Structural activity relationship studies of zebra mussel antifouling and antimicrobial agents from verongid sponges

Several dibromotyramine derivatives including moloka'iamine were selected as potential zebra mussel (Dreissena polymorpha) antifoulants due to the noteworthy absence of fouling observed on sponges of the order Verongida. Sponges of the order Verongida consistently produce these types of bromotyrosine-derived secondary metabolites. Previously reported antifouling data for the barnacle Balanus amphitrite(EC50 = 12.2 microM) support the results reported here that the compound moloka'iamine may be a potential zebra mussel antifoulant compound (EC50 = 10.4 microM). The absence of phytotoxic activity of the compound moloka'iamine toward Lemna pausicostata and, most importantly, the compound's significant selectivity against macrofouling organisms such as zebra mussels suggest the potential utility of this compound as a naturally derived antifoulant lead.