Development and application of an inclusive protocol to prove the effectiveness of active sunscreen ingredients for the skin health of black individuals

• Grant number: 24/01920-0
• Support Opportunities: Regular Research Grants
• Duration: July 01, 2024 - June 30, 2026
• Field of knowledge: Health Sciences - Pharmacy
• Principal Investigator: André Rolim Baby
• Grantee: André Rolim Baby
• Host Institution: Faculdade de Ciências Farmacêuticas (FCF). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

It is relevant to note that Brazil receives a significant incidence of ultraviolet (UV) radiation, and the majority of Brazilians self-identify as brown and black. This investigation was motivated by the explicit need for the development of a robust and innovative protocol, widely applicable to society, to prove the efficacy of active sunscreen ingredients, develop new and specific sunscreen products, and provide proper guidance on their use for the brown and black population. Regarding sun protection, although it is internationally recognized and accepted, the in vivo assay applied to prove the photoprotective efficacy, through the determination of the sun protection factor (SPF), a globally diffused protection parameter, does not include participants with higher phototypes in its inclusion criteria, thus excluding brown and black individuals from knowledge of efficacy against solar radiation. Therefore, there is a demand for development and advancements in a protocol that can evaluate efficacy against UV radiation independently of phototype and/or ethnicity, allowing for the investigation of sun protection on brown and black skin through biological responses other than erythema formation. Thus, in this investigation, we propose the development of a protocol for determining sun protection on brown and black skin using the following techniques: HPLC-TBARS-EVSC assay (bioanalytical quantification of lipid peroxidation in the human stratum corneum obtained by ex vivo method) and quantification of trans-urocanic acid in the ex vivo stratum corneum by high-performance liquid chromatography (HPLC). Additionally, in addition to the inclusion of brown and black participants in the protocols mentioned above (which do not depend on skin color for obtaining biological responses), in research by our research group, they do not expose volunteers to UV radiation for their executions, as both use the participant's stratum corneum obtained by tape-stripping, a non-invasive or minimally invasive technique. Furthermore, there will be mapping of the potential interaction of these active ingredients (UV filters) on superficial skin hydration and transepidermal water loss. Finally, considering that brown and black skin is complex for identifying the formation of perceptible erythema after exposure to radiation, which is fundamental for in vivo SPF calculation, there is difficulty in indicating the most suitable sunscreens for black and brown individuals. Moreover, there are limited studies demonstrating how black skin behaves in response to UV radiation, making it difficult to determine the best way to protect it in this context. Therefore, it is questioned what the optimal strategy is for developing an efficacy analysis method and developing products for better skin protection for black and brown skin, what biomarkers are involved when the stratum corneum is exposed to UV radiation, and which active ingredients would be most suitable for the black population to improve and maintain skin health. (AU)