3-[[(1S)-1-[[(5S)-5-amino-5-carboxy-pentyl]carbamoyl]-3-methyl-butyl]c arbamoyl]oxirane-2-carboxylic acid

AM 4299 B is a novel thiol protease inhibitor.

AM4299B is an inhibitor for thiol protease. AM4299B inhibits bovine spleen cathepsin B, human kidney cathepsin L and papain with IC50s of 0.7, 0.5 and 20 μM, respectively. AM4299B can be used in research in osteoporosis, and has potential to be used as an antiparasitic agent[1].

cathepsin L: 0.5 μM (IC₅₀); Cathepsin B: 0.7 μM (IC₅₀)

[1] Morishita A, et al., AM4299 A and B, novel thiol protease inhibitors. J Antibiot (Tokyo). 1994 Sep;47(9):1065-8. DOI:10.7164/antibiotics.47.1065