Antioxidant Efficacy on Human Skin in vivo Investigated by UVA-Induced Chemiluminescence Decay Analysis via Induced Chemiluminescence of Human Skin

Abstract

Background/Aims: Exogenous factors (e.g. physical: UV irradiation; or chemical: hydrogen peroxide) and endogenous metabolic processes (e.g. cellular respiration, oxidative burst, etc.) generate oxidative stress in living tissues which are in balance with enzymatic antioxidative systems and ingested antioxidants under normal conditions. These complex biological reactions are accompanied by chemiluminescence (ultraweak photon emission). However, knowledge about the chemiluminescence decay characteristics of human skin and the modulatory influence of topically applied antioxidants is still scarce. Methods: Using ICL-S (induced chemiluminescence of human skin), a highly sensitive in vivo method, the decay characteristics of UVA-induced photon emission caused by different UVA doses were investigated in detail. In addition, modulatory properties of topical antioxidant pretreatment were examined for 2 weeks. Results: UVA-induced chemiluminescence signals were generally characterized by two distinct decay phases: an initial burst (0–5 s), contributing approximately 80% of the complete signal with an inverse dose-response relationship (UVA dose vs. chemiluminescence intensity), followed by a second decay phase (delayed chemiluminescence, 5–200 s) showing a direct correlation. Antioxidant pretreatment caused a reduction in signal intensity of approximately 50%, which was calculated by signal integration and confirmed using the modulation of the intersection point of decay curves resulting from irradiation with different UVA doses at constant intensity with and without treatment. Conclusion: In addition to the established UVA filter testing (independent from UVB filter content) on human skin in vivo, ICL-S is also a valuable tool for the efficacy testing of topically applied antioxidants under in vivo conditions in humans. The first rapid, but short, decay phase not only provides approximately 80% of the complete chemiluminescence signal, but is also essential for the investigation of antioxidant-mediated effects. Chemiluminescence signal modulations induced by UVA intensity reduction (e.g. UV filters in daily care products) can be clearly distinguished from antioxidant-mediated signal modulations. The probe head dimensions permit comprehensive in vivo testing in humans on practically every skin area (e.g. arms, legs, back, abdomen and face).

Methods for the Evaluation of the Protective Efficacy of Sunscreen Products

“…Determining the average sum transmission in the entire UV range, the described method refers not only to UVB-induced sunburn but also to the visible and IR spectral ranges. This is of particular importance as visible and IR irradiation of the sun can also cause the formation of free radicals and skin damage [15,16,17]. As a defense system against the action of free radicals in this optical window, topical antioxidants incorporated in cosmetic formulations [18,19,20], and the systemic [21,22,23] and combined application of antioxidants [21,24,25], are advised.…”

<i>Coriandrum sativum</i> L. Protects Human Keratinocytes from Oxidative Stress by Regulating Oxidative Defense Systems

“…The skin, the largest organ of the human body, is constantly exposed to pro-oxidant environmental stresses, such as ultraviolet (UV) radiation [1,2] . Chronic exposure of the skin to pro-oxidants results in the development of oxidative damage, leading to several skin disorders, including hyperpigmentation, immunosuppression, inflammation and premature aging of the skin [2] .…”

Spontaneous ultraweak photon emission imaging of oxidative metabolic processes in human skin: effect of molecular oxygen and antioxidant defense system

“…27,28 The ultraweak photon emission or weak chemiluminescence is the most frequent noninvasive technique used for the measurement of oxidative stress because of its direct correlation with the oxidative metabolic processes. [29][30][31][32][33][34][35] The effect of scavengers on ultraweak photon emission was studied in human skin exposed to various types of physical (ultraviolet and ultrasonic radiation) and chemical (hydrogen peroxide, ozone, cigarette smoke) stress factors. [30][31][32][33] It has been demonstrated that topical application of ascorbic acid prior to exposure of human skin to ultraviolet radiation (UV) significantly reduced UV-induced ultraweak photon emission.…”

“…33 More recently, a topical application of antioxidant system (tocopheryl acetate, ferulic acid, and rutin) on human skin has been shown to significantly decrease UV-induced ultraweak photon emission. 29 Hagens et al (2008) demonstrated that exposure of human skin to ozone and cigarette smoke caused an enhancement in ultraweak photon emission, whereas topical application of antioxidant (ascorbate and α-glucosylrutin) to human skin reduced ultraweak photon emission. 31 Whereas the application of ultraweak photon emission for the detection of the oxidative metabolic processes in human skin exposed to physical and chemical stress factors is widely used, the application of spontaneous ultraweak photon emission for the detection of oxidative processes in the skin the related to the normal metabolic processes, i.e., without the use of any exogenous stress factor has received less attention.…”