Cyclo(S-Pro-R-Leu)

Cyclo[D-Leu-L-Pro-]

Cyclo-L-prolyl-D-leucine

Cyclo(L-prolyl-D-leucyl)

(3R,8aS)-Hexahydro-3-(2-methylpropyl)pyrrolo[1,2-a]pyrazine-1,4-dione

(3R,8aS)-Octahydro-3-(2-methylpropyl)pyrrolo[1,2-a]pyrazine-1,4-dione