Structurally Unprecedented Metabolites from Marine Sponges

Marine sponges represent a prolific and chemically diverse source of secondary metabolites, some of which feature hitherto unprecedented carbon skeletons that continue to attract the interest of natural product researchers. The novel chemistry of these metabolites is often accompanied by exceptional bioactivity profiles suggesting these compounds to be potential leads for drug discovery. In recent years, advances in chromatographic and spectroscopic techniques have allowed the identification of structurally complex natural products, even at nanomolar concentrations, thus uncovering the vast potential of marine sponges as sources of novel bioactive compounds. In this review, we present an overview on selected natural products reported from marine sponges from 2010 to 2016. In total, 182 different compounds belonging mainly to the groups of alkaloids, peptides, terpenoids, or polyketides are highlighted based on their unique structural features as well as on their reported bioactivities, which are primarily in the fields of anticancer agents, antibiotics, anti-inflammatory compounds, and neuroprotective agents.