2-[(3R,6R,9S,12S,15S)-6-(1H-indol-3-ylmethyl)-9-(2-methylpropyl)-2,5,8,11,14-pentaoxo-12-thiophen-2-yl-1,4,7,10,13-pentazabicyclo[13.3.0]octadecan-3-yl]acetic acid 2-[(3R,6R,9S,12S,15S)-6-(1H-indol-3-ylmethyl)-9-isobutyl-2,5,8,11,14-pentaoxo-12-(2-thienyl)-1,4,7,10,13-pentazabicyclo[13.3.0]octadecan-3-yl]acetic acid 2-[(3R,6R,9S,12S,15S)-6-(1H-indol-3-ylmethyl)-9-isobutyl-2,5,8,11,14-pentaketo-12-(2-thienyl)-1,4,7,10,13-pentazabicyclo[13.3.0]octadecan-3-yl]acetic acid 2-[(3R,6R,9S,12S,15S)-6-(1H-indol-3-ylmethyl)-9-(2-methylpropyl)-2,5,8,11,14-pentaoxo-12-thiophen-2-yl-1,4,7,10,13-pentazabicyclo[13.3.0]octadecan-3-yl]ethanoic acid BQ 518 C11589