Antifouling sesterterpenes from the New Zealand marine sponge Semitaspongia bactriana.

Three antifouling (AF) sesterterpenes have been isolated from the New Zealand marine sponge Semitaspongia bactriana with toxicity against the diatom Nitzschia closterium and bryozoan Bugula neritina. The three metabolites have been characterised by spectroscopic techniques as 7E,12E,20Z-variabilin (1), cavernosolide (2) and lintenolide A (3) (also called spongianolide C) and have low micromolar activity against our two test species. The gamma-hydroxybutenolide containing sesterterpenes (2 and 3) show the most promise, with relative stability and suitable lipophilicity for incorporation of either these metabolites, or synthetic analogues, as biocides to produce paints or plastics with AF properties.