In vivo anti-infrared study by Synelvia

A Sirvent (1), C Lhéritier (1), A Moga (2), F Girard (1)
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

Direct link to the complete article

If sunscreens protect against UV radiations, several studies point now the deleterious impact of infra-red (IR) and the fact that an IR protection should also be added to the products [1-3]. Indeed, IR is involved in cutaneous ageing and probably in carcinogenesis [4]; it is mainly responsible for the increase in skin temperature and leads to free radicals and matrix metalloproteinase-1 (MMP-1) production deep in the dermis [5-7].
An efficient protection against IR should be obtained via the presence of optical absorbers in the IR range, reflection of photons and scattering and/or free radical scavengers [8].
The aim of this study was to propose simple methodologies in order to evaluate the IR protection enabled by cosmetic products.

…/…

1. BLOCKING EVALUATION OF TWO SUNSCREEN PRODUCTS

  • Effects of IR radiations on cutaneous parameters
  • Influence of phototype
  • Effect of sunscreens X or Y

2. EVALUATION OF THE CELLULAR PROTECTION AGAINST IR OF A SUNSCREEN PRODUCT

CONCLUSION

• The 1st approach takes advantage of the blocking power of sunscreens. All the chosen parameters (cutaneous temperature, color and microcirculation) were increased after IR radiation. Darker skin types reacted more importantly than lighter ones: they absorbed more heat and vasodilation was more important. This approach allowed to discriminate two sunscreens: sunscreen X had no effect on skin heating under IR whereas sunscreen Y reduced the 3 parameters.
• The 2nd approach studied some cellular makers of stress: oxidation and detoxification. We were able to demonstrate that a sunscreen product that limit skin heating also limit the cellular aggression (reduced generation of MDA as well as reduced needs in SOD and CAT).
These two approaches can be used in the future in order to test the IR protection of a cosmetic product.

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