Antioxidant activity of Brown Seaweed Sargassum sp. extract from Tanjung Tinggi Beach, Belitung Island

Oxidative stress occurs when there is an imbalance between free radicals and the body's ability to counteract them with antioxidants. Antioxidants are compounds that help neutralize or prevent the formation of free radicals. This study aimed to evaluate the effects of different extraction solvents (70% ethanol, 70% acetone, and aquadest) on the polyphenol content of Sargassum sp., harvested from Tanjung Tinggi Beach (Belitung Island, Indonesia), and to determine its antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl method. The results showed that distilled water (aquadest) extraction yielded the highest total phenolic (7.32 mg GAE/g) and tannin (10.47 mg TAE/g) contents, while 70% ethanol extraction resulted in the highest total flavonoid content (6.40 mg QE/g). Fourier transform infrared analysis detected hydroxyl groups, indicating the presence of polyphenol compounds in the Sargassum extract. Furthermore, the aquadest extract exhibited the highest radical scavenging activity (43.65%) compared to other solvents. These findings indicate that Sargassum extract may act as a natural antioxidant and holds potential for use as a pharmaceutical agent.