Antineoplastic agents.: 542.: Isolation and structure of sesterstatin 6 from the Indian ocean sponge Hyrtios erecta

A new scalarane-type pentacyclic sesterterpene, sesterstatin 6 (6), was isolated in 8.3 x 10(-7)% yield from the Republic of Maldives marine sponge Hyrtios erecta. The structure was elucidated by analyses of HRMS and high-field 2-D NMR spectra. Sesterstatin 6 showed significant cancer cell growth inhibition against murine P388 lymphocytic leukemia and a series of human tumor cell lines (ED50 0.17 mu g/mL, GI(50) 1.8-8.9 x 10(-1) mu g/mL) and proved to be the most inhibitory of the series.