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Topical application and uptake of vitamin E acetate by the skin conversion to free vitamin E

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Radioactive tocopherol acetate was diluted with either (1) unlabelled tocopherol acetate or (2) Delios S (Henkel, a medium chain triglyceride prepared from fractionated coconut oil), a cosmetic base. These preparations were applied topically to a 2 cm diameter circle of skin. After 24 hours the percent of label which was still removable by swabbing the skin surface was 1.7% for (1) and 11.5% for (2). The central circles contained 2.86% of the label applied in 259 mg skin for (1) and 24.2% of the label applied in 226 mg skin for Delios S for (2). Surprisingly, combined samples of approximately one third of the side skin contained 0.7% of the label applied in 460 mg for (1) and 13.2% of the applied label in one third of the side skin in 523 mg for (2). The percent conversion to tocopherol in the skin central areas was 4.52% by HPLC and 4.13% by TLC for (1) and 5.97% for (2). In the side skin the percent conversion to tocopherol was 5.0% for (1) and 6.01% for (2).
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... The determined tocopherol and tocopheryl acetate contents were mostly within the expected range for facial leaveon cosmetics (0.03-2% for tocopherol and 0.003-6% for tocopheryl acetate), based on industry data on cosmetic products formulations [13] and research data (0.107-0.670% tocopheryl acetate in four commercial cosmetics on the Kuwait market [47]). Despite the differing information on tocopheryl acetate conversion to tocopherol (from 0% to 50%) found in the literature [10,48,49], the determined tocopherol and tocopheryl acetate contents were generally lower than the minimal effective tocopherol concentration of 1.0%, as recommended by Nada et al. [48]. A trend of increasing vitamin E content among the higher-priced products was not observed ( Figure 5). ...
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... Together with other studies (Lopez-Torres et al. 1998), this work suggests that topically applied vitamin E has the potential to penetrate into dermal layers, where much of oxidative protein oxidation occurs (Sander et al. 2002), and thus protects against photoaging. Vitamin E esters, particularly vitamin E acetate, were also shown to be promising agents in reducing UV-induced skin damage (Beijersbergen van Henegouwen et al. 1995;Burke et al. 2000;Record et al. 1991;Trevithick and Mitton 1993). Also vitamin E has been used successfully in chronic inflammatory skin conditions, either alone (Tsoureli-Nikita et al. 2002;Keller and Fenske 1998) or in combination with vitamin C (Hayakawa et al. 1981) or vitamin D (Javanbakht et al. 2011), thus suggesting a true anti-inflammatory action. ...
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Orientadora : Mayumi Eliza Otsuka Sato Dissertaçăo (mestrado) - Universidade Federal do Paraná, Setor de Cięncias da Saúde, Programa de Pós-Graduaçăo em Cięncias Farmacęuticas. Defesa: Curitiba, 2006 Inclui bibliografia Área de concentraçăo: Insumos, medicamentos e correlatos
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The cardiomyopathy produced by the widely used anticancer drug adriamycin (ADR) is believed to be related to the production of reaction oxygen species and consumption of reduced glutathione (GSH) during redox cycling of the drug. Protection by vitamin E against the toxicity of ADR was studied in a model of compromised isolated hepatocytes, generated by physiological alterations in the concentration of cell calcium. A decrease in cell calcium concentration leads to a greater loss of endogenous alpha-tocopherol and enhances the intracellular hydrolysis of exogenous alpha-tocopheryl esters. With this model, vitamin E (alpha-tocopheryl succinate) at 25 microM protected the calcium-depleted hepatocytes against the toxicity of ADR, in association with greater cellular alpha-tocopherol content as compared to calcium-adequate cells. The incubation of calcium-adequate hepatocytes with increasing concentrations of alpha-tocopheryl succinate up to 200 microM demonstrated that maximal protection by vitamin E was directly dependent on the alpha-tocopherol content of the cells, regardless of the concentration of cell calcium. The viability of the cells was closely associated with the alpha-tocopherol-mediated maintenance of cellular protein thiols. Viability and protein thiol content of the cells were maximal at cellular alpha-tocopherol levels in the range 0.6-1.0 nmol/10(6) cells in both calcium-depleted and -adequate cells. It is suggested that the potential use of vitamin E as a protective agent against ADR toxicity in vivo be reevaluated with an emphasis placed on the threshold level of intracellular alpha-tocopherol in the critical target tissue.
