Widyastuti Widyastuti, Adewirli Putra, D. Rosi
Excessive ultraviolet (UV) exposure triggers oxidative stress and skin damage, increasing the demand for natural-based sunscreens. Karamunting fruit (Rhodomyrtus tomentosa (Aiton) Hassk.) is rich in phenolic and flavonoid compounds with potential antioxidant and photoprotective activity, yet remains underexplored in topical emulsion formulations with varied carrier oils. This study aimed to evaluate the effect of extraction methods (maceration and soxhlet) on in vitro antioxidant and sunscreen activity, and to formulate and assess the physical stability of karamunting fruit ethanol extract emulsions using three oil bases (VCO, olive oil, and black cumin seed oil). Extraction was performed with 96% ethanol, followed by phytochemical screening, DPPH assay, and SPF determination by UV-Vis spectrophotometry (290–350 nm). Six M/A emulsion formulas were prepared with Tween 80 and PEG 400 co-surfactant, then evaluated for organoleptic properties, pH, specific gravity, centrifugation, freeze thaw test, and SPF. Ethyl acetate extract showed IC50 DPPH of 88.35 μg/mL (strong category) and SPF of 88.014 (ultra protection). Emulsion F6 (black cumin seed oil + extract) provided the highest SPF (122.18; ultra protection) at a concentration of 500 μg/mL, accompanied by good physical stability for 28 days. In conclusion, maceration using ethyl acetate solvent is the best extraction method for the antioxidant activity of karamunting fruit, and black cumin seed oil-based emulsion has the potential as a herbal sunscreen preparation..