Synthesis and biological activity of tripeptide FR113680 analogues containing unconventional amino acids.
In order to further develop structure-activity relationships and to get information about the biological active conformations we synthetized analogues tripeptide to the FR 113680 [Ac-Thr-D-Trp(CHO)-PheNMeBzl; Ac: acethyl], in which the phenylalanine residue was replaced by unconventional amino acids [1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (Tic); (3aS, 7aS)-octahydroindole-2-carboxylic acid (Oic); (S,S,S)-2-azabiciclo[3.3.0]octane-3-carboxylic acid (Aoc); 3-(1'-naphthyl)alanine (Nap); phenylglicine (Phg); thienylalanine (Thi)]. The biological activity of the peptides was performed on guinea pig ileum for neurokinin 1 (NK-1) and on rat colon for neurokinin 2 (NK-2). In particular, the replacement of the Phe3 by the Oic (8a) gave an higher antagonist activity in both NK-1 and NK-2 receptors, but no improvement in selectivity with respect to reference tripeptide (FR113680). The compound (8a) represent the first example of highly potent peptides that do not contain an aromatic amino acid of the third position as had been previously considered essential.
Caliendo
G
G
Dipartimento di Chimica, Farmaceutica e Tossicologica, Università di Napoli Federico II, Italy.
Calignano
A
A
Grieco
P
P
Mancuso
F
F
Perissutti
E
E
Santini
A
A
Santagada
V
V
D000595:Amino Acid Sequence; D000596:Amino Acids; D000818:Animals; D003106:Colon / Q000502:physiology; D006168:Guinea Pigs; D007082:Ileum / Q000502:physiology; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D008297:Male; D008969:Molecular Sequence Data; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D064729:Neurokinin-1 Receptor Antagonists; D009842:Oligopeptides / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D018040:Receptors, Neurokinin-1 / Q000502:physiology; D018041:Receptors, Neurokinin-2 / Q000037:antagonists & inhibitors* / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
D000596:Amino Acids; D007202:Indicators and Reagents; D064729:Neurokinin-1 Receptor Antagonists; D009842:Oligopeptides; D018040:Receptors, Neurokinin-1; D018041:Receptors, Neurokinin-2; C076202:FR 113680