Free radicals induced by sunlight in different spectral regions – in vivo versus ex vivo study

Abstract

Sunlight represents an exogenous factor stimulating formation of free radicals which can induce cell damage. To assess the effect of the different spectral solar regions on the development of free radicals in skin, in vivo electron paramagnetic resonance (EPR) investigations with human volunteers and ex vivo studies on excised human and porcine skin were carried out. For all skin probes, the ultraviolet (UV) spectral region stimulates the most intensive radical formation, followed by the visible (VIS) and the near infrared (NIR) regions. A comparison between the different skin models shows that for UV light, the fastest and highest production of free radicals could be detected in vivo, followed by excised porcine and human skin. The same distribution pattern was found for the VIS/NIR spectral regions, whereby the differences in radical formation between in vivo and ex vivo were less pronounced. An analysis of lipid composition in vivo before and after exposure to UV light clearly showed modifications in several skin lipid components; a decrease of ceramide subclass [AP2] and an increase of ceramide subclass [NP2], sodium cholesterol sulphate and squalene (SQ) were detectable. In contrast, VIS/NIR irradiation led to an increase of ceramides [AP2] and SCS, and a decrease of SQ. These results, which are largely comparable for the different skin models investigated in vivo and ex vivo, indicate that radiation exposure in different spectral regions strongly influences radical production in skin and also results in changes in skin lipid composition, which is essential for barrier function.

Radical-Scavenging Activity of a Sunscreen Enriched by Antioxidants Providing Protection in the Whole Solar Spectral Range

“…In this study, the NIR irradiance dose was 2.1 J/cm 2 and therefore lower than the natural sunlight radiation, which makes a realistic extrapolation to in vivo conditions possible. New results on the comparison between ex vivo and in vivo findings have shown that in vivo many more radicals are formed compared to ex vivo [37]. Therefore, in vivo a protection could be relevant.…”

A review of protection against exposome factors impacting facial skin barrier function with 89% mineralizing thermal water

“…Krutmann et al 2017 1 Krutmann et al 2012 5 Bonnet et al 2015 7 Dupont et al 2013 8 Marionnet et al 2015 9 Lohan et al 2016 10 McDaniel et al 2018 18 Solar radiation UV VL IR UV, VL, IR affect the epidermis, dermis, and hypodermis leading to inflammation and oxidative damage. Although all UV wavelengths contribute to photo-aging, UVA1 causes major radiation damage due to its long wavelength.…”

“…Visible light and infrared light penetrate into the dermis and have been shown to induce inflammation leading to dermal matrix degradation 7,10. Infrared light can cause skin darkening in darker skin types, which was not significant in the lighter skin types 7,10.…”

High‐energy visible light at ambient doses and intensities induces oxidative stress of skin—Protective effects of the antioxidant and Nrf2 inducer Licochalcone A in vitro and in vivo

“…In contrast to other wavelengths of VIS, HEVIS exposure leads to a significant decrease in viability of different skin cell lines and more pronounced shrinkage of the extracellular matrix (ECM) . Like UVA, HEVIS appears to exert its effects mainly through the generation of ROS, accounting for a substantial part of the amount generated by natural midday sunlight in human skin . Blue light photon ROS production efficacy corresponds to 25% of UVA in human keratinocyte mitochondria .…”