Search Results (199)

The increasing crisis of antimicrobial resistance requires innovative therapeutic strategies that can overcome the limitations of conventional antibiotics. Based on our previous finding that AP10 (a derivative of AP29) possesses antimicrobial activity but lacks thermal stability, we rationally redesigned ten new AP10 analogues to enhance functional robustness while maintaining efficacy. Among these, AP10RW is identified as the optimal candidate due to its exceptional broad-spectrum activity against both drug-sensitive and multidrug-resistant (MDR) bacterial pathogens. Structural analysis reveals that AP10RW adopts an environmentally responsive conformation, transitioning from random coil to amphiphilic α-helix in membrane-mimicking environments, while demonstrating remarkable stability under challenges including serum exposure, varying pH, high salt concentrations, and thermal stress. Mechanistic studies indicate that AP10RW exerts its effects through multiple bactericidal mechanisms involving initial high-affinity binding to bacterial characteristic molecules (LTA, LPS and PGN), followed by rapid membrane depolarization, ultrastructural damage and the induction of lethal oxidative stress. Notably, this potent antimicrobial efficacy is coupled with exceptional biosafety, demonstrating little hemolysis and negligible cytotoxicity against mammalian cells. This systematic optimization represents a significant advancement in antimicrobial peptide engineering. We have successfully transformed a thermally unstable peptide into a robust therapeutic candidate and positioned AP10RW as a promising clinical candidate for addressing the growing threat of multidrug-resistant infections. Full article

An upgraded GAFF2 force field has been used to simulate two fluorinated alcohols, TFE and HFIP, in aqueous solutions at several concentrations. The same force field has also been employed to simulate a 26-residue amphiphilic peptide in several cosolvent/water mixtures to verify and clarify its efficacy in stabilizing the secondary structure. The calculated thermodynamic and structural properties are in agreement with experimental findings. The force field allows a correct description of the secondary structure and affords an accurate characterization of the spatial organization of cosolvent molecules around the peptide. Full article

Biosurfactants produced by halophilic bacteria are gaining attention as eco-friendly and biocompatible alternatives to synthetic surfactants due to their high surface activity, stability under extreme conditions, and intrinsic antimicrobial properties. These amphiphilic biomolecules hold great promise for bioremediation, biomedical, and pharmaceutical applications. In this study, moderately halophilic bacteria capable of biosurfactant production were isolated from saline mud collected at the Burgas solar salterns (Bulgaria). The halophilic microbiota was enriched in Bushnell–Haas (BH) medium containing 10% NaCl amended with different carbon sources. Primary screening in BH liquid medium evaluated the isolates’ ability to degrade n-hexadecane while at the same time producing biosurfactants. Thirty halophilic bacterial strains were isolated on BH agar plates supplemented with 2% n-hexadecane, 2% olive oil, or 2% glycerol. Four isolates—BS7OL, BS8OL, BS9GL, and BS10HD—with strong emulsifying activity (E₂₄ = 56%) and reduced surface tension in the range of 27.3–45 mN/m were derived after 7 days of batch fermentation. Strain BS10HD was chosen as the most potent biosurfactant producer. Its phylogenetic affiliation was determined by 16S rRNA gene sequence analysis; according to the nucleotide sequence, it was assigned to Halomonas ventosae. The extract material was analysed by thin-layer chromatography (TLC) and Fourier transform infrared spectroscopy (FTIR). Upon spraying the TLC plate with ninhydrin reagent, the appearance of a pink spot indicated the presence of amine functional groups. FTIR analysis showed characteristic peaks for both lipid and peptide functional groups. Based on the observed physicochemical properties and analytical data, it can be suggested that the biosurfactant produced by Halomonas ventosae BS10HD is a lipopeptide compound. Full article

