 times for α-TocH, PQQH2, and UQ10H2, respectively, was observed for the solutions including two kinds of AOHs. Measurements of the regeneration rates of α-tocopheroxyl radical (α-Toc•) to α-TocH by PQQH2 and UQ10H2 were performed in DMSO, using double-mixing stopped-flow spectrophotometry. Second-order rate constants (kr) obtained for PQQH2 and UQ10H2 were 1.08 × 105 and 3.57 × 104 M−1 s−1, respectively, indicating that the kr value of PQQH2 is 3.0 times larger than that of UQ10H2. It has been clarified that PQQH2 and UQ10H2 having two HO groups within a molecule may rapidly regenerate two molecules of α-Toc• to α-TocH. The result indicates that the prooxidant effect of α-Toc• is suppressed by the coexistence of PQQH2 or UQ10H2.
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Affiliation(s)
- Aya Ouchi
- Department of Chemistry, Faculty of Science, Ehime University , Matsuyama 790-8577, Japan
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15
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Nagaoka SI, Nagai K, Fujii Y, Ouchi A, Mukai K. Development of a new free radical absorption capacity assay method for antioxidants: aroxyl radical absorption capacity (ARAC). JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:10054-10062. [PMID: 24063575 DOI: 10.1021/jf402811m] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
A new free radical absorption capacity assay method is proposed with use of an aroxyl radical (2,6-di-tert-butyl-4-(4'-methoxyphenyl)phenoxyl radical) and stopped-flow spectroscopy and is named the aroxyl radical absorption capacity (ARAC) assay method. The free radical absorption capacity (ARAC value) of each tocopherol was determined through measurement of the radical-scavenging rate constant in ethanol. The ARAC value could also be evaluated through measurement of the half-life of the aroxyl radical during the scavenging reaction. For the estimation of the free radical absorption capacity, the aroxyl radical was more suitable than the DPPH radical, galvinoxyl, and p-nitrophenyl nitronyl nitroxide. The ARAC value in tocopherols showed the same tendency as the free radical absorption capacities reported previously, and the tendency was independent of an oxygen radical participating in the scavenging reaction and of a medium surrounding the tocopherol and oxygen radical. The ARAC value can be directly connected to the free radical-scavenging rate constant, and the ARAC method has the advantage of treating a stable and isolable radical (aroxyl radical) in a user-friendly organic solvent (ethanol). The ARAC method was also successfully applied to a palm oil extract. Accordingly, the ARAC method would be useful in free radical absorption capacity assay of antioxidative reagents and foods.
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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
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Mukai K, Ouchi A, Nakaya S, Nagaoka SI. Aroxyl-Radical-Scavenging Rate Increases Remarkably under the Coexistence of α-Tocopherol and Ubiquinol-10 (or Vitamin C): Finding of Synergistic Effect on the Reaction Rate. J Phys Chem B 2013; 117:8378-91. [DOI: 10.1021/jp403239q] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Kazuo Mukai
- Department
of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
| | - Aya Ouchi
- Department
of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
| | - Saori Nakaya
- Department
of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
| | - Shin-ichi Nagaoka
- Department
of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
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Pyo YH, Seong KS. Effects of Monascus-fermented grain extracts on plasma antioxidant status and tissue levels of ubiquinones and α-tocopherol in hyperlipidemic rats. Food Chem 2013; 141:428-35. [PMID: 23768376 DOI: 10.1016/j.foodchem.2013.02.110] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 12/29/2012] [Accepted: 02/26/2013] [Indexed: 11/17/2022]
Abstract
We investigated the effects of Monascus-fermented mixed grain extracts (MFGEs) enriched with bioactive mevinolins (natural statins) and coenzyme Qs (CoQ9+CoQ10) on the blood lipids, antioxidant status, and tissue levels of CoQs and α-tocopherol (α-Toc) in hyperlipidemic rats. The oral administration of MFGEs (300 mg/kg body weight per day) for 8 weeks resulted in a significant decrease in blood levels of total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), and LDL-C/high-density lipoprotein cholesterol (HDL-C) ratio compared to the control and lovastatin supplement group of a dosage of 20mg/kg per day (p<0.05). Furthermore, a significant increase in the ratios of α-Toc/LDL-C and CoQs/LDL-C in plasma and tissues and improvement in plasma antioxidant status as measured by TBARS and TRAP were observed in hypercholesterolemic rats (p<0.05). Regarding the effects of MFGEs on antioxidant levels of plasma and tissues, there were significant increases in the levels of α-Toc (p<0.05) and CoQs (p<0.01) after the 8-week MFGEs treatment. These data indicate that MFGEs supplementation not only decreases blood lipids and lipid peroxidation but also increases levels of antioxidants such as α-Toc and CoQs and may improve plasma antioxidant status as well as a hypolipidemic effect.
