Dual Mode Of Action Research Articles

Rhodesain inhibitors on the edge of reversibility-irreversibility

A comparative study of Michael acceptor and keto-Michael acceptor inhibitors of the cysteine protease rhodesain has been performed. Five new inhibitors have been prepared bearing the peptide structure of the known cysteine protease inhibitor K11777 and differing on the warhead. For the preparation of the Michael acceptor warhead, a Horner-Wadsworth-Emmons reaction was used. In the synthetic routes of the keto-Michael acceptor warheads, keto-enoate and keto-vinyl sulfone, a metathesis reaction and a radical sulfonylation were the key steps, respectively. Interestingly, keto-Michael acceptors inhibited rhodesain through a dual mode of action, showing reversibility at low inhibitor concentrations and irreversibility at high inhibitor concentrations.

The Dual Mode of Antibacterial Action of the Synthetic Small Molecule DCAP Involves Lipid II Binding.

The synthetic small molecule DCAP is a chemically well-characterized compound with antibiotic activity against Gram-positive and Gram-negative bacteria, including drug-resistant pathogens. Until now, its mechanism of action was proposed to rely exclusively on targeting the bacterial membrane, thereby causing membrane depolarization, and increasing membrane permeability (Eun et al. 2012, J. Am. Chem. Soc. 134 (28), 11322-11325; Hurley et al. 2015, ACS Med. Chem. Lett. 6, 466-471). Here, we show that the antibiotic activity of DCAP results from a dual mode of action that is more targeted and multifaceted than previously anticipated. Using microbiological and biochemical assays in combination with fluorescence microscopy, we provide evidence that DCAP interacts with undecaprenyl pyrophosphate-coupled cell envelope precursors, thereby blocking peptidoglycan biosynthesis and impairing cell division site organization. Our work discloses a concise model for the mode of action of DCAP which involves the binding to a specific target molecule to exert pleiotropic effects on cell wall biosynthetic and divisome machineries.

Design and structure-activity relationships of ether-linked alkylides: Hybrids of 3-O-descladinosyl macrolides and quinolone motifs

Ketolides (3-keto) such as TE-802 and acylides (3-O-acyl) like TEA0929 are ineffective against constitutively resistant pathogens harboring erythromycin ribosomal methylation (erm) genes. Following our previous work on alkylides (3-O-alkyl), we explored the structure–activity relationships of hybrids combining (R/S) 3-descladinosyl erythromycin with 6/7-quinolone motifs, featuring extended ether-linked spacers, with a focus on their efficacy against pathogens bearing constitutive erm gene resistance. Optimized compounds 17a and 31f not only reinstated efficacy against inducibly resistant pathogens but also demonstrated significantly augmented activities against constitutively resistant strains of Streptococcus pneumoniae and Streptococcus pyogenes, which are typically refractory to existing C-3 modified macrolides. Notably, hybrid 31f (coded ZN-51) represented a pioneering class of agents distinguished by its dual modes of action, with ribosomes as the primary target and topoisomerases as the secondary target. As a novel chemotype of macrolide-quinolone hybrids, alkylide 31f is a valuable addition to our armamentarium against macrolide-resistant bacteria.

Broad-Spectrum Efficacy and Modes of Action of Two Bacillus Strains against Grapevine Black Rot and Downy Mildew.

Black rot (Guignardia bidwellii) and downy mildew (Plasmopara viticola) are two major grapevine diseases against which the development of efficient biocontrol solutions is required in a context of sustainable viticulture. This study aimed at evaluating and comparing the efficacy and modes of action of bacterial culture supernatants from Bacillus velezensis Buz14 and B. ginsengihumi S38. Both biocontrol agents (BCA) were previously demonstrated as highly effective against Botrytis cinerea in grapevines. In semi-controlled conditions, both supernatants provided significant protection against black rot and downy mildew. They exhibited antibiosis against the pathogens by significantly decreasing G. bidwellii mycelial growth, but also the release and motility of P. viticola zoospores. They also significantly induced grapevine defences, as stilbene production. The LB medium, used for the bacterial cultures, also showed partial effects against both pathogens and induced plant defences. This is discussed in terms of choice of experimental controls when studying the biological activity of BCA supernatants. Thus, we identified two bacterial culture supernatants as new potential biocontrol products exhibiting multi-spectrum antagonist activity against different grapevine key pathogens and having a dual mode of action.

