| abstract |
Highly active and long lasting cyclic hexapeptide analogs of somatostatin are prepared. A single amino acid of D-configuration, functioning as a spacer for the remaining amino acids, replaces seven of the ring amino acids of somatostatin. The amino acid adjacent to this spacer amino acid is methylated on the nitrogen and is of the D-configuration. The two amino acids on either side of this dipeptide are also of D-configuration. The remaining two amino acids, Trp and Lys are either D- or L-. The order of the amino acids is reversed relative to the sequence found in somatostatin. The structures therefore represent a modified form of D-retro peptide analogs. The cyclic hexapeptides are easier to synthesize, have a longer duration of activity, and many have a greater level of activity than somatostatin. The compounds have the properties of inhibiting the release of glucagon, growth hormone and insulin. Certain of the compounds also are capable of inhibiting the release of gastric acid secretions. The compounds are particularly useful in the treatment of acromegaly, diabetes, diabetic retinopathy and peptic ulcers. These cyclic hexapeptides are prepared by the solid phase method. |