Neopetromin, a Cyclic Tripeptide with a C–N Cross-Link, from the Marine Sponge <i>Neopetrosia</i> sp., That Causes Vacuole Fragmentation in Tobacco BY‑2 Cells

HPLC-MS analysis revealed the presence of an unreported peptide in the extract of the marine sponge Neopetrosia sp. Its structure was determined as a tripeptide, named neopetromin (1), composed of two tyrosine and one tryptophan residues with a heteroaromatic C–N cross-link between side chains. The absolute configuration of amino acids was determined using Marfey’s method after ozonolysis and hydrolysis of 1. Compound 1 promoted vacuole fragmentation in an actin-independent manner in tobacco BY-2 cells.