Photo-stability and photo-sensitizing characterization of selected sunscreens’ ingredients

Sunscreen products are mostly used to protect human skin from adverse effects of ultra-violet light like DNA damage, photo-aging and sunburns. Photo-stability is one of the critical requirements for an effective sunscreen. However, most commercially available sunscreen compounds exhibit photo-reactions leading to formation of harmful products. The objective of the current research was to investigate the photo-chemical and photo-physical properties of few selected sunscreens formulations and also to explore photo-stability and photo-sensitizing properties of few selected organic UV filters used in the sunscreens. Photo-degradation mechanisms of the selected sunscreens ingredients were analysed using time-resolved Laser Flash Photolysis and steady-state HPLC coupled with Mass Spectrometry. Oxybenzone (OXB) was revealed to be a sufficiently stable UV filter even after 24 h of radiation exposure, whereas, Avobenzone (AVOB) and Ecamsule (ECAM) were found to be a photo-unstable sunscreen.