Romidepsin is a cyclodepsipeptide consisting of the cyclic disulfide of (2Z)-2-aminobut-2-enoyl, L-valyl, (3S,4E)-3-hydroxy-7-sulfanylhept-4-enoyl, D-valyl and D-cysteinyl residues coupled in sequence and cyclised head-to tail. It has a role as an antineoplastic agent and an EC 3.5.1.98 (histone deacetylase) inhibitor. It is a cyclodepsipeptide, an organic disulfide and a heterocyclic antibiotic.