ISOLATION AND EVALUATION OF ANTIOXIDANT AND ANTIBACTERIAL ACTIVITIES OF FUCOIDAN RICH EXTRACT (FRE) FROM INDIAN BROWN SEAWEED,Sargassum wightii

Brown seaweed, Sargassum spp. has been traditionally used in the Chinese medicine as a food ingredient for the treatment of Scrofula, goiter, tumor, edema, testicular pain and swelling. Now-a-days isolation of fucoidan, a bioactive compound present in this brown seaweed is getting increasing interest because of its multifunction including antibacterial and antioxidant activity. A simple alcohol-water method was used for the extraction of fucoidan from Indian brown seaweed Sargassum wightii. The crude fucoidan yield was 5.5% of dry weight of seaweed and the L-fucose content was 31.61mg/g dried seaweed powder. Three antioxidant activity screening assays such as diphenylpicrylhydrozyl (DPPH) scavenging activity, ferric reducing antioxidant power assay (FRAP) and total phenolic assays (TPA) were selected to identify the antioxidant activity of fucoidan rich extract (FRE). The antioxidant activity of FRE exhibited a linear relationship, y = 9.01x + 19.18; R² = 0.97, y = 20.09x + 25.29; R² = 0.98 and y = 13.46x - 11.61; R² = 0.99 respectively for DPPH, FRAP and TPA. The antibacterial activity was estimated by minimum bactericidal concentration (MBC) and minimum inhibitory concentration (MIC).The FRE also inhibited the growth of Staphylococcus aureus, Micrococcus luteus and Aeromonas hydrophila at MIC of 62.5, 125.0 and 62.5 µl/ml, respectively. Hence, Sargassum wightii possesses antibacterial activity against gram positive and gram negative pathogens and contains good antioxidant activity as well