1
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Shimray SA, Ningthoujam A, Khaidem DKS, Chipem FAS. Theoretical studies on the photo protective mechanism of curcuminoids. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 305:123449. [PMID: 37774584 DOI: 10.1016/j.saa.2023.123449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Revised: 09/16/2023] [Accepted: 09/20/2023] [Indexed: 10/01/2023]
Abstract
In this work, the deactivation pathways of curcuminoids after photoexcitation was studied by employing density functional theory to explore their UVA radiation screening capacity. A comprehensive computational characterization of the excited-state processes of curcumin, demethoxycurcumin, and bis-demethoxycurcumin was done. The molecules exist in diketo and enol forms which are in equilibrium and interconvertible through keto-enol tautomerism. The enolic forms of each of the studied molecules have eight geometric cis-trans isomers as a result of torsion rotation about three different carbon-carbon double bonds across the aliphatic chain. For each geometric isomer, sixteen possible rotamers are found to exist due to rotation about five different carbon-carbon single bond rotations, also across the skeleton of the aliphatic chain. Upon photoexcitation, the studied molecules follow three main pathways of radiationless decay: (a) rotamerism and interconversion between rotamers of comparable energies which are in equilibrium, (b) interconversion between the cis-trans geometrical isomers where an efficient vibrational relaxation path is formed at ∼90° during torsion rotation about carbon-carbon double bond, and (c) excited state intramolecular proton transfer in a single O-H stretching vibration through a cyclic intramolecular hydrogen bonded ring formed at the centre of the molecule giving back the original structure. The absorption and emission spectra of the molecules were also simulated where the theoretically obtained absorption and emission maxima are close to the reported experimental values.
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Affiliation(s)
- Sophy A Shimray
- Department of Chemistry, Manipur University, Canchipur 795 003, India
| | - Amar Ningthoujam
- Department of Chemistry, Manipur University, Canchipur 795 003, India
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2
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Dalton J, Toldo JM, Allais F, Barbatti M, Stavros VG. Understanding the Impact of Symmetrical Substitution on the Photodynamics of Sinapate Esters Using Gas-Phase Ultrafast Spectroscopy. J Phys Chem Lett 2023; 14:8771-8779. [PMID: 37738948 PMCID: PMC10561265 DOI: 10.1021/acs.jpclett.3c02134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 09/08/2023] [Indexed: 09/24/2023]
Abstract
Two model biomimetic systems, ethyl sinapate (ES) and its symmetrical analogue, diethyl 2-(4-hydroxy-3,5-dimethoxybenzylidene)malonate (or diethyl sinapate, DES), are stripped to their core fundamentals through gas-phase spectroscopy to understand the underlying photophysics of photothermal materials. Following photoexcitation to the optically bright S1(ππ*) state, DES is found to repopulate the electronic ground state over 3 orders of magnitude quicker than its nonsymmetrical counterpart, ES. Our XMS-CASPT2 calculations shed light on the experimental results, revealing crucial differences in the potential energy surfaces and conical intersection topography between ES and DES. From this work, a peaked conical intersection, seen for DES, shows vital importance for the nonradiative ground-state recovery of photothermal materials. This fundamental comparative study highlights the potential impact that symmetrical substitution can have on the photodynamics of sinapate esters, providing a blueprint for future advancement in photothermal technology.
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Affiliation(s)
- Jack Dalton
- Department
of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K.
| | | | - Florent Allais
- URD
Agro-Biotechnologies Industrielles, CEBB, AgroParisTech, 51110 Pomacle, France
| | - Mario Barbatti
- Aix Marseille Université,
CNRS, ICR, Marseille, France
- Institut
Universitaire de France, 75231 Paris, France
| | - Vasilios G. Stavros
- Department
of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, U.K.
- School
of Chemistry, University of Birmingham, Birmingham B15 2TT, U.K.
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3
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González Moreno A, Woolley JM, Domínguez E, de Cózar A, Heredia A, Stavros VG. Synergic photoprotection of phenolic compounds present in tomato fruit cuticle: a spectroscopic investigation in solution. Phys Chem Chem Phys 2023; 25:12791-12799. [PMID: 37129056 DOI: 10.1039/d3cp00630a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Coumaric acids and flavonoids play pivotal roles in protecting plants against ultraviolet radiation (UVR) exposure. In this work, we focus our photoprotection studies on p-coumaric acid and the flavonoid naringenin chalcone. Photoprotection is well-understood in p-coumaric acid; in contrast, information surrounding photoprotection in naringenin chalcone is lacking. Additionally, and vitally, how these two species work in unison to provide photoprotection across the UV-B and UV-A is unknown. Herein, we employ transient absorption spectroscopy together with steady-state irradiation studies to unravel the photoprotection mechanism of a solution of p-coumaric acid and naringenin chalcone. We find that the excited state dynamics of p-coumaric acid are significantly altered in the presence of naringenin chalcone. This finding concurs with quenching of the p-coumaric acid fluorescence with increasing concentration of naringenin chalcone. We propose a Förster energy transfer mechanism is operative via the formation of dipole-dipole interactions between p-coumaric acid and naringenin chalcone. To our knowledge, this is the first demonstration in plants of a synergic effect between two classes of phenolics to bypass the potentially damaging effects of UVR.
