Antimicrobial peptides (AMPs) are considered a promising therapeutic approach against multi-drug resistant microorganisms. Besides their advantages, there are limitations to be overcome so that these molecules can become market competitive. One of the biggest limitations is proteolytic susceptibility, which could be overcome by structural modifications such as cyclization, especially for helix-constraining strategies. Over the years, many helix stabilization techniques have arisen, such as lactam-bridging, triazole-based, N-alkylation and all-hydrocarbon stapling. All-hydrocarbon stapling takes advantage of modified amino acid residues and olefinic cross-linking to constrain peptide helices. Despite being a well-established strategy and presenting efficient stability results, there are different limitations especially related to toxicity. In this review, recent studies on stapled AMPs for antimicrobial usage are explored with the aim of understanding the future of these molecules as putative antimicrobial agents.

Antimicrobial resistance is a global health threat, which has been worsened by the slow development of new antibiotics. The rational design of natural-derived antimicrobial peptides (AMPs) offers a promising alternative for enhancing the efficacy of AMPs and accelerating drug discovery. This paper describes the rational design of improved peptide derivatives starting from hylin-Pul3, a peptide previously isolated from the frog Boana pulchella, by optimizing its hydrophobicity, cationicity, and amphipathicity. In silico screening identified six promising candidates: dHP3-31, dHP3-50, dHP3-50.137, dHP3-50.190, dHP3-84, and dHP3-84.39. These derivatives exhibited enhanced activity against Gram-negative bacteria, emphasizing the role of cationicity and the strategic arginine incorporation. Hemolytic assays revealed the derivatives’ improved selectivity, particularly for the derivatives with “imperfect amphipathicity”. In fibroblast assays, dHP3-84 was well-tolerated, while dHP3-84.39 promoted cell proliferation. Antioxidant assays (ABTS assays) highlighted the Trp-containing derivatives’ (dHP3-50.137, dHP3-31) significant activity. The lipid membrane interaction studies showed that hylin-Pul3 disrupts membranes directly, while dHP3-84.39, dHP3-50, and dHP3-50.137 promote vesicle aggregation. Conversely, dHP3-84 did not induce membrane disruption or aggregation, suggesting an intracellular mode of action. Machine learning models were effective in predicting bioactivity, as these predicted AMPs showed enhanced selectivity and potency. Among them, dHP3-84 demonstrated broad-spectrum potential. These findings highlight the value of rational design, in silico screening, and structure–activity studies in optimizing AMPs for therapeutic applications.

As we face the threat from bacterial pathogens that are resistant to many conventional antibiotics, many current research efforts focus on expanding our arsenal of antimicrobial compounds. However, identifying use cases in which such new antimicrobials can effectively target pathogens while minimizing collateral damage in the commensal microbiota remains a challenge. To tackle this challenge, we focused on one new antimicrobial, the synthetic antimicrobial peptide SET-M33, and examined its ability to target porcine respiratory pathogens and a collection of porcine commensal nasal microbiota members in vitro . Our experiments revealed three key results. First, there were large differences in SET-M33 sensitivity across the tested strains. In particular, pathogenic Glaesserella parasuis was highly sensitive to SET-M33 at concentrations that did not affect the growth of most commensal strains. Second, some of the tested commensal strains ( Rothia nasimurium and Staphylococcus aureus ) were able to inactivate SET-M33 during in vitro cultivation. Third, despite this potential for SET-M33 inactivation by commensal strains, SET-M33 was still able to selectively eliminate pathogenic G. parasuis from in vitro co-cultures that also contained R. nasimurium . Overall, this study highlights the substantial complexity that emerges from the interplay between antimicrobials, pathogens, and commensals, even within a comparatively simple in vitro system, and provides a template for identifying suitable use cases for newly developed antimicrobials. IMPORTANCE: Antimicrobial resistance in pathogenic bacteria is a major global challenge. To tackle it, antimicrobial peptides (AMPs) have emerged as particularly promising candidates, and recent years have seen a rapid expansion of the available AMP arsenal. However, identifying good “use cases” for such AMPs—that is, scenarios in which an AMP not only inhibits a pathogen of interest but also avoids disrupting the commensal microbiota—remains challenging. Here, we aimed to develop an experimental framework that enables the rapid detection of such use cases in vitro . As a test case, we focused on the synthetic AMP SET-M33 and examined its effect on several respiratory porcine pathogens and a collection of commensal nasal microbiota strains. We found that even within such a comparatively simple in vitro model system, there is substantial complexity that emerges from the interplay among AMPs, pathogens, and commensals.

Implantable polymeric meshes are used to mechanically reinforce tissues and stabilize the surgical pocket of artificial implants, including cardiac implantable electronic devices and implantable neuromodulators. Their function depends on the mesh architecture formed by interlaced microfilaments and yarns. Antimicrobial protection can be added through uniform antibiotic‐eluting coatings; however, these polymeric layers increase mesh rigidity and reduce porosity and compliance, thereby compromising mechanical performance. An alternative strategy enables drug elution from a distinct, contiguous component that does not alter the intrinsic structural properties of the mesh. For this approach, a multiphysics structural model was developed to evaluate how the mesh influences drug distribution and antimicrobial protection. The model captures the key transport phenomena governing soluble molecule movement in the mesh and accurately predicts the temporal and spatial extent of antimicrobial protection. In vitro and in vivo validation support the use of distinct implantable meshes and drug‐eluting components to protect both the implant interface and the surgical pocket from bacterial contamination while preserving the mesh structure.

Mosses are non-vascular plants widely distributed across multiple habitats and capable of thriving in extreme environments, such as Antarctica and the Arctic. However, knowledge of the genetic, metabolic, and molecular diversity of polar species remains limited, necessitating a better understanding of their mechanisms of response to harsh conditions. In this context, axenic in vitro cultivation under laboratory conditions is a powerful tool for plant sciences to elucidate physiological and biochemical responses. Nevertheless, in vitro cultivation of polar mosses can be challenging, as most species lack viable sporophytes or are predominantly sterile. Alternatively, gametophores can be used; however, many fail to withstand surface decontamination or are subsequently overrun by microorganisms. To establish an efficient and replicable decontamination method, we compared the efficacy of treatments applied to field‑collected gametophores from three sites and pre‑cultured leafy shoots of Warnstorfia sarmentosa (Wahlenb.) Hedenäs as a model species, using different concentrations of sodium dichloroisocyanurate (NaDCC) and sodium hypochlorite (NaClO). Explants derived from pre-cultured tissue achieved an overall success rate of 64.1%, compared with 12.7% for field-collected material, and success among field samples varied markedly across collection sites (0–28%). For pre-cultured material, NaDCC (0.1% and 0.5%) was more effective than NaClO (0.5% and 1%) ( p = 0.0309). This optimized method was subsequently applied to other species. Currently, 33 ecotypes from 12 polar moss species are successfully maintained under axenic conditions, providing a valuable resource for applications including stress tolerance studies, metabolite profiling, ex situ conservation of endangered taxa, and biotechnological exploitation.