Oxidative Targets in the Stratum corneum

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α-Tocopherol, the major biologically active form of vitamin E, represents a frequently added lipophilic compound of skin care products. Despite its emerging use in rinse-off formulations, little is known on its efficacy with respect to its deposition or its antioxidant potential in human skin. The objective of this study was to investigate whether the single use of an α-tocopherol-enriched rinse-off product provides effective deposition of α-tocopherol on human stratum corneum. To test this, forearm skin of 13 volunteers was washed either with an α-tocopherol-enriched rinse-off product (test product, TP) or with an α-tocopherol-free vehicle control (control product, CP) (contralateral arm) using a standardized wash protocol. Thereafter, skin surface lipids were extracted with pure ethanol after the wash procedure as well as after 24 h. Additionally, one group of volunteers was subjected to irradiation of their forearms with low-dose UVA (8 J/cm²) prior to lipid extraction. Skin lipid extracts were analyzed by high performance liquid chromatography using electrochemical detection for vitamin E and UV detection for squalene (SQ) and squalene monohydroperoxide. The results of this in vivo study demonstrated that (1) while CP treatment lowers, TP treatment strongly increases α-tocopherol levels of skin barrier lipids; (2) increased vitamin E deposition levels were maintained for a period of at least 24 h, and (3) TP treatment significantly inhibited photooxidation of SQ. In conclusion, the use of α-tocopherol-enriched rinse-off products may help to maintain the integrity of the skin barrier by providing protection against photooxidative stress at the level of skin surface lipids.

Section: Introductionmentioning

confidence: 99%

Vitamin E Delivery to Human Skin by a Rinse-Off Product: Penetration of α-Tocopherol versus Wash-Out Effects of Skin Surface Lipids

Ekanayake‐Mudiyanselage

Tavakkol

Polefka

et al. 2004

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“…The skin is frequently and directly exposed to a prooxidative environment, including solar ultraviolet radiation (UVR), air pollutants, and other xenobiotics [1]. Such exposure results in the formation of potentially harmful reactive oxygen species and other oxygenderived free radicals, which subsequently react with skin biomolecules such as lipids [2][3][4], proteins [5,6] and nucleic acids [7,8].…”

Section: Introductionmentioning

confidence: 99%

Impact of Ultraviolet Radiation and Ozone on the Transepidermal Water Loss as a Function of Skin Temperature in Hairless Mice

Thiele

Dreher²,

Maibach³

et al. 2003

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Exposure to ultraviolet radiation or ozone leads to skin damage including oxidation of skin biomolecules, as well as to depletion of constitutive antioxidants. The highly organized stratum corneum forming the main barrier against most xenobiotics is particularly susceptible to such damage and possible barrier perturbation may be the consequence. Whereas ample evidence exists for an increased permeability for different solutes including water after exposure to ultraviolet radiation, such an effect has not yet been reported for ozone. This study reports on the effect of such oxidative stressors using the hairless mouse as the skin model and measuring temperature-controlled transepidermal water loss (TEWL) as an indicator for skin barrier integrity. First, a strong dependency of the TEWL on skin temperature was observed, an effect that was clearly more pronounced than that found in man. Given this temperature dependency in untreated animals, we proceeded to determine the effects of both ultraviolet radiation and ozone on TEWL over a relevant physiological skin temperature range. Solar-simulated ultraviolet radiation (0.75–3 minimal erythemal dose) resulted in a delayed and dose-dependent skin barrier disruption over the entire temperature range investigated. Conversely, daily ozone exposure at 2 ppm for 1 week, however, did not significantly alter TEWL up to 72 h after the last exposure. The results demonstrate a differential response of the epidermis to two environmental stressors associated with oxidative damage; they suggest that chronic ozone exposure at relevant environmental levels does not lead to a detectable skin barrier defect, while solar UV exposure was demonstrated to increase epidermal water loss. Furthermore, experimental evidence clearly suggests that future studies applying TEWL measurements in animal models should be performed under carefully controlled skin temperature conditions.

“…The outermost layer of the largest human organ is always exposed to UV light and oxygen as noxious environmental influences [7]. UV radiation can lead to lipid peroxidation via a free-radical-mediated mechanism [8].…”

Section: Introductionmentioning

confidence: 99%

Mass Spectrometric Examinations of Stratum corneum Lipid Models Exposed to Ultraviolet Irradiation

Trommer

Plätzer

Wolf

et al. 2003

Lipid model systems consisting of the major components of the stratum corneum intercellular lipid matrix were studied to investigate the ultraviolet-radiation-mediated damage of these biomolecules. Pure lipids and liposomes were irradiated using a lamp emitting a solar radiation spectrum. The influences of the irradiation and the effects of added iron ions were studied by electrospray ionization mass spectrometry (MS) with an ion trap analyser. Exact mass measurements were carried out using a time-of-flight mass spectrometer. Only linolenic acid and cholesterol were found to be subject to oxidative changes caused by UV irradiation whereas the other lipids examined (dipalmitoylphosphatidylcholine, ceramide III and cholesterol sulphate) were stable to oxidative stress. Several lipid adducts were observed upon analysis of the liposomes. The composition of these adducts was identified by MS/MS experiments.