The influence of pre‐irradiation on the predictability of <i>in vivo</i> UVA protection with a new <i>in vitro</i> method

Wendel, V.; Klette, E.; Wittern, Klaus‐Peter; Gers‐Barlag, H.

doi:10.1034/j.1600-0781.2003.00017.x

Cited by 8 publications

(7 citation statements)

References 2 publications

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“…Star‐rated sunscreens include UVA as well as UVB filters; however, it was found previously that the protection against free‐radical production in skin (measured using the ascorbate radical) afforded by sunscreens is relatively low (1). Sunscreens with a sun protection factor (SPF) rating of 20+ (indicative of UVB protection) were found to afford only 55% protection against free radicals, giving a calculated protection factor of 2, which is lower than reported UVA protection factors measured in vivo , as far as this information is available to the general public (2). The extent to which solar wavelengths other than UVB (classically linked with non‐melanoma skin cancers) are involved in the initiation and/or promotion of skin cancers remains to be conclusively established, and results from animal models continue to be confounding.…”

Section: Introductionmentioning

confidence: 84%

Relevance of Sunscreen Application Method, Visible Light and Sunlight Intensity to Free‐radical Protection: A Study of ex vivo Human Skin

Haywood¹

2006

Photochem & Photobiology

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With the continued rise in skin cancers worldwide there is a need for effective skin protection against sunlight damage. It was shown previously that sunscreens, which claimed UVA protection (SPF 20+), provided limited protection against UV-induced ascorbate radicals in human skin. Here the results of an electron spin resonance (ESR) investigation to irradiate ex vivo human skin with solar-simulated light are reported. The ascorbate radical signal in the majority of skin samples was directly proportional to the irradiance over relevant sunlight intensities (0.9-2.9 mW cm(-2)). Radical production (substratum-corneum) by UV (wavelengths < 400 nm) and visible components (> 400 nm) was approximately 67% and 33% respectively. Ascorbate radicals were in steady state concentration at low irradiance (approximately 1 mW cm(-2) equivalent to UK sunlight), but at higher irradiance (approximately 3 mW cm(-2)) decreased with time, suggesting ascorbate depletion. Radical protection by a four star-rated sunscreen (with UVA protection) was optimal when applied as a thin film (40-60% at 2 mg cm(-2)) but less so when rubbed into the skin (37% at 4 mg cm(-2) and no significant protection at 2 mg cm(-2)), possibly due to cream filling crevices, which reduced film thickness. This study validates ESR determinations of the ascorbate radical for quantitative protection measurements. Visible light contribution to radical production, and loss of protection when sunscreen is rubbed into skin, has implications for sunscreen design and use for the prevention of free-radical damage.

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Section: Introductionmentioning

confidence: 84%

Relevance of Sunscreen Application Method, Visible Light and Sunlight Intensity to Free‐radical Protection: A Study of ex vivo Human Skin

Haywood¹

2006

Photochem & Photobiology

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“…A serial concentration of bacterial‐derived melanin was prepared in cream excipient from Renmin Hospital of Wuhan University. A layer of 2 mg/cm 2 melanin cream was applied evenly on quartz plate with presaturated finger‐cot, according to the procedure 22 . After the sample had been dried for 20 min, the transmission at the 360 nm was read by UV spectrophotometers (Shanghai Spectrum Instruments Company, Shanghai, China), and measurements were performed at three different positions on each plate.…”

Section: Methodsmentioning

confidence: 99%

Photoprotection of bacterial‐derived melanin against ultraviolet A–induced cell death and its potential application as an active sunscreen

Geng¹,

Tang²,

Wan³

et al. 2008

Acad Dermatol Venereol

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“…In the method, the effectiveness of sunscreens can be obtained by mixing them with polystyrene nanospheres in an aqueous suspension. There are some methods to obtain SPF that use layers of sunscreen (7,18,19), but in practical application the sunscreen molecules are distributed in the epidermis; there may be water on one side and biomolecules (proteins and lipid membranes) on the other side.…”

Section: Discussionmentioning

confidence: 99%

“…The in vitro sun protection factor of the sunscreens is obtained using transmission spectra of the sunscreens ( I 8, 19). In this skincell-mimicking system formed by polystyrene nanospheres, using the fluorescence of nanospheres we obtained the apparent transmission spectra of the sunscreens.…”

Section: Apparent Transmission and Absorptionmentioning

confidence: 99%

A New Method to Test the Effectiveness of Sunscreen Ingredients in a Novel Nano-surface Skin Cell Mimic

Krishnan¹,

Elmets²,

Nordlund³

2006

Photochem Photobiol

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Photophysical properties of sunscreens are commonly studied in solvent media, which do not mimic the skin, or in complex artificial skin systems, which are difficult to handle. In an earlier study, we showed that polystyrene nanosphere suspensions mimic the mixed polarity environment of skin cell systems. This paper presents a new method to quantify the effectiveness of sunscreens in the polystyrene nanosphere environment. This method utilizes the intrinsic UV-B fluorescence of polystyrene nanospheres. We studied three UV-B sunscreens by this new method and compared their extinction coefficients with observed values in solvent. The values follow the trend observed in solvents, but the ratio of their extinction coefficient in solvent to the value obtained by this new method is 1.3-1.8 instead of 1. This difference might be caused by the mixed polarity or the microgeometry of the nanosphere system. Regardless of the difference in the extinction coefficients, this new system can be used to test hundreds of chemicals for their sunscreening potential in a cost-effective way. One marked advantage of this new method is its ability to test both hydrophobic and hydrophilic sunscreening chemicals in the same environment. This is virtually impossible for current solvent-based models, which require different solvents for hydrophobic and hydrophilic chemicals. The new method also allows the simultaneous evaluation of a host of photophysical properties of sunscreening chemicals.

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The influence of pre‐irradiation on the predictability of in vivo UVA protection with a new in vitro method

Cited by 8 publications

References 2 publications

Relevance of Sunscreen Application Method, Visible Light and Sunlight Intensity to Free‐radical Protection: A Study of ex vivo Human Skin

Relevance of Sunscreen Application Method, Visible Light and Sunlight Intensity to Free‐radical Protection: A Study of ex vivo Human Skin

Photoprotection of bacterial‐derived melanin against ultraviolet A–induced cell death and its potential application as an active sunscreen

A New Method to Test the Effectiveness of Sunscreen Ingredients in a Novel Nano-surface Skin Cell Mimic

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