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Affiliation(s)
- Ana González Moreno
- IHSM-UMA-CSIC La Mayora, Departamento de Biología Molecular y Bioquímica, Universidad de Málaga (UMA), 29071, Málaga, Spain.
| | - Jack M Woolley
- Department of Chemistry, University of Warwick, Coventry, UK.
| | - Eva Domínguez
- IHSM-UMA-CSIC La Mayora, Plant breeding and Biotechnology, CSIC, 29750 Algarrobo-Costa, Málaga, Spain
| | - Abel de Cózar
- Departamento de Química Orgánica I/Kimika Organikoa I Saila, Facultad de Química/Kimika Fakultatea, Universidad del País Vasco/Euskal Herriko Unibertsitatea (UPV/EHU) and Donostia International Physics Center (DIPC), P. K, 1072, 20018 San Sebastián - Donostia, Spain
- Ikerbasque, Basque Foundation for Science, Plaza Euskadi 5, 48009, Bilbao, Spain
| | - Antonio Heredia
- IHSM-UMA-CSIC La Mayora, Departamento de Biología Molecular y Bioquímica, Universidad de Málaga (UMA), 29071, Málaga, Spain.
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4
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Abiola TT, Toldo JM, do Casal MT, Flourat AL, Rioux B, Woolley JM, Murdock D, Allais F, Barbatti M, Stavros VG. Direct structural observation of ultrafast photoisomerization dynamics in sinapate esters. Commun Chem 2022; 5:141. [PMID: 36697608 PMCID: PMC9814104 DOI: 10.1038/s42004-022-00757-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 10/13/2022] [Indexed: 01/27/2023] Open
Abstract
Sinapate esters have been extensively studied for their potential application in 'nature-inspired' photoprotection. There is general consensus that the relaxation mechanism of sinapate esters following photoexcitation with ultraviolet radiation is mediated by geometric isomerization. This has been largely inferred through indirect studies involving transient electronic absorption spectroscopy in conjunction with steady-state spectroscopies. However, to-date, there is no direct experimental evidence tracking the formation of the photoisomer in real-time. Using transient vibrational absorption spectroscopy, we report on the direct structural changes that occur upon photoexcitation, resulting in the photoisomer formation. Our mechanistic analysis predicts that, from the photoprepared ππ* state, internal conversion takes place through a conical intersection (CI) near the geometry of the initial isomer. Our calculations suggest that different CI topographies at relevant points on the seam of intersection may influence the isomerization yield. Altogether, we provide compelling evidence suggesting that a sinapate ester's geometric isomerization can be a more complex dynamical process than originally thought.
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Affiliation(s)
- Temitope T. Abiola
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
| | - Josene M. Toldo
- grid.462456.70000 0004 4902 8637Aix Marseille Université, CNRS, ICR, Marseille, France
| | - Mariana T. do Casal
- grid.462456.70000 0004 4902 8637Aix Marseille Université, CNRS, ICR, Marseille, France
| | - Amandine L. Flourat
- grid.417885.70000 0001 2185 8223URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
| | - Benjamin Rioux
- grid.417885.70000 0001 2185 8223URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
| | - Jack M. Woolley
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
| | - Daniel Murdock
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
| | - Florent Allais
- grid.417885.70000 0001 2185 8223URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
| | - Mario Barbatti
- grid.462456.70000 0004 4902 8637Aix Marseille Université, CNRS, ICR, Marseille, France ,grid.440891.00000 0001 1931 4817Institut Universitaire de France, 75231 Paris, France
| | - Vasilios G. Stavros
- grid.7372.10000 0000 8809 1613Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry, CV4 7AL UK
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5
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Fan J, Finazzi L, Jan Buma W. Elucidating the photoprotective properties of natural UV screening agents: ZEKE-PFI spectroscopy of methyl sinapate. Phys Chem Chem Phys 2022; 24:3984-3993. [PMID: 35099484 DOI: 10.1039/d1cp05958k] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
As a prominent derivative of a natural sunscreen, methyl sinapate is an ideal candidate to provide fundamental insight into strategies on how to come to a rational design of artificial sunscreen filters with improved photoprotective properties. Here, static and time-resolved Zero Kinetic Energy-Pulsed Field Ionization (ZEKE-PFI) photoelectron spectroscopy has been used to study the spectroscopy and decay pathways of its electronically excited states. We find that different conformers are subject to distinct structural changes upon electronic excitation, and trace the structural changes that occur upon excitation back to the character of the LUMO. Ionization efficiency spectra in combination with pump-probe ZEKE-PFI spectra are consistent with the conclusion that the long-lived electronically excited state observed in the decay of the lowest excited singlet state is the lowest excited triplet state. Concurrently with providing information on the electronically excited states, the studies allow for a detailed characterization of the spectroscopic properties of the ground state of the radical ion, which is important in the context of the use of cinnamates in nature as antioxidants. Our studies determine the adiabatic ionization energies of the syn/cis, anti/cis and anti/trans conformers as 60 291.1 ± 0.5, 60 366.9 ± 0.5 and 60 503.9 ± 1.0 cm-1, respectively, and provide accurate vibrational fequencies of low-frequency modes of the molecular ion in its electronic ground state. Finally, the studies emphasize the important role of vibrational and electronic autoionization processes that start to dominate the ionization dynamics in non-rigid molecules of the present size.
