Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Photochemical and Oxidative Degradation of Chamazulene Contained in Artemisia, Matricaria and Achillea Essential Oils and Setup of Protection Strategies

Version 1 : Received: 6 May 2024 / Approved: 6 May 2024 / Online: 6 May 2024 (09:45:02 CEST)

How to cite: Gabbanini, S.; Neba, J. N.; Matera, R.; Valgimigli, L. Photochemical and Oxidative Degradation of Chamazulene Contained in Artemisia, Matricaria and Achillea Essential Oils and Setup of Protection Strategies. Preprints 2024, 2024050280. https://doi.org/10.20944/preprints202405.0280.v1 Gabbanini, S.; Neba, J. N.; Matera, R.; Valgimigli, L. Photochemical and Oxidative Degradation of Chamazulene Contained in Artemisia, Matricaria and Achillea Essential Oils and Setup of Protection Strategies. Preprints 2024, 2024050280. https://doi.org/10.20944/preprints202405.0280.v1

Abstract

Chamazulene (CA) is an intensely blue molecule with a wealth of biological properties. In cosmetics chamazulene is exploited as a natural coloring and soothing agent. CA is unstable and tends to spontaneous degradation accelerated by light. We studied the photodegradation of CA upon controlled exposure to UVB-UVA irradiation by multi-ple techniques, including GC-MS, UHPLC-PDA-ESI-MS/MS and by direct infusion in ESI-MSn, which were matched to in silico mass spectral simulations to identify degra-dation products. Seven byproducts formed upon UVA exposure for 3 h at 70mW/cm2 (blue-to-green color change) were identified, including CA dimers and CA benzenoid which were not found on extended 6 h irradiation (green-to-yellow fading). Photosta-bility tests with reduced irradiance conducted in various solvents in the pres-ence/absence of air indicated highest degradation in acetonitrile in the presence of ox-ygen, suggesting a photo-oxidative mechanism. Testing in the presence of antioxidants (tocopherol, ascorbyl palmitate, hydroxytyrosol, bakuchiol, γ-terpinene, TEMPO and their combinations) indicated highest protection by tocopherol and TEMPO. Sun-screens ethylhexyl methoxycinnamate and particularly Tinosorb® S (but not octo-crylene) showed good CA photoprotection. Thermal stability tests indicated no degra-dation of CA in acetonitrile at 50°C in the dark for 50 days; however, accelerated deg-radation occurred in the presence of ascrorbyl palmitate.

Keywords

Artemisia arborescence; blue color; analysis; UHPLC MS/MS; GC-MS; photodegradation; anti-oxidant; sunscreen

Subject

Chemistry and Materials Science, Analytical Chemistry

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