INDEKS AKTIVITAS ANTIOKSIDAN EKSTRAK RUMPUT LAUT COKLAT (Sargassum aquifolium)
Antioxidant activity index was improved for standardization of the antioxidant activity strength on extracts or pure compounds. Development of this method based on reduction of diphenylpicrylhydrazyl radical by antioxidant substances. Brown seaweed has been known containing antioxidant compounds that it capable to reduce reactivity of free radical. Th e purpose of this study was to determine antioxidant activity index of Sargassum aquifolium extracts. S. aquifolium was obtained from the shoreline of Talango Island, Sumenep district. Sample was cleaned, washed, dried, powdered and macerated by ethanol, acetone 70%, methanol, ethanol 80%, methanol 80% and aquadest (1:3 w/v), respectively, three times on 4oC for 24 hours. Filtrate was combined, concentrated and dried to obtain extract. Aft er that it was reacted against diphenylpicrylhydrazyl radical. Decreasing of radical absorbance was observed with spectrophotometer at 517 nm. Th e result showed that the inhibition concentration 50% of S. aquifolium methanols extract was the lower than the others. Th e antioxidant activity index of S. aquifolium methanol extract was 0.54. According to the antioxidant activity index, methanol extract of S. aquifolium was included a medium antioxidant and potential improved as antioxidant nutraceutical.