1
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Shen GB, Gao SH, Jia YW, Zhu XQ, Qian BC. Establishing the Thermodynamic Cards of Dipine Models' Oxidative Metabolism on 21 Potential Elementary Steps. Molecules 2024; 29:3706. [PMID: 39125109 PMCID: PMC11313972 DOI: 10.3390/molecules29153706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2024] [Revised: 07/26/2024] [Accepted: 07/29/2024] [Indexed: 08/12/2024] Open
Abstract
Dipines are a type of important antihypertensive drug as L-calcium channel blockers, whose core skeleton is the 1,4-dihydropyridine structure. Since the dihydropyridine ring is a key structural factor for biological activity, the thermodynamics of the aromatization dihydropyridine ring is a significant feature parameter for understanding the mechanism and pathways of dipine metabolism in vivo. Herein, 4-substituted-phenyl-2,6-dimethyl-3,5-diethyl-formate-1,4-dihydropyridines are refined as the structurally closest dipine models to investigate the thermodynamic potential of dipine oxidative metabolism. In this work, the thermodynamic cards of dipine models' aromatization on 21 potential elementary steps in acetonitrile have been established. Based on the thermodynamic cards, the thermodynamic properties of dipine models and related intermediates acting as electrons, hydrides, hydrogen atoms, protons, and two hydrogen ions (atoms) donors are discussed. Moreover, the thermodynamic cards are applied to evaluate the redox properties, and judge or reveal the possible oxidative mechanism of dipine models.
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Affiliation(s)
- Guang-Bin Shen
- College of Medical Engineering, Jining Medical University, Jining 272000, China; (G.-B.S.); (S.-H.G.); (Y.-W.J.)
| | - Shun-Hang Gao
- College of Medical Engineering, Jining Medical University, Jining 272000, China; (G.-B.S.); (S.-H.G.); (Y.-W.J.)
| | - Yan-Wei Jia
- College of Medical Engineering, Jining Medical University, Jining 272000, China; (G.-B.S.); (S.-H.G.); (Y.-W.J.)
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Bao-Chen Qian
- College of Medical Engineering, Jining Medical University, Jining 272000, China; (G.-B.S.); (S.-H.G.); (Y.-W.J.)
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2
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Shen GB, Qian BC, Luo GZ, Fu YH, Zhu XQ. Thermodynamic Evaluations of Amines as Hydrides or Two Hydrogen Ions Reductants and Imines as Protons or Two Hydrogen Ions Acceptors, as Well as Their Application in Hydrogenation Reactions. ACS OMEGA 2023; 8:31984-31997. [PMID: 37692224 PMCID: PMC10483529 DOI: 10.1021/acsomega.3c03804] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Accepted: 08/10/2023] [Indexed: 09/12/2023]
Abstract
Since the hydrogenation of imines (X) and the dehydrogenation of amines (XH2) generally involve the two hydrogen ions (H- + H+) transfer, the thermodynamic abilities of various amines releasing hydrides or two hydrogen ions as well as various imines accepting protons or two hydrogen ions are important and characteristic physical parameters. In this work, the pKa values of 84 protonated imines (XH+) in acetonitrile were predicted. Combining Gibbs free energy changes of amines releasing hydrides in acetonitrile from our previous work with the pKa(XH+) values, the Gibbs free energy changes of amines releasing two hydrogen ions and imines accepting two hydrogen ions were derived using Hess's law by constructing thermochemical cycles, and the thermodynamic evaluations of amines as hydrides or two hydrogen ions reductants and imines as protons or two hydrogen ions acceptors are well compared and discussed. Eventually, the practical application of thermodynamic data for amines and imines on hydrogenation feasibility, mechanism, and possible elementary steps was shown and discussed in this paper from the point of thermodynamics.
