Abstract Description

Marine sponges of the genus Oceanapia are prolific producers of bioactive secondary metabolites. Four known bifunctional sphingolipids are isolated: isorhizochalin (1), rhizochalin (2), rhizochalin C (3), and oceanapiside (4) from Oceanapia ramsayi sponges. These compounds are derivatized to form aglycones (1b-4b), perbenzoates (1c–4c), and bis-oxazoline (2e). The compounds and their derivatives are investigated for their cytotoxicity against three breast cancer cell lines (HCC70, MDA-MB-231, MCF7). All four sphingolipids are cytotoxic with significant selectivity indices (SI) for the three breast cancer cells. Compound 1 has high selectivity against the HCC70 cell line, 4 against the MDA-MB-231 cells, and aglycon 4b against both the MDA-MB-231 and MCF7 cell lines, respectively, demonstrating the functional importance of the sugar units and terminal amino-alcohol stereochemistry. Compounds 1–4 also show promising antibacterial activity against Staphylococcus aureus, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli, and the multiple antibiotic-resistant Klebsiella pneumoniae test strains, with compound 2 exhibiting the greatest activity. Derivatization diminished potency, indicating that the sugar moiety and stereochemistry are functionally important for antibacterial activity.