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In this procedure for determination of vitamin E by "high-performance" liquid chromatography with electrochemical detection, 25-microL serum specimens are deproteinized with ethanol. Vitamin E (alpha-tocopherol), its derivatives (beta- and gamma-tocopherols), and the internal standard (delta-tocopherol) are extracted into heptane and the extract is evaporated and the residue reconstituted with methanol before injection into the chromatograph. Within- and between-run CVs for an alpha-tocopherol concentration of 13.6 mg/L were 5.1% (n = 28) and 6.0% (n = 5), respectively. The standard curve is linear to 100 mg/L; the minimum concentration detectable is 0.1 mg/L. Analytical recovery ranged from 99.8% to 104.8%. In 36 specimens collected from apparently healthy subjects who were not taking vitamin supplements, alpha-tocopherol as determined by this method ranged from 4.3 to 9.7 mg/L, from 1.8 to 3.9 mg/L for beta- and gamma-tocopherols. Results by this method (y) and an HPLC-ultraviolet method (x) correlate reasonably (r = 0.81): y = 0.88x - 0.55 mg/L (n = 45). This procedure is adaptable to automated analysis, and the small sample requirement facilitates its applicability to neonates.
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By spraying 14C-labeled α-tocopheryl acetate on the surface of the skin, and by conducting microradiographic investigations on the condition of its absorption in seven cases and 14 samples, the following observation have been acquired, and at the same time, some discussion have been made.1. α-Tocopheryl acetate is absorbed well through the healthy hartless skin.2. There are two routes of absorption from the surface of the skin to the dermis. The first one leads through the horny layer, the epidermis and the borderline between the epidermis and the dermis. The second one goes through the pilo-sebaceous canal, the interior of hair follicles, inner and outer root sheaths and connective-tissue sheaths. No route through the sebaceous gland and sweat ducts has been detected.3. The material has proven to have a high affinity for small blood vessels everywhere.4. Hesitation in the absorption of the material has been observed in line with the lower part of the horny layer, the borderline between the epidermis and dermis, the borderline of inner and outer root sheaths, and the borderline between epidermal and connective-tissue hair follicles.5. Noticeable observations on the study of microdistribution are as follows:(a) In a comparatively short period of time, a large quantity of the material has appeared in hair papillae.(b) Although a large quantity of the material is seen in the sebaceous gland and excretory ducts, it is scarcely detected in the environment of those systems.(c) The material has not been seen in the sweat gland and sweat ducts. However, a large quantity of the agent has been witnessed in the environment of these systems and also in the blood vessels around them.(d) Although the agent has not been observed in the fatty cell, it was seen in the fatty intercellular septum in large quantities.
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The ability to discriminate between stereoisomers of alpha-tocopherol was studied in five patients with abetalipoproteinemia (ABL) because an impairment in secretion of apolipoprotein B-containing lipoproteins might impede the normally enhanced plasma transport of RRR-alpha-tocopherol. An oral dose containing 3.7 g of each 2R, 4'R,8'R-alpha-[5-C2H3]tocopheryl acetate (d3RRR-alpha-tocopheryl acetate) and 2RS,4'RS,8'RS-alpha-[5,7-(C2H3)2]tocopheryl acetate (d6 all rac-alpha-tocopheryl acetate) was administered, then the labeled and unlabeled alpha-tocopherol contents of plasma and red blood cells from multiple blood samples obtained at selected times up to 72 h following the dose were quantitated. ABL plasma contained about 1%-10% of the d3-RRR-alpha-tocopherol concentrations of normal subjects given only 150 mg of each isotope. Three of the patients discriminated between forms of alpha-tocopherol with ratios of RRR-/allrac-alpha-tocopherol > or = 1.8, similar to normals. These data suggest that the hepatic tocopherol binding protein is present and functional in ABL patients. Although two of the patients did not discriminate between stereoisomers of alpha-tocopherol, it is likely that this resulted from nearly a complete block in very low density lipoprotein (VLDL) secretion. Thus, the ability of ABL patients to absorb and transport orally administered vitamin E is markedly impaired and variable among patients.
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The photoprotective effect of topically applied alpha-tocopheryl acetate (vitamin E acetate), a stable derivative of alpha-tocopherol (vitamin E), and its possible bioconversion to the active antioxidant species (alpha-tocopherol) was examined in skin tissue of female hairless mice (HRS/J) exposed to UV-B irradiation. Our results indicate that topically applied alpha-tocopheryl acetate is absorbed into and retained by skin tissue. Furthermore, skin tissue from UV-B-irradiated animals that received daily topical alpha-tocopheryl acetate treatments contained significantly higher levels (P < 0.001) of alpha-tocopheryl acetate than non-UV-B-irradiated mice that received identical daily topical alpha-tocopheryl acetate treatments. Finally, free alpha-tocopherol levels in skin also were significantly increased (P < 0.001) by topical applications of alpha-tocopheryl acetate and skin levels of free alpha-tocopherol were significantly greater (P < 0.001) in UV-B-irradiated animals that received daily topical alpha-tocopheryl acetate treatments than in non-UV-B-irradiated animals. These results suggest that UV-B irradiation enhances both the absorption of alpha-tocopheryl acetate and its bioconversion to free alpha-tocopherol.
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