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Affiliation(s)
- Guang-Bin Shen
- School
of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Bao-Chen Qian
- School
of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Guang-Ze Luo
- School
of Medical Engineering, Jining Medical University, Jining, Shandong 272000, P. R. China
| | - Yan-Hua Fu
- College
of Chemistry and Environmental Engineering, Anyang Institute of Technology, Anyang, Henan 455000, China
| | - Xiao-Qing Zhu
- The
State Key Laboratory of Elemento-Organic Chemistry, Department of
Chemistry, Nankai University, Tianjin 300071, China
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3
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Xie W, Xu J, Md Idros U, Katsuhira J, Fuki M, Hayashi M, Yamanaka M, Kobori Y, Matsubara R. Metal-free reduction of CO 2 to formate using a photochemical organohydride-catalyst recycling strategy. Nat Chem 2023:10.1038/s41557-023-01157-6. [PMID: 36959509 DOI: 10.1038/s41557-023-01157-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/09/2023] [Indexed: 03/25/2023]
Abstract
Increasing levels of CO2 in the atmosphere is a problem that must be urgently resolved if the rise in current global temperatures is to be slowed. Chemically reducing CO2 into compounds that are useful as energy sources and carbon-based materials could be helpful in this regard. However, for the CO2 reduction reaction (CO2RR) to be operational on a global scale, the catalyst system must: use only renewable energy, be built from abundantly available elements and not require high-energy reactants. Although light is an attractive renewable energy source, most existing CO2RR methods use electricity and many of the catalysts used are based on rare heavy metals. Here we present a transition-metal-free catalyst system that uses an organohydride catalyst based on benzimidazoline for the CO2RR that can be regenerated using a carbazole photosensitizer and visible light. The system is capable of producing formate with a turnover number exceeding 8,000 and generates no other reduced products (such as H2 and CO).
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Affiliation(s)
- Weibin Xie
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Japan
| | - Jiasheng Xu
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Japan
| | - Ubaidah Md Idros
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Japan
| | - Jouji Katsuhira
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Japan
| | - Masaaki Fuki
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Japan
- Molecular Photoscience Research Center, Kobe University, Kobe, Japan
| | - Masahiko Hayashi
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Japan
| | - Masahiro Yamanaka
- Department of Chemistry and Research Center for Smart Molecules, Rikkyo University, Tokyo, Japan.
| | - Yasuhiro Kobori
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Japan.
- Molecular Photoscience Research Center, Kobe University, Kobe, Japan.
| | - Ryosuke Matsubara
- Department of Chemistry, Graduate School of Science, Kobe University, Kobe, Japan.
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4
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Mayer RJ, Moran J. Quantification of the hydride donor abilities of NADH, NADPH, and BH 3CN - in water. Org Biomol Chem 2022; 21:85-88. [PMID: 36472236 PMCID: PMC9768570 DOI: 10.1039/d2ob02041f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The nucleophilic reactivities of the hydride donors NADH, NADPH, and BH3CN- in water were quantified using kinetic measurements with benzhydrylium ions as reference electrophiles. All three hydride donors were found to possess almost identical nucleophilic reactivities, providing a potential explanation for why they are involved in similar transformations in biochemistry and organic synthesis, respectively.
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Affiliation(s)
- Robert J. Mayer
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS), CNRS UMR 7006, Université de Strasbourg8 Allée Gaspard Monge67000 StrasbourgFrance
| | - Joseph Moran
- Institut de Science et d'Ingénierie Supramoléculaires (ISIS), CNRS UMR 7006, Université de Strasbourg8 Allée Gaspard Monge67000 StrasbourgFrance,Institut Universitaire de France (IUF)75005 ParisFrance
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5
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Fu Y, Yang L, Zhou Z, Jia T, Shen G, Zhu X. Comparison of Thermodynamic Energies for Elementary Steps of Anionic Hydrides to Release Hydride Ions in Acetonitrile. ChemistrySelect 2022. [DOI: 10.1002/slct.202203626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Yan‐Hua Fu
- College of Chemistry and Environmental Engineering Anyang Institute of Technology Anyang Henan 455000 China
| | - Li‐Guo Yang
- College of Chemistry and Environmental Engineering Anyang Institute of Technology Anyang Henan 455000 China
| | - Zhong‐Yuan Zhou
- College of Chemistry and Environmental Engineering Anyang Institute of Technology Anyang Henan 455000 China
| | - Taixuan Jia
- College of Chemistry and Environmental Engineering Anyang Institute of Technology Anyang Henan 455000 China
| | - Guang‐Bin Shen
- School of Medical Engineering Jining Medical University Jining Shandong 272000 P. R. China
| | - Xiao‐Qing Zhu
- Department of Chemistry Nankai University Tianjin 300071 China
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6
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Fu Y, Wang K, Shen G, Zhu X. Quantitative Comparison of the Actual Antioxidant Activity of Vitamin C, Vitamin E and NADH. J PHYS ORG CHEM 2022. [DOI: 10.1002/poc.4358] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yan‐Hua Fu
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology Anyang Henan China
| | - Kai Wang
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology Anyang Henan China
| | - Guang‐Bin Shen
- School of Medical Engineering Jining Medical University Jining Shandong P.R.China
| | - Xiao‐Qing Zhu
- The State Key Laboratory of Elemento‐Organic Chemistry, College ofChemistry Nankai University Tianjin China
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7
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Fu YH, Wang Z, Wang K, Shen GB, Zhu XQ. Evaluation and comparison of antioxidant abilities of five bioactive molecules with C–H and O–H bonds in thermodynamics and kinetics. RSC Adv 2022; 12:27389-27395. [PMID: 36275999 PMCID: PMC9513755 DOI: 10.1039/d2ra04839f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 09/10/2022] [Indexed: 11/21/2022] Open
Abstract
In this work, the antioxidant abilities of NADH coenzyme analogue BNAH, F420 reduction prototype analogue F420H, vitamin C analogue iAscH−, caffeic acid, and (+)-catechin in acetonitrile in chemical reactions were studied and discussed.
