H-GLY-PEN-GLY-ARG-GLY-ASP-SER-PRO-CYS-ALA-OH H-Gly-Pen-Gly-Arg-Gly-Asp-Ser-Pro-Cys-Ala-OH, (Disulfide bond between Pen2 and Cys9) H-Gly-Pen-Gly-Arg-Gly-Asp-Ser-Pro-Cys-Ala-OH trifluoroacetate salt (Disulfide bond between Pen2 and Cys) H-Gly-Pen-Gly-Arg-Gly-Asp-Ser-Pro-Cys-Ala-OH (Disulfide bond between Pen2 and Cys?) L-Alanine, glycyl-3-mercapto-L-valylglycyl-L-arginylglycyl-L-α-aspartyl-L-seryl-L-prolyl-L-cysteinyl-, cyclic (2→9)-disulfide Pyrrolo[2,1-g][1,2,5,8,11,14,17,20,23]dithiaheptaazacyclohexacosine,cyclic peptide deriv