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Affiliation(s)
- Jiayun Fan
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
| | - Laura Finazzi
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands.
| | - Wybren Jan Buma
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands. .,Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7c, 6525 ED Nijmegen, The Netherlands
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6
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Abiola TT, Auckloo N, Woolley JM, Corre C, Poigny S, Stavros VG. Unravelling the Photoprotection Properties of Garden Cress Sprout Extract. Molecules 2021; 26:molecules26247631. [PMID: 34946713 PMCID: PMC8705737 DOI: 10.3390/molecules26247631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 12/07/2021] [Accepted: 12/12/2021] [Indexed: 12/03/2022] Open
Abstract
Plants, as with humans, require photoprotection against the potentially damaging effects of overexposure to ultraviolet (UV) radiation. Previously, sinapoyl malate (SM) was identified as the photoprotective agent in thale cress. Here, we seek to identify the photoprotective agent in a similar plant, garden cress, which is currently used in the skincare product Detoxophane nc. To achieve this, we explore the photodynamics of both the garden cress sprout extract and Detoxophane nc with femtosecond transient electronic absorption spectroscopy. With the assistance of liquid chromatography-mass spectrometry, we determine that the main UV-absorbing compound in garden cress sprout extract is SM. Importantly, our studies reveal that the photoprotection properties of the SM in the garden cress sprout extract present in Detoxophane nc are not compromised by the formulation environment. The result suggests that Detoxophane nc containing the garden cress sprout extract may offer additional photoprotection to the end user in the form of a UV filter booster.
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Affiliation(s)
- Temitope T. Abiola
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK; (T.T.A.); (N.A.); (J.M.W.); (C.C.)
| | - Nazia Auckloo
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK; (T.T.A.); (N.A.); (J.M.W.); (C.C.)
- Warwick Integrative Synthetic Biology Centre and School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Jack M. Woolley
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK; (T.T.A.); (N.A.); (J.M.W.); (C.C.)
| | - Christophe Corre
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK; (T.T.A.); (N.A.); (J.M.W.); (C.C.)
- Warwick Integrative Synthetic Biology Centre and School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Stéphane Poigny
- Mibelle Group Biochemistry, Mibelle AG, Bolimattstrasse 1, CH-5033 Buchs, Switzerland;
| | - Vasilios G. Stavros
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK; (T.T.A.); (N.A.); (J.M.W.); (C.C.)
- Correspondence:
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7
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Abiola TT, Rioux B, Toldo JM, Alarcan J, Woolley JM, Turner MAP, Coxon DJL, Telles do Casal M, Peyrot C, Mention MM, Buma WJ, Ashfold MNR, Braeuning A, Barbatti M, Stavros VG, Allais F. Towards developing novel and sustainable molecular light-to-heat converters. Chem Sci 2021; 12:15239-15252. [PMID: 34976344 PMCID: PMC8634993 DOI: 10.1039/d1sc05077j] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Accepted: 10/18/2021] [Indexed: 12/18/2022] Open
Abstract
Light-to-heat conversion materials generate great interest due to their widespread applications, notable exemplars being solar energy harvesting and photoprotection. Another more recently identified potential application for such materials is in molecular heaters for agriculture, whose function is to protect crops from extreme cold weather and extend both the growing season and the geographic areas capable of supporting growth, all of which could help reduce food security challenges. To address this demand, a new series of phenolic-based barbituric absorbers of ultraviolet (UV) radiation has been designed and synthesised in a sustainable manner. The photophysics of these molecules has been studied in solution using femtosecond transient electronic and vibrational absorption spectroscopies, allied with computational simulations and their potential toxicity assessed by in silico studies. Following photoexcitation to the lowest singlet excited state, these barbituric absorbers repopulate the electronic ground state with high fidelity on an ultrafast time scale (within a few picoseconds). The energy relaxation pathway includes a twisted intramolecular charge-transfer state as the system evolves out of the Franck–Condon region, internal conversion to the ground electronic state, and subsequent vibrational cooling. These barbituric absorbers display promising light-to-heat conversion capabilities, are predicted to be non-toxic, and demand further study within neighbouring application-based fields. The synthesis and photophysical properties of phenolic barbiturics are reported. These molecules convert absorbed ultraviolet light to heat with high fidelity and may be suitable for inclusion in foliar sprays to boost crop protection and production.![]()
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Affiliation(s)
- Temitope T Abiola
- Department of Chemistry, University of Warwick Gibbet Hill Road Coventry CV4 7AL UK
| | - Benjamin Rioux
- URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech 51110 Pomacle France
| | | | - Jimmy Alarcan
- Department of Food Safety, German Federal Institute for Risk Assessment Max-Dohrn-Str. 8-10 10589 Berlin Germany
| | - Jack M Woolley
- Department of Chemistry, University of Warwick Gibbet Hill Road Coventry CV4 7AL UK
| | - Matthew A P Turner
- Department of Chemistry, University of Warwick Gibbet Hill Road Coventry CV4 7AL UK .,Department of Physics, University of Warwick Gibbet Hill Road Coventry CV4 7AL UK
| | - Daniel J L Coxon
- Department of Chemistry, University of Warwick Gibbet Hill Road Coventry CV4 7AL UK .,Department of Physics, University of Warwick Gibbet Hill Road Coventry CV4 7AL UK.,EPSRC Centre for Doctoral Training in Diamond Science and Technology UK
| | | | - Cédric Peyrot
- URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech 51110 Pomacle France
| | - Matthieu M Mention
- URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech 51110 Pomacle France
| | - Wybren J Buma
- Van 't Hoff Institute for Molecular Sciences, University of Amsterdam Amsterdam The Netherlands.,Institute for Molecules and Materials, FELIX Laboratory, Radboud University 6525 ED Nijmegen The Netherlands
| | - Michael N R Ashfold
- School of Chemistry, University of Bristol Cantock's Close Bristol BS8 1TS UK
| | - Albert Braeuning
- Department of Food Safety, German Federal Institute for Risk Assessment Max-Dohrn-Str. 8-10 10589 Berlin Germany
| | - Mario Barbatti