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Affiliation(s)
- Yan-Hua Fu
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology, Anyang, Henan, 455000, China
| | - Zhen Wang
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology, Anyang, Henan, 455000, China
| | - Kai Wang
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology, Anyang, Henan, 455000, China
| | - Guang-Bin Shen
- School of Medical Engineering, Jining Medical University, Jining, Shandong, 272000, P. R. China
| | - Xiao-Qing Zhu
- Department of Chemistry, Nankai University, Tianjin, 300071, China
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8
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Shen GB, Qian BC, Fu YH, Zhu XQ. Thermodynamics of the elementary steps of organic hydride chemistry determined in acetonitrile and their applications. Org Chem Front 2022. [DOI: 10.1039/d2qo01310j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
This review focuses on the thermodynamics of the elementary step of 421 organic hydrides and unsaturated compounds releasing or accepting hydride or hydrogen determined in acetonitrile as well as their potential applications.
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Affiliation(s)
- Guang-Bin Shen
- School of Medical Engineering, Jining Medical University, Jining, Shandong, 272000, P. R. China
| | - Bao-Chen Qian
- School of Medical Engineering, Jining Medical University, Jining, Shandong, 272000, P. R. China
| | - Yan-Hua Fu
- College of Chemistry and Environmental Engineering, Anyang Institute of Technology, Anyang, Henan, 455000, China
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin 300071, China
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9
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PCET to bound-superoxide by NADH and NADHX in aqueous-acid media: a kinetic inspection. J CHEM SCI 2021. [DOI: 10.1007/s12039-021-01994-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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10
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Fu Y, Shen G, Wang K, Zhu X. Comparison of Thermodynamic, Kinetic Forces for Three NADH Analogues to Release Hydride Ion or Hydrogen Atom in Acetonitrile. ChemistrySelect 2021. [DOI: 10.1002/slct.202102048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Yan‐Hua Fu
- College of Chemistry and Environmental Engineering Anyang Institute of Technology, Anyang Henan 455000 China
| | - Guang‐Bin Shen
- School of Medical Engineering Jining Medical University Jining, Shandong 272000 P. R. China
| | - Kai Wang
- College of Chemistry and Environmental Engineering Anyang Institute of Technology, Anyang Henan 455000 China
| | - Xiao‐Qing Zhu
- Collaborative Innovation Center of Chemical Science and Engineering Nankai University Tianjin 300071 China
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11
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Chiu YH, Wu YW, Hung JI, Chen MC. Epigallocatechin gallate/L-ascorbic acid-loaded poly-γ-glutamate microneedles with antioxidant, anti-inflammatory, and immunomodulatory effects for the treatment of atopic dermatitis. Acta Biomater 2021; 130:223-233. [PMID: 34087444 DOI: 10.1016/j.actbio.2021.05.032] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/20/2021] [Accepted: 05/20/2021] [Indexed: 01/28/2023]
Abstract
Epigallocatechin gallate (EGCG) is a potential therapeutic agent for treatment of atopic dermatitis (AD) due to its antioxidant and anti-inflammatory activities. However, inherent instability of EGCG greatly limits its bioavailability and clinical efficacy. In this study, we developed a poly-γ-glutamate (γ-PGA)-based microneedle (MN) formulation capable of maintaining EGCG's stability and efficiently delivering EGCG into the skin to ameliorate AD symptoms. The γ-PGA MN can not only protect EGCG from oxidation, but also serve as an immunomodulator to downregulate T helper type 2 (Th2)-type immune responses. Encapsulation of EGCG into the γ-PGA MN and utilization of L-ascorbic acid (AA) as a stabilizer preserved 95% of its structural stability and retained 93% of its initial antioxidant activity after 4 weeks of storage. Once-weekly administration of EGCG/AA-loaded MNs to an Nc/Nga mouse model of AD for 4 weeks significantly ameliorated skin lesions and epidermal hyperplasia by reducing serum IgE (from 12156 ± 1344 to 5555 ± 1362 ng/mL) and histamine levels (from 81 ± 18 to 40 ± 5 pg/mL) and inhibiting IFN-γ (from 0.10 ± 0.01 to 0.01 pg/mg total protein) and Th2-type cytokine production, when compared to the AD (no treatment) group (p < 0.05). Notably, once-weekly MN therapy was at least as effective as the daily topical application of an EGCG + AA solution but markedly reduced the administration frequency and required dose. These results show that EGCG/AA-loaded γ-PGA MNs may be a convenient and promising therapeutic option for AD treatment. STATEMENT OF SIGNIFICANCE: This study describes epigallocatechin gallate (EGCG)/L-ascorbic acid (AA)-loaded poly-γ-glutamate (γ-PGA) microneedles (MN) capable of providing antioxidant, anti-inflammatory, and immunomodulatory effects on inflamed skin for ameliorating atopic dermatitis (AD) symptoms in Nc/Nga mice. After skin insertion, the γ-PGA MN can be quickly dissolved in the skin and remain in the dermis for sustained release of encapsulated active ingredients for 6 days. We demonstrated that once-weekly MN therapy effectively alleviated skin lesions and modulated immune response to relieve Th2-polarized allergic response in mice. Once-weekly MN dosing regimen may provide patients with a more convenient, therapeutically equivalent option to daily topical dosing, and may increase compliance and long-term persistence with AD therapy.
