Bioconversion of tocopheryl acetate to tocopherol in human skin: Use of human skin organ culture models

Nabi, Zeenat F.; Tavakkol, Amir; Soliman, Nesreen Gamal; Polefka, Thomas G.

doi:10.1016/s0928-4680(98)81031-6

Cited by 3 publications

(4 citation statements)

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“…The OES shown in Fig. 1 was designed by Brian Tarkington (UC‐Sacramento) and built by the Colgate‐Palmolive Company [17, 18]. It consists of three modules: (i) air blower and O 3 generation device; (ii) O 3 chamber; and (iii) O 3 monitor and O 3 disposal/purge unit, all connected in sequence as shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…A 36’’‐wide stainless steel exposure chamber with glass windows similar to a double face glove box was constructed (Fig. 1) [17, 18]. The chamber provides two forearm entry ports on either side for simultaneous exposure for two subjects.…”

Section: Methodsmentioning

confidence: 99%

“…Vitamin E was detected with a Waters UV‐Vis model 484 detector (Millipore, Milford, MA, U.S.A.) set to 288 nm, as previously described [17]. Under these conditions the typical retention time for vitamin E was 5 min [18]. To accurately quantify low levels of vitamin E, an ESA Cuolochem II electrochemical detector (EST Inc., Chelmford, MA, U.S.A.) was used.…”

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confidence: 99%

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Effects of environmentally realistic levels of ozone on stratum corneum function

Tavakkol

Wietecha

et al. 2006

Intern J of Cosmetic Sci

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The impact of troposphere ozone (O(3)), the major oxidant in photochemical smog, on the overall wellbeing of skin is of considerable interest. To date, limited information is available on the impact of O(3) on human skin. Using a specially designed O(3) exposure chamber, we provide the first evidence that exposure of human skin to O(3) (0.8 ppm, 2-h time-weighted average) significantly reduced vitamin E by 70% and concomitantly increased lipid hydroperoxides by 2.3 fold in the superficial stratum corneum (SC). Although the dose of O(3) used here reduced the resident microflora population by 50% and created a state of oxidative stress within the SC, it did not affect several key enzymes involved in SC homeostasis including the redox-sensitive transglutaminase and the SC tryptic (KLK5) and chymotryptic (KLK7) proteases. Importantly, no signs of skin dryness or erythema were observed. We hypothesize that the limited effects of low doses of O(3) on SC function is attributable to several factors including: (i) protection provided by the anti-oxidant defence system; (ii) inability of O(3) to penetrate the SC; and (iii) limited water available to catalyse the Criegee reaction. Although chronic exposure to O(3) may produce a different outcome than that reported here, our data suggest that exposure to environmentally relevant doses of O(3), at best, induces a moderate state of oxidative stress, without producing a visible clinical response. In our opinion, exposure of skin to UV radiation is a much more significant threat than exposure to ground-level O(3).

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Effects of environmentally realistic levels of ozone on stratum corneum function

Tavakkol

Wietecha

et al. 2006

Intern J of Cosmetic Sci

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“…Vitamin E protects biological membranes and fatsoluble parts of the cell, such as the low-density lipoprotein, cholesterol (20). Human skin bioconverts tocopherol acetate to tocopherol (21), thereby reducing the severity of the oxidative stress response by tocopherol antioxidant release and action.…”

Section: Introductionmentioning

confidence: 99%

An Evaluation of the Effects of Photoactivation of Bithionol, Amiodarone and Chlorpromazine on Human KeratinocytesIn Vitro

2007

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Human skin is a continual target for chemical toxicity, due to its constant exposure to xenobiotics. The skin possesses a number of protective antioxidant systems, including glutathione and enzymic pathways, which are capable of neutralising reactive oxygen species (ROS). In combination with certain chemicals, the presence of ROS might augment the levels of toxicity, due to photoactivation of the chemical or, alternatively, due to an oxidatively-stressed state in the skin which exisited prior to exposure to the chemical. Bithionol is a phototoxic anti-parasitic compound. The mechanism of its toxicity and the possible methods of protection from its damaging effects have been explored. The capacity of keratinocytes to protect themselves from bithionol and other phototoxic chemicals has been investigated. In addition, the potential of endogenous antioxidants, such as vitamin C and E, to afford protection to the cells, has been evaluated. The intracellular glutathione stores of HaCaT keratinocytes were reduced following treatment with biothionol. Following photoactivation, both bithionol and chlorpromazine had similar effects, which suggests that glutathione is important in the detoxification pathway of these chemicals. This was confirmed by means of the visual identification of fluorescently-labelled glutathione. Endogenous antioxidants were unable to protect the HaCaT keratinocytes from bithionol toxicity or chlorpromazine phototoxicity. Amiodarone was shown to have no effect on cellular glutathione levels, which suggests that an alternative mechanism of detoxification was occurring in this case. This was supported by evidence of the protection of HaCaT cells from amiodarone phototoxicity via endogenous antioxidants. Thus, it appears that amiodarone toxicity is dependent on the levels of non-gluathione antioxidants present, whilst bithionol and chlorpromazine detoxification relies on the glutathione antioxidant system. This type of approach could indicate the likely mechanisms of phototoxicity of chemicals in vitro, with relevance to potential effects in vivo.

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Nonionic Model Microemulsions to Study Interactions with Active Components and Antioxidant Activity

Balogh¹,

Marques²,

Lopes³

2012

Microemulsions - An Introduction to Properties and Applications

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Bioconversion of tocopheryl acetate to tocopherol in human skin: Use of human skin organ culture models

Cited by 3 publications

References 0 publications

Effects of environmentally realistic levels of ozone on stratum corneum function

Effects of environmentally realistic levels of ozone on stratum corneum function

An Evaluation of the Effects of Photoactivation of Bithionol, Amiodarone and Chlorpromazine on Human KeratinocytesIn Vitro

Nonionic Model Microemulsions to Study Interactions with Active Components and Antioxidant Activity

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