N-((S)-1-{(S)-1-[Imino-(2,2,5,7,8-pentamethyl-chroman-6-sulfonylamino)-methyl]-piperidin-3-ylmethyl}-2-oxo-2-thiazol-2-yl-ethyl)-2-[(S)-2-naphthalen-2-ylmethyl-3,6-dioxo-4-(3-phenyl-propyl)-piperazin-1-yl]-acetamide

2-[(S)-3,6-Dioxo-4-(3-phenyl-propyl)-2-pyridin-3-ylmethyl-piperazin-1-yl]-N-((S)-1-{(S)-1-[imino-(2,2,5,7,8-pentamethyl-chroman-6-sulfonylamino)-methyl]-piperidin-3-ylmethyl}-2-oxo-2-thiazol-2-yl-ethyl)-acetamide

[(S)-2-Methyl-3,6-dioxo-4-(3-phenyl-propyl)-piperazin-1-yl]-acetic acid

[((S)-2-Amino-3-cyclohexyl-propionyl)-(3-phenyl-propyl)-amino]-acetic acid methyl ester

[(S)-2-Isopropyl-3,6-dioxo-4-(3-phenyl-propyl)-piperazin-1-yl]-acetic acid