Neopetrosiamides, Peptides from the Marine Sponge Neopetrosia sp. That Inhibit Amoeboid Invasion by Human Tumor Cells

[structure: see text] Neopetrosiamdes A (1) and B (2), two diastereomeric tricyclic peptides that inhibit amoeboid invasion of human tumor cells, have been isolated from the marine sponge Neopetrosia sp. collected in Papua New Guinea. The structures of the neopetrosiamides were elucidated by analysis of MS and NMR data and confirmed by chemical degradation.