Assessment of the photo-degradation of UV-filters and radical-induced peroxidation in cosmetic sunscreen formulations

Abstract

Photo-instability of common UV-filters is a well documented phenomenon. This study develops a method for concomitant measurement of photostability and photo-induced ROS generation in cosmetic formulations. Oil-in-water formulations containing three common UV filters (OMC, BMDBM, EHT), individually or combined, were further supplemented with phosphatidylcholine and exposed to UVA. All filters show spectral decrease after UVA exposure. OMC and EHT do not induce significant lipid-peroxidation (as measured by TBARS production) while BMDBM does. In the latter case, this is reduced when BMDBM is combined with OMC but not with EHT. Neither OMC nor EHT stabilize BMDBM with respect to loss of absorbance. ROS-generation assessed via TBARS formation was supported by EPR experiments. The UV-induced changes in UV-filter performance, as monitored in the model formulations and in commercial sunscreens, demonstrate that this is a simple and effective method for stability assessment of sunscreen filters under conditions of use.

Photolysis of the organic UV filter, avobenzone, combined with octyl methoxycinnamate by nano-TiO2 composites

“…Modern sunscreen formulations now incorporate organic UV filters, which are compounds designed to absorb specific wavelengths of ultraviolet radiation, namely UVA (320-400 nm), UVB (290-320 nm) or both UVA and UVB radiation [3]. These organic UV filters should remain stable during the entire period of sun exposure [4]; however, a number of UV filters are photochemically unstable, which can impair their absorbance after UV exposure. The most common UVA and UVB filters in sunscreens are avobenzone and OMC, respectively, although it has been shown that their combination is photounstable [5].…”

Prevention of UVA-Induced Oxidative Damage in Human Dermal Fibroblasts by New UV Filters, Assessed Using a Novel In Vitro Experimental System

“…For irradiation of formulations, the protocol described in [13] was used. Briefly, an amount equivalent to 50±2 mg (checked by weighing), as recommended by the COLIPA sun protection factor test method [27], was spread onto 25 cm 2 glass plates with a gloved finger, left to dry for 30 min in the dark, and then the plates were exposed to 15 min UVA as described above.…”

Lipid Nanoparticles as Carrier for Octyl-Methoxycinnamate: In Vitro Percutaneous Absorption and Photostability Studies

“…An in vitro study was performed using a method reported elsewhere22 to evaluate lipid nanoparticle photoprotective effect against UVA radiation. Briefly, each formulation was loaded onto a 5 × 5 cm 2 glass (2 mg/cm 2 ) and spread with a gloved finger.…”