Cupolamide A: A cytotoxic cyclic heptapeptide from two samples of the sponge Theonella cupola

A new cyclic heptapeptide cupolamide A (1) was isolated from two samples of the sponge Theonella cupola collected in Indonesia and Okinawa. It contains two L-Val, one D-Leu, and one D-Ser, and three uncommon amino acid residues, D-homoarginine (Har), trans-4-hydroxy-L-proline (Hyp), and L-2,4-diaminobutanoic acid (Dba). The structure elucidation of 1 was performed by NMR spectroscopic techniques and the stereochemistry was determined by Marfey's method. Cupolamide A (1) was active against P388 murine leukemia cells with an IC50 = 7.5 mu g/mL.