Antioxidant Activity of Brown Algae Sargassum species Extract from the Coastline of Java Island

The coastlines with rocky shores at Java Island Indonesia, Gunung Kidul (Yogyakarta) and Jepara (Central Java), have abundant resources of brown algae Sargassum sp. Little effort, however, has been made to explore the antioxidant potential of the algae harvested from these area. Tropical brown algae have proven to produce a very effective antioxidant defence system due to the strong UV radiation in the tropical environment. The Total Phenolic Content (TPC) of the extracts were evaluated by using Follin Ciocalteau reagent, while antioxidant activities were evaluated by using 2,2-Diphenyl-1-Picrylhydrzyl Radical Scavenging Activity (DPPH-RSA) and Ferrous Ion-Chelating (FIC) ability. The effects of treatments on TPC and antioxidant activities were analysed using analysis of variance models. There were four treatments and three replicates. These treatments were extract types (cytoplasmic and membrane bound), harvest sites (Gunung Kidul and Jepara), harvest seasons (dry and rainy) and various Sargassum species. The TPC of extracts varied from 0.006-0.65 and 6.72-21.99 g phloroglucinol equivalent/100 g dried extract for cytoplasmic and membrane bound extract, respectively. The DPPH-RSA in extracts concentration of 0.45 mg mL^-1 were in the range of 14.61-48.71 % for membrane bound and 0.17-44.05 % for cytoplasmic extracts. The FIC in extract concentration of 3.3 mg mL^-1 were in the range of 2.0512.51 and 26.77-68.80 % for cytoplasmic and membrane bound extract, respectively. Nevertheless, these extracts had lower activity when compared with BHT and EDTA as positive control of RSA-DPPH and FIC, respectively. The antioxidant activities of Sargassum were influenced by types of extracts, harvest sites, seasons and species. The antioxidant activity of membrane bound was higher than cytoplasmic extract. The increasing of DPPH-RSA and FIC were proportional to TPC. The highest antioxidant activity was found at S. hystrix from Gunung Kidul area harvested during dry season.