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Affiliation(s)
- Yu-Hsiu Chiu
- Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Yan-Wei Wu
- Department of Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Jui-I Hung
- Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan
| | - Mei-Chin Chen
- Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan.
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12
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Danehchin M, Esmaeili AA. Biomimetic hydrogenation of electron deficient olefins using in situ generated 2-arylbenzimidazoline: synthesis of novel 3-benzylbenzo[4,5]thiazolo[3,2-a]pyrimidin-4-ones. Mol Divers 2021; 26:1191-1199. [PMID: 34117585 DOI: 10.1007/s11030-021-10246-y] [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: 03/05/2021] [Accepted: 06/03/2021] [Indexed: 11/28/2022]
Abstract
In the present study, 2-Arylbenzimidazoline generated in situ from reaction of aromatic aldehydes and o-phenylenediamine used as biomimetic reductive agents for reductive alkylation of 2-hydroxy-4H-benzo[4,5]thiazolo[3,2-a]pyrimidin-4-one for synthesis of novel 3-benzyl-2-hydroxy-4H-benzo[4,5]thiazolo[3,2-a]pyrimidin-4-ones is described. The main benefits of this protocol include simplicity, reaction mildness, high yield, easy work up, and simple purification. The molecular structures were characterized by IR spectrophotometry, mass spectrometry, NMR spectroscopy, and elemental analysis.
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Affiliation(s)
- Maryam Danehchin
- Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, 9177948974, Iran
| | - Abbas Ali Esmaeili
- Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, 9177948974, Iran.
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13
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Rono CK, Chu WK, Darkwa J, Meyer D, Makhubela BCE. Triazolyl RuII, RhIII, OsII, and IrIII Complexes as Potential Anticancer Agents: Synthesis, Structure Elucidation, Cytotoxicity, and DNA Model Interaction Studies. Organometallics 2019. [DOI: 10.1021/acs.organomet.9b00440] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Charles K. Rono
- Department of Chemistry, University of Johannesburg, Kingsway Campus, 2006 Auckland Park, South Africa
| | - William K. Chu
- Department of Chemistry, University of Johannesburg, Kingsway Campus, 2006 Auckland Park, South Africa
| | - James Darkwa
- Department of Chemistry, University of Johannesburg, Kingsway Campus, 2006 Auckland Park, South Africa
| | - Debra Meyer
- Department of Biochemistry, University of Johannesburg, Kingsway Campus, 2006 Auckland Park, South Africa
| | - Banothile C. E. Makhubela
- Department of Chemistry, University of Johannesburg, Kingsway Campus, 2006 Auckland Park, South Africa
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14
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Zhao H, Li Y, Zhu XQ. Thermodynamic Parameters of Elementary Steps for 3,5-Disubstituted 1,4-Dihydropyridines To Release Hydride Anions in Acetonitrile. ACS OMEGA 2018; 3:13598-13608. [PMID: 31458065 PMCID: PMC6645033 DOI: 10.1021/acsomega.8b01815] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 10/09/2018] [Indexed: 06/10/2023]
Abstract
A series of 3,5-disubstituted 1,4-dihydropyridine derivatives including the derivative with two chiral centers, 6H (R2 = CH3, CH2Ph), as a new type of organic hydride source were synthesized and characterized. The thermodynamic driving forces (defined as enthalpy changes or standard redox potentials) of the 6 elementary steps for the organic hydrides to release hydride ions in acetonitrile were measured by isothermal titration calorimetry and electrochemical methods. The impacts of the substituents and functional groups bearing the N1 and C3/C5 positions on the thermodynamic driving forces of the 6 elementary steps were examined and analyzed. Moreover, the results showed that the reaction mechanism between the chiral organic hydride and activated ketone (ethyl benzoylformate) was identified as the concerted hydride transfer pathway based on the thermodynamic analysis platform. These valuable and crucial thermodynamic parameters will provide a broadly beneficial impact on the applications of 3,5-disubstituted 1,4-dihydropyridine derivatives in organic synthesis and pharmaceutical chemistry.
