Boc-D-FMK is a cell-permeable, irreversible pan-caspase inhibitor. Also known as Boc-D(OMe)-FMK, this compound contains a methyl ester group, which facilitates uptake by cells and subsequently is removed by cytoplasmic esterases, leaving the functional inhibitor. Boc-D-FMK blocks apoptosis stimulated by TNF-α in neutrophils (IC50 = 39 μM), by bile duct ligation in hepatocytes, and by TNF-α in renal endothelial cells. The FMK pharmacophore is known to interact with non-caspase cysteine proteases, presumably explaining why Boc-D-FMK also inhibits cathepsins H and L.