Interação fungicida-requeima na síntese de compostos fenólicos e atividade de enzimas de defesa em tomateiro

Due to the significant impact of late blight (LB) (Phytophthora infestans [Mont.]) on tomato (Solanum lycopersicum L.), we investigated the interaction between fungicides and this disease to understand how some plant defense mechanisms are affected over time. Following a randomized design, we evaluated the synthesis of phenolic compounds (PHE) and the activity of phenylalanine ammonium lyase (PAL), peroxidases (POX) and superoxide dismutase (SOD). The experiment involved the application of fosetyl-Al and fluoxastrobin (fungicides with dual modes of action) on healthy and infected tomato plants. LB severity was assessed weekly and leaf samples were collected at various intervals for biochemical analysis. The Kruskal-Wallis test (α = 0.05) analyzed main effects of infection, fungicide, and time on response variables, followed by Bonferroni post hoc for significant group differences and regression models to evaluate variable effects over time. The application of fungicides had no effect on enzymatic activity or PHE accumulation. While PAL and SOD activities were not significantly affected by infection, POX activity was significantly higher in healthy plants (4793.8 U g-1 fresh weight) compared to infected plants (1858.1 U g-1 fresh weight). A complex interaction between PHE accumulation in relation to LB severity and time was observed, with a notable increase in PHE levels at 50 days after transplant when disease severity was between 25 and 50%. Future studies should consider including a broader range of genotypes and isolates of P. infestans, a more extensive set of biochemical responses, and evaluations of the overexpression of genes related to plant defense.

Carborane Conjugates with Ibuprofen, Fenoprofen and Flurbiprofen: Synthesis, Characterization, COX Inhibition Potential and In Vitro Activity.

The most effective anticancer drugs currently entail substantial and formidable side effects, and resistance of tumors to chemotherapeutic agents is a further challenge. Thus, the search for new anticancer drugs as well as novel therapeutic methods is still extremely important. Non-steroidal anti-inflammatory drugs (NSAIDs) can inhibit COX (cyclooxygenase), overexpressed in some tumors. Carboranes are emerging as promising pharmacophores. We have therefore combined both moieties in a single molecule to design drugs with a dual mode of action and enhanced effectiveness. The NSAIDs ibuprofen, flurbiprofen, and fenoprofen were connected with 1,2-dicarba-closo-dodecaborane(12) via methylene, ethylene or propylene spacers. Three sets of carborane-NSAID conjugates were synthesized and analyzed through multinuclear (1H, 11B, and 13C) NMR spectroscopy. Conjugates with methylene spacers exhibited the most potent COX inhibition potential, particularly conjugates with flurbiprofen and fenoprofen, displaying higher selectivity towards COX-1. Furthermore, conjugates with methylene and ethylene spacers were more efficient in suppressing the growth of human cancer cell lines than their propylene counterparts. The carborane-flurbiprofen conjugate with an ethylene spacer was the most efficient and selective toward the COX-2-negative cell line HCT116. Its mode of action was basically cytostatic with minor contribution of apoptotic cell death and dominance of cells trapped in the division process.

Synthesis of Bridged Bicyclic Systems peri‐Annulated to the Indole Ring: Tropane‐Fused Indoles

AbstractYtterbium triflate catalysed domino reaction of (3‐formyl‐4‐indolyl)‐derived donor‐acceptor cyclopropane with primary amines provides a simple approach to an unprecedented tetracyclic skeleton in which tropane system is peri‐annulated with an indole core. This process involves the formation of an imine and its (3+2)‐cross‐cycloaddition with donor‐acceptor cyclopropane moiety, yielding tropane‐fused indole core under mild reaction conditions. These products are of significant interest for pharmacology as potential hybrid molecules with a dual mode of action.

Butyl isothiocyanate exhibits antifungal and anti-biofilm activity against Candida albicans by targeting cell membrane integrity, cell cycle progression and oxidative stress.

The prevalence of Candida albicans infection has increased during the past few years, which contributes to the need for new, effective treatments due to the increasing concerns regarding antifungal drug toxicity and multidrug resistance. Butyl isothiocyanate (butylITC) is a glucosinolate derivative, and has shown a significant antifungal effect contrary to Candida albicans. Additionally, how butylITC affects the virulence traits of C. albicans and molecular mode of actions are not well known. Present study shows that at 17.36 mM concentration butylITC inhibit planktonic growth. butylITC initially slowed the hyphal transition at 0.542 mM concentration. butylITC hampered biofilm development, and inhibits biofilm formation at 17.36 mM concentration which was analysed using metabolic assay (XTT assay) and Scanning Electron Microscopy (SEM). In addition, it was noted that butylITC inhibits ergosterol biosynthesis. The permeability of cell membranes was enhanced by butylITC treatment. Moreover, butylITC arrests cells at S-phase and induces intracellular Reactive Oxygen Species (ROS) accumulation in C. albicans. The results suggest that butylITC may have a dual mode of action, inhibit virulence factors and modulate cellular processes like inhibit ergosterol biosynthesis, cell cycle arrest, induces ROS production which leads to cell death in C. albicans.

