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Radical generating factor in sunscreen formulations

IP.com Disclosure Number: IPCOM000245957D
Publication Date: 2016-Apr-20
Document File: 9 page(s) / 125K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is the assessment of the impact of single UV filters as well as of UV filter mixtures on the generation of free radicals upon UV irradiation inside a cosmetic formulation.

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This is the abbreviated version, containing approximately 42% of the total text.

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Background

When applied on skin, sunscreen formulations are exposed to UV radiation, which might be the source for some ingredients to generate free radicals that may then lead to radical chain reactions in the formulation film. Perfume compounds, unsaturated oils, or UV filters might trigger these radical chain reactions or act as catalysts (1). The generation of UV-induced hydroxyperoxides and other peroxide free radicals are known to induce photo allergic dermatisis, the most common being Acne Aestivalis commonly known as Mallorca Acne. The relationship between the level of UV-induced free radicals as well as the impact of the filter mixture on the elicitation of Mallorca Acne was demonstrated (1).

The present works aims at assessing the impact of single UV filters as well as of UV filter mixtures on the generation of free radicals upon UV irradiation inside a cosmetic formulation. To this end, we measured the amount of free radicals produced by the addition of different UV filters / UV filter mixtures into a formulation containing standard excipients (no perfume, no sensitive compounds). ESR spectroscopy was used to quantitatively measure the amount of free radicals produced under UV exposure into the tested formulations.

Method used for measurement of free radicals

The concentration of a semi stable spin proble PCA (2,2,5,5-tetramethyl pyrrolidine N-oxyl) added to the diluted formulation is monitored by ESR spectroscopy before and after UV irradiation of the formulation sample. The PCA spin probe being inherently photo stable will react with the UV-

Radical generating factor in sunscreen formulations

Radical generating factor in sunscreen formulations



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Formulations

Both, sunscreen formulations containing either a single UV filter or a mixture of different UV filters were investigated for their Radical Potential.

• In total, 15 formulations containing a single UV filter were prepared, each of following UV filter was added at a concentration of 3% active.

o Tinosorb S: Bis.ethylhexylphenol, Methoxyphenyl Triazine (BEMT)
o Tinosorb M: Methylene Bis-benzotriazolyl Tetramethylbutylphenol (MBBT) o Tinosorb A2B: Tris Biphenyl Triazine (TBPT)
o Uvinul T150: Ethylhexyl Triazone (EHT)
o Uvinul MC80: Ethylhexyl Methoxycinnamate (EHMC)
o Uvinul N539T: Octocrylene (OCR)
o Uvinul A Plus: Diethylamino Hydroxybenzoyl Hexyl Benzoate (DHHB)
o Ethylhexyl salicylate (EHS)
o Butyl Methoxydibenzoylmethane (BMDBM)
o Titanium Dioxide (TiO2)

• Moreover, several sunscreen formulations with SPF 30 based on a mixture of different UV filters were also investigated. The UV filter compositions are given in tables below.

Radical generating factor in sunscreen formulations

generated free radicals inside the formulation sample. The amount of reduced PCA can be calculated from a calibration curve and subsequently the amount of the UV-produced free radicals can then be quantitatively deduced.


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