An in vitro systematic spectroscopic examination of the photostabilities of a random set of commercial sunscreen lotions and their chemical UVB/UVA active agents

Abstract

The photostabilities of a random set of commercially available sunscreen lotions and their active ingredients are examined spectroscopically subsequent to simulated sunlight UV exposure. Loss of filtering efficacy can occur because of possible photochemical modifications of the sunscreen active agents. Changes in absorption of UVA/ UVB sunlight by agents in sunscreen lotions also leads to a reduction of the expected photoprotection of human skin and DNA against the harmful UV radiation. The active ingredients were investigated in aqueous media and in organic solvents of various polarities (methanol, acetonitrile, and n-hexane) under aerobic and anaerobic conditions The UV absorption features are affected by the nature of the solvents with properties closely related to oil-in-water (o/w) or water-in-oil (w/o) emulsions actually used in sunscreen formulations, and by the presence of molecular oxygen. The photostabilities of two combined chemical ingredients (oxybenzone and octyl methoxycinnamate) and the combination oxybenzone/titanium dioxide were also explored. In the latter case, oxybenzone undergoes significant photodegradation in the presence of the physical filter TiO2.

Advances in analytical methods and occurrence of organic UV-filters in the environment — A review

“…This happens mainly due to the inability to convert the energy absorbed fast enough, so the molecule stays excited and chemically react (Díaz-Cruz et al, 2008). This compromise the products' efficiency, since the UV-filters lose their photoprotective properties and photodegradation reactions may change their physical properties, namely the maximum absorption wavelength and absorbance coefficient (Díaz-Cruz et al, 2008;Serpone et al, 2002). Considering that these compounds are added to personal care products and applied frequently and in large quantities, it is essential to study their transformation products, since they can accumulate in human skin, posing a threat to human health, and afterwards will end up in the environment (Negreira et al, 2008).…”

Photodynamics of potent antioxidants: ferulic and caffeic acids

“…[11][12][13] In particular, some reports have highlighted the possibility that certain photoexcited sunscreen molecules may produce harmful reactive oxygen species (ROS). 14,15 This has led to the concept of including molecules with antioxidant properties within sunscreen products either to increase the photostability of sunscreen molecules, or to ''mop up'' any ROS. [15][16][17] A particularly potent set of antioxidants are hydroxycinnamic acids, which include: ferulic acid (3-(4-hydroxy-3-methoxyphenyl)-2-propenoic acid) and caffeic acid (3-(3,4-dihydroxyphenyl)-2-propenoic acid), shown in Fig.…”

Probing the Ultrafast Energy Dissipation Mechanism of the Sunscreen Oxybenzone after UVA Irradiation

“…3,6-10 It displays broadband UV absorption (spanning the UVA and UVB regions; see Supporting Information (SI), Figure S1) and remains photostable after several hours, 11 but the mechanism by which it provides these beneficial properties remains to be established. There is also some controversy in observed adverse dermatological effects from skin-OB contact.…”