Polyamine-Mediated Sensitization of Klebsiella pneumoniae to Macrolides through a Dual Mode of Action.

Chemicals bacteria encounter at the infection site could shape their stress and antibiotic responses; such effects are typically undetected under standard lab conditions. Polyamines are small molecules typically overproduced by the host during infection and have been shown to alter bacterial stress responses. We sought to determine the effect of polyamines on the antibiotic response of Klebsiella pneumoniae, a Gram-negative priority pathogen. Interestingly, putrescine and other natural polyamines sensitized K. pneumoniae to azithromycin, a macrolide protein translation inhibitor typically used for Gram-positive bacteria. This synergy was further potentiated in the physiological buffer, bicarbonate. Chemical genomic screens suggested a dual mechanism, whereby putrescine acts at the membrane and ribosome levels. Putrescine permeabilized the outer membrane of K. pneumoniae (NPN and β-lactamase assays) and the inner membrane (Escherichia coli β-galactosidase assays). Chemically and genetically perturbing membranes led to a loss of putrescine-azithromycin synergy. Putrescine also inhibited protein synthesis in an E. coli-derived cell-free protein expression assay simultaneously monitoring transcription and translation. Profiling the putrescine-azithromycin synergy against a combinatorial array of antibiotics targeting various ribosomal sites suggested that putrescine acts as tetracyclines targeting the 30S ribosomal acceptor site. Next, exploiting the natural polyamine-azithromycin synergy, we screened a polyamine analogue library for azithromycin adjuvants, discovering four azithromycin synergists with activity starting from the low micromolar range and mechanisms similar to putrescine. This work sheds light on the bacterial antibiotic responses under conditions more reflective of those at the infection site and provides a new strategy to extend the macrolide spectrum to drug-resistant K. pneumoniae.

Exploration of novel isoxazole-fused quinone derivatives as anti-colorectal cancer agents through inhibiting STAT3 and elevating ROS level

Colorectal cancer (CRC) is trending to be a major health problem throughout the world. Therapeutics with dual modes of action have shown latent capacity to create ideal anti-tumor activity. Signal transducer and activator of transcription 3 (STAT3) has been proved to be a potential target for the development of anti-colon cancer drug. In addition, modulation of tumor redox homeostasis through deploying exogenous reactive oxygen species (ROS)-enhancing agents has been widely applied as anti-tumor strategy. Thus, simultaneously targeting STAT3 and modulation ROS balance would offer a fresh avenue to combat CRC. In this work, we designed and synthesized a novel series of isoxazole-fused quinones, which were evaluated for their preliminary anti-proliferative activity against HCT116 cells. Among these quinones, compound 41 exerted excellent in vitro anti-tumor effect against HCT116 cell line with an IC50 value of 10.18 ± 0.4 nM. Compound 41 was proved to bind to STAT3 by using Bio-Layer Interferometry (BLI) assay, and can significantly inhibit phosphorylation of STAT3. It also elevated ROS of HCT116 cells by acting as a substrate of NQO1. Mitochondrial dysfunction, apoptosis, and cell cycle arrest, which was caused by compound 41, might be partially due to the inhibition of STAT3 phosphorylation and ROS production induced by 41. Moreover, it exhibited ideal anti-tumor activity in human colorectal cancer xenograft model and good safety profiles in vivo. Overall, this study provided a novel quinone derivative 41 with excellent anti-tumor activity by inhibiting STAT3 and elevating ROS level, and gave insights into designing novel anti-tumor therapeutics by simultaneously modulation of STAT3 and ROS.

Dual-action compounds unleash a one-two punch against tuberculosis

In this issue of Cell Chemical Biology, Gries etal.1 employ an innovative screening approach to identify anti-tuberculosis compounds with dual modes of action: anti-virulence against the type VII secretion system ESX-1 and enhanced ethionamide efficacy. These compounds hold promise for developing multi-target tuberculosis drugs with potential clinical applications.

