Synthesis and biological activities of two ACTH-analogues containing L-norarginine in position 8.

Two new ACTH-analogues, an octadecapeptide amide and a tetracosapeptide containing the lower homologue of arginine (norarginine) in position 8, have been synthesized by the generally accepted method. Special attention was paid to the synthesis of the required tetrapeptide representing the 7-10 sequence, which was obtained either by direct introduction of L-nitronorarginine or by amidination of the gamma-amino function in a protected peptide containing alpha, gamma-diaminobutyric acid. Biological activity determination showed that the shortening e arginine side chain in position 8 results in the formation of active ACTH-analogues.