Echinosulfonic Acids A−C and Echinosulfone A: Novel Bromoindole Sulfonic Acids and a Sulfone from a Southern Australian Marine Sponge, Echinodictyum

The crude EtOH extract of an Echinodictyum sp. collected during trawling operations in the Great Australian Bight, Australia, displayed antibacterial and antiparasitic properties. Bioassay-directed fractionation yielded three novel sulfonic acids, the echinosulfonic acids A to C (1-3), and a new sulfone, echinosulfone A (4). Structures were assigned to these compounds on the basis of detailed spectroscopic analysis. It was determined that echinosulfonic acids A-C (1-3) and echinosulfone A (4) contributed to the antibacterial but not antiparasitic activity of the crude extract.