Epoxomicin was originally isolated from the culture medium of an Actinomycetes strain based on its in vivo antitumor activity against murine B16 melanoma. Epoxomicin is a selective proteasome inhibitor with anti-inflammatory activity. Despite its promising antitumor activity, epoxomicin did not draw much attention as a potential drug lead from the pharmaceutical industry, presumably because epoxomicin has seemingly poor drug-like properties, namely the presence of a peptide backbone and the labile epoxy ketone pharmacophore. Despite its drawbacks, epoxomicin’s pharmacophore was found to provide unprecedented selectivity for the proteasome. Epoxomicin also served as a scaffold for the generation of a synthetic tetrapeptide epoxyketone with improved activity.

N-Acetyl dihydrosphingosine is dihydroceramide derivative and isomer of cedefingol with minimal anticancer activity. N-Acetyl dihydrosphingosine shows minimal apoptotic activity against human leukemia cells.