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A novel characteristic of UV absorbers, salicylates: suppression of Corapan TQ-photosensitized singlet oxygen generation

Abstract

2-Ethylhexyl salicylate (EHS, octyl salicylate) and homomenthyl salicylate (HMS, homosalate) are UV-B absorbers used in cosmetic sunscreens. Diethylhexyl 2,6-naphthalate (DEHN, tradename Corapan TQ) used as a mildly effective photostabilizer for labile butylmethoxydibenzoylmethane, the most widely used UV-A absorber, is an efficient singlet oxygen photosensitizer with a high quantum yield of singlet oxygen generation ΦΔ = 0.44 in ethanol. The effects of EHS, HMS, L-ascorbic acid (AA, vitamin C), 3-O-ethyl-L-ascorbic acid (3-EtAA) and Trolox (TX, a water-soluble analogue of vitamin E) on the DEHN-photosensitized singlet oxygen generation have been studied through measurements of time-resolved near-infrared phosphorescence in ethanol. These compounds suppress the DEHN-photosensitized singlet oxygen generation. 40% of ΦΔ is decreased by adding 32 mmol dm–3 EHS or HMS. ΦΔ is decreased to a half by adding 3.0 mmol dm–3 TX. Fluorescence and transient absorption measurements suggest that the observed suppression is due to the quenching of the excited singlet state of DEHN by EHS, HMS, AA and 3-EtAA. These compounds do not quench the excited triplet state of DEHN. On the other hand, TX quenches the excited both singlet and triplet states of DEHN. It was shown that these UV-B absorbers have a novel characteristic as a suppressor of photosensitized singlet oxygen generation. Suppressing the singlet oxygen generation is an important method for prevention of skin damage. To the best of our knowledge, this is the first report of the suppression of photosensitized singlet oxygen generation by UV absorbing molecules.

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Publication details

The article was received on 01 Mar 2019, accepted on 15 Apr 2019 and first published on 16 Apr 2019


Article type: Paper
DOI: 10.1039/C9PP00104B
Citation: Photochem. Photobiol. Sci., 2019, Accepted Manuscript

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    A novel characteristic of UV absorbers, salicylates: suppression of Corapan TQ-photosensitized singlet oxygen generation

    S. Fukuchi, M. Yagi, N. Oguchi-Fujiyama, J. Kang and A. Kikuchi, Photochem. Photobiol. Sci., 2019, Accepted Manuscript , DOI: 10.1039/C9PP00104B

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