Antineoplastic agents 323. Isolation and structure of phakellistatin 6 from a Chuuk archipelago marine sponge

Abstract

Phakellistatin 6 (7), a trace (7.5 × 10 −7% yield) constituent of the marine sponge Phakellia costata located in the Federated States of Micronesia has been found to significantly inhibit growth of certain human cancer cell lines (GI 50, 0.1 to 0.01 μg/ml). The structure of phakellistatin 6 (7) was deduced as cyclo (Pro-Trp-Leu-Pro-Ile-Pro-Phe) employing a combination of MS/MS and high field (500 MHz) 2D-NMR procedures followed by chiral (all S amino acids) assignments using hydrolysis → derivatisation → chiral chromatographic techniques.