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Affiliation(s)
- Hui Zhao
- The
State Key Laboratory of Elemento-Organic Chemistry and Collaborative
Innovation Center of Chemical Science and Engineering (Tianjin), College
of Chemistry, Nankai University, Tianjin 300071, P. R. China
| | - Yang Li
- The
State Key Laboratory of Elemento-Organic Chemistry and Collaborative
Innovation Center of Chemical Science and Engineering (Tianjin), College
of Chemistry, Nankai University, Tianjin 300071, P. R. China
| | - Xiao-Qing Zhu
- The
State Key Laboratory of Elemento-Organic Chemistry and Collaborative
Innovation Center of Chemical Science and Engineering (Tianjin), College
of Chemistry, Nankai University, Tianjin 300071, P. R. China
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15
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Li Y, Zhu XQ. Theoretical Prediction of Activation Free Energies of Various Hydride Self-Exchange Reactions in Acetonitrile at 298 K. ACS OMEGA 2018; 3:872-885. [PMID: 31457934 PMCID: PMC6641257 DOI: 10.1021/acsomega.7b01911] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2017] [Accepted: 01/08/2018] [Indexed: 05/30/2023]
Abstract
Hydride transfer reactions are very important chemical reactions in organic chemistry. It has been a chemist's dream to predict the rate constants of hydride transfer reactions by only using the physical parameters of the reactants. To realize this dream, we have developed a kinetic equation (Zhu equation) in our previous papers to predict the activation free energies of various chemical reactions using the activation free energies of the corresponding self-exchange reactions and the related bond dissociation energies or redox potentials of the reactants. Because the activation free energy of the hydride self-exchange reaction is difficult to measure using the experimental method, in this study, the activation free energies of 159 hydride self-exchange reactions in acetonitrile at 298 K were systematically computed using an accurately benchmarked density functional theory method with a precision of 1.1 kcal mol-1. The results show that the range of the activation free energies of the 159 hydride self-exchange reactions is from 16.1 to 46.6 kcal mol-1. The activation free energies of 25 122 hydride transfer reactions in acetonitrile at 298 K can be estimated using the activation free energies of the 159 hydride self-exchange reactions and the corresponding heterolytic bond dissociation free energies of the reactants. The effects of the heteroatom, substituent, and aromaticity on the activation free energies of hydride self-exchange reactions were examined. The results show that heteroatoms, substituents at the reaction center, and the aromaticity of reactants, all have remarkable effects on the activation free energy of hydride self-exchange reactions. All kinetic information provided in this work on the hydride self-exchange reactions in acetonitrile at 298 K should be very useful in chemical labs and chemical industry.
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Affiliation(s)
- Yang Li
- The State Key Laboratory of Elemento-Organic Chemistry, College of
Chemistry, and Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, P. R. China
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, College of
Chemistry, and Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, P. R. China
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16
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Skaisgirski M, Guo X, Wenger OS. Electron Accumulation on Naphthalene Diimide Photosensitized by [Ru(2,2′-Bipyridine)3]2+. Inorg Chem 2017; 56:2432-2439. [DOI: 10.1021/acs.inorgchem.6b02446] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- Michael Skaisgirski
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Xingwei Guo
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
| | - Oliver S. Wenger
- Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056 Basel, Switzerland
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17
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Fu YH, Shen GB, Li Y, Yuan L, Li JL, Li L, Fu AK, Chen JT, Chen BL, Zhu L, Zhu XQ. Realization of Quantitative Estimation for Reaction Rate Constants Using only One Physical Parameter for Each Reactant. ChemistrySelect 2017. [DOI: 10.1002/slct.201601799] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Yan-Hua Fu
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Guang-Bin Shen
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Yang Li
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Lin Yuan
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Jun-Ling Li
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Le Li
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - An-Kun Fu
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Jin-Ting Chen
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Bao-Long Chen
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Li Zhu
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry; Department of Chemistry; Nankai University; Tianjin 300071 China
- Collaborative Innovation Center of Chemical Science and Engineering; Nankai University; Tianjin 300071 China
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18
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Meng FK, Zhu XQ. Elemental steps of the thermodynamics of dihydropyrimidine: a new class of organic hydride donors. Org Biomol Chem 2016; 15:197-206. [PMID: 27892585 DOI: 10.1039/c6ob02195f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
25 Dihydropyrimidine derivatives, a new class of organo-hydrides, were designed and synthesized by the Biginelli reaction. For the first time, the thermodynamic driving forces of the six elemental steps to obtain a hydride in acetonitrile were determined by isothermal titration and electrochemical methods, respectively. The effects of molecular structures and substituents on these thermodynamic parameters were examined, uncovering some interesting structure-reactivity relationships. Both the thermodynamic and kinetic studies show that the hydride transfer from dihydropyrimidines to 9-phenylxanthylium (PhXn+ClO4-) prefers a concerted mechanism.
