Uptake and bioconversion of alpha-tocopheryl acetate to alpha-tocopherol in skin of hairless mice

Antioxidants in Sunscreens: Which and What For?

Ultraviolet (UV) radiation promotes the generation of reactive oxygen species (ROS) and nitrogen species (RNS), resulting in skin damage. Cosmetic industries have adopted a strategy to incorporate antioxidants in sunscreen formulations to prevent or minimize UV-induced oxidative damage, boost photoprotection effectiveness, and mitigate skin photoaging. Many antioxidants are naturally derived, mainly from terrestrial plants; however, marine organisms have been increasingly explored as a source of new potent antioxidant molecules. This work aims to characterize the frequency of the use of antioxidants in commercial sunscreens. Photoprotective formulations currently marketed in parapharmacies and pharmacies were analyzed with respect to the composition described on the label. As a result, pure compounds with antioxidant activity were found. The majority of sunscreen formulations contained antioxidants, with vitamin E and its derivatives the most frequent. A more thorough analysis of these antioxidants is also provided, unveiling the top antioxidant ingredients found in sunscreens. A critical appraisal of the scientific evidence regarding their effectiveness is also performed. In conclusion, this work provides an up-to-date overview of the use of antioxidants in commercial sunscreens for a better understanding of the advantages associated with their use in photoprotective formulations.

Skin Health from the Inside Out

The skin is the main interface between the body and the environment, providing a biological barrier against an array of chemical and physical pollutants (e.g., ultraviolet light, ozone, etc.). Exposure of the skin to these outdoor stressors generates reactive oxygen species (ROS), which can overwhelm the skin's endogenous defense systems (e.g., catalase, vitamins C and E, etc.), resulting in premature skin aging due to the induction of DNA damage, mitochondrial damage, lipid peroxidation, activation of inflammatory signaling pathways, and formation of protein adducts. In this review, we discuss how topical application of antioxidants, including vitamins C and E, carotenoids, resveratrol, and pycnogenol, can be combined with dietary supplementation of these antioxidant compounds in addition to probiotics and essential minerals to protect against outdoor stressor-induced skin damage, including the damage associated with aging.

Photostability of alpha-tocopherol ester derivatives in solutions and liposomes. Spectroscopic and LC-MS studies

α-Tocopherol (Toc) is known to degrade to the tocopheroxyl radicals (Toc) by exposure to UV light irradiation. In the present study, the stability of Toc ester derivatives exposed to UV light was investigated and compared with Toc in organic solution and in phospholipid vesicles. To follow the depletion of Toc and its esters the absorbance and fluorescence methods were applied whereas degradation products were detected using LC-MS method. The irradiation with UVB light of air-equilibrated solutions of di-α-Tocopheryl malonate (DTMO), α-Tocopheryl malonate (TMO) and α-Tocopheryl succinate (TS) strongly modifies their absorption and fluorescence spectra. Upon UVB irradiation, absorption band at 279/285nm becomes less pronounced indicating the photodegradation of esters. During irradiation, the fluorescence maximum of esters at 305nm shifts to 326nm, a maximum characteristic for Toc. Photorecovery of Toc from its esters derivatives was finally confirmed by LC-MS method. Among studied esters, only α-tocopheryl nicotinate (TN) did not undergo depletion and appeared resistant to UVB radiation. Kinetic studies indicated that photoinduced transformation occurs through the first order consecutive reaction chain mechanism. The photodissociation of Toc esters in the liposomes occurred with one order of magnitude slower than in organic solvents. Using MS/MS method it was found that final stable product of irradiation was α-tocopheryl quinone (TQ), an animal and plant metabolite of Toc.

α-Tocopherol protects keratinocytes against ultraviolet A irradiation by suppressing glutathione depletion, lipid peroxidation and reactive oxygen species generation