- Aix Marseille Université, CNRS, ICR Marseille France .,Institut Universitaire de France 75231 Paris France
| | - Vasilios G Stavros
- Department of Chemistry, University of Warwick Gibbet Hill Road Coventry CV4 7AL UK
| | - Florent Allais
- URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech 51110 Pomacle France
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8
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Toldo JM, do Casal MT, Barbatti M. Mechanistic Aspects of the Photophysics of UVA Filters Based on Meldrum Derivatives. J Phys Chem A 2021; 125:5499-5508. [PMID: 34151555 DOI: 10.1021/acs.jpca.1c03315] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Skin photoprotection against UVA radiation is crucial, but it is hindered by the sparsity of approved commercial UVA filters. Sinapoyl malate (SM) derivatives are promising candidates for a new class of UVA filters. They have been previously identified as an efficient photoprotective sunscreen in plants due to their fast nonradiative energy dissipation. Combining experimental and computational results, in our previous letter (J. Phys. Chem. Lett. 2021, 12, 337-344) we showed that coumaryl Meldrum (CMe) and sinapoyl Meldrum (SMe) are outstanding candidates for UVA filters in sunscreen formulations. Here, we deliver a comprehensive computational characterization of the excited-state dynamics of these molecules. Using reaction pathways and excited-state dynamics simulations, we could elucidate the photodeactivation mechanism of these molecules. Upon photoexcitation, they follow a two-step logistic decay. First, an ultrafast and efficient relaxation stabilizes the excited state alongside a 90° twisting around the allylic double bond, giving rise to a minimum with a twisted intramolecular excited-state (TICT) character. From this minimum, internal conversion to the ground state occurs after overcoming a 0.2 eV barrier. Minor differences in the nonradiative decay and fluorescence of CMe and SMe are associated with an additional minimum present only in the latter.
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Affiliation(s)
- Josene M Toldo
- Aix Marseille Université, CNRS, ICR, Av. Esc. Normandie-Niemen BJ5-D22, Marseille 13397, France
| | - Mariana T do Casal
- Aix Marseille Université, CNRS, ICR, Av. Esc. Normandie-Niemen BJ5-D22, Marseille 13397, France
| | - Mario Barbatti
- Aix Marseille Université, CNRS, ICR, Av. Esc. Normandie-Niemen BJ5-D22, Marseille 13397, France
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9
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Nguyen VPT, Stewart JD, Ioannou I, Allais F. Sinapic Acid and Sinapate Esters in Brassica: Innate Accumulation, Biosynthesis, Accessibility via Chemical Synthesis or Recovery From Biomass, and Biological Activities. Front Chem 2021; 9:664602. [PMID: 34055737 PMCID: PMC8161205 DOI: 10.3389/fchem.2021.664602] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 04/28/2021] [Indexed: 11/17/2022] Open
Abstract
Sinapic acid (SinA) and corresponding esters are secondary metabolites abundantly found in plants of Brassica family. Belonging to the family of p-hydroxycinnamic acids, SinA and its esters analogues are present in different plant parts and involved in multiple biological processes in planta. Moreover, these metabolites are also found in relatively large quantities in agro-industrial wastes. Nowadays, these metabolites are increasingly drawing attention due to their bioactivities which include antioxidant, anti-microbial, anti-cancer and UV filtering activities. As a result, these metabolites find applications in pharmaceutical, cosmetic and food industries. In this context, this article reviews innate occurrence, biosynthesis, accessibility via chemical synthesis or direct extraction from agro-industrial wastes. Biological activities of SinA and its main corresponding esters will also be discussed.
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Affiliation(s)
- V P Thinh Nguyen
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, Pomacle, France.,Department of Chemistry, University of Florida, Gainesville, FL, United States
| | - Jon D Stewart
- Department of Chemistry, University of Florida, Gainesville, FL, United States
| | - Irina Ioannou
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, Pomacle, France
| | - Florent Allais
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, Pomacle, France.,Department of Chemistry, University of Florida, Gainesville, FL, United States
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10
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Chang XP, Zhang TS, Fang YG, Cui G. Quantum Mechanics/Molecular Mechanics Studies on the Photophysical Mechanism of Methyl Salicylate. J Phys Chem A 2021; 125:1880-1891. [PMID: 33645980 DOI: 10.1021/acs.jpca.0c10589] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methyl salicylate (MS) as a subunit of larger salicylates found in commercial sunscreens has been shown to exhibit keto-enol tautomerization and dual fluorescence emission via excited-state intramolecular proton transfer (ESIPT) after the absorption of ultraviolet (UV) radiation. However, its excited-state relaxation mechanism is unclear. Herein, we have employed the quantum mechanics(CASPT2//CASSCF)/molecular mechanics method to explore the ESIPT and excited-state relaxation mechanism of MS in the lowest three electronic states, that is, S0, S1, and T1 states, in a methanol solution. Based on the optimized geometric and electronic structures, conical intersections and crossing points, and minimum-energy paths combined with the computed linearly interpolated Cartesian coordinate paths, the photophysical mechanism of MS has been proposed. The S1 state is a spectroscopically bright 1ππ* state in the Franck-Condon region. From the initially populated S1 state, there exist three nonradiative relaxation paths to repopulate the S0 state. In the first one, the S1 system (i.e., ketoB form) first undergoes an ESIPT path to generate an S1 tautomer (i.e., enol form) that exhibits a large Stokes shift in experiments. The generated S1 enol tautomer further evolves toward the nearby S1/S0 conical intersection and then hops to the S0 state, followed by the backward ground-state intramolecular proton transfer (GSIPT) to the initial ketoB form S0 state. In the second one, the S1 system first hops through the S1 → T1 intersystem crossing (ISC) to the T1 state, which then further decays to the S0 state via T1 → S0 ISC at the T1/S0 crossing point. In the third path, the T1 system that stems from the S1 → T1 ISC process via the S1/T1 crossing point first takes place a T1 ESIPT to generate a T1 enol tautomer, which can further decay to the S0 state via T1-to-S0 ISC. Finally, the GSIPT occurs to back the system to the initial ketoB form S0 state. Our present work could contribute to understanding the photophysics of MS and its derivatives.