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Affiliation(s)
- Fan-Kun Meng
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China.
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China.
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19
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Yuan L, Mu YY, Shen GB, Zhu XQ. Thermodynamic, kinetic, and mechanistic examination of 1,5- dihydro-3,4-dihydroxy-2-pyrrolone derivatives as a new type of antioxidants to mimic vitamin C. J PHYS ORG CHEM 2016. [DOI: 10.1002/poc.3670] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Lin Yuan
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry; Nankai University; Tianjin China
| | - Yuan-Yuan Mu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry; Nankai University; Tianjin China
| | - Guang-Bin Shen
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry; Nankai University; Tianjin China
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry; Nankai University; Tianjin China
- Collaborative Innovation Center of Chemical Science and Engineering; Nankai University; Tianjin China
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20
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Yuan L, Shen GB, Fu YH, Zhu XQ. What are the differences between Hantzsch ester and H2as two-hydrogen-atom donors in acetonitrile on the thermodynamics of elementary steps? J PHYS ORG CHEM 2016. [DOI: 10.1002/poc.3599] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Lin Yuan
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Guang-Bin Shen
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Yan-Hua Fu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry; Nankai University; Tianjin 300071 China
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry; Nankai University; Tianjin 300071 China
- Collaborative Innovation Center of Chemical Science and Engineering; Nankai University; Tianjin 300071 China
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21
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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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22
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Lei NP, Fu YH, Zhu XQ. Elemental step thermodynamics of various analogues of indazolium alkaloids to obtaining hydride in acetonitrile. Org Biomol Chem 2015; 13:11472-85. [PMID: 26451708 DOI: 10.1039/c5ob01715g] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of analogues of indazolium alkaloids were designed and synthesized. The thermodynamic driving forces of the 6 elemental steps for the analogues of indazolium alkaloids to obtain hydride in acetonitrile were determined using an isothermal titration calorimeter (ITC) and electrochemical methods, respectively. The effects of molecular structure and substituents on the thermodynamic driving forces of the 6 steps were examined. Meanwhile, the oxidation mechanism of NADH coenzyme by indazolium alkaloids was examined using the chemical mimic method. The result shows that the oxidation of NADH coenzyme by indazolium alkaloids in vivo takes place by one-step concerted hydride transfer mechanism.
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Affiliation(s)
- Nan-Ping Lei
- The State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071, China.
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23
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Yoon H, Lee YM, Nam W, Fukuzumi S. Hydride transfer from NADH analogues to a nonheme manganese(IV)-oxo complex via rate-determining electron transfer. Chem Commun (Camb) 2015; 50:12944-6. [PMID: 25220234 DOI: 10.1039/c4cc05313c] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydride transfer from NADH analogues to a nonheme Mn(iv)-oxo complex, [(Bn-TPEN)Mn(IV)(O)](2+), proceeds via a rate-determining electron transfer step with no deuterium kinetic isotope effect (KIE = 1.0 ± 0.1); a charge-transfer complex formed between the Mn(IV)(O) complex and NADH analogues is involved in the hydride transfer reaction.
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Affiliation(s)
- Heejung Yoon
- Department of Material and Life Science Graduate School of Engineering, Osaka University and ALCA (JST), 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan.
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24
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Xia K, Shen GB, Zhu XQ. Thermodynamics of various F420 coenzyme models as sources of electrons, hydride ions, hydrogen atoms and protons in acetonitrile. Org Biomol Chem 2015; 13:6255-68. [DOI: 10.1039/c5ob00538h] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
32 F420 coenzyme model were designed and synthesized; their thermodynamic driving forces to release electrons, hydride ions, hydrogen atoms and protons in acetonitrile were determined. The difference between F420 coenzyme and NADH coenzyme as sources of electrons, hydride ions, hydrogen atoms and protons was examined.
