Structural modification and antitumor activity of antimicrobial peptide HYL

Therapeutic stapled peptides: Efficacy and molecular targets

Peptide stapling, by employing a stable, preformed alpha-helical conformation, results in the production of peptides with improved membrane permeability and enhanced proteolytic stability, compared to the original peptides, and provides an effective solution to accelerate the rapid development of peptide drugs. Various reviews present peptide stapling chemistries, anchoring residues and one- or two-component cyclization, however, therapeutic stapled peptides have not been systematically summarized, especially focusing on various disease-related targets. This review highlights the latest advances in therapeutic peptide drug development facilitated by the application of stapling technology, including different stapling techniques, synthetic accessibility, applicability to biological targets, potential for solving biological problems, as well as the current status of development. Stapled peptides as therapeutic drug candidates have been classified and analysed mainly by receptor- and ligand-based stapled peptide design against various diseases, including cancer, infectious diseases, inflammation, and diabetes. This review is expected to provide a comprehensive reference for the rational design of stapled peptides for different diseases and targets to facilitate the development of therapeutic peptides with enhanced pharmacokinetic and biological properties.

Application of the All-Hydrocarbon Stapling Technique in the Design of Membrane-Active Peptides

The threats of drug resistance and new emerging pathogens have led to an urgent need to develop alternative treatment therapies. Recently, considerable research efforts have focused on membrane-active peptides (MAPs), a category of peptides in drug discovery with antimicrobial, anticancer, and cell penetration activities that have demonstrated their potential to be multifunctional agents. Nonetheless, natural MAPs have encountered various disadvantages, which mainly include poor bioavailability, the lack of a secondary structure in short peptides, and high production costs for long peptide sequences. Hence, an "all-hydrocarbon stapling system" has been applied to these peptides and proven to effectively stabilize the helical conformations, improving proteolytic resistance and increasing both the potency and the cell permeability. In this review, we summarized and categorized the advances made using this powerful technique in the development of stapled MAPs. Furthermore, outstanding issues and suggestions for future design within each subcategory were thoroughly discussed.

Design, synthesis, and biological evaluation of stapled ascaphin-8 peptides

Ascaphin-8 is an α-helical anti-tumor and antimicrobial peptide containing 19 residues, which was isolated from norepinephrine-stimulated skin secretions of the North American tailed frog Ascaphus truei. To improve both its stability and biological activities, a series of hydrocarbon-stapled analogs of Ascaphin-8 were synthesized and investigated for their potential antiproliferative activities. The activity studies were evaluated using the CCK-8 method and colony formation assay on human cancer cell lines. Ascaphin-8-3, as the most active peptide, showed a stronger inhibition effect when compared with the parent peptide for the tested cell lines. In addition, the effect of Ascaphin-8-3 on inhibiting the metastatic capabilities of A549 cells was more powerful than that of the parent peptide. This peptide derivative showed potentiality for further optimization in antitumor drugs.

Effects of Glycosylation and d-Amino Acid Substitution on the Antitumor and Antibacterial Activities of Bee Venom Peptide HYL

Glycosylation is a promising strategy for modulating the physicochemical properties of peptides. However, the influence of glycosylation on the biological activities of peptides remains unknown. Here, we chose the bee venom peptide HYL as a model peptide and 12 different monosaccharides as model sugars to study the effects of glycosylation site, number, and monosaccharide structure on the biochemical properties, activities, and cellular selectivities of HYL derivatives. Some analogues of HYL showed improvement not only in cell selectivity and proteolytic stability but also in antitumor and antimicrobial activity. Moreover, we found that the helicity of glycopeptides can affect its antitumor activity and proteolytic stability, and the α-linked d-monosaccharides can effectively improve the antitumor activity of HYL. Therefore, it is possible to design peptides with improved properties by varying the number, structure, and position of monosaccharides. What's more, the glycopeptides HYL-31 and HYL-33 show a promising prospect for antitumor and antimicrobial drugs development, respectively. In addition, we found that the d-lysine substitution strategy can significantly improve the proteolytic stability of HYL. Our new approach provides a reference or guidance for the research of novel antitumor and antimicrobial peptide drugs.