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Affiliation(s)
- Xue-Ping Chang
- College of Chemistry and Chemical Engineering, Xinyang Normal University, Xinyang 464000, P. R. China
| | - Teng-Shuo Zhang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Ye-Guang Fang
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China
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11
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Abiola TT, Rodrigues NDN, Ho C, Coxon DJL, Horbury MD, Toldo JM, do Casal MT, Rioux B, Peyrot C, Mention MM, Balaguer P, Barbatti M, Allais F, Stavros VG. New Generation UV-A Filters: Understanding Their Photodynamics on a Human Skin Mimic. J Phys Chem Lett 2021; 12:337-344. [PMID: 33353308 DOI: 10.1021/acs.jpclett.0c03004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The sparsity of efficient commercial ultraviolet-A (UV-A) filters is a major challenge toward developing effective broadband sunscreens with minimal human- and eco-toxicity. To combat this, we have designed a new class of Meldrum-based phenolic UV-A filters. We explore the ultrafast photodynamics of coumaryl Meldrum, CMe, and sinapyl Meldrum (SMe), both in an industry-standard emollient and on a synthetic skin mimic, using femtosecond transient electronic and vibrational absorption spectroscopies and computational simulations. Upon photoexcitation to the lowest excited singlet state (S1), these Meldrum-based phenolics undergo fast and efficient nonradiative decay to repopulate the electronic ground state (S0). We propose an initial ultrafast twisted intramolecular charge-transfer mechanism as these systems evolve out of the Franck-Condon region toward an S1/S0 conical intersection, followed by internal conversion to S0 and subsequent vibrational cooling. Importantly, we correlate these findings to their long-term photostability upon irradiation with a solar simulator and conclude that these molecules surpass the basic requirements of an industry-standard UV filter.
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Affiliation(s)
| | | | | | - Daniel J L Coxon
- EPSRC Centre for Doctoral Training in Diamond Science and Technology, Coventry, United Kingdom
| | - Michael D Horbury
- School of Electrical and Electronic Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom
| | | | | | - Benjamin Rioux
- URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
| | - Cédric Peyrot
- URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
| | - Matthieu M Mention
- URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
| | | | | | - Florent Allais
- URD Agro-Biotechnologies (ABI), CEBB, AgroParisTech, 51110 Pomacle, France
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12
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Leriche-Grandchamp M, Flourat A, Shen H, Picard F, Giordana H, Allais F, Fayeulle A. Inhibition of Phenolics Uptake by Ligninolytic Fungal Cells and Its Potential as a Tool for the Production of Lignin-Derived Aromatic Building Blocks. J Fungi (Basel) 2020; 6:jof6040362. [PMID: 33322772 PMCID: PMC7770579 DOI: 10.3390/jof6040362] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 12/04/2020] [Accepted: 12/07/2020] [Indexed: 01/03/2023] Open
Abstract
Lignin is the principal natural source of phenolics but its structural complexity and variability make it difficult to valorize through chemical depolymerization approaches. White rots are one of the rare groups of organisms that are able to degrade lignin in ecosystems. This biodegradation starts through extracellular enzymes producing oxidizing agents to depolymerize lignin and continue with the uptake of the generated oligomers by fungal cells for further degradation. Phanerochaete chrysosporium is one of the most studied species for the elucidation of these biodegradation mechanisms. Although the extracellular depolymerization step appears interesting for phenolics production from lignin, the uptake and intracellular degradation of oligomers occurring in the course of the depolymerization limits its potential. In this study, we aimed at inhibiting the phenolics uptake mechanism through metabolic inhibitors to favor extracellular oligomers accumulation without preventing the ligninases production that is necessary for extracellular depolymerization. The use of sodium azide confirmed that an active transportation phenomenon is involved in the phenolics uptake in P. chrysosporium. A protocol based on carbonyl cyanide m-chlorophenyl hydrazone enabled reaching 85% inhibition for vanillin uptake. This protocol was shown not to inhibit, but on the contrary, to stimulate the depolymerization of both dehydrogenation polymers (DHPs) and industrial purified lignins.