Brewers’ spent grain (BSG) represents the major byproduct of the brewing industry and remains largely underutilized. While BSG contains a rather high amount of protein, poor functional properties limit its use as a functional ingredient for foods without additional processing. In this work, we investigate emulsifying peptides embedded in the major BSG proteins based on a mass spectrometry-based proteomic analysis and subsequent bioinformatic prediction to explore the utilization of BSG as a raw material for the production of protein-based emulsifying ingredients. Forty-eight peptides were selected based on EmulsiPred score, amino acid sequence, and protein abundance for evaluation. All peptides effectively reduced the interfacial tension between oil–water, but only 15 could produce and stabilize emulsions with droplet sizes below 5 µm. Some peptides were able to produce stable emulsions with sub-micron droplet sizes, implying very promising emulsifying properties. This study demonstrated promising emulsifying properties of BSG peptides and suggested that the functionality could be predicted using bioinformatic tools. However, the used tool needs to be further optimized for higher success rate. Full article

Background: Cancer remains a major global health challenge, with current therapies often limited by high toxicity and poor selectivity. Lipopeptides, due to their amphiphilic architecture and synthetic accessibility, have emerged as promising anticancer agents. In this study, the in vitro cytotoxic potential and structure–activity relationships (SARs) of a library of 60 synthetic linear lipopeptides (LLPs), including lipopeptide–peptoid chimeras generated via the Ugi four-component reaction, were evaluated against four cancer cell lines (B16F10, HeLa, HT-29, and PC3). Methods: Cytotoxicity was assessed using MTT and crystal violet (CV) assays, and the natural cyclic lipopeptide surfactin was included as a reference. SAR analysis explored the effects of C-terminal functional groups, lipophilic tail length, peptide core size, and side chain modifications. Mechanistic studies involved cell cycle analysis, apoptosis markers (Annexin V/PI staining, caspase-3 activation), and oxidative stress assessment (ROS/RNS and NO production). Results: Several synthetic LLPs showed potent and selective anticancer activity, with IC₅₀ values approximately 3–15 times lower than that of surfactin and with minimal toxicity toward non-cancerous NIH3T3 fibroblasts. Key structural determinants for activity included the presence of a C-terminal ester group, a lipophilic tail of 14–19 carbon atoms, and a tetrapeptide core. LLPs containing phenyl or azide side chains further enhanced cytotoxicity in a cell line-dependent manner. Mechanistic investigations confirmed that active LLPs induce caspase-dependent apoptosis, cell cycle arrest, and oxidative stress. These findings highlight that the synthetic LLPs demonstrate high in vitro anticancer efficacy with favorable selectivity. Conclusions: Synthetic LLPs exhibit potent and selective anticancer activity in vitro. SAR insights and mechanistic findings support their development as next-generation lipopeptide-based therapeutics. Full article

A promising strategy for pancreatic cancer therapy involves developing nanocarriers capable of simultaneously delivering various antitumor substances with diverse physicochemical properties, often resulting in synergistic effects. In the present work, novel biocomposites were developed using amphiphilic N-vinylpyrrolidone polymer incorporating bortezomib (BTZ) and modified with either the DR5-selective TRAIL cytokine (DR5-B) or its fusion with the iRGD effector peptide (DR5-B-iRGD), resulting in AmphPVP-BTZ-DR5-B and AmphPVP-BTZ-DR5-B-iRGD formulations. The release of BTZ was most extensive at acidic pH 5.6, mimicking endolysosomal compartments, while at near-neutral pH 7.4 and alkaline pH 8.2 the release was slower and less complete, indicating a smart pH-responsive behavior suitable for triggered release in the tumor microenvironment. Both AmphPVP-BTZ-DR5-B and AmphPVP-BTZ-DR5-B-iRGD significantly inhibited the growth of pancreatic adenocarcinoma cell lines PANC-1, BxPC-3, and MIA PaCa-2 and induced more rapid internalization of the DR5 receptor in MIA PaCa-2 cells than unmodified particles and free DR5-B or DR5-B-iRGD. Importantly, AmphPVP-BTZ-DR5-B-iRGD exhibited a more pronounced DR5 internalization rate and cytotoxic effect than AmphPVP-BTZ-DR5-B owing to the presence of fusion protein with internalizing iRGD peptide. Both biocomposites induced cell death via the apoptotic pathway while exhibiting minimal cytotoxic effects on healthy cells. Therefore, biocomposites incorporating BTZ and functionalized with DR5-selective TRAIL variants DR5-B or DR5-B-iRGD represent a promising avenue for future studies in pancreatic cancer animal models. Full article

