The molecule is a didemnin that is didemin B in which the hydroxy group of the 1-(2-hydroxypropanoyl)-L-prolinamide moiety has been oxidised to the corresponding ketone. It was originally isolated from the Mediterranean tunicate Aplidium albicans. It has a role as a marine metabolite and an antineoplastic agent.
(2S)-N-[(2R)-1-[[(3S,6S,8S,12S,13R,16S,17R,20S,23S)-13-[(2S)-butan-2-yl]-12-hydroxy-20-[(4-methoxyphenyl)methyl]-6,17,21-trimethyl-3-(2-methylpropyl)-2,5,7,10,15,19,22-heptaoxo-8-propan-2-yl-9,18-dioxa-1,4,14,21-tetrazabicyclo[21.3.0]hexacosan-16-yl]amino]-4-methyl-1-oxopentan-2-yl]-N-methyl-1-(2-oxopropanoyl)pyrrolidine-2-carboxamide