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Affiliation(s)
| | - Amandine Flourat
- AgroParisTech, CEBB, URD Agro-Biotechnologies Industrielles (ABI), 51110 Pomacle, France
| | - Hangchen Shen
- AgroParisTech, CEBB, URD Agro-Biotechnologies Industrielles (ABI), 51110 Pomacle, France
- TIMR (Integrated Transformations of Renewable Matter), ESCOM, Centre de Recherche Royallieu, Université de Technologie de Compiègne, CS 60 319, 60203 Compiègne, France
| | - Flavien Picard
- AgroParisTech, CEBB, URD Agro-Biotechnologies Industrielles (ABI), 51110 Pomacle, France
- TIMR (Integrated Transformations of Renewable Matter), ESCOM, Centre de Recherche Royallieu, Université de Technologie de Compiègne, CS 60 319, 60203 Compiègne, France
| | - Heloïse Giordana
- AgroParisTech, CEBB, URD Agro-Biotechnologies Industrielles (ABI), 51110 Pomacle, France
- TIMR (Integrated Transformations of Renewable Matter), ESCOM, Centre de Recherche Royallieu, Université de Technologie de Compiègne, CS 60 319, 60203 Compiègne, France
| | - Florent Allais
- AgroParisTech, CEBB, URD Agro-Biotechnologies Industrielles (ABI), 51110 Pomacle, France
| | - Antoine Fayeulle
- TIMR (Integrated Transformations of Renewable Matter), ESCOM, Centre de Recherche Royallieu, Université de Technologie de Compiègne, CS 60 319, 60203 Compiègne, France
- Correspondence:
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13
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Fan J, Roeterdink W, Buma WJ. Excited-state dynamics of isolated and (micro)solvated methyl sinapate: the bright and shady sides of a natural sunscreen. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1825850] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jiayun Fan
- Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Wim Roeterdink
- Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Wybren Jan Buma
- Van ‘t Hoff Institute for Molecular Sciences, University of Amsterdam, Amsterdam, The Netherlands
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Nijmegen, The Netherlands
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14
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Whittock AL, Turner MAP, Coxon DJL, Woolley JM, Horbury MD, Stavros VG. Reinvestigating the Photoprotection Properties of a Mycosporine Amino Acid Motif. Front Chem 2020; 8:574038. [PMID: 33102444 PMCID: PMC7546825 DOI: 10.3389/fchem.2020.574038] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/26/2020] [Indexed: 12/28/2022] Open
Abstract
With the growing concern regarding commercially available ultraviolet (UV) filters damaging the environment, there is an urgent need to discover new UV filters. A family of molecules called mycosporines and mycosporine-like amino acids (referred to as MAAs collectively) are synthesized by cyanobacteria, fungi and algae and act as the natural UV filters for these organisms. Mycosporines are formed of a cyclohexenone core structure while mycosporine-like amino acids are formed of a cyclohexenimine core structure. To better understand the photoprotection properties of MAAs, we implement a bottom-up approach by first studying a simple analog of an MAA, 3-aminocyclohex-2-en-1-one (ACyO). Previous experimental studies on ACyO using transient electronic absorption spectroscopy (TEAS) suggest that upon photoexcitation, ACyO becomes trapped in the minimum of an S1 state, which persists for extended time delays (>2.5 ns). However, these studies were unable to establish the extent of electronic ground state recovery of ACyO within 2.5 ns due to experimental constraints. In the present studies, we have implemented transient vibrational absorption spectroscopy (as well as complementary TEAS) with Fourier transform infrared spectroscopy and density functional theory to establish the extent of electronic ground state recovery of ACyO within this time window. We show that by 1.8 ns, there is >75% electronic ground state recovery of ACyO, with the remaining percentage likely persisting in the electronic excited state. Long-term irradiation studies on ACyO have shown that a small percentage degrades after 2 h of irradiation, plausibly due to some of the aforementioned trapped ACyO going on to form a photoproduct. Collectively, these studies imply that a base building block of MAAs already displays characteristics of an effective UV filter.
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Affiliation(s)
- Abigail L Whittock
- Analytical Science Centre for Doctoral Training, Senate House, University of Warwick, Coventry, United Kingdom.,Department of Chemistry, University of Warwick, Coventry, United Kingdom
| | - Matthew A P Turner
- Department of Chemistry, University of Warwick, Coventry, United Kingdom.,Molecular Analytical Science Centre for Doctoral Training, Senate House, University of Warwick, Coventry, United Kingdom.,Department of Physics, University of Warwick, Coventry, United Kingdom
| | - Daniel J L Coxon
- Department of Chemistry, University of Warwick, Coventry, United Kingdom.,Department of Physics, University of Warwick, Coventry, United Kingdom.,Diamond Science and Technology Centre for Doctoral Training, University of Warwick, Coventry, United Kingdom
| | - Jack M Woolley
- Department of Chemistry, University of Warwick, Coventry, United Kingdom
| | - Michael D Horbury
- School of Electronic and Electrical Engineering, University of Leeds, Leeds, United Kingdom
| | - Vasilios G Stavros
- Department of Chemistry, University of Warwick, Coventry, United Kingdom
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15
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Baker LA, Staniforth M, Flourat AL, Allais F, Stavros VG. Conservation of ultrafast photoprotective mechanisms with increasing molecular complexity in sinapoyl malate derivatives. Chemphyschem 2020; 21:2006-2011. [PMID: 32638475 PMCID: PMC7586465 DOI: 10.1002/cphc.202000429] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 06/24/2020] [Indexed: 11/09/2022]
Abstract
Sinapoyl malate is a natural plant sunscreen molecule which protects leaves from harmful ultraviolet radiation. Here, the ultrafast dynamics of three sinapoyl malate derivatives, sinapoyl L-dimethyl malate, sinapoyl L-diethyl malate and sinapoyl L-di-t-butyl malate, have been studied using transient electronic absorption spectroscopy, in a dioxane and methanol solvent environment to investigate how well preserved these dynamics remain with increasing molecular complexity. In all cases it was found that, upon photoexcitation, deactivation occurs via a trans-cis isomerisation pathway within ∼20-30 ps. This cis-photoproduct, formed during photodeactivation, is stable and longed-lived for all molecules in both solvents. The incredible levels of conservation of the isomerisation pathway with increased molecular complexity demonstrate the efficacy of these molecules as ultraviolet photoprotectors, even in strongly perturbing solvents. As such, we suggest these molecules might be well-suited for augmentations to further improve their photoprotective efficacy or chemical compatibility with other components of sunscreen mixtures, whilst conserving their underlying photodynamic properties.
