Influence of Repetitive UVA Stimulation on Skin Protection Capacity and Antioxidant Efficacy

Abstract

Background/Aims: Topically applied antioxidants (AOs) are widely used in cosmetic products – especially in day and sun care – to help reduce oxidative stress caused by exogenous influences such as ultraviolet (UV) radiation. Despite several advances in recent years, little is known about the duration of protective effects by application of topical AOs, AO protection capacity (APC) or the activation of an endogenous protection capacity (EPC). Methods: By measuring oxidative-stress-induced photon emission of human skin in vivowith the ICL-S method (induced chemiluminescence of human skin), the protective effect of daily AO treatment for 2 weeks was examined on 4 consecutive days after treatment. UVA-dose-independent effects were investigated by decay curve intersection point analysis. In addition, chemiluminescence signal integration was used to investigate the influence of different UVA doses for stimulation on the determined APC as well as the modulation of the EPC by repetitive UVA stimulation both forming the skin protection capacity (SPC). Results: The SPC showed a strong dependency on the UVA dose used for stimulation. AO pretreatment was more effective against lower UVA doses. Over the course of 4 days, the AO-induced SPC did not change significantly for a given UVA dose. Analyzing the decay curve intersection point for 2 different UVA doses, however, revealed a decrease in SPC with time. In addition, we found that a repetitive UVA irradiation of 1 J/cm² caused a statistically significant protective effect against UVA irradiation by stimulation of endogenous mechanisms. Conclusion: Topically supplemented AOs provide a protective effect against oxidative stress for at least 3 days, supporting their widespread use in cosmetic products. Especially their interaction with cutaneous protective mechanisms should be investigated in more detail for maximal protection, as endogenous defense mechanisms are already triggered by 2 low-dose UVA irradiations within 24 h. In summary, the in vivo measurement of UVA-induced cutaneous chemiluminescence permits the UVA-dose-independent determination of the AO efficacy for better comparability of the results while also taking endogenous defense mechanisms into account.

Gain or Loss? Sunscreen Efficiency after Cosmetic Pretreatment of the Skin

“…Therefore, their additional use might be a reasonable attempt to increase the protective effect of sunscreens. As a matter of fact, the sequential application of skin care and sun protection products is currently recommended by a number of experts [17], which, in accordance with our own investigations, reflects a widespread tendency under real-life conditions. However, no data is available investigating the effects of combined usage.…”

Alcohol Consumption Decreases the Protection Efficiency of the Antioxidant Network and Increases the Risk of Sunburn in Human Skin

“…Ethanol-induced oxidative stress is the result of the combined impairment of antioxidant defenses and the production of reactive oxygen species (ROS) by the mitochondrial electron transport chain, the alcohol-inducible cytochrome P450 (CYP) 2E1 and activated phagocytes and hydroxyethyl free radicals generated during alcohol metabolism by CYP 2E1 [6,9]. ROS, in turn, are able to damage or cause complete degradation of essential complex molecules in the cells, including lipids, proteins and DNA [6,10,11,12]. …”

The relationship between skin aging and steady state ultraweak photon emission as an indicator of skin oxidative stress in vivo

“…It is well known that UPE is correlated with oxidative stress (13,14,17,18,20,21). Most of those studies used stress-induced UPE, especially UV-induced UPE.…”

“…Under these circumstances, ultraweak photon emission (UPE) is considered a useful method to evaluate oxidative stress of the skin in vivo according to previous instances of its application on human skin and its noninvasive nature (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19). All living organisms emit spontaneous ultraweak photons whose intensity is less than approximately 10 À16 W/cm 2 on the surface and which cover the spectral range spanning from the UV to the near-infrared wavelength regions.…”

“…The application of UPE for the detection of oxidative metabolic processes in human skin has mainly been used for cases of exposure to physical and chemical stress factors (13)(14)(15)(16)(17)(18)(19). On the other hand, regarding the application of UPE without the use of any exogenous stress factor (hereafter termed steady state UPE), a few experimental studies have been reported (9)(10)(11)(12).…”