Gr. Pettit et al., ANTINEOPLASTIC AGENTS .323. ISOLATION AND STRUCTURE OF PHAKELLISTATIN6 FROM A CHUUK ARCHIPELAGO MARINE SPONGE, Bioorganic & medicinal chemistry letters, 4(22), 1994, pp. 2677-2682
Phakellistatin 6 (7), a trace (7.5 x 10(-7)% yield) constituent of the
marine sponge Phakellia costata located in the Federated States of Mi
cronesia has been found to significantly inhibit growth of certain hum
an cancer cell lines (GI(50) 0.1 to 0.01 mu g/ml). The structure of ph
akellistatin 6 (7) was deduced as cycle (Pro-Trp-Leu-Pro-Ile-Pro-Phe)
employing a combination of MS/MS and high field (500 MHz) 2D-NMR proce
dures followed by chiral (all S amino acids) assignments using hydroly
sis --> derivatisation --> chiral chromatographic techniques.