Effect of Topical Antioxidants on UV-Induced Erythema Formation when Administered after Exposure

Abstract

Background: Photoprotective effects of topically applied antioxidants when applied before ultraviolet radiation (UVR) exposure are well known. Their protective effect when applied after UVR exposure is, however, less established. Objective: In a randomized, double-blinded, placebo-controlled human study the short-term photoprotective effects of different antioxidants and of their combinations were evaluated when applied after UVR exposure. Methods: Melatonin (N-acetyl-5-methoxytryptamine), vitamin E (α-tocopherol) and vitamin C (ascorbic acid) were topically administered alone or in combination following UVR exposure as single applications (immediately or 30 min after irradiation, respectively) or as multiple applications (three times: 30 min, 1 h and 2 h after irradiation). The erythemal reaction was evaluated visually and noninvasively with bioengineering methods (skin color and skin blood flow). Results: No significant protective effect of melatonin or the vitamins when applied alone or in combination were obtained when antioxidants were applied after UVR exposure. No improved photoprotective effect was obtained when multiple applications were done. Conclusion: UVR-induced skin damage is a rapid event, and antioxidants possibly prevent such damage only when present in relevant concentration at the site of action beginning and during oxidative stress.

Dehydroascorbic acid uptake in a human keratinocyte cell line (HaCaT) is glutathione-independent

“…Skin damage is a rapid event, and vitamin C prevents such damage only when present in relevant concentrations during oxidative stress [35]. Impaired AA recycling can result in a rapid vitamin C depletion and decreased antioxidant defence.…”

On the Role of Melatonin in Skin Physiology and Pathology

“…5 and 63 ). Clinical studies indicated that melatonin is able to prevent sun damage only when it is administered before UVR and it is present in relevant concentrations directly at the irradiation site ( [64][65][66][67] ). These observation have strong experimental support from in vitro studies.…”

Investigation of Model Sunscreen Formulations Comparing the Sun Protection Factor, the Universal Sun Protection Factor and the Radical Formation Ratio

“…This had not been observed during USPF and RF testing, despite it being evidenced in previous research. It could be demonstrated that topically applied antioxidants exhibit protective effects during UV irradiation [21,22], whereas previously, diets rich in antioxidants had been shown to reduce erythema formation [23]. As cream 1 was not tested, no conclusions regarding the protective effects of antioxidants independent of the presence of chemical filters could be drawn in this study.…”