(S)-3-(1H-Indol-3-yl)-2-[4-(1H-indol-3-yl)butyrylamino]propionic acid 406726-77-0 IBA-L-Trp Indolebutyric acid-tryptophan conjugate L-Tryptophan, N-[4-(1H-indol-3-yl)-1-oxobutyl]- (9CI) L-tryptophan, N-[4-(1H-indol-3-yl)-1-oxobutyl]-