Involvement of Type-I and Type-II Photodynamic Reactions in Photosensitization of Fragrance Ingredient 2-acetonaphthone.

Abstract

2-Acetonaphthone (2-ACN) is a synthetic fragrance material used in various cosmetics as an adulterant. Due to its frequent use, we have conducted an in-depth study to understand the photosensitizing potential of 2-ACN. Results of this study illustrate that 2-ACN showed photodegradation in 4 h under ambient UV radiation (UVR) and sunlight exposure. It generated (1-25 µg mL-1 ) superoxide anion radical (O2 ·- ) and singlet oxygen (1 O2 ) in the presence of UVR/sunlight through in chemico and invitro test systems. 2-ACN (10 µg mL-1 ) showed a 43.9% and 57.4% reduction in cell viability under UVA and sunlight, respectively. Photosensitized 2-ACN generated intracellular reactive oxygen species (ROS) (6-folds in UVA and 8-folds in sunlight), which compromises the endoplasmic reticulum and mitochondrial membrane potential leading to cell death. Acridine orange/ethidium bromide dual staining and annexin-V/PI uptake showed cell death caused via 2-ACN under UVR exposure. The above findings signify the role of ROS via Type-I and Type-II photodynamic pathways in photosensitization of 2-ACN that ultimately promotes photodamage of important cellular organelles leading to cell death. The study advocates that solar radiation should be avoided by the users after the application of cosmetic products containing 2-ACN.