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Poster De Conférence Année : 2023

Mechanistic Investigation of the Antioxidant Properties of Crocin by Radiolysis and Molecular Simulations

Sarah Al Gharib
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  • PersonId : 1266210
Daniel Adjei
Jacqueline Belloni
  • Fonction : Auteur
  • PersonId : 1266212
Mehran Mostafavi

Résumé

Crocin is the gentiobiose ester of crocetin, its radiolytic oxidation by the OH radical has been studied in the past [1] and recently revisited with pulse and γ radiolysis. [2] Pulse radiolysis shows that at short times the oxidation product displays a typical absorption band at 670 nm We have applied quantum chemistry [3] and our Monte-Carlo molecular simulation method [4,5] to the methanol ester of crocetin (Figure 1, middle), a simpler molecule with the same polyen chain. The computations show that: 1. The methyl groups -CaH3 and -CbH3 of the polyen chain are oxidable by the OH radical without barrier, the other CH groups are also oxidable, but with a positive (0.1 eV) potential barrier. 2. Molecular simulations of the corresponding -CaH2 and -CbH2 radicals, with the lc- ωPBE functional and the SMD simulation of the water solvent [3] give a low energy absorption band at 642 nm, in good agreement with the measurement. Our calculations also suggest that the products observed in pulse radiolysis at long times are due to dimerization of these radicals and that the products observed in γ radiolysis are due to dismutation of the same radicals, yielding closed shell cyclic molecules. References [1] W. Bors et al., Int. J. Radiat. Biol., 1982, 41(5), 493. [2] S. Al Gharib et al., to be submitted 2023. [3] Gaussian 16, Rev B01, Gaussian Inc. [4] P. Ungerer et al. Technip Ed. Paris 2005 [5] P. Archirel et al., J. Phys. Chem. B, 2019, 123, 9087

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Chimie
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Dates et versions

hal-04149109 , version 1 (18-07-2023)

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  • HAL Id : hal-04149109 , version 1

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Pierre Archirel, Sarah Al Gharib, Daniel Adjei, Jacqueline Belloni, Mehran Mostafavi. Mechanistic Investigation of the Antioxidant Properties of Crocin by Radiolysis and Molecular Simulations. 32nd Miller Conference on Radiation Chemistry, Jun 2023, Furiani (la Marana), France. ⟨hal-04149109⟩
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