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Affiliation(s)
- Ke Xia
- The State Key Laboratory of Elemento-Organic Chemistry
- Department of Chemistry
- Collaborative Innovation Center of Chemical Science and Engineering
- Nankai University
- Tianjin 300071
| | - Guang-Bin Shen
- The State Key Laboratory of Elemento-Organic Chemistry
- Department of Chemistry
- Collaborative Innovation Center of Chemical Science and Engineering
- Nankai University
- Tianjin 300071
| | - Xiao-Qing Zhu
- The State Key Laboratory of Elemento-Organic Chemistry
- Department of Chemistry
- Collaborative Innovation Center of Chemical Science and Engineering
- Nankai University
- Tianjin 300071
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25
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Liu F, Zhu X. Unusual Reaction Constant for Hydride Transfer from a Carbanion to 9-Arylxanthyliums. European J Org Chem 2014. [DOI: 10.1002/ejoc.201403023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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26
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Liu F, Yan S, Zhu X. Mechanism of Hydride Transfer Reaction from β-Substituted Carbanions to a Carbocation. CHEM LETT 2014. [DOI: 10.1246/cl.140385] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Fengrui Liu
- State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University
| | - Shengyi Yan
- State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University
| | - Xiaoqing Zhu
- State Key Laboratory of Elemento-Organic Chemistry, Department of Chemistry, Nankai University
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27
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Stankiewicz A, Szczygieł I, Szczygieł B. Summary of Existing Models of the Ni-P Coating Electroless Deposition Process. INT J CHEM KINET 2013. [DOI: 10.1002/kin.20810] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- A. Stankiewicz
- Department of Inorganic Chemistry; Wrocław University of Economics; 53-345; Wrocław; Poland
| | - I. Szczygieł
- Department of Inorganic Chemistry; Wrocław University of Economics; 53-345; Wrocław; Poland
| | - B. Szczygieł
- Faculty of Chemistry; Wrocław University of Technology; 50-370; Wrocław; Poland
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28
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Yin J, Andersen ML, Skibsted LH. Reduction of ferrylmyoglobin by theanine and green tea catechins. Importance of specific Acid catalysis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:3159-3166. [PMID: 23461366 DOI: 10.1021/jf400219r] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Reduction of the hypervalent heme pigment ferrylmyoglobin by green tea catechins in aqueous solution of pH = 7.5 was investigated by stopped-flow spectroscopy. Reduction by the gallic acid esters epigallocatechin gallate (EGCG, k2 = 1460 L mol(-1) s(-1), 25.0 °C, 0.16 ionic strength) and epicatechin gallate (ECG, 1410 L mol(-1) s(-1)) was found faster than for epicatechin (EC, 300 L mol(-1) s(-1)) and epigallocatechin (EGC, 200 L mol(-1) s(-1)), even though the gallate ion (G, 330 L mol(-1) s(-1)) is similar in rate to EC. The rate for reduction by EC, EGC, ECG, EGCG, and G shows no correlation with their oxidation potentials or phenolic hydrogen-oxygen bond dissociation energy, but with the pKa of the most acidic phenol group. Theanine, with an acidity similar to that of EC, reduces ferrylmyoglobin with a similar rate (200 L mol(-1) s(-1)), in support of general acid catalysis with an initial proton transfer prior to electron transfer.
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Affiliation(s)
- Jie Yin
- Food Chemistry, Department of Food Science, University of Copenhagen, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark
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29
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Zhu XQ, Deng FH, Yang JD, Li XT, Chen Q, Lei NP, Meng FK, Zhao XP, Han SH, Hao EJ, Mu YY. A classical but new kinetic equation for hydride transfer reactions. Org Biomol Chem 2013; 11:6071-89. [DOI: 10.1039/c3ob40831k] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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30
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Giokas DL, Christodouleas DC, Vlachou I, Vlessidis AG, Calokerinos AC. Development of a generic assay for the determination of total trihydroxybenzoate derivatives based on gold-luminol chemiluminescence. Anal Chim Acta 2012; 764:70-7. [PMID: 23374217 DOI: 10.1016/j.aca.2012.12.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 12/07/2012] [Accepted: 12/14/2012] [Indexed: 11/24/2022]
Abstract
A selective assay for the determination of one of the most important class of phenolic compounds, namely trihydroxybenzoates (monomeric and polymeric compounds having at least one gallate moiety) based on their enhancing effect on the chemiluminogenic reaction between gold ions and luminol is described for the first time. In the presence of trihydroxybenzoate derivatives, the light emission generated when alkaline luminol is oxidized by gold ions is amplified several orders of magnitude compared to other common phenolic compounds which exhibit minor reactivity or no reactivity at all (e.g. hydroxycinnamates, flavonols, benzenediols). Based on this property, the experimental conditions were optimized in order to enable the determination of total trihydroxybenzoates in complex mixtures without resorting to separation techniques. The method was applied to samples of different composition (teas, herbal infusions and wines) with satisfactory analytical features yielding detection limits at the 10(-7) mol L(-1) level, intra-day precision of 3.1%, inter-day precision less than 10% and recoveries between 88.7 and 97.6%. The strengths and weaknesses of the method were identified and discussed in relation to its application in real samples.