This study aimed to investigate whether α-tocopherol is able to protect keratinocytes against ultraviolet A (UVA) radiation by increasing glutathione (γ-glutamylcysteinylglycine; GSH) levels or decreasing lipid peroxidation and reactive oxygen species (ROS) generation. The cell survival fraction was 43.6% when keratinocytes were irradiated with UVA at a dose of 8 J/cm². α-Tocopherol was added prior to UVA irradiation and the cell viability was assayed. The cell survival fractions were 60.2, 77.1, 89.0, 92.9 and 96.2% when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. These results suggested that α-tocopherol is capable of protecting keratinocytes against UVA irradiation. Furthermore, the levels of GSH, lipid peroxidation and ROS were measured. The levels of GSH were 0.354 and 0.600 mmol/g protein in keratinocytes irradiated with UVA (8 J/cm²) and in non-irradiated cells, respectively, whereas they were 0.364, 0.420, 0.525, 0.540 and 0.545 mmol/g protein when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. The levels of lipid peroxidation were 20.401 or 5.328 μmol/g [malondialdehyde (MDA)/protein] in keratinocytes irradiated with UVA (8 J/cm²) and in non-irradiated cells, respectively, whereas they were 11.685, 6.544, 5.847, 4.390 and 2.164 μmol/g (MDA/protein) when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. The levels of ROS were 3,952.17 or 111.87 1/mg protein in keratinocytes irradiated with UVA (8 J/cm²) and in non-irradiated cells, respectively, whereas they were 742.48, 579.36, 358.16, 285.63 and 199.82 1/mg protein when α-tocopherol was added at concentrations of 2.9, 5.9, 8.8, 11.8 and 14.7 IU/ml, respectively. These findings suggested that α-tocopherol protects keratinocytes against UVA irradiation, possibly through increasing the levels of GSH or decreasing the levels of lipid peroxidation and ROS generation.

Evaluation of the antioxidative capability of commonly used antioxidants in dermocosmetics by in vivo detection of protein carbonylation in human stratum corneum

We present an in vivo test platform to evaluate the antioxidative capability of seven frequently used dermocosmetic antioxidants on the human stratum corneum (SC). It has been reported that the protein carbonylation could be used as a biomarker for oxidative stress. The current study detects the change of the level of exposed protein carbonyl group in the most outer layer of human SC. The concentration of the antioxidant in each subject emulsion formulation was 0.5% (w/w). The data indicated that alpha-tocopherol (α-Vit E) and ascorbic acid (Vit C) have excellent antioxidative capability and α-Vit E-acetate possesses better than the average antioxidative capability. The bioconversion of α-Vit E-acetate to α-Vit E may occur in the human SC during a less than 2 weeks time course test. Lipoic acid possessed moderate antioxidative capability. Ascorbyl 6-palmitate had a low antioxidative capability. Ascorbic acid 2-glucoside represented an insignificant antioxidative capability. Glutathion (GSH) had no effect on reducing oxidative damage to human SC proteins, implying that the GSH recycling system could be absent in human SC. This test platform is an useful tool to evaluate the antioxidative efficiency of antioxidants on human SC proteins.

Stability and sensory assessment of emulsions containing propolis extract and/or tocopheryl acetate

The prevention of skin aging has been one of the main aims of cosmetic products. Propolis and tocopheryl acetate can be promising substances because of their antioxidant properties. In this study, propolis extract was obtained and associated with tocopheryl acetate in a cream formulation, which then underwent stability and sensory assessment. The formulation containing propolis extract and tocopheryl acetate proved to be stable in the preliminary stability study, demonstrating gradual darkening and slight pH decrease when subjected to 60ºC for 28 days, but showing stability on rheological study. In the sensory analysis, the formulation containing these two components was preferred by the product testers over the base cream and creams containing propolis extract or tocopheryl acetate alone. In conclusion, given the stability of the formulation and the preference of the product testers for this formulation, this association proved promising for use in cosmetic formulations.

Vitamin E in human skin: organ-specific physiology and considerations for its use in dermatology

Vitamin E has been used for more than 50 years in experimental and clinical dermatology. While a large number of case reports were published in this time, there is still a lack of controlled clinical studies providing a rationale for well defined dosages and clinical indications. In contrast, advances in basic research on the physiology, mechanism of action, penetration, bioconversion and photoprotection of vitamin E in human skin has led to the development of numerous new formulations for use in cosmetics and skin care products. This article reviews basic mechanisms and possible cosmetic as well as clinical implications of the recent advances in cutaneous vitamin E research. Experimental evidence suggests that topical and oral vitamin E has antitumorigenic, photoprotective, and skin barrier stabilizing properties. While the current use of vitamin E is largely limited to cosmetics, controlled clinical studies for indications such as atopic dermatitis or preventions of photocarcinogenesis are needed to evaluate the clinical benefit of vitamin E.

