The potential of seaweed extracts from Suli Beach, Central Maluku: Antioxidant and photoprotective activities for natural cosmetic applications

Excessive ultraviolet (UV) radiation exposure is one of the main causes of premature aging, sunburn, and an increased risk of skin cancer. Many commercial sunscreens contain synthetic ingredients such as oxybenzone and octinoxate, which are reported to act as endocrine disruptors and harm coral reef ecosystems. Therefore, natural and eco-friendly alternatives are needed. This study aimed to evaluate the antioxidant activity, total phenolic content (TPC), and sun protection factor (SPF) of methanolic extracts of seaweeds from Suli Beach, Central Maluku. Antioxidant activity was determined using the DPPH method, TPC was measured by the Folin–Ciocalteu assay, and SPF values were calculated in vitro using UV–Vis spectrophotometry. The results showed that Turbinaria sp. extract exhibited higher antioxidant activity (112.47 ± 2.13 mg AEAC/g) than Sargassum sp. (100.69 ± 2.29 mg AEAC/g). However, Sargassum sp. contained higher TPC (18.71 mg GAE/g) compared to Turbinaria sp. (9.69 mg GAE/g). The SPF values increased with concentration, with the highest protection at 200 ppm (12.45 for Turbinaria sp. and 10.22 for Sargassum sp.). Phytochemical screening confirmed the presence of flavonoids, steroids, saponins, and tannins in both extracts, while alkaloids were detected only in Sargassum sp. Thin layer chromatography revealed distinct metabolite profiles, suggesting species-specific differences. These findings identify seaweed extracts, particularly Turbinaria sp., as promising candidates for the development of eco-friendly cosmetic ingredients with antioxidant and photoprotective properties.