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Affiliation(s)
- Dimosthenis L Giokas
- Laboratory of Analytical Chemistry, Department of Chemistry, University of Ioannina, 45110 Ioannina, Greece.
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31
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Han X, Hao W, Zhu XQ, Parker VD. A Thermodynamic and Kinetic Study of Hydride Transfer of a Caffeine Derivative. J Org Chem 2012; 77:6520-9. [DOI: 10.1021/jo301042d] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiaozhen Han
- State Key Laboratory of Elemento-Organic
Chemistry, Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Weifang Hao
- Department of Chemistry and
Biochemistry, Utah State University, Logan,
Utah 84322, United States
| | - Xiao-Qing Zhu
- State Key Laboratory of Elemento-Organic
Chemistry, Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Vernon D. Parker
- Department of Chemistry and
Biochemistry, Utah State University, Logan,
Utah 84322, United States
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32
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Zhu XQ, Li XT, Han SH, Mei LR. Conversion and Origin of Normal and Abnormal Temperature Dependences of Kinetic Isotope Effect in Hydride Transfer Reactions. J Org Chem 2012; 77:4774-83. [DOI: 10.1021/jo3005952] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiao-Qing Zhu
- State Key Laboratory
of Elemento-Organic Chemistry,
Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Xiu-Tao Li
- State Key Laboratory
of Elemento-Organic Chemistry,
Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Su-Hui Han
- State Key Laboratory
of Elemento-Organic Chemistry,
Department of Chemistry, Nankai University, Tianjin 300071, China
| | - Lian-Rui Mei
- State Key Laboratory
of Elemento-Organic Chemistry,
Department of Chemistry, Nankai University, Tianjin 300071, China
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33
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Woldu AS, Mai J. Computation of the bond dissociation enthalpies and free energies of hydroxylic antioxidants using the ab initio Hartree-Fock method. Redox Rep 2012; 17:252-74. [PMID: 23339861 PMCID: PMC6837695 DOI: 10.1179/1351000212y.0000000030] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
INTRODUCTION A new method for calculating theoretical bond dissociation enthalpy (BDE) and bond dissociation free energy (BDFE) of hydroxylic antioxidants is forwarded. BDE and BDFE may be understood as activation energies accompanying the formation of transition states, which may undergo downhill homolytic dissociation. The new method does not involve the complete fission of O-H bonds. METHOD Theoretical gas phase BDE values were calculated with the ab initio unrestricted Hartree-Fock (UHF) method, as changes in enthalpy between ground singlet states (GS) and triplet dissociative states (DS). Similarly, gas phase BDFEs were estimated from the corresponding changes in Gibbs free energy. The results were then compared with reliable experimental reports. RESULTS The proposed theoretical approach of BDE and BDFE determination was tested using 10 simple phenols, 5 flavonoids, and l-ascorbic acid derivatives. The agreement between our calculated gas phase results and the adopted experimental values were generally within 0.5 kcal mol(-1), with a very few exceptions. DISCUSSION Generally, steric interactions as well as intramolecular hydrogen bonding involving the dissociating OH group should be minimized in the GS. The DS are both electronically and vibrationally exited transition states. They have one unpaired electron on the carbon atom, which bears the homolytically dissociating OH group and are second order saddle points with a fixed CONCLUSION It was concluded that ab initio UHF was well suited for the estimation of gas phase BDE and BDFE. The method presented has a good potential for application across a range of hydroxylic antioxidants. Currently, work is underway to extend its application in other class of antioxidants.
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Affiliation(s)
- Ameha Seyoum Woldu
- Department of Pharmaceutical Chemistry and Pharmacognosy, School of Pharmacy, College of Health Sciences, Addis Ababa University, Addis Ababa, Ethiopia.
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