Background/Objectives: There is a growing demand for the development of novel antimicrobial agents due to their efficacy being eroded by increasing antimicrobial resistance. Antimicrobial hydrogels have been reported as a method to treat bacterial infections. Methods: This study explores how different structural features are important for the hydrogelation properties of amphiphilic antimicrobial peptide-mimics through rheology and AFM, as well as properties important for antimicrobial activity measured through MIC. Results: Eleven novel peptide-mimicking anthranilamides containing various structural features were synthesised in 4–7 steps. Of these peptide-mimics, three novel compounds formed hydrogels, and it was identified that their mechanical strength, secondary structure, and fibre morphology could be tuned by altering the aromatic cap or the amino acid side chain. In conjunction, several structural features were identified that reduce hydrogelation strength and stiffness. Conclusions: This work provides an insight into how the structural features of low-molecular-weight self-assembling hydrogels can translate to differing physical and potent antimicrobial properties. This work provides a rational guide to optimising physical hydrogel properties, as well as highlighting features that may reduce hydrogelation. Full article

Self-assembled nanoparticles formed with amphiphilic block or graft copolymers are being extensively studied for their use in a variety of biological and industrial applications, including targeted drug delivery. This study reports a novel strategy to tune the structure of self-assembled nanoparticles for enhancing the cellular uptake by varying the hydrophilic ratio of amphiphilic graft copolymers. We synthesized poly(aspartic acid) (PAsp) substituted with octadecyl chains (C18) at varying degrees of substitution (DS), ranging from 4.5 to 37.5 mol%, which could form self-assemblies in an aqueous solution. As the DS increased, a morphological transition was observed—from spherical assemblies (DS 4.5 and 9.1) to rod-like (DS 19.0), vesicular (DS 25.7), and lamellar-like structures (DS 37.6). Further, Trans-Activator of Transcription (TAT) as the cell penetrating peptide to the synthesized amphiphilic graft copolymers leads to an enhanced cellular uptake of the biomimetic self-assembly. In particular, the lamellar-like self-assemblies resulted in a 1.3-fold increase of cellular uptake, as compared to the spherical self-assemblies, and a 3.6-fold increase, as compared to the vesicles. Therefore, tuning the structure of poly(aspartic acid)s’ self-assemblies was proven as an effective strategy to enhance the cellular uptake, while minimizing invasive cell damage. This new strategy to tune the morphologies of self-assemblies will serve to improve the cell penetrating activity for targeted drug delivery. Full article

Background/Objectives: Resistance of pathogenic microorganisms to antibiotics poses a serious threat to public health and often leads to devastating consequences. In this context, one of the pressing challenges in pharmacochemistry is the search for new, effective antibiotics to combat severe human diseases. Cyclic lipopeptides have emerged as some of the most promising candidates and have been widely studied. These compounds are a class of microbial secondary metabolites produced by various microorganisms, and they possess significant medical and biotechnological importance. The defining structural feature of these compounds is the presence of both a hydrophobic fragment, primarily a hydrocarbon tail of varying length, and a hydrophilic cyclic peptide moiety. This hydrocarbon tail confers amphiphilic properties to the lipopeptides, which are essential for their broad spectrum of biological activities. Their mechanism of action involves disruption of the cell membrane, and in many cases, the formation of ion-permeable defects has also been shown. Results: This review summarizes the data on cyclic lipopeptides produced by Pseudomonas spp., Streptomyces spp., and Bacillus spp. that modify membrane permeability through the formation of ion channels. The main emphasis is on understanding how the structure of the CLP can be related to the probability and mode of pore formation. Conclusions: The findings can contribute to expanding the arsenal of effective antimicrobial agents with a mechanism of action that reduces the risk of developing resistance. Full article

