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Vagkidis N, Marsh J, Chechik V. The Role of Polyphenolic Antioxidants from Tea and Rosemary in the Hydroxyl Radical Oxidation of N-Acetyl Alanine. Molecules 2023; 28:7514. [PMID: 38005236 PMCID: PMC10673243 DOI: 10.3390/molecules28227514] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 11/04/2023] [Accepted: 11/05/2023] [Indexed: 11/26/2023] Open
Abstract
In dead biological tissues such as human hair, the ability of antioxidants to minimise autoxidation is determined by their chemical reactions with reactive oxygen species. In order to improve our understanding of factors determining such antioxidant properties, the mechanistic chemistry of four phenolic antioxidants found in tea and rosemary extracts (epicatechin, epigallocatechin gallate, rosmarinic and carnosic acids) has been investigated. The degradation of N-acetyl alanine by photochemically generated hydroxyl radicals was used as a model system. A relatively high concentration of the antioxidants (0.1 equivalent with respect to the substrate) tested the ability of the antioxidants to intercept both initiating hydroxyl radicals (preventive action) and propagating peroxyl radicals (chain-breaking action). LC-MS data showed the formation of hydroxylated derivatives, quinones and hydroperoxides of the antioxidants. The structure of the assignment was aided by deuterium exchange experiments. Tea polyphenolics (epicatechin and epigallocatechin gallate) outperformed the rosemary compounds in preventing substrate degradation and were particularly effective in capturing the initiating radicals. Carnosic acid was suggested to act mostly as a chain-breaking antioxidant. All of the antioxidants except for rosmarinic acid generated hydroperoxides which was tentatively ascribed to the insufficient lability of the benzylic C-H bond of rosmarinic acid.
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Affiliation(s)
- Nikolaos Vagkidis
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK;
- Institute of Organic Chemistry, Justus Liebig University Giessen, Heinrich-Buff-Ring 17, 35392 Giessen, Germany
| | - Jennifer Marsh
- The Procter & Gamble Company, Mason Business Center, 8700 Mason-Montgomery Road, Mason, OH 45040, USA;
| | - Victor Chechik
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK;
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Vagkidis N, Li L, Marsh J, Chechik V. Synergy of UV light and heat in peptide degradation. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2023.114627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
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Brown E, Mandzhieva I, TomHon PM, Theis T, Castellano FN. Triplet Photosensitized para-Hydrogen Induced Polarization. ACS CENTRAL SCIENCE 2022; 8:1548-1556. [PMID: 36439314 PMCID: PMC9686209 DOI: 10.1021/acscentsci.2c01003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Indexed: 06/16/2023]
Abstract
Despite its enormous utility in structural characterization, nuclear magnetic resonance (NMR) spectroscopy is inherently limited by low spin polarization. One method to address the low polarization is para-hydrogen (p-H2) induced polarization (PHIP) which uses the singlet spin isomer of H2 to generate disparate nuclear spin populations to amplify the associated NMR signals. PHIP often relies on thermal catalysis or, more infrequently, UV-activated catalytic hydrogenation. Light-activated hydrogenation enables direct and timed control over the hyperpolarization of target substrates, critical for identifying short-lived intermediates. Here, we use an established Ir(III) triplet photosensitizer (PS) to visible light sensitize the triplet ligand-field states in the d6-transition metal dihydride Ru(CO)(PPh3)3(H)2 (1). Excitation inside a 9.4 T NMR spectrometer with the PS and a 420 nm blue LED, under 3 atm of p-H2, successfully photosensitized hyperpolarization in 1 and in a range of unsaturated substrates at and below room temperature, up to 1630-fold. In otherwise identical experimental conditions without light activation, no polarization was realized in 1 or the substrates evaluated. We believe triplet-sensitized PHIP (Trip-PHIP) represents a facile experimental means for probing triplet sensitized light activation in transition metal catalysts possessing low-lying triplet ligand-field states, providing mechanistic insight of potentially tremendous value in chemical catalysis.