Vitamin E: Critical Review of Its Current Use in Cosmetic and Clinical Dermatology

BACKGROUND AND OBJECTIVE

The lipophilic antioxidant vitamin E has been used for more than 50 years in clinical and experimental dermatology. However, although a large number of case reports were published, there is still a lack of controlled clinical studies providing a rationale for clinical indications and dosage. In contrast, advances in basic research on the physiology, mechanism of action, penetration, bioconversion, and photoprotection of vitamin E in human skin have led to the development of numerous new formulations for use in cosmetics and skin care products.

RESULTS

This article reviews the basic mechanisms and possible cosmetical and clinical implications of the recent advances in cutaneous vitamin E research. Experimental evidence suggests that topical and oral vitamin E has anticarcinogenic, photoprotective, and skin barrier-stabilizing properties.

CONCLUSION

Although its current use is largely limited to cosmetics, controlled clinical studies for indications such as atopic dermatitis or prevention of photocarcinogenesis are needed to evaluate the clinical benefit of vitamin E.

Skin absorption and metabolism of a new vitamin E prodrug, δ-tocopherol-glucoside: in vitro evaluation in human skin models

The aim of this study was to investigate the cutaneous penetration and metabolism of the new vitamin E prodrug delta-tocopherol glucoside (delta-TG), as compared to those of common vitamin E acetate, in vitro, both in reconstituted human epidermis and in viable human skin. Better diffusion was observed with alpha-tocopherol acetate (alpha-TAc) than with delta-tocopherol glucoside in both skin models, at 0.1% and 0.05% in a myritol solution; however, no metabolism was detected with alpha-tocopherol acetate. In all conditions tested (two skin models, two concentrations, three test times, and compartmental analysis) the delta-tocopherol glucoside was metabolized into free tocopherol. In the reconstituted human epidermis, after 18 h, over 90% of the delta-tocopherol glucoside was bioconverted. In the viable human skin, the extent of metabolism was about 20%, with 0.12 and 0.10 microg/cm2 of delta-tocopherol glucoside in the stratum corneum and epidermis, respectively. After topical application, the delta-tocopherol glucoside had a considerable reservoir effect, associated with gradual delivery of free tocopherol. The use of this gluco-conjugated vitamin E at a low concentration shows the capability of the skin to metabolize the prodrug in a slow and prolonged manner, making this gluco-conjugated vitamin E an excellent candidate for continuous reinforcement of antioxidants in the skin.

Protective effect of alpha-tocopherol-6-O-phosphate against ultraviolet B-induced damage in cultured mouse skin

The ability of the novel water-soluble provitamin E, alpha-tocopherol-6-O-phosphate, to protect against ultraviolet B-induced damage in cultured mouse skin was investigated and compared with the protectiveness of alpha-tocopherol acetate in cultured mouse skin. Pretreatment of skin with 0.5% (9.4 mM) alpha-tocopherol-6-O-phosphate in medium for 3 h significantly prevented such photodamage as sunburn cell formation, DNA degradation, and lipid peroxidation, which were induced in control cultured skin by a single dose of ultraviolet B irradiation at 0 to 40 kJ per m2 (290-380 nm, maximum 312 nm). This protection was greater than that seen with alpha-tocopherol acetate, the most common provitamin E that is used in commercial human skin care products. The concentration of alpha-tocopherol in cultured skin pretreated with 0.5% alpha-tocopherol-6-O-phosphate rose to approximately two to three times that found in the control skin and the reduction in cutaneous alpha-tocopherol that was induced by ultraviolet irradiation was significantly inhibited. In the group pretreated with 0.5% alpha-tocopherol acetate, however, conversion of alpha-tocopherol acetate to alpha-tocopherol was not observed, although the level of provitamin incorporated into the cultured skin was the same as that for alpha-tocopherol-6-O-phosphate. These findings indicated that the enhanced ability of alpha-tocopherol-6-O-phosphate to protect against ultraviolet B-induced skin damage compared with alpha-tocopherol acetate may have been due to alpha-tocopherol-6-O-phosphate's conversion to alpha-tocopherol. Moreover, following pretreatment with a 0.5% alpha-tocopherol-6-O-phosphate, alpha-tocopherol-6-O-phosphate was incorporated into the human skin in a three-dimensional model and 5% of the incorporated alpha-tocopherol-6-O-phosphate was converted to alpha-tocopherol. These results suggest that treatment with the novel provitamin E, alpha-tocopherol-6-O-phosphate may be useful in preventing ultraviolet-induced human skin damage.