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Affiliation(s)
- Lewis A. Baker
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUnited Kingdom
- Faculty of Engineering and Physical SciencesUniversity of Surrey388 Stag HillGuildfordGU2 7XHUnited Kingdom
| | - Michael Staniforth
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUnited Kingdom
| | - Amandine L. Flourat
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech51110PomacleFrance
| | - Florent Allais
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech51110PomacleFrance
| | - Vasilios G. Stavros
- Department of ChemistryUniversity of WarwickGibbet Hill RoadCoventryCV4 7ALUnited Kingdom
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16
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Abiola TT, Whittock AL, Stavros VG. Unravelling the Photoprotective Mechanisms of Nature-Inspired Ultraviolet Filters Using Ultrafast Spectroscopy. Molecules 2020; 25:E3945. [PMID: 32872380 PMCID: PMC7504748 DOI: 10.3390/molecules25173945] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 08/26/2020] [Accepted: 08/27/2020] [Indexed: 02/07/2023] Open
Abstract
There are several drawbacks with the current commercially available ultraviolet (UV) filters used in sunscreen formulations, namely deleterious human and ecotoxic effects. As a result of the drawbacks, a current research interest is in identifying and designing new UV filters. One approach that has been explored in recent years is to use nature as inspiration, which is the focus of this review. Both plants and microorganisms have adapted to synthesize their own photoprotective molecules to guard their DNA from potentially harmful UV radiation. The relaxation mechanism of a molecule after it has been photoexcited can be unravelled by several techniques, the ones of most interest for this review being ultrafast spectroscopy and computational methods. Within the literature, both techniques have been implemented on plant-, and microbial-inspired UV filters to better understand their photoprotective roles in nature. This review aims to explore these findings for both families of nature-inspired UV filters in the hope of guiding the future design of sunscreens.
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Affiliation(s)
- Temitope T. Abiola
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK; (T.T.A.); (A.L.W.)
| | - Abigail L. Whittock
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK; (T.T.A.); (A.L.W.)
- AS CDT, Senate House, University of Warwick, Coventry CV4 7AL, UK
| | - Vasilios G. Stavros
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK; (T.T.A.); (A.L.W.)
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17
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Berenbeim JA, Wong NGK, Cockett MCR, Berden G, Oomens J, Rijs AM, Dessent CEH. Unravelling the Keto-Enol Tautomer Dependent Photochemistry and Degradation Pathways of the Protonated UVA Filter Avobenzone. J Phys Chem A 2020; 124:2919-2930. [PMID: 32208697 PMCID: PMC7168606 DOI: 10.1021/acs.jpca.0c01295] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
![]()
Avobenzone (AB) is
a widely used UVA filter known to undergo irreversible
photodegradation. Here, we investigate the detailed pathways by which
AB photodegrades by applying UV laser-interfaced mass spectrometry
to protonated AB ions. Gas-phase infrared multiple-photon dissociation
(IRMPD) spectra obtained with the free electron laser for infrared
experiments, FELIX, (600–1800 cm–1) are also
presented to confirm the geometric structures. The UV gas-phase absorption
spectrum (2.5–5 eV) of protonated AB contains bands that correspond
to selective excitation of either the enol or diketo forms, allowing
us to probe the resulting, tautomer-dependent photochemistry. Numerous
photofragments (i.e., photodegradants) are directly identified for
the first time, with m/z 135 and
161 dominating, and m/z 146 and
177 also appearing prominently. Analysis of the production spectra
of these photofragments reveals that that strong enol to keto photoisomerism
is occurring, and that protonation significantly disrupts the stability
of the enol (UVA active) tautomer. Close comparison of fragment ion
yields with the TD-DFT-calculated absorption spectra give detailed
information on the location and identity of the dissociative excited
state surfaces, and thus provide new insight into the photodegradation
pathways of avobenzone, and photoisomerization of the wider class
of β-diketone containing molecules.