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Shimogawa R, Muroi Y, Noguchi N, Konishi GI, Takao T, Suzuki H. Photo-Induced Reaction of Cp*Ru(μ-H) 4RuCp* with Arenes Resulting in Irreversible Formation of μ-η 2:η 2-Cyclohexadiene Complexes. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Affiliation(s)
- Ryuichi Shimogawa
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Yuki Muroi
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Naoya Noguchi
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Gen-ichi Konishi
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Toshiro Takao
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
| | - Hiroharu Suzuki
- Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8552, Japan
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Turner JJ, George MW, Poliakoff M, Perutz RN. Photochemistry of transition metal carbonyls. Chem Soc Rev 2022; 51:5300-5329. [PMID: 35708003 DOI: 10.1039/d1cs00826a] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The purpose of this Tutorial Review is to outline the fundamental photochemistry of metal carbonyls, and to show how the advances in technology have increased our understanding of the detailed mechanisms, particularly how relatively simple experiments can provide deep understanding of complex problems. We recall some important early experiments that demonstrate the key principles underlying current research, concentrating on the binary carbonyls and selected substituted metal carbonyls. At each stage, we illustrate with examples from recent applications. This review first considers the detection of photochemical intermediates in three environments: glasses and matrices; gas phase; solution. It is followed by an examination of the theory underpinning these observations. In the final two sections, we briefly address applications to the characterization and behaviour of complexes with very labile ligands such as N2, H2 and alkanes, concentrating on key mechanistic points, and also describe some principles and examples of photocatalysis.
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Affiliation(s)
- James J Turner
- School of Chemistry University of Nottingham, NG7 2RD, UK.
| | | | | | - Robin N Perutz
- Department of Chemistry, University of York, York, YO10 5DD, UK.
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Fanara PM, Vigneswaran V, Gunasekera PS, MacMillan SN, Lacy DC. Reversible Photoisomerization in a Ru cis-Dihydride Catalyst Accessed through Atypical Metal–Ligand Cooperative H2 Activation: Photoenhanced Acceptorless Alcohol Dehydrogenation. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00648] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Paul M. Fanara
- Department of Chemistry, University at Buffalo, State University of New York; Buffalo, New York14260, United States
| | - Vipulan Vigneswaran
- Department of Chemistry, University at Buffalo, State University of New York; Buffalo, New York14260, United States
| | - Parami S. Gunasekera
- Department of Chemistry, University at Buffalo, State University of New York; Buffalo, New York14260, United States
| | - Samantha N. MacMillan
- Department of Chemistry and Chemical Biology, Cornell University; Ithaca, New York14853, United States
| | - David C. Lacy
- Department of Chemistry, University at Buffalo, State University of New York; Buffalo, New York14260, United States
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Dickinson DP, Evans SW, Grellier M, Kendall H, Perutz RN, Procacci B, Sabo-Etienne S, Smart KA, Whitwood AC. Photochemical Oxidative Addition of Germane and Diphenylgermane to Ruthenium Dihydride Complexes. Organometallics 2019. [DOI: 10.1021/acs.organomet.8b00770] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- David P. Dickinson
- Department of Chemistry, University of York, York, YO10 5DD, United Kingdom
| | - Simon W. Evans
- Department of Chemistry, University of York, York, YO10 5DD, United Kingdom
| | - Mary Grellier
- LCC−CNRS, CNRS, UPS, Université de Toulouse, 31077 Toulouse, France
| | - Hannah Kendall
- Department of Chemistry, University of York, York, YO10 5DD, United Kingdom
| | - Robin N. Perutz
- Department of Chemistry, University of York, York, YO10 5DD, United Kingdom
| | - Barbara Procacci
- Department of Chemistry, University of York, York, YO10 5DD, United Kingdom
| | | | | | - Adrian C. Whitwood
- Department of Chemistry, University of York, York, YO10 5DD, United Kingdom
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