A didemnin that is didemin B in which the hydroxy group of the 1-(2-hydroxypropanoyl)-<small>L</small>-prolinamide moiety has been oxidised to the corresponding ketone. It was originally isolated from the Mediterranean tunicate <em>Aplidium albicans</em>. ChEBI: Plitidepsin 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 an anticoronaviral agent, an antineoplastic agent and a marine metabolite.