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Linoleic acid and squalene are oxidized by discrete oxidation mechanisms in human sebum
Author(s) -
Ishikawa Ayano,
Ito Junya,
Shimizu Naoki,
Kato Shunji,
Kobayashi Eri,
Ohnari Hiroki,
Sakata Osamu,
Naru Eiji,
Nakagawa Kiyotaka
Publication year - 2021
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/nyas.14615
Subject(s) - squalene , chemistry , singlet oxygen , oxygen , autoxidation , lipid oxidation , linoleic acid , photochemistry , organic chemistry , antioxidant , fatty acid
Previous studies suggest that squalene (SQ) in sebum is oxidized by a photooxidation mechanism (i.e., singlet oxygen oxidation) to create SQ hydroperoxide (SQOOH), a compound that causes adverse skin conditions. However, oxidation of other lipids in sebum, such as linoleic acid (LA), has not been fully understood. Elucidating their oxidation, especially its mechanisms, may lead to a further understanding of the relationship between sebum oxidation and skin conditions. In this study, using HPLC–MS/MS, we aimed to detect LA hydroperoxide (LAOOH) directly from sebum and identify the oxidation mechanism of LA in sebum through analysis of LAOOH isomers. We developed extraction and HPLC–MS/MS analysis conditions that can sufficiently quantify each LAOOH isomer in sebum. Using this method, LAOOH was detected in samples from healthy individuals, demonstrating the presence of LAOOH in human sebum. Moreover, isomer analysis of LAOOH and SQOOH indicated that LA and SQ are oxidized in sebum by discrete oxidation mechanisms (LA oxidized by free radical oxidation, whereas SQ oxidized by singlet oxygen oxidation). Such results may further lead to the development of mechanism‐specific ways to prevent oxidation of sebum via a selection of appropriate antioxidants, ultimately leading to the promotion of skin health.