In vitro water resistance evaluation of a bioactive sunscreen containing distinct film/ barrier-forming agents

Abstract

The use of functional bioactive ingredients and the property of water resistance are differentials in the choice of more effective and safer sunscreens. Water-resistance tests are expensive, time-consuming, and usually performed on subjects that expose them to irradiation and long immersion times. Thus, the study of in vitro water resistance using different film/ barrier-forming agents is relevant for obtaining sunscreen resistant to rinsing. We aimed to evaluate the water resistance of a rutin-based bioactive sunscreen containing distinct film/barrier-forming agents by an in vitro method. The in vitro water resistance assessment (% WRR) was carried out in a water bath. In vitro sun protection factor (SPF), critical λ (nm), UVA/UVB ratio, and UVA protection factor (UVA-PF(0)) were evaluated before and after rinsing using a diffuse reflectance spectrophotometer with integration sphere. The formulation with dimethicone showed higher values of SPF after rinsing and achieved the requirement of % WRR greater than 50%. All formulations showed similar variations for all other parameters. The results highlighted the property of water resistance provided by the dimethicone, indicating that this emollient is an interesting ingredient choice for sunscreens.