Photoprotective actions of topically applied vitamin E

Topical application of vitamin E has been shown to decrease the incidence of ultraviolet (UV)-induced skin cancer in mice. Vitamin E provides protection against UV-induced skin photodamage through a combination of antioxidant and UV absorptive properties. Topical application of alpha-tocopherol on mouse skin inhibits the formation of cyclobutane pyrimidine photoproducts. However, topically applied alpha-tocopherol is rapidly depleted by UVB radiation in a dose-dependent manner. The photooxidative fate of the alpha-tocopherol depends on the local environment of the vitamin E. alpha-Tocopherol quinone and alpha-tocopherol quinone epoxides are principal photoproducts of vitamin E that has penetrated into the epidermal layer of the skin, whereas tocopherol dimers and trimers are formed from alpha-tocopherol in a bulk phase at the skin surface. Dimer and trimer products may participate in prevention of UV-induced photodamage.

Potentials and limitations of the natural antioxidants RRR-alpha-tocopherol, L-ascorbic acid and beta-carotene in cutaneous photoprotection

Sun exposure has been linked to several types of skin damage including sun burn, photoimmunosuppression, photoaging and photocarcinogenesis. In view of the increasing awareness of the potentially detrimental long term side effects of chronic solar irradiation there is a general need for safe and effective photoprotectants. One likely hypothesis for the genesis of skin pathologies due to solar radiation is the increased formation of reactive oxidants and impairment of the cutaneous antioxidant system. Consequently, oral antioxidants that scavenge reactive oxidants and modulate the cellular redox status may be useful; systemic photoprotection overcomes some of the problems associated with the topical use of sunscreens. Preclinical studies amply illustrate the photoprotective properties of supplemented antioxidants, particularly RRR-alpha-tocopherol, L-ascorbate and beta-carotene. However, clinical evidence that these antioxidants prevent, retard or slow down solar skin damage is not yet convincing. The purpose of this review is to provide the reader with current information on cutaneous pathophysiology of photoxidative stress, to review the literature on antioxidant photoprotection and to discuss the caveats of the photo-oxidative stress hypothesis.

Effect of UVB on hydrolysis of alpha-tocopherol acetate to alpha-tocopherol in mouse skin

We have assessed the hydrolysis of alpha-tocopherol acetate (alpha-TAc) to the active antioxidant alpha-tocopherol (alpha-TH) in mouse epidermis and in supernatant from epidermal homogenates. Topically administered alpha-TH prevents UVB photocarcinogenesis in C3H mice, whereas alpha-TAc does not. Hydrolysis in skin was monitored in mice treated topically with deuterium labeled alpha-TAc (d3-alpha-TAc). Epidermal samples were isolated from mice and analyzed for endogenous (d0-alpha-TAc) and d3-alpha-TH by gas chromatography-mass spectrometry. Within 24 h, the levels of d3-alpha-TH increased up to 10-fold over endogenous d0-alpha-TH levels; however, in mice irradiated with UVB prior to the application of d3-alpha-TAc, levels of d3-alpha-TH increased up to 30-40-fold over endogenous d0-alpha-TH. This enhancement of alpha-TAc hydrolysis increased with increasing UVB dose. Prior UVB exposure may increase hydrolysis of alpha-TAc by increasing epidermal esterase activity. Nonspecific esterase activity was measured in the 2000 x g supernatant from epidermis of unirradiated and irradiated mice. Alpha-napthyl acetate, a nonspecific esterase substrate, was converted to alpha-napthol in supernatants from unirradiated mice. Hydrolysis to alpha-napthol increased approximately 3-fold in supernatants from irradiated mice. Hydrolysis of alpha-TAc to alpha-TH also occurred in supernatant from unirradiated mice, and this hydrolysis increased approximately 3-fold in supernatant from irradiated animals. These data indicate that nonspecific esterase activity was increased by UVB in the skin, that alpha-TAc is converted to alpha-TH in the homogenate fraction containing nonspecific esterase, and that UVB exposure modulates the metabolism of alpha-TAc to alpha-TH in vivo.

