Development of Antioxidant-Rich Sunscreen Cream Containing Avocado (Persea americana Mill.) Seed Extract: Physicochemical Characterization and In Vitro Photoprotective Evaluation

Ultraviolet (UV) radiation contributes to oxidative stress, premature skin aging, inflammation, hyperpigmentation, and skin carcinogenesis. Although synthetic UV filters are commonly used in sunscreens, concerns regarding phototoxicity, endocrine disruption, and environmental impact have increased interest in safer plant-derived photoprotective agents. Avocado (Persea Americana Mill.) seeds, an underutilized agro-industrial byproduct, contain phenolic and flavonoid compounds that influence the antioxidant and UV-absorbing properties. Therefore, this study aimed to formulate oil-in-water (O/W) sunscreen creams containing avocado seed ethanolic extract and evaluate their physicochemical characteristics, antioxidant activity, and in vitro photoprotective performance. Avocado seed extract was prepared by ethanolic maceration and characterized through phytochemical screening, total phenolic content (TPC), total flavonoid content (TFC), and DPPH radical scavenging activity. Cream formulations containing 6% (F1), 9% (F2), and 12% (F3) extract were evaluated for organoleptic properties, homogeneity, pH, spreadability, viscosity, and emulsion type. Photoprotective activity was determined spectrophotometrically using sun protection factor (SPF), percentage transmission of erythema (%Te), and percentage transmission of pigmentation (%Tp). Statistical analysis was performed using one-way ANOVA. The extract showed high phenolic content (287.06 ± 6.28 mg GAE/g extract), flavonoid content (11.34 ± 0.18 mg QE/g extract), and strong antioxidant activity with an IC50 value of 73.94 ± 0.06 μg/mL. All cream formulations exhibited acceptable physicochemical properties and O/W emulsion characteristics. Increasing extract concentration significantly increased viscosity and SPF values while decreasing spreadability, %Te, and %Tp. The F3 formulation showed the highest SPF value (32.70 ± 0.40), indicating strong photoprotective activity against both UVB and UVA. These findings suggest avocado seed extract has potential as a sustainable natural ingredient for eco-friendly cosmeceutical sunscreen formulations.