Exploration of Antifouling Potential of the Brown Algae Laminaria 'Sanhai'

Seaweeds are one of the largest producers of biomass in the marine environment. It has been well known that marine algae, especially brown algae was a rich source of biogenic compounds with antifouling potential that could be ideal alternatives of tributyltin (TBT). In this paper, antifouling potential of the brown algae Laminaria 'sanhai' was explored. Firstly, the dried alga was extracted and the antialgal and antilarval activities were investigated. The EC50 and LC50 values of crude extract of Laminaria 'sanhai' against diatom (Skeletonema costatum) and barnacle larval (Chthamalus challengeri) were 8.9 mu g mL(-1) and 12.0 mu g mL(-1) respectively. Then, guided by bioassay, the bioactive substances were isolated by liquid-liquid extraction. The antialgal and antilarval activities of isolated fraction were improved with the EC50 value of 7.4 mu g mL(-1) against S. costatum and LC(50 )value of 9.7 mu g mL(-1) against C. challengeri larvae. Identification by IR, Q-TOFMS and GC-MS of the isolated bioactive substances revealed the abundance of fatty acids. These fatty acids, most with 16, 18 or 20 carbon atoms, contained myristic, hexadecanoic, oleic, linolenic, arachidonic and eicosapentaenoic acids. The results indicated that both the crude extract and the isolated bioactive substances had high antialgal and antilarval activities with no highlighted cytotoxicity which made the brown algae Laminaria 'sanhai' a promising source of the environmentally friendly antifoulants.