D. kyselina (S)-2-[(3S,8aR)-3-(4-aminobutyl)-1,2,3,4,6,7,8,8a-oktahydro-1,4-dioxopirrolo[1,2-a]-piperazin-2-yl]-4-fenylbutanová (R,S,S-diketopiperazin),
D. kyselina (S)-2-[(3S,8aR)-3-(4-aminobutyl)-1,2,3,4,6,7,8,8a-oktahydro-1,4-dioxopirrolo[1,2-a]-piperazin-2-yl]-4-fenylbutanová (R,S,S-diketopiperazin),