Scheme 1. Overview of the steps involved in the solid phase synthesis of cyclic peptides. Amino acid residues are represented in three-letter notation: Arg, L-arginine; Trp, L-tryptophan; Dip, 3,3-diphenyl-L-alanine; Nal, 3-(2-naphthyl)-L-alanine. D-amino acids, arg, trp, dip, and nal are indicated in bold font with an underline. Cationic and hydrophobic residues are depicted in blue and red color, respectively.