Efficacy of topically applied tocopherols and tocotrienols in protection of murine skin from oxidative damage induced by UV-irradiation

To assess the efficacy of various forms of vitamin E in protection of skin from UV-light-induced oxidative stress, vitamin E (tocotrienol-rich fraction of palm oil, TRF) was applied to mouse skin and the contents of antioxidants before and after exposure to UV-light were measured. Four polypropylene plastic rings (1 cm2) were glued onto the animals' backs, and 20 microliters 5% TRF in polyethylene glycol-400 (PEG) was applied to the skin circumscribed by two rings and 20 microliters PEG to the other two rings. After 2 h, the skin was washed and half of the sites were exposed to UV-irradiation (2.8 mW/cm2 for 29 mi: 3 MED). TRF treatment (n = 19 mice) increased mouse skin alpha-tocopherol 28 +/- 16-fold, alpha-tocotrienol 80 +/- 50-fold, gamma-tocopherol 130 +/- 108-fold, and gamma-tocotrienol 51 +/- 36-fold. A significantly higher percentage of alpha-tocopherol was present in the skin as compared with that in the applied TRF. After UV-irradiation, all vitamin E forms decreased significantly (p < .01), while a larger proportion of the vitamin E remained in PEG-treated (approximately 80%) compared with TRF-treated (approximately 40%) skin. Nonetheless, vitamin E concentrations in irradiated TRF-treated skin were significantly higher than in the nonirradiated PEG-treated (control) skin (p < .01). Thus, UV-irradiation of skin destroys its antioxidants: however, prior application of TRF to mouse skin results in preservation of vitamin E.

Disposition and metabolism of topically administered alpha-tocopherol acetate: a common ingredient of commercially available sunscreens and cosmetics

Skin cancers are a serious health problem in the United States. One common method of skin cancer primary prevention is use of sunscreens. Research has been conducted to ascertain the role of active ingredients of sunscreen products in photoprotection and possible carcinogenesis. In contrast, little is known about the "other ingredients", listed or unlisted, on sunscreen product labels. One such ingredient is vitamin E. usually in the form of alpha-tocopherol acetate. Results of recent studies of skin carcinogenesis in an ultraviolet (UV) B mouse carcinogenesis model suggest that topically applied alpha-tocopherol acetate does not prevent and, under some conditions, enhances skin cancer development and growth, whereas the free unesterified from of alpha-tocopherol significantly reduces experimental UVB carcinogenesis. We have performed a Phase II cancer prevention study to evaluate whether topically applied alpha-tocopherol acetate is absorbed in human skin and metabolizes to the free or other forms. In this double-blind study, 19 men and women > 30 years of age who had at least three actinic keratoses on their forearms were randomly assigned to apply alpha-tocopherol acetate (125 mg/g) or difluoromethylornithine cream to their arms twice daily for three months. Blood samples and photographs and punch biopsies of actinic keratoses were obtained before and at the end of the study (Month 4). Plasma and skin concentrations of free alpha-tocopherol, alpha-tocopherol acetate, and gamma-tocopherol were analyzed by high-performance liquid chromatography at Month 4. The results of this report focus only on data obtained from the 11 participants randomized to the alpha-tocopherol acetate arm of the study. Topically applied alpha-tocopherol acetate was substantially absorbed in skin, with no evidence of conversion within skin to its unesterified form (i.e., free alpha-tocopherol). There was no evidence of systemic availability or biotransformation of topically applied alpha-tocopherol acetate. In summary, we have determined that alpha-tocopherol acetate is not metabolized to the free form of alpha-tocopherol in plasma or skin.

Importance of the form of topical vitamin E for prevention of photocarcinogenesis

