A new antifouling hexapeptide from a palauan sponge, Haliclona sp.

Bioassay-guided fractionation of an extract of the sponge Haliclona sp. provided a known hexapeptide, waiakeamide (1), and a new sulfone derivative (2). The structures of hexapeptides 1 and 2 were elucidated by extensive NMR analyses and the advanced Marfey's method with LC/MS. These compounds showed repellent activity against the blue mussel, Mytilus edulis galloprovincialis.