Toward the Synthesis and Biological Screening of a Cyclotetrapeptide from Marine Bacteria

The first synthesis of a naturally occurring tetrapeptide cyclo-(isoleucyl-prolyl-leucyl- alanyl) has been achieved using a solution-phase technique via coupling of dipeptide segments Boc-l-Pro-l-Leu-OH and l-Ala-l-Ile-OMe. Deprotection of the linear tetrapeptide unit and its subsequent cyclization gave a cyclopeptide, identical in all aspects to the naturally occurring compound. Bioactivity results indicated the antifungal and antihelmintic potential of the synthesized peptide against pathogenic dermatophytes and earthworms.