UVA irradiation of fatty acids and their oxidized products substantially increases their ability to generate singlet oxygen

Abstract

UVA radiation plays an important role for adverse reactions in human tissue. UVA penetrates epidermis and dermis of skin being absorbed by various biomolecules, especially endogenous photosensitizers. This may generate deleterious singlet oxygen ( O 2 under UVA irradiation. In conclusion, fatty acids along with peroxidized products are weak endogenous photosensitizers but become strong photosensitizers under continuous UVA irradiation. Since fatty acids and their oxidized products are ubiquitous in living cells and in skin, which is frequently and long-lasting exposed to UVA radiation, this photosensitizing effect may contribute to initiation of deleterious photooxidative processes in tissue.

Evaluation of the photooxidation of galactosyl‐ and lactosylceramide by electrospray ionization mass spectrometry

“…Nevertheless, oxidation due to ROS, namely hydroxyl radical, formed during UV irradiation might have occurred to some extent inducing sugar oxidation and oxidative depolymerization as reported in the literature . Singlet oxygen can be generated via a sensitizer and, in spite of lipids being considered poor photosensitizers, previous data have confirmed their ability to generate singlet oxygen, which is probably enhanced as lipids accumulate oxidative modifications . The complete mechanism of UVA photooxidation remains however a matter of debate and some features are essentially unclear.…”

“…UVA photooxidation induces singlet oxygen formation in in vitro conditions, and can be used as a biomimetic model of singlet oxygen damage in vivo such as phagocytosis . Recently, it was proved that monounsaturated and polyunsaturated fatty acids can act as endogenous photosensitizers inducing the formation of singlet oxygen . UVA photooxidation might oxidize target molecules via two distinct reactions: type I reactions, which involve free radicals formations, and type II reactions, which involve energy transfer and singlet oxygen generation (Fig.…”

“…it was proved that monounsaturated and polyunsaturated fatty acids can act as endogenous photosensitizers inducing the formation of singlet oxygen. [17] UVA photooxidation might oxidize target molecules via two distinct reactions: type I reactions, which involve free radicals formations, and type II reactions, which involve energy transfer and singlet oxygen generation (Fig. 9).…”

“…[39] Singlet oxygen can be generated via a sensitizer and, in spite of lipids being considered poor photosensitizers, previous data have confirmed their ability to generate singlet oxygen, which is probably enhanced as lipids accumulate oxidative modifications. [17] The complete mechanism of UVA photooxidation remains however a matter of debate and some features are essentially unclear. Nevertheless, oxidative modification of GSL species may be the cause of sphingolipidome distortions with putative implications in health and disease.…”

Photoinitiated thiol–epoxy addition for the preparation of photoinduced self-healing fatty coatings

“…This could be explained by the presence of hydroperoxydes in the vegetable oil, which are well known to generate 1 O 2 under UV radiation. 32,33 This oxygen molecule could then oxidize the residual ethylenic double bonds of the epoxidized cottonseed oil.…”