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Affiliation(s)
- Jacob A Berenbeim
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Natalie G K Wong
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Martin C R Cockett
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
| | - Giel Berden
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen, 6500 HC, The Netherlands
| | - Jos Oomens
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen, 6500 HC, The Netherlands
| | - Anouk M Rijs
- Institute for Molecules and Materials, FELIX Laboratory, Radboud University, Toernooiveld 7, Nijmegen, 6500 HC, The Netherlands
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18
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Horbury MD, Holt EL, Mouterde LMM, Balaguer P, Cebrián J, Blasco L, Allais F, Stavros VG. Towards symmetry driven and nature inspired UV filter design. Nat Commun 2019; 10:4748. [PMID: 31628301 PMCID: PMC6802189 DOI: 10.1038/s41467-019-12719-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 09/26/2019] [Indexed: 12/13/2022] Open
Abstract
In plants, sinapate esters offer crucial protection from the deleterious effects of ultraviolet radiation exposure. These esters are a promising foundation for designing UV filters, particularly for the UVA region (400 – 315 nm), where adequate photoprotection is currently lacking. Whilst sinapate esters are highly photostable due to a cis-trans (and vice versa) photoisomerization, the cis-isomer can display increased genotoxicity; an alarming concern for current cinnamate ester-based human sunscreens. To eliminate this potentiality, here we synthesize a sinapate ester with equivalent cis- and trans-isomers. We investigate its photostability through innovative ultrafast spectroscopy on a skin mimic, thus modelling the as close to true environment of sunscreen formulas. These studies are complemented by assessing endocrine disruption activity and antioxidant potential. We contest, from our results, that symmetrically functionalized sinapate esters may show exceptional promise as nature-inspired UV filters in next generation sunscreen formulations. Sinapate esters are promising nature-inspired sunscreen and antioxidant agents but their photoisomerization may lead to ineffective or harmful species. Here the authors propose a symmetric ester with indistinguishable trans and cis isomers and prove its effectiveness by optical spectroscopies on a skin mimic.
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Affiliation(s)
- Michael D Horbury
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL, UK. .,School of Electronic and Electrical Engineering, University of Leeds, Leeds, LS2 9JT, UK.
| | - Emily L Holt
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL, UK.,Molecular Analytical Science Centre for Doctoral Training, Senate House, University of Warwick, Coventry, CV4 7AL, UK
| | - Louis M M Mouterde
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, 51110, Pomacle, France
| | | | - Juan Cebrián
- Lubrizol Advanced Materials, C/Isaac Peral 17-Pol. Industrial Cami Ral, 08850, Gava, Spain
| | - Laurent Blasco
- Lubrizol Advanced Materials, C/Isaac Peral 17-Pol. Industrial Cami Ral, 08850, Gava, Spain
| | - Florent Allais
- URD Agro-Biotechnologies Industrielles (ABI), CEBB, AgroParisTech, 51110, Pomacle, France
| | - Vasilios G Stavros
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL, UK.
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19
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Holt EL, Stavros VG. Applications of ultrafast spectroscopy to sunscreen development, from first principles to complex mixtures. INT REV PHYS CHEM 2019. [DOI: 10.1080/0144235x.2019.1663062] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Emily L. Holt
- Molecular Analytical Science Centre for Doctoral Training, Senate House, University of Warwick, Coventry, UK
- Department of Chemistry, University of Warwick, Coventry, UK
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20
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Direct Observation of Photochemical Free Radical Production from the Sunscreen 2‐Phenylbenzimidazole‐5‐Sulfonic Acid via Laser‐Interfaced Mass Spectrometry. CHEMPHOTOCHEM 2019. [DOI: 10.1002/cptc.201900149] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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21
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Bull JN, Silva GD, Scholz MS, Carrascosa E, Bieske EJ. Photoinitiated Intramolecular Proton Transfer in Deprotonated para-Coumaric Acid. J Phys Chem A 2019; 123:4419-4430. [DOI: 10.1021/acs.jpca.9b02023] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- James N. Bull
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Gabriel da Silva
- Department of Chemical Engineering, University of Melbourne, Parkville, VIC 3010, Australia
| | - Michael S. Scholz
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
| | - Eduardo Carrascosa
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
| | - Evan J. Bieske
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
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22
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Wong NGK, Berenbeim JA, Hawkridge M, Matthews E, Dessent CEH. Mapping the intrinsic absorption properties and photodegradation pathways of the protonated and deprotonated forms of the sunscreen oxybenzone. Phys Chem Chem Phys 2019; 21:14311-14321. [PMID: 30680382 DOI: 10.1039/c8cp06794e] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Sunscreens provide vital protection against the photodamaging effects of UV radiation, however, many fundamental questions remain about the detailed mechanisms by which they dissipate UV energy. One such issue is the extent to which the pH environment of an organic sunscreen molecule alters its effectiveness, both in terms of ability to absorb UV radiation, and also its potential to photodegrade. Here, we use gas-phase laser photodissociation spectroscopy for the first time to measure the intrinsic UVA-UVC absorption spectra and associated photodegradation products of protonated and deprotonated oxybenzone, away from the complications of bulk mixtures. Our results reveal that protonation state has a dramatic effect on the absorption and photodissociation properties of this sunscreen. While the UV absorption profile of oxybenzone is only modestly affected by protonation across the range from 400-216 nm, deprotonated oxybenzone displays a significantly modified absorption spectrum, with very low photoabsorption between 370-330 nm. Protonated oxybenzone primarily photofragments by rupture of the bonds on either side of the central carbonyl group, producing cationic fragments with m/z 151 and 105. Additional lower mass photofragments (e.g. m/z 95 and 77) are also observed. The production spectra for the photofragments from protonated oxybenzone fall into two distinct categories, which we discuss in the context of different excited state decay pathways. For deprotonated oxybenzone, the major photofragments observed are m/z 211 and 212, which are associated with the ejection of methane and the methyl free radical from the parent ion, respectively. Implications for the suitability of oxybenzone in its protonated and deprotonated forms as an optimum sunscreen molecule are discussed.
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Affiliation(s)
- Natalie G K Wong
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
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