Infrared radiation increases skin damage induced by other wavelengths in solar urticaria

Phenolic Extract from Aralia nudicaulis L. Rhizomes Inhibits Cellular Oxidative Stresses

UV-B and IR-A radiation are important inducers of biological changes in skin involving ROS generation. The overloading of antioxidant defense mechanisms by ROS production could lead to photoaging and photocarcinogenesis processes. Various traditional usages are reported for Aralia nudicaulis L. extracts, including treatment of dermatological disorders. Antioxidant and anti-inflammatory properties have already been reported for other Aralia species possibly due to the presence of phenolic compounds. However, the phenolic composition and the potential activity of A. nudicaulis rhizomes extract against oxidative stress and UV/IR damages have not been investigated. The main aims of this study were to prepare a fraction enriched in phenolic compounds (FEPC) from A. nudicaulis rhizomes, to identify its major phenolic compounds and to assess its potential for protective effects against oxidative stress induced by UV-B, IR-A or inflammation. A quantitative LC-MS study of FEPC shows that chlorogenic, caffeic and protocatechuic acids are the main phenolic compounds present, with concentrations of 15.6%, 15.3% and 4.8% of the total composition, respectively. With a validated analytical method, those compounds were quantified over different stages of the growing period. As for biological potential, first this extract demonstrates antioxidant and anti-inflammatory activities. Furthermore, ROS generation induced by IR-A and UV-B were strongly inhibited by A. nudicaulis extract, suggesting that Aralia nudicaulis L. rhizome extract could protect dermal cells against oxidative stress induced by UV-B and IR-A.

A novel in vivo test method for evaluating the infrared radiation protection provided by sunscreen products

BACKGROUND

Infrared radiation (IR) exposure generates reactive oxygen species and induces matrix metalloproteinase-1 expression in human skin. Moreover, while not as acute as ultraviolet radiation, repeated infrared irradiation can result in the photoaging of skin. Broad-spectrum sunscreens can protect skin from IR, but no human in vivo test methods for the evaluation of sunscreens' IR protection effect have been developed. We aimed to develop such a method.

MATERIALS AND METHODS

We included 155 Korean subjects in our three-part clinical study. The IR reflectance of subjects' skin was measured using a benchtop model of an IR light source and a reflectance measuring probe. We measured the IR reflectance in relation to skin color and hydration level to set up our experimental conditions. We then calculated the infrared protection factors (IPFs) of cosmetic emulsions as the IR reflectance ratio between cosmetic sunscreen-applied skin and non-sunscreen-applied skin and assessed the relationship between IPFs and the amount of sunscreen ingredients. Finally, this method was validated using several commercial sunscreen cosmetics.

RESULTS

Skin color and hydration level did not influence the IR reflectance of subjects' skin. The IPFs of cosmetic sunscreens showed a positive correlation with the amount of inorganic sunscreen ingredients.

CONCLUSION

In this study, we developed a simple, fast, and ethically acceptable human in vivo test method for evaluating the IPFs of cosmetic sunscreens.

Water-Filtered Infrared Radiation Decreases the Generation of Photodermatoses Dependent on Ultraviolet and Visible Radiation

The potential role of infrared radiation in photodermatoses has received very little attention, even though the main sources of radiation used for photobiological studies (UVA, UVB and visible light) include infrared radiation. The objective of the work was to assess whether infrared radiation is involved in the development of skin lesions in patients with different types of photodermatoses. Twenty patients with different photodermatoses were exposed to UVA, UVB and visible radiation using a high-pressure mercury UVA lamp, a fluorescent broadband UVB lamp, a tungsten bulb and a slide projector for visible radiation. Part of the radiation emitted by these lamps was water-filtered to block infrared radiation above 1300 nm. All 20 patients developed lesions when exposed to different light sources used for phototest. When exposed to same sources without infrared radiation, 17 patients (85%) did not develop any lesions and the other three (15%) developed less severe lesions than in the area exposed to unfiltered light. Our results show that infrared radiation was necessary for the development of skin lesions in 85% of the patients with photodermatoses in our study. We believe that infrared radiation studies should be included in standard photobiology protocols.

Fernblock Prevents Dermal Cell Damage Induced by Visible and Infrared A Radiation

Sun overexposure leads to higher risk of photoaging and skin cancer. The contribution of infrared (IR) and visible light (VIS) radiation is currently being taken into account in their pathogenesis. Erythema, hyperpigmentation, genotoxicity or the increase of matrix metalloproteinases (MMPs) expression are some of the effects induced by these types of radiation. Extracts of various botanicals endowed with antioxidant activity are emerging as new photoprotective compounds. A natural extract from Polypodium leucotomos (Fernblock^®, FB) has antioxidant and photoprotective properties and exhibits a strong anti-aging effect. In this study, we evaluated the protective capacity of FB against the detrimental effects of infrared A (IRA) and VIS radiation in human dermal fibroblasts. We analyzed the effects of FB on the morphology, viability, cell cycle and expression of extracellular matrix components of fibroblasts subjected to VIS and IRA. Our results indicate that FB prevents cell damage caused by VIS and IRA. Moreover, it reduces the increase in MMP-1 and cathepsin K expression induced by both VIS and IRA radiation, and curbs alterations in fibrillin 1, fibrillin 2 and elastin expression. All these findings support FB as a feasible approach to prevent or treat skin damage caused by IRA or VIS exposure.