Conservation of ultrafast photoprotective mechanisms with increasing molecular complexity in sinapoyl malate derivatives

Baker, Lewis A.; Staniforth, Michael; Flourat, Amandine L.; Allais, Florent; Stavros, Vasilios G.

doi:10.1002/cphc.202000429

Cited by 11 publications

(10 citation statements)

References 47 publications

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“…The assignment of EADS 4 to the cis-isomer is supported through a comparison of the transient absorption profile obtained at ∆t = 2 ns, shown as an inset in Figure 3E,F and Figure 4C, to those reported for SM and its derivatives previously [14,30], which show an identical long-lived feature assigned to the cis-isomer.…”

Section: Discussionsupporting

confidence: 54%

“…This dynamical process results in a fraction of the excited state population reforming the original trans-isomer, while another fraction completes the isomerisation along the allylic C=C double bond to generate the cis-isomer photoproduct. The cis-isomer photoproduct accounts for the absorption of EADS 4 (at ~360 nm) with a time constant τ 4 , which is >2 ns [14,15,17,19,22,23,25,30].…”

Section: Discussionmentioning

confidence: 99%

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Unravelling the Photoprotection Properties of Garden Cress Sprout Extract

et al. 2021

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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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Section: Discussionsupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

Unravelling the Photoprotection Properties of Garden Cress Sprout Extract

et al. 2021

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“…τ 2 and τ 3 can be associated with the trans - cis isomerization process. In particular, τ 2 relates to the vibrational cooling in the excited state and likely correspond to motion along the ππ * state, while τ 3 describes the internal conversion to the ground state along the photoisomerization coordinate 35 . Finally, a fourth time, τ 4 , present in some instances, has been ascribed to long-lived species with lifetimes of nanoseconds; in the case of the solution of p -coumaric acid, this long lifetime is ascribed to the presence of the cis-isomer.…”

Section: Resultsmentioning

confidence: 99%

Radiationless mechanism of UV deactivation by cuticle phenolics in plants

et al. 2022

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Hydroxycinnamic acids present in plant cuticles, the interphase and the main protective barrier between the plant and the environment, exhibit singular photochemical properties that could allow them to act as a UV shield. Here, we employ transient absorption spectroscopy on isolated cuticles and leaf epidermises to study in situ the photodynamics of these molecules in the excited state. Based on quantum chemical calculations on p-coumaric acid, the main phenolic acid present in the cuticle, we propose a model in which cuticle phenolics display a photoprotective mechanism based in an ultrafast and non-radiative excited state deactivation combined with fluorescence emission. As such, the cuticle can be regarded as the first and foremost protective barrier against UV radiation. This photostable and photodynamic mechanism seems to be universal in land plants giving a special role and function to the presence of different aromatic domains in plant cuticles and epidermises.

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“…Ultraviolet (UV) radiation has a comprehensive impact on human health, such as appropriate exposure to UV can generate vitamin D that has a beneficial effect on human health, but excessive UV exposure can cause detrimental effects such as sunburn, photocarcinogenesis, and photoaging. − Sunscreens are believed to be an effective tool in providing photoprotection for our skin against the UV radiation. The chemical filters used in modern commercial sunscreens play a critical role in photoprotection, which can dissipate the absorbed excessive UV radiation energy as heat through some nondestructive pathways to provide an additionally effective photoprotection for the skin. − Thus, in recent years, a large number of experimental and theoretical studies have focused on the excited-state relaxation dynamics of a variety of chemical UV filters including cinnamates, − eumelanins, − benzophenones, − camphor, , octocrylenes, − and salicylates. − …”

Section: Introductionmentioning

confidence: 99%

Quantum Mechanics/Molecular Mechanics Studies on the Photophysical Mechanism of Methyl Salicylate

et al. 2021

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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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Conservation of ultrafast photoprotective mechanisms with increasing molecular complexity in sinapoyl malate derivatives

Cited by 11 publications

References 47 publications

Unravelling the Photoprotection Properties of Garden Cress Sprout Extract

Unravelling the Photoprotection Properties of Garden Cress Sprout Extract

Radiationless mechanism of UV deactivation by cuticle phenolics in plants

Quantum Mechanics/Molecular Mechanics Studies on the Photophysical Mechanism of Methyl Salicylate

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