With increasing solar ultraviolet (UV)-B radiation reaching the Earth's surface and the incidence of skin cancer rising steadily, there is an ever-increasing need to determine agents that modulate photocarcinogenesis and to understand the mechanisms underlying this modulation. Our laboratory has demonstrated that topical application of the dl-alpha-tocopherol form of vitamin E to mice prevents skin cancer and the immunosuppression induced by UVB irradiation. However, dl-alpha-tocopherol has limited stability at room temperature. The current study was designed to ask whether the thermostable esters of vitamin E, alpha-tocopheryl acetate, or alpha-tocopheryl succinate prevent skin cancer and immunosuppression induced in mice by UV radiation. In the alpha-tocopheryl acetate study, skin cancers developed in 70% of UVB-irradiated control mice and in 90%, 73%, and 90% of mice receiving topical applications of 12.5, 25, and 50 mg of dl-alpha-tocopheryl acetate, respectively. In the alpha-tocopheryl succinate study, skin cancer developed in 59.3% of control UVB-irradiated mice and in 82%, 100%, and 81.5% of mice treated with 2.5, 12.5, and 25 mg d-alpha-tocopheryl succinate, respectively. Thus neither alpha-tocopheryl acetate nor alpha-tocopheryl succinate prevented photocarcinogenesis. At 12.5 and 25 mg/treatment, alpha-tocopheryl acetate and alpha-tocopheryl succinate, respectively, enhanced photocarcinogenesis (p = 0.0114 and 0.0262, respectively, log rank test). On the basis of high-performance liquid chromatography analysis at 16-17 weeks after the first vitamin E treatment, the esterified forms of vitamin E applied epicutaneously accumulated in the skin, but the levels of free alpha-tocopherol remained low. Neither alpha-tocopheryl acetate nor alpha-tocopheryl succinate prevented the induction by UV radiation of immunosusceptibility to implanted syngeneic antigenic UV-induced tumor cells. Thus alpha-tocopheryl acetate or alpha-tocopheryl succinate not only failed to prevent photocarcinogenesis, but may have enhanced to process. Considering that alpha-tocopherol esters are included in many skin lotions, cosmetics, and sunscreens, further studies are needed to determine the conditions under which topical alpha-tocopheryl acetate and alpha-tocopheryl succinate enhance photocarcinogenesis.

Hydrolysis of RRR-alpha-tocopheryl acetate (vitamin E acetate) in the skin and its UV protecting activity (an in vivo study with the rat)

Vitamin E acetate is often used rather than vitamin E as an ingredient of skin care products and dermatological preparations, because it lacks the free phenolic OH group. However, because of this the acetate as such is biologically inactive. In spite of this intrinsic inactivity, the skin is protected against the harmful effects of sunlight after topical application of vitamin E acetate. Therefore it is supposed that hydrolysis takes place in the skin and that the reaction product, the radical scavenger vitamin E, is responsible for the protection observed. In this in vivo study with the rat, we have investigated the hydrolysis of RRR-alpha-tocopheryl acetate (vitamin E acetate) in the epidermis in relation to UV radiation protection. (As a measure of protection, we used the UV-induced binding of 8-methoxypsoralen to epidermal biomacromolecules.) After a period of 5 h from a single application of vitamin E acetate, hydrolysis into free vitamin E was not observed. No protection was found at this time point, corresponding with the absence of vitamin E. After treatment for 5 days, consisting of one topical application daily, the percentage of acetate present in the stratum corneum which was hydrolysed into free vitamin E was less than 1%, whereas the corresponding value for the viable layer of the epidermis was about 5%. The hydrolysis of vitamin E acetate in the epidermis proceeded very slowly. As a result, the absolute amount of free vitamin E, found in the total epidermis after treatment for 5 days with the acetate, was only a few times higher than the normal level. Yet, this very small amount of free vitamin E proved to be sufficient for maximal protection in this animal model. The results show that vitamin E acetate acts as a prodrug, which very slowly releases minute amounts of active vitamin E.

Effect of topically applied tocopherol on ultraviolet radiation-mediated free radical damage in skin

Previously, we demonstrated by electron paramagnetic resonance (EPR) spectroscopy that ultraviolet radiation induces free-radical formation in Skh-1 hairless mouse skin. Because free-radical oxidative stress is thought to play a principal role in skin photoaging and cancer, oxidative stress and subsequent photodamage should be decreased by supplementation of skin with antioxidants. Using both the ascorbate free radical and an EPR spin-trapping system to detect short-lived radicals, we evaluated the effect of the topically applied antioxidants tocopherol sorbate, alpha-tocopherol, and tocopherol acetate on ultraviolet radiation-induced free-radical formation. We show that tocopherol sorbate significantly decreases the ultraviolet radiation-induced radical flux in skin. With our chronically exposed mouse model, tocopherol sorbate was also found to be significantly more protective against skin photoaging than alpha-tocopherol and tocopherol acetate. These results extend our previous observations of ultraviolet radiation-induced free-radical generation in skin and indicate the utility of tocopherol sorbate as an antioxidant in providing significant protection against ultraviolet radiation-induced oxidative damage.