Desenvolvimento e validação da metodologia para determinação do FPS in vitro de formulações fotoprotetoras naturais

Abstract

Sunlight stimulates vitamin D production, helps control some chronic skin diseases and causes a sense of well-being. However, sunlight can also cause damage to skin. Damage includes not only sunburn, but skin cancers, wrinkling and other changes associated with aging skin. Several studies have investigated the photoprotection activity of plant extracts. Thus, the aim of this study was to develop formulations containing crude extracts and fractions obtained by column chromatography of three plant species from Brazilian Cerrado. A new in vitro method was proposed to evaluate the sunscreen photoprotective activity of plants extracts against UV radiation. The method was validated by testing nine commercial formulations authorized by ANVISA. The experimental design was composed of a lamp to simulate the solar spectrum, a base containing the tested sample, placed at 15 cm from the solar lamp, and a sensor to capture the radiation transmitted through the sample, all this sealed inside a black iron box. The method was based on a relationship between not transmitted UV radiation percentage and the sun protection factor determined by Sayre and collaborators. Through this relationship, it is possible to determine the SPF of the tested samples. Statistic analysis showed that the test results are in agreement with the prediction by the manufacturers. After validated, the same method was applied to evaluate the photoprotective capacity of natural formulations. The values obtained for natural formulations were then compared with the previously validated method described by Mansour. Results have shown that the procedure can be a good alternative to cosmetic methods with a rapid, sensitive and reproducible evaluation of the sunscreen activity of either commercial formulations or plant extracts.