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Affiliation(s)
- Young-Hee Pyo
- Department of Food and Nutrition, Sungshin Women's University, 76-Gagil Dobong-ro Kangbuk-Gu, Seoul 142-732, Republic of Korea.
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Mukai K, Kohno Y, Ouchi A, Nagaoka SI. Notable Effects of Metal Salts on UV–Vis Absorption Spectra of α-, β-, γ-, and δ-Tocopheroxyl Radicals in Acetonitrile Solution. The Complex Formation between Tocopheroxyls and Metal Cations. J Phys Chem B 2012; 116:8930-41. [DOI: 10.1021/jp305039z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kazuo Mukai
- Department of Chemistry, Faculty
of Science, Ehime University, Matsuyama
790-8577, Japan
| | - Yutaro Kohno
- Department of Chemistry, Faculty
of Science, Ehime University, Matsuyama
790-8577, Japan
| | - Aya Ouchi
- Department of Chemistry, Faculty
of Science, Ehime University, Matsuyama
790-8577, Japan
| | - Shin-ichi Nagaoka
- Department of Chemistry, Faculty
of Science, Ehime University, Matsuyama
790-8577, Japan
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Mukai K, Oi M, Ouchi A, Nagaoka SI. Kinetic study of the α-tocopherol-regeneration reaction of ubiquinol-10 in methanol and acetonitrile solutions: notable effect of the alkali and alkaline earth metal salts on the reaction rates. J Phys Chem B 2012; 116:2615-21. [PMID: 22316107 DOI: 10.1021/jp2118086] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A kinetic study of regeneration reaction of α-tocopherol (α-TocH) by ubiquinol-10 has been performed in the presence of four kinds of alkali and alkaline earth metal salts (LiClO(4), NaClO(4), NaI, and Mg(ClO(4))(2)) in methanol and acetonitrile solutions, using double-mixing stopped-flow spectrophotometry. The second-order rate constants (k(r)'s) for the reaction of α-tocopheroxyl (α-Toc•) radical with ubiquinol-10 increased and decreased notably with increasing concentrations of metal salts in methanol and acetonitrile, respectively. The k(r) values increased in the order of no metal salt < NaClO(4) ~ NaI < LiClO(4) < Mg(ClO(4))(2) at the same concentration of metal salts in methanol. On the other hand, in acetonitrile, the k(r) values decreased in the order of no metal salt > NaClO(4) ~ NaI > LiClO(4) > Mg(ClO(4))(2) at the same concentration of metal salts. The metal salts having a smaller ionic radius of cation and a larger charge of cation gave a larger k(r) value in methanol, and a smaller k(r) value in acetonitrile. The effect of anion was almost negligible in both the solvents. Notable effects of metal cations on the UV-vis absorption spectrum of α-Toc• radical were observed in aprotic acetonitrile solution, suggesting complex formation between α-Toc• and metal cations. On the other hand, effects of metal cations were negligible in protic methanol, suggesting that the complex formation between α-Toc• and metal cations is hindered by the hydrogen bond between α-Toc• and methanol molecules. The difference between the reaction mechanisms in methanol and acetonitrile solutions was discussed on the basis of the results obtained. High concentrations of alkali and alkaline earth metal salts coexist with α-TocH and ubiquinol-10 in plasma, blood, and many tissues, suggesting the contribution of the metal salts to the above regeneration reaction in biological systems.
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Affiliation(s)
- Kazuo Mukai
- Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan.
