A Sirvent1, A Moga2, C Lhéritier1, F Girard1

1. Laboratoire Dermscan: 114 Bd du 11 novembre 1918, 69100 Villeurbanne, FRANCE
2. Synelvia SAS, Prologue Biotech: 516 rue Pierre et Marie Curie, 31670 Labège Cedex, FRANCE

Introduction

Today, it is well known that UV radiation is responsible of various harmful responses at the cutaneous level. UV rays generate reactive oxygen species and are a source of oxidative stress [1, 2].

The aim of this study was to explore the impact of a single UV exposure on several indicators of cellular damages thanks to a new non invasive in vivo skin surface sampling and to confirm its interest for the evaluation of the antioxidant capacity of a formulation.

Results and Discussion

Preventive action

The preventive action of the AO formulation and its vehicle were tested after a single application, either one hour (zones C or D) or 24 hours (zones E or F) before UV radiation. Results were compared to either the non-treated, non-irradiated zone (versus A) or the non-treated, irradiated zone (versus B).

  • Effect of UV radiation (see B versus A): significant increases in lipid peroxidation (squalene peroxides, MDA) and detoxification systems (SOD, CAT) were measured.
  • Effect of AO application (see C and E zones versus B): a single application of AO formulation BEFORE UV aggression reversed all modifications and conferred a significant protection on lipid peroxidation markers and detoxification systems.
  • The preventive effect appeared more important when the AO formulation was applied 24h before compared to 1 hour before UV radiation.
  • Comparison AO versus Vehicle: results were significantly different for detoxification markers (p<0,05) and limit significant for lipid peroxidation markers (p<0.1). Preventive effect of AO application was superior to its vehicle.

Curative action

  • Application of the anti-oxidant formulation did not modify the studied markers except for MDA and CAT (see Δ% [G-A])
  • UV radiation (see Δ% [B-A]): as seen in the first study, significant increases in lipid peroxidation markers and detoxification systems were noticed. Fatty acids content was significantly reduced.
  • Protection of AO (see Δ% [H-B]): when performed immediately AFTER the UV aggression, a single application of AO formulation reversed all modifications and conferred a significant protection on lipid peroxidation markers, detoxification systems and lipid content.

N.B. In another study performed on 6 women, we compared the curative action of AO versus its vehicle. Results obtained on the 2 zones were significantly different from each other for MDA and SOD markers (p<0.02) and near significant for Squalene ratio and CAT (p<0.10) (data not shown).

These results highlighted the superiority of curative action of the AO formulation on its vehicle, after UV radiation.

Conclusion

The present study highlighted the effects of a single UV exposure (1.5 MED) on several biomarkers of oxidative stress, in vivo. One day (T24h) after the aggression, it was observed: lipid peroxidation markers (squalene peroxides and MDA) detoxification systems (SOD and CAT) fatty content

The single application of an antioxidant mix 24h before or immediately after UV radiation was able to significantly reversed these alterations.

Skin surface sampling was performed thanks to an innovative technique. A specific surface swabbing was used, presenting several advantages: easy to performed; non-invasive; it provided a lot of biological material and preserved it from any biochemical alteration, facilitating its analysis later on.

The sensitive approach used in these 2 studies will be useful to evaluate the preventive and/or curative effects of cosmetic formulations on UV radiation.