Design, synthesis and biological activity of new neurohypophyseal hormones analogues conformationally restricted in the N-terminal part of the molecule. Highly potent OT receptor antagonists

A rationally engineered small antimicrobial peptide with potent antibacterial activity

Antimicrobial resistance (AMR) is a silent pandemic declared by the WHO that requires urgent attention in the post-COVID world. AMR is a critical public health concern worldwide, potentially affecting people at different stages of life, including the veterinary and agriculture industries. Notably, very few new-age antimicrobial agents are in the current developmental pipeline. Thus, the design, discovery, and development of new antimicrobial agents are required to address the menace of AMR. Antimicrobial peptides (AMPs) are an important class of antimicrobial agents for combating AMR due to their broad-spectrum activity and ability to evade AMR through a multimodal mechanism of action. However, molecular size, aggregability, proteolytic degradation, cytotoxicity, and hemolysis activity significantly limit the clinical application of natural AMPs. The de novo design and engineering of a short synthetic amphipathic AMP (≤16 aa, Mol. Wt. ≤ 2 kDa) with an unusual architecture comprised of coded and noncoded amino acids (NCAAs) is presented here, which demonstrates potent antibacterial activity against a few selected bacterial strains mentioned in the WHO priority list. The designer AMP is conformationally ordered in solution and effectively permeabilizes the outer and inner membranes, leading to bacterial growth inhibition and death. Additionally, the peptide is resistant to proteolysis and has negligible cytotoxicity and hemolysis activity up to 150 μM toward cultured human cell lines and erythrocytes. The designer AMP is unique and appears to be a potent therapeutic candidate, which can be subsequently subjected to preclinical studies to explicitly understand and address the menace of AMR.

Micelle-bound conformations of neurohypophyseal hormone analogues modified with a Cα-disubstituted residue: NMR and molecular modelling studies

In this study, by applying a combined approach of NMR measurements and molecular modelling, the conformations and the interactions with membrane-like environment of five arginine vasopressin (AVP) or oxytocin (OT) analogues modified with Cα-disubstituted cis-1-amino-4-phenylcyclohexane-1-carboxylic acid in position 2 have been determined. In addition, the AVP analogues were prepared in N-acylated forms with various bulky acyl groups. All of the peptides studied interacted with the mixed dodecylphosphocholine:sodium dodecyl sulphate micelle, providing a model of biological membrane. A different polarities of the AVP- and OT-like peptides resulted in their different position relative to the micelle surface. Thus, the arrangement of the former was nearly perpendicular, whereas the latter was rather parallel to the micelle's surface. Moreover, the results of our studies have shown that the binding sites for antagonists may be overlapped with that for agonists, as well as it may be quite different. Nevertheless, the aromatic-aromatic contacts represent the most important interactions for antagonists, whereas the hydrophilic interactions seem to be crucial for agonists.