Phytofluene as a Highly Efficient UVA Photosensitizer of Singlet Oxygen Generationстатья
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Дата последнего поиска статьи во внешних источниках: 9 декабря 2020 г.
Аннотация:Phytoene and phytofluene – uncolored C40 carotenoids with short chain of conjugated double bonds (3 and 5, respectively) – are known to be universal precursors in biosynthesis of colored carotenoids in photosynthesizing organisms. It is commonly recognized that C40 carotenoids are photoprotectors of cells and tissues. We have shown that phytofluene is an exception to this rule. By measuring photosensitized phosphorescence of singlet oxygen (1O2) we found out that phytofluene was very effective photosensitizer of 1O2 formation in aerated solutions under UVA irradiation (quantum yieldof 85 ± 5%), whereas phytoene was almost inactive in this process. It was demonstrated that both carotenoids quench singlet oxygen in the dark. The obtained quenching rate constants [(4 ± 1) × 106 M–1·s–1 for phytoene and (2 ± 0.5) x 107 M–1·s–1 for phytofluene] were smaller than the rate constant of the diffusioncontrolled reactions by 34 orders of magnitude. Thus, both carotenoids displayed rather weak protector properties. Moreover, phytofluene due to its high photosensitizing activity might be considered as a promoter of cell photodamage and a promising UVA photosensitizer for medical purposes.