Preliminary formulation and physical evaluation of <i>Centella</i> asiatica-based lotion for sunscreen application

Ultraviolet radiation is a primary factor causing skin damage and oxidative stress. This study explores the preliminary formulation and physical evaluation of herbal sunscreen lotions incorporating Centella asiatica extract. Recognized for its antioxidant and anti-inflammatory properties, C. asiatica is a promising botanical candidate for photoprotective skincare products. Five emulsion-based formulations were developed with varying extract concentrations, and their viscosity and density were assessed over a 21-day period. Results showed that higher concentrations of C. asiatica led to increased viscosity, indicating enhanced emulsion structuring, particularly in formulation F2 (18.47% extract), which consistently exhibited the highest viscosity values. Meanwhile, density did not correlate linearly with extract concentration, with the highest value observed in formulation F3 (11.05% extract), suggesting optimal emulsifierextract interaction. No visual signs of instability such as phase separation were observed in any formulation during the study period. These findings highlight the role of C. asiatica in modifying the rheological properties of emulsions and support its feasibility for integration into phytocosmetic sunscreen products. The results provide a physical foundation for future investigations, including SPF analysis and biological efficacy studies, aiming to optimize herbal formulations for dermatological use.