Liposomes have emerged as versatile carriers in the food industry due to their amphiphilic structure, biocompatibility, and ability to encapsulate both hydrophilic and lipophilic bioactive compounds. They offer promising benefits by enhancing the solubility and bioavailability of food ingredients such as vitamins, polyphenols, carotenoids, peptides, and omega-3 fatty acids. However, liposomes in aqueous form often suffer from poor stability, leakage of encapsulated compounds, and sensitivity to environmental conditions. To address these challenges, hybrid delivery systems have been developed by incorporating liposomes into various solid or semi-solid encapsulation matrices such as nanofibers, particles, cast films, hydrogels, and emulsions. These combinations can offer synergistic advantages, including improved structural integrity, enhanced protection during processing and storage, extended-release profiles under digestive conditions, and versatile applicability across different applications. This review comprehensively discusses liposome structure, preparation methods, and their incorporation into various encapsulation matrices, focusing exclusively on food-grade ingredients. It highlights recent advancements in hybrid liposome-based systems tailored for food applications, with an emphasis on their functional performance and delivery efficiency. Overall, these hybrid systems hold great promise for developing next-generation functional foods with improved health benefits and shelf stability. Full article

Cancer treatment continues to face significant challenges due to the limitations of conventional therapies, including non-specific toxicity, poor bioavailability, and drug resistance. Nanotechnology, particularly peptide-based nanoparticles (NPs), is increasingly recognized as a valuable strategy to address these obstacles. Peptides provide a versatile platform offering high biocompatibility, specificity, biodegradability, and minimal immunogenicity, making them ideal for targeted cancer therapies. This review comprehensively examines recent advancements in peptide-based nanoparticle systems, highlighting the mechanisms driving peptide self-assembly, such as amphiphilicity, non-covalent interactions, and metal coordination. It distinguishes between non-bioactive peptide nanoparticles, which primarily serve as drug carriers, and bioactive peptide nanoparticles, which integrate targeting peptides, cell-penetrating peptides (CPPs), and therapeutic peptides to enhance specificity, internalization, and anticancer efficacy. Emphasis is placed on innovative designs that exploit active targeting, stimuli-responsive release, and immunomodulatory strategies to maximize therapeutic outcomes while minimizing side effects. Despite promising preclinical outcomes, the clinical translation of peptide nanoparticles struggles with challenges involving stability, delivery efficiency, scalability, regulatory compliance, and manufacturing complexity. The review concludes by outlining future directions, emphasizing personalized nanomedicine, combination therapies, and advanced peptide engineering as crucial pathways toward successful clinical implementation. Full article

Monomer-to-excimer transition has become a valuable technique in fluorescence imaging because of its ability to enhance imaging contrast. However, from a practical perspective, the accuracy of excimer formation at target sites warrants further exploration. Enzyme-triggered peptide self-assembly provides a promising solution to this limitation. As a proof-of-concept, in this study, we developed a furin-triggered peptide self-assembling fluorescent probe RF-Cou by coupling a coumarin dye 7-(diethylamino)-2-oxo-2H-chromene-3-carboxylic acid (Cou) with a furin-responsive peptide scaffold for precision live-cell imaging. Upon entering furin-overexpressing 4T1 tumor cells, RF-Cou underwent enzymatic cleavage, releasing an amphiphilic peptide motif and self-assembling into nanoparticles largely concentrated in the Golgi apparatus to confine the diffusion of Cou. During this process, the Cou excimers were formed and induced a red shift in the fluorescence emission, validating the feasibility of RF-Cou in efficient excimer imaging of furin-overexpressing tumor cells. We expect that our findings will highlight the potential of stimuli-responsive small molecular peptide probes to advance excimer-based imaging platforms, particularly for enzyme-specific cell imaging and therapeutic monitoring. Full article

Herein we describe the development of the first model amphiphilic polymer conetwork (APCN) comprising a short hydrophobic hexa(L-alanine) segment being the outer block of an amphiphilic four-armed star block copolymer with inner poly(ethylene glycol) (PEG) blocks bearing benzaldehyde terminal groups and end-linked with another four-armed star PEG homopolymer (tetraPEG star) bearing aryl-substituted acylhydrazide terminal groups. The present successful synthesis that yielded the peptide-containing model APCN was preceded by several unsuccessful efforts that followed different synthetic strategies. In addition to the synthetic work, we also present the structural characterization of the peptide-bearing APCN in D₂O using small-angle neutron scattering (SANS). Full article

