Cosmetics, Vol. 6, Pages 14: Skin Retention of Sorbates for a Broad Photoprotection

Cosmetics, Vol. 6, Pages 14: Skin Retention of Sorbates for a Broad Photoprotection

Cosmetics doi: 10.3390/cosmetics6010014

Authors: Cristina Padula Silvia Pescina Leticia Grolli Lucca Anna Demurtas Patrizia Santi Sara Nicoli

Overexposure to sunlight is widely accepted as the underlying cause of cutaneous melanoma. UV radiation induces the formation of DNA photoproducts that, if unrepaired, can induce carcinogenic mutations. Recent data indicate that sorbates can be useful to widen the protection against UV radiation by acting as a triplet-state quencher in the melanocyte. The aim of the present work was to prepare a sunscreen formulation containing ethylsorbate or sorbic acid in order to combine the UV-filter action with the triplet-state quenching activity of these molecules. Ethylsorbate and sorbic acid were characterized in terms of solubility and partition coefficient, and their transdermal permeation and skin accumulation were studied in vitro from simple solutions and in the presence of cyclodextrins (alpha and hydroxypropylbeta) as a complexing agent. The goal was to reduce as much as possible sorbates permeation while sustaining their skin levels. The obtained results indicated that the addition of alphacyclodextrins determined a 6-folds (ethylsorbate ) or 4-folds (sorbic acid) reduction of the transdermal permeation. Sorbic acid and alphacyclodextrin (1:1 and 1:3 molar ratio) were then formulated in a sunscreen vehicle using 1.5% hyaluronic acid (sodium salt) as a thickener and hydrating agent and 5 mg/mL benzophenone 4 (BP4) as UVB/UVA filter. The addition of hyaluronic acid and BP4 gave rise to a formulation with good cosmetic properties, no BP4 permeation, good sorbate (0.2–0.3 µmol/cm2) and BP4 (0.3–0.5 µmol/cm2) skin levels (stratum corneum + viable epidermis) and thus a broad protection against UV radiation.

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