We have previously reported that substantial amounts of tocotrienols were present in the skin of animals fed a diet containing a tocopherols andtocotrienols rich fraction (T-mix) extracted from palm oil, and further, that sesame lignans enhanced tocotrienol levels in the skin. The present studies were undertaken to determine whether dietary tocotrienols and those with sesamin could protect the skin from damage induced by UVB irradiation in hairless mice fed four diets: a vitamin E-free diet, a 50 mg/kg alpha-tocopherol diet, a 229 mg/kg T-mix (with 50 mg alpha-tocopherol) diet and a 229 mg/kg T-mix with 2 g/kg sesamin diet. In Experiment 1, mice were fed the diets for 6 wk, and half of the mice were exposed to 180 mJ/cm(2 )of UVB light once daily for 7 d. After the intensity of sunburn was scored, vitamin E and thiobarbituric acid reactive substances (TBARS) concentrations in the skin and liver were determined. In Experiment 2, hairless mice were initiated with a single application of 7, 12-dimethylbenz[a]anthracene (DMBA), then 1 wk later mice were fed the experimental diets and subjected to 180 mJ/cm(2) UVB irradiation twice weekly for 20 wk. Tumor incidences were counted once a week. Tocotrienols were detected in the skin of mice fed T-mix, but their concentrations were significantly lower than for alpha-tocopherol. Sesamin elevated tocotrienol contents in the skin. In spite of the high alpha-tocopherol contents, the effects of alpha-tocopherol on sunburn and incidence of tumor were slight. T-mix fed groups reduced the extent of sunburn and incidence of tumor, and further reduction of sunburn and incidence of tumor were observed in the T-mix with sesamin group. These results suggest that dietarytocotrienols protect the skin more strongly than alpha-tocopherol against damage induced by UVB and sesamin enhances tocotrienol effects.
Skin Care
Palm oil alleviates 12-O-tetradecanoyl-phorbol-13-acetate-induced tumor promotion response in murine skin
Kausar H, Bhasin G, Zargar MA, Athar M.
Cancer Lett. 2003 Mar 31;192(2):151-60.
Palm oil is a rich source of vitamin E, carotenoids, tocotrienols and tocopherols which are natural antioxidants and act as scavengers of oxygen free radicals. 12-O-Tetradecanoyl-phorbol-13-acetate (TPA) is a known oxidant that promotes tumorigenesis in mouse skin through the elaboration of oxidative stress. In this study we therefore assessed the anti-tumor promoting potential of palm oil against TPA-mediated skin tumorigenesis in 7,12-dimethylbenz[a]anthracene-initiated Swiss albino mice. Topical application of palm oil 1 h prior to application of TPA resulted in a significant protection against skin tumor promotion. The animals pre-treated with palm oil showed a decrease in both tumor incidence and tumor yield as compared to the TPA (alone)-treated group. Palm oil application also reduced the development of malignant tumors. Since TPA-induced epidermal ornithine decarboxylase (ODC) activity and [(3)H]thymidine incorporation are conventionally used markers of skin tumor promotion, we also assessed the effect of pre-application of palm oil on these parameters, and it was observed that the application of palm oil prior to the application of TPA alleviated both these TPA-induced markers of tumor promotion. The effect of pre-application of palm oil on TPA-mediated depletion in the non-enzymatic and enzymatic molecules was also assessed and it was observed that palm oil application prior to TPA application resulted in the recovery of TPA-mediated depletion in the levels of these molecules viz. glutathione, glutathione peroxidase, glutathione reductase, glutathione-S-transferase and catalase. Similarly, palm oil also exhibited a protective effect against Fe(2+)-ascorbate-induced lipid peroxidation in the epidermal microsomes. The results of the present study thus suggest that palm oil possesses anti-skin tumor promoting effects, and that the mechanism of such effects may involve the inhibition of tumor promoter-induced epidermal ODC activity, [(3)H]thymidine incorporation and cutaneous oxidative stress.
HPLC analysis of vitamin E isoforms in human epidermis: Correlation with minimal erythema dose and free radical scavenging activity
Fuchs J, Weber S, Podda M, Groth N, Herrling T, Packer L, Kaufmann R.
Free Radic Biol Med. 2003 Feb 1;34(3):330-6.
The content and composition of different vitamin E isoforms was analyzed in normal human skin. Interestingly the epidermis contained 1% alpha-tocotrienol, 3% gamma-tocotrienol, 87% alpha-tocopherol, and 9% gamma-tocopherol. Although the levels of tocotrienol in human epidermis appear to be considerably lower than reported in the hairless mouse, the presence of significant amounts of tocotrienol levels leads to speculation about the physiological function of tocotrienols in skin. Besides antioxidant activity and photoprotection, tocotrienols may have skin barrier and growth-modulating properties. A good correlation was found for epidermal alpha-tocopherol (r = 0.7909, p <.0003), gamma-tocopherol (r = 0.556, p <.025), and the total vitamin E content (r = 0.831, p <.0001) with the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging in epidermis, as assessed by electron paramagnetic resonance (EPR) spectroscopy. In human epidermis, alpha-tocopherol is quantitatively the most important vitamin E isoform present and comprises the bulk of first line free radical defense in the lipid compartment. Epidermal tocotrienol levels were not correlated with DPPH scavenging activity. The minimal erythema dose (MED), an individual measure for sun sensitivity and a crude indicator for skin cancer susceptibility, did not correlate with the epidermal content of the vitamin E isoforms. Hence it is concluded that vitamin E alone is not a determinant of individual photosensitivity in humans.
