Leupeptin

Leupeptin is a broad-spectrum, membrane-permeable protease inhibitor. Leupeptin potently inhibits serine, cysteine and threonine proteases. Leupeptin inhibits M^pro (the main protease of SARS-CoV-2) and also has anti-inflammatory activity^[1][2][3]. IC50 & Target:Cathepsin B, Cathepsin H, Cathepsin L, Ser/Thr Protease, Mpro^[1][2][3]. In Vitro:Leupeptin (0.06-200 µM; 72 h) significantly decreases copy numbers of SARS-CoV-2 viral RNA (vRNA) in Vero cells^[1]
Leupeptin inhibits RNA levels of SARS-CoV-2 in Vero cells, with an EC₅₀ value of 42.34 µM^[1].
Leupeptin has some inhibitory activity against M^pro, with an IC₅₀ value of 127.2 µM^[1].
Leupeptin againsts human coronavirus strain 229E with an IC₅₀ value of 0.4 µg/mL (about 1 µM)^[1]. In Vivo:Leupeptin (0, 9, 18, 36 mg/kg; i.p.; single) is well tolerated by the animals and produces a strong, dose-dependent increase in LC3b-II in both the total tissue extracts and the lysosome and autophagosome-enriched pellet fraction^[2].