investigation of causal relationships, optimization and quality assessment of herbal sunscreen formulation

Background: herbal-based sunscreens are gaining popularity due to their ability to protect against ultraviolet (uv) rays and offer additional benefits such as moisturizing and anti-aging effects derived from bioactive compounds. objectives: the present study aimed to investigate cause-effect relationships, optimize, and assess the quality of a herbal sunscreen formulated from polypodium leucotomos, almond oil, camellia sinensis, and lycopersicum esculentum. methods: a total of 19 sunscreen formulations were designed using bcpharsoft software and the d-optimal model. independent variables included p. leucotomosleaves extract (x1), almond oil (x2), and a mixture of stearic acid and cetyl alcohol in a 1:1 ratio (x3). these variables were selected to enhance sun protection factor (spf) and spreadability. results: the optimized herbal sunscreen formulation consisted of 20% p. leucotomosleaves extract, 8% almond oil, and 5% stearic acid-cetyl alcohol mixture. the formulation achieved an spf of 47.32 ± 0.66 and a spreadability of 28.17 ± 1.00 cm², meeting established quality standards. conclusions: this study contributes to advancements in natural cosmetics, meeting the growing demand for eco-friendly products and supporting the expansion of vietnam's sunscreen market.