Topical alpha-tocotrienol supplementation inhibits lipid peroxidation but fails to mitigate increased transepidermal water loss after benzoyl peroxide treatment of human skin
Weber SU, Thiele JJ, Han N, Luu C, Valacchi G, Weber S, Packer L.
Free Radic Biol Med. 2003 Jan 15;34(2):170-6.
Benzoyl peroxide (BPO) is a commonly used drug in the treatment of acne vulgaris, but it induces unwanted side effects related to stratum corneum (SC) function. Since it has been recently shown to oxidize SC antioxidants, it was hypothesized that antioxidant supplementation may mitigate the BPO-induced SC changes. To test this, 11 subjects were selected to be topically supplemented with alpha-tocotrienol (5% w/vol) for 7 d on defined regions of the upper back, while the contralateral region was used for vehicle-only controls. Starting on day 8, all test sites were also treated with BPO (10%) for 7 d; the alpha-tocotrienol supplementation was continued throughout the study. A single dose of BPO depleted 93.2% of the total vitamin E. While continuing the BPO exposure for 7 d further depleted vitamin E in both vehicle-only and alpha-tocotrienol-treated sites, significantly more vitamin E remained in the alpha-tocotrienol-treated areas. Seven BPO applications increased lipid peroxidation. Alpha-tocotrienol supplementation significantly mitigated the BPO-induced lipid peroxidation. The transepidermal water loss was increased 1.9-fold by seven BPO applications, while there was no difference between alpha-tocotrienol treatment and controls. The data suggest that alpha-tocotrienol supplementation counteracts the lipid peroxidation but not the barrier perturbation in the SC induced by 10% BPO.
Selective uptake of dietary tocotrienols into rat skin
Ikeda S, Niwa T, Yamashita K.
J Nutr Sci Vitaminol (Tokyo). 2000 Jun;46(3):141-3.
Using a vitamin E mixture extracted from palm oil, the tissue distribution of dietary tocotrienols and tocopherols was examined in rats and mice. Wistar rats (4-wk-old) were fed a diet containing 48.8 mg/kg alpha-tocopherol, 45.8 mg/kg alpha-tocotrienol and 71.4 mg/kg gamma-tocotrienol for 8 wk. Nude mice (BALB/c Slc-nu, 8-wk-old) and hairless mice (SKH1, 8-wk-old) were fed the same diet for 4 wk. alpha-Tocopherol was abundantly retained in the skin, liver, kidney and plasma of rats and mice. alpha-Tocotrienol and gamma-tocotrienol were detected slightly in the liver, kidney and plasma, while substantial amounts of these tocotrienols were detected in the skin of both rats and mice. The present study suggests that the skin is a unique tissue in respect to its ability to discriminate between various vitamin E analogs.
The effects of topical vitamin E on the cosmetic appearance of scars
Baumann LS, Spencer J.
Dermatol Surg. 1999 Apr;25(4):311-5.
BACKGROUND: Vitamin E is a generic term for a group of tocol and tocotrienol derivatives. Since the discovery that vitamin E is the major lipid soluble antioxidant in skin, this substance has been tried for the treatment of almost every type of skin lesion imaginable. Anecdotal reports claim that vitamin E speeds wound healing and improves the cosmetic outcome of burns and other wounds. Many lay people use vitamin E on a regular basis to improve the outcome of scars and several physicians recommend topical vitamin E after skin surgery or resurfacing.
OBJECTIVE: We attempted to determine whether topically applied vitamin E has any effect on the cosmetic appearance of scars as suggested by multiple anectodal reports.
METHODS: Fifteen patients who had undergone skin cancer removal surgery were enrolled in the study. All wounds were primarily closed in 2 layers. After the surgery, the patients were given two ointments each labeled A or B. A was Aquaphor, a regular emollient, and the B was Aquaphor mixed with vitamin E. The scars were randomly divided into parts A and B. Patients were asked to put the A ointment on part A and the B ointment on part B twice daily for 4 weeks. The study was double blinded. The physicians and the patients independently evaluated the scars for cosmetic appearance on Weeks 1, 4, and 12. The criteria was simply to recognize which side of the scar looked better if there was any difference. The patients’ and the physicians’ opinions were recorded. A third blinded investigator was shown photographs of the outcomes and their opinion was also noted.
RESULTS: The results of this study show that topically applied vitamin E does not help in improving the cosmetic appearance of scars and leads to a high incidence of contact dermatitis.
