Isolation and structure of the unusual Indian Ocean Cephalodiscusgilchristi components, cephalostatins 5 and 6

Abstract

<jats:p> The Indian Ocean (South African) marine worm Cephalodiscusgilchristi (Hemichordata phylum) has been found to contain a series of unusual disteroidal alkaloids, designated the cephalostatins, that possess exceptionally potent lymphocytic leukemia (murine P388) cell line inhibitory activity (to ED<jats:sub>50</jats:sub> 10<jats:sup>−9</jats:sup> μg/mL). Two of the less prominent members with P388 ED<jats:sub>50</jats:sub> 10<jats:sup>−3</jats:sup>–10<jats:sup>−2</jats:sup> μg/mL, cephalostatins 5 (2) and 6 (3), were isolated and assigned structures based on rigorous interpretation of two-dimensional 400-MHz <jats:sup>1</jats:sup>H and <jats:sup>13</jats:sup>C nuclear magnetic resonance. Keywords: cephalostatins 5 and 6, disteroidal alkaloids, lymphocytic leukemia, cytostatic, Cephalodiscusgilchristi.