Antineoplastic Agents. 510. Isolation and structure of dolastatin 19 from the Gulf of California sea hare Dolabella auricularia.

The Gulf of California shell-less mollusc Dolabella auricularia has been found to contain a new 14-membered macrocyclic lactone linked to a 2,4-di-O-methyl-l-alpha-rhamnopyranoside, designated dolastatin 19 (1). The new cancer cell growth inhibitor (1, 8.33 x 10(-8)% yield) was obtained by bioassay (P388 lymphocytic leukemia and human cancer cell lines) directed isolation, accompanied by debromoaplysiatoxin (9.17 x 10(-7)% yield) and anhydrodebromoaplysiatoxin (2.0 x 10(-7)% yield). The structures were determined on the basis of analyses of high-resolution mass spectra and high-field NMR data. All the relative stereochemistry for the chiral centers was designated by utilizing NMR techniques.