CONCLUSIONS: This study shows that there is no benefit to the cosmetic outcome of scars by applying vitamin E after skin surgery and that the application of topical vitamin E may actually be detrimental to the cosmetic appearance of a scar. In 90% of the cases in this study, topical vitamin E either had no effect on, or actually worsened, the cosmetic appearance of scars. Of the patients studied, 33% developed a contact dermatitis to the vitamin E. Therefore we conclude that use of topical vitamin E on surgical wounds should be discouraged.
Penetration and distribution of alpha-tocopherol, alpha- or gamma-tocotrienols applied individually onto murine skin
Traber MG, Rallis M, Podda M, Weber C, Maibach HI, Packer L.
Lipids. 1998 Jan;33(1):87-91.
To evaluate skin penetration of various vitamin E homologs, a 5% solution of either alpha-tocopherol, alpha-tocotrienol, or gamma-tocotrienol in polyethylene glycol was topically applied to SKH-1 hairless mice. After 0.5, 1, 2, or 4 h (n = four per time point and four per vitamin E homolog), the skin was washed, the animals killed, the skin rapidly removed, frozen on dry ice, and a biopsy taken and sectioned: stratum corneum (two uppermost, 5-micron sections–SC1 and SC2), epidermis (next two 10-micron sections–E1 and E2), papillary dermis (next 100 microns, PD), dermis (next 400 microns, D), and subcutaneous fat (next 100 microns, SF). SC1 contained the highest vitamin E concentrations per mu thickness. To compare the distribution of the various vitamin E forms into the skin layers, the percentage of each form was expressed per its respective total. Most surprising was that the largest fraction of skin vitamin E following topical application was found in the deeper subcutaneous layers–the lowest layers, PD (40 +/- 15%) and D (36 +/- 15%), contained the major portion of the applied vitamin E forms. Although PD only represents about 16% of the total skin thickness, it contains sebaceous glands–lipid secretory organs, and, thus, may account for the vitamin E affinity for this layer. Hence, applied vitamin E penetrates rapidly through the skin, but the highest concentrations are found in the uppermost 5 microns.
Efficacy of topically applied tocopherols and tocotrienols in protection of murine skin from oxidative damage induced by UV-irradiation
Weber C, Podda M, Rallis M, Thiele JJ, Traber MG, Packer L.
Free Radic Biol Med. 1997;22(5):761-9.
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.
Interactions between vitamin E homologues and ascorbate free radicals in murine skin homogenates irradiated with ultraviolet light
Kitazawa M, Podda M, Thiele J, Traber MG, Iwasaki K, Sakamoto K, Packer L.
Photochem Photobiol. 1997 Feb;65(2):355-65.
The mechanism of oxidation of ascorbic acid in mouse skin homogenates by UV light was investigated by measuring ascorbate free radical formation using electron spin resonance signal formation. Addition of vitamin E (alpha-tocopherol or alpha-tocotrienol) had no effect, whereas short-chain homologues (2,5,7,8-tetramethyl-6-hydroxychroman-2-carboxylic acid [Trolox] and 2,2,5,7,8-pentamethyl-6-hydroxychromane [PMC]) accelerated ascorbate oxidation. The similar hydrophilicity of ascorbate, Trolox and PMC increased their interaction, thus rapidly depleting ascorbate. When dihydrolipoic acid was added simultaneously with the vitamin E homologues, the accelerated ascorbate oxidation was prevented. This was due to the regeneration of ascorbate and PMC from their free radicals by a recycling mechanism between ascorbate, vitamin E homologues and dihydrolipoic acid. Potentiation of antioxidant recycling may be protective against UV irradiation-induced damage. The rate of ascorbate oxidation in the presence of vitamin E homologues was enhanced by a photosensitizer (riboflavin) but was not influenced by reactive oxygen radical quenchers, superoxide dismutase or 5,5-dimethyl-1-pyrroline-N-oxide. These experimental results suggest that the UV irradiation-induced ascorbate oxidation in murine skin homogenates is caused by photoactivated reactions rather than reactive oxygen radical reactions.
Ozone depletes tocopherols and tocotrienols topically applied to murine skin
Thiele JJ, Traber MG, Podda M, Tsang K, Cross CE, Packer L.
FEBS Lett. 1997 Jan 20;401(2-3):167-70.
To evaluate ozone damage to hairless mouse skin, two parameters of oxidative damage, vitamin E depletion and malondialdehyde (MDA) production, were measured in vitamin E-enriched and in control skin from mice exposed to ozone (10 ppm). A 5% vitamin E solution (tocotrienol-rich fraction, TRF) in polyethylene glycol (PEG) was applied to 2 sites on the back of hairless mice, PEG to 2 sites. After 2 h, the sites were washed, one of each pair of sites covered and the mice exposed ozone for 2 h. Ozone exposure (compared with covered sites) increased epidermal MDA in PEG-treated sites, while vitamin E was unchanged. In contrast, ozone exposure significantly depleted vitamin E in TRF-treated sites, while significant MDA accumulation was prevented. This is the first demonstration that ozone exposure causes damage to cutaneous lipids, an effect which can be attenuated by vitamin E application.