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Inagaki T, Yamamoto T, Kato S. Proton-coupled electron transfer of the phenoxyl/phenol couple: effect of Hartree-Fock exchange on transition structures. J Comput Chem 2011; 32:3081-91. [PMID: 21815176 DOI: 10.1002/jcc.21892] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Revised: 06/10/2011] [Accepted: 06/24/2011] [Indexed: 11/08/2022]
Abstract
Proton-coupled electron transfer (PCET) and hydrogen atom transfer (HAT) reactions of the phenoxyl/phenol couple are studied theoretically by using wave function theory (WFT) as well as DFT methods. At the complete active space self-consistent field (CASSCF) level, geometry optimization is found to give two transition states (TSs); one is the PCET type with two benzene rings being nearly coplanar, and the other is the HAT type with two benzene rings taking a stacking structure. Geometry optimization at the (semilocal) DFT level, on the other hand, is found to give only one transition state (i.e., the PCET-type one) and fail to obtain the stacking TS structure. By comparing various levels of theories (including long-range corrected DFT functionals), we demonstrate that the Hartree-Fock exchange at long range plays a critical role in obtaining the sufficient stacking stabilization of the present open-shell system, and that the sole addition of empirical dispersion correction to semilocal DFT functionals may not be adequate for describing such a stacking interaction. Next, we investigate the solvent effect on the PCET and HAT TS thus obtained using the reference interaction site model self-consistent field (RISM-SCF) method. The results suggest that the free energy barrier increases with increasing polarity of the solvent, and that the solvent effects are stronger for the PCET TS than the stacking HAT TS pathway. The reason for this is discussed based on the dipole moment of different TS structures in solution.
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Affiliation(s)
- Taichi Inagaki
- Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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Kohno Y, Fujii M, Matsuoka C, Hashimoto H, Ouchi A, Nagaoka SI, Mukai K. Notable effects of the metal salts on the formation and decay reactions of α-tocopheroxyl radical in acetonitrile solution. The complex formation between α-tocopheroxyl and metal cations. J Phys Chem B 2011; 115:9880-8. [PMID: 21739987 DOI: 10.1021/jp205126a] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
The measurement of the UV-vis absorption spectrum of α-tocopheroxyl (α-Toc(•)) radical was performed by reacting aroxyl (ArO(•)) radical with α-tocopherol (α-TocH) in acetonitrile solution including four kinds of alkali and alkaline earth metal salts (MX or MX(2)) (LiClO(4), LiI, NaClO(4), and Mg(ClO(4))(2)), using stopped-flow spectrophotometry. The maximum wavelength (λ(max)) of the absorption spectrum of the α-Toc(•) at 425.0 nm increased with increasing concentration of metal salts (0-0.500 M) in acetonitrile, and it approached constant values, suggesting an [α-Toc(•)-M(+) (or M(2+))] complex formation. The stability constants (K) were determined to be 9.2, 2.8, and 45 M(-1) for LiClO(4), NaClO(4), and Mg(ClO(4))(2), respectively. By reacting ArO(•) with α-TocH in acetonitrile, the absorption of ArO(•) disappeared rapidly, while that of α-Toc(•) appeared and then decreased gradually as a result of the bimolecular self-reaction of α-Toc(•) after passing through the maximum. The second-order rate constants (k(s)) obtained for the reaction of α-TocH with ArO(•) increased linearly with an increasing concentration of metal salts. The results indicate that the hydrogen transfer reaction of α-TocH proceeds via an electron transfer intermediate from α-TocH to ArO(•) radicals followed by proton transfer. Both the coordination of metal cations to the one-electron reduced anions of ArO(•) (ArO:(-)) and the coordination of counteranions to the one-electron oxidized cations of α-TocH (α-TocH(•)(+)) may stabilize the intermediate, resulting in the acceleration of electron transfer. A remarkable effect of metal salts on the rate of bimolecular self-reaction (2k(d)) of the α-Toc(•) radical was also observed. The rate constant (2k(d)) decreased rapidly with increasing concentrations of the metal salts. The 2k(d) value decreased at the same concentration of the metal salts in the following order: no metal salt > NaClO(4) > LiClO(4) > Mg(ClO(4))(2). The complex formation between α-Toc(•) and metal cations may stabilize the energy level of the reactants (α-Toc(•) + α-Toc(•)), resulting in the decrease of the rate constant (2k(d)). The alkali and alkaline earth metal salts having a smaller ionic radius of cation and a larger charge of cation gave larger K and k(s) values and a smaller 2k(d) value.
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Affiliation(s)
- Yutaro Kohno
- Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan
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