m-calpain

PD151746 is a calpain inhibitor with a 20-fold selectivity for u-calpain (Ki = 0.26 ± 0.03 μM) over m-calpain (Ki = 5.33 ± 0.77 μM). Its IC50 values are 0.26 ± 0.03 μM (Ki for μ-calpain) and 5.33 ± 0.77 μM (Ki for m-calpain) [1]. In vitro, PD151746 targets calpain and reduces oxLDL-induced cytotoxicity [2].

PD150606 is a selective nonpeptide calpain inhibitor with neuroprotective activity that inhibits μ-calpains and m-calpains. Inhibits erythrocyanine-induced Ca2+ efflux and interferes with excitotoxicity-dependent motor neuron death.

Penicillide is a fungal metabolite originally isolated from Penicillium that has diverse biological activities. It is an inhibitor of calpain 2/m-calpain (IC50 = 7.1 μM) and acyl-coenzyme A:cholesterol acyltransferase (ACAT; IC50 = 22.9 μM). It is also an antagonist of oxytocin receptors (IC50 = 67 μM). Penicillide inhibits RNA synthesis in P388 murine leukemia cells.

Calpastatin (184-210), an acetylated synthetic peptide derived from human calpastatin, effectively inhibits the calcium-dependent cysteine proteases, calpain I (µ-calpain) and calpain II (m-calpain), which require micromolar and millimolar calcium concentrations, respectively. Unlike its action on calpains, this 27 amino acid peptide does not inhibit papain (a cysteine protease) or trypsin (a serine protease). Encoded by exon 1B of Ac-calpastatin (184-210), it aligns with a section of inhibitory domain 1, showcasing its specificity and inhibitory function towards calpain enzymes.