Background: Peptide amphiphile micelles (PAMs) are a promising lipid-based nanotechnology currently in development for a variety of applications ranging from atherosclerosis to cancer therapy. Especially relevant for immune applications, PAMs improve trafficking through lymphatic vessels, enhance uptake by antigen-presenting cells, and inhibit the protease-mediated degradation of cargo. However, the creation of the peptide amphiphiles (PAs) necessary to induce micellization often requires modifying an immunotarget peptide with non-native moieties, which can induce the production of off-target antibodies. Methods: PAs containing different linkers between the antigen and non-native flanking regions were synthesized and physically characterized. BALB/c mice were then subcutaneously immunized on days 0 and 14 with these formulations and ELISAs were conducted on the sera collected from vaccinated mice on day 35 to evaluate antibody responses. Results: We determined that Palm₂K-M2_2–16-(KE)₄ PAMs elicited off-target antibody responses and sought to avoid these unintended responses by adding linkers in between the M2_2–16 antigen and the non-native flanking regions (i.e., Palm₂K- and -(KE)₄) of the PA. Most significantly, the addition of diproline linkers on either side of the M2_2–16 antigen conferred a loss of β-sheet structure, whereas changing the method of lipid attachment from Palm₂K- to Pam₂CS-induced the formation of primarily spherical micelles compared to a mixture of spherical and short cylindrical micelles. Despite these morphological changes, all linker-containing PAMs still induced the production of off-target antibodies. Excitingly, however, the formulation containing a Pam₂CS moiety (intended to mimic the adjuvanticity of the TLR2 agonist adjuvant Pam₂CSK₄) elicited high on-target antibody titers similar to those induced by PAMs co-delivered with Pam₂CSK₄. Conclusions: While the linkers tested did not completely eliminate the production of off-target antibodies elicited by the PAMs, the inclusion of a Pam₂CS moiety both increased the amount of on-target antibodies and improved the ratio of on-target to off-target antibodies in response to the M2_2–16 vaccine. Full article

Objective: Dermo-cosmetics have significantly advanced, focusing on innovative and effective products such as cosmeceuticals—cosmetics infused with bioactive ingredients for skin benefits. Synthetic peptides are prominent among these bioactive molecules, noted for their enhanced effects in cellular processes related to skin physiology. Specifically, the glycoprotein E-cadherin plays a crucial role in cellular adhesion and has shown promise in wound healing studies, although its broader cellular functions remain underexplored. Despite their widespread use, many cosmetic peptides lack genetic validation of their effects. This study focuses on the synthetic, amphiphilic acetyl hexapeptide-1, aimed to possess wound healing and anti-aging properties, with a novel exploration of its molecular mechanisms, specifically its effect on the expression of the CDH-1 gene, which encodes E-cadherin—a key protein in cellular adhesion and wound healing. Methods: In this investigation, the acetyl hexapeptide-1 was synthesized in house, followed by cell culture assessment and molecular evaluation. Human hepatocytes HepG2 were exposed to the synthetic hexapeptide to assess cytotoxic effects and examine its impact on gene expression, specifically targeting the wound healing-associated gene CDH-1, as well as apoptosis-related genes BAX, Bcl-2, Caspase-9, and Cyclin D1. Results: No cytotoxic effects were observed in cell cultures. Gene expression analysis revealed a significant increase in E-cadherin expression, along with the NO modulation of apoptosis-related genes (BAX, Bcl-2, Caspase-9) and the cell cycle-related gene Cyclin D1. These findings suggest peptide’s role in enhancing cellular adhesion, without any cytotoxic effects. Conclusions: The findings of this study provide promising insights into the potential molecular properties of synthetic acetyl hexapeptide-1, implying its applicability in cosmeceuticals. These cosmetic peptides hold enormous potential and diverse applications not only within skincare. To fully understand their benefits and expand their scope, additional investigations are warranted to comprehensively explore their molecular mechanisms across a spectrum of applications. Full article