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Abstract: In order to further examine the properties of pseudopeptides containing the 2-hydrazonoacyl fragment, two new series of analogs of the prototypical chemotactic N-formyl-tripeptide HCO-Met-Leu-Phe-OMe were designed and synthesized. The first group contains the new fragment as the N-terminal residue and is represented by the N-aryl derivatives p-Cl-C[sub 6]H[sub 4]-NH-N=C(R)-CO-Leu-Phe-OMe (2 and 3) and by the corresponding N-aroyl analogs p-CH[sub 3]-C[sub 6]H[sub 4]-CO-NH-N=C(R)-CO-Leu-Phe-OMe (4). The second group contains the new fragment in place of the central Leu residue and is represented by compounds HCO-Xaa-NH-N=C(R)-CO-Phe-OMe (7a and 7b) where Xaa is Nle and Met, respectively. The conformational and biochemical properties of the new products were examined. [ABSTRACT FROM AUTHOR]

Abstract: In order to obtain chemotactic peptides with selective bioactivity, a new type of structural modification was introduced at the N‐terminal position of HCO‐Nle‐Leu‐Phe‐OMe. Two groups of analogs have been synthesized both containing a N‐terminal residue of the X=C(R)‐CO‐type replacing the native HCO‐NH‐CH(R)‐CO‐. In particular, the A group of pseudopeptides (2a‐d) possesses a N‐terminal oximic fragment (X=HO‐N) and the B group (3a‐d) a formylhydrazone fragment (X=HCO‐NH‐N). These new ligands have been examined for their capacity to induce chemotaxis and other cellular responses such as superoxide anion production and lysozyme release; although significantly active as chemoattractants they have been found to be practically devoid of secretagog activity, thus exhibiting selective behavior. The adopted chemical modification seems extensible in designing a new class of pseudopeptides (hydrazonopeptides) structurally related to both hydrazinopeptides and peptides containing α,β‐unsaturated residues. [ABSTRACT FROM AUTHOR]