Abstract 6658: TcE armed oncolytic virus VSV-GP combines oncolysis and T-cell retargeting for improved efficacy

Abstract Background: Oncolytic viruses, such as the chimeric vesicular stomatitis virus variant VSV-GP have dual modes of action, direct tumor-cell killing, and activation of tumor-specific immunity. While tumor cells deficient in type I interferon (IFN) response are permissive to VSV-GP replication and killing, IFN competent tumor cells are protected from VSV-GP-mediated oncolysis. Our previous data demonstrated that VSV-GP therapy turns immunologically ‘cold’ tumors ‘hot’ by increasing infiltration of T cells into the tumor. The aim of this study was to use the VSV-GP platform to locally express a T cell engager (TcE) molecule to redirect these T cells to destroy non-permissive IFN competent tumor cells expressing the target of the TcE on their cell surface. Methods: We selected EpCAM as the target antigen and used a bispecific EpCAM-TcE molecule consisting of two variable single chain fragments against EpCAM and CD3, respectively. VSV-GP encoding EpCAM-TcE (VSV-GP-EpCAM-TcE) or an invariant control TcE (VSV-GP-TNP-TcE) were generated as previously described. T cells were co-cultured with human target cells expressing EpCAM on their cell surface, either infected with the VSV-GP-EpCAM-TcE virus or with supernatant from VSV-GP-EpCAM-TcE infected cells. T cell activation, proliferation, degranulation and cytokine secretion were analyzed by flow cytometry and multiplex cytokine assays as a measure of TcE mediated cross-linking of T cells to their target on cancer cells. Patient-derived head and neck squamous cell carcinoma (HNSCC) tumors were sectioned into approximately 200 µM slices and infected with the virus. T cell activation was measured by cytokine secretion. The therapeutic potential of VSV-GP-EpCAM-TcE was tested in vivo in cell-line derived xenograft (CDX) models implanted in immunodeficient mice humanized with donor-derived PBMCs or CD34+ cells. Results: Virus fitness was maintained for VSV-GP encoding the TcE molecule. Using co-culture assays, we demonstrated that EpCAM-TcE molecule is successfully expressed by VSV-GP and can activate both CD4+ and CD8+ T cells resulting in proliferation, degranulation, and cytokine secretion. Furthermore, we validated the concept using patient-derived HNSCC tumor slices which are representative of complex human tumor ecosystems. We could confirm that cancer cells infected by VSV-GP-EpCAM-TcE virus express functional TcE molecule and activates T cells to secrete IFNγ and TNFα. Finally, we tested the concept in two different CDX models where VSV-GP-EpCAM-TcE showed improved tumor growth inhibition due to a combined effect of oncolysis and T cell activation by EpCAM-CD3 TcE. Summary: The oncolytic virus VSV-GP can be successfully armed with a TcE to redirect tumor-infiltrating T cells to destroy tumor cells which are not permissive to viral replication. This resulted in an enhanced therapeutic efficacy compared to just the oncolytic effect. Citation Format: Aparna Ponnurangam, Theresa Schwaiger, Sophie Walter, Simone Bartl, Melissa Mayr, Monika Petersson, Tanja Schoenberger, Fabian Heinemann, Peter Gross, Wolfgang Rist, Srinath Kasturirangan, Charlotte Lempp, Jutta Petschenka, Krishna Das, Nolden Tobias. TcE armed oncolytic virus VSV-GP combines oncolysis and T-cell retargeting for improved efficacy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6658.

Abstract 514: Salt-inducible kinase inhibitor OMX-0407 drives cell-cycle arrest in vitro and in vivo: An in-depth MoA analysis by phospho-proteomics

Abstract Based on iOmx’ proprietary iOTargTM genetic screening platform, salt-inducible kinase (SIK) 3 was identified as a novel cell signaling modulator in cancer biology. OMX-0407, an orally available, spectrum-selective kinase inhibitor targets several members of the SIK family and is known to prevent tumor-promoting function of the SIK-family through repolarization of the tumor microenvironment by enhancing caspase-mediated apoptosis upon death-receptor signaling. In addition, OMX-0407 inhibits individual key members of the tyrosine and tyrosine-like kinase family that are involved in cancer cell proliferation and cell cycle regulation. Via this dual mode of action, OMX-0407 has the potential to effectively fight solid tumors as exemplified by its striking single-agent efficacy in multiple pre-clinical tumor models. A comprehensive anti-tumor viability screen of >200 human cancer cell lines revealed striking effects of OMX-0407 on cancer cell viability across various cancer indications, resulting in a distinct sensitivity profile across various tumor indications with particularly strong effects on renal cell carcinoma (RCC) and squamous non-small cell lung cancer (sqNSCLC). Phospho-proteomics screening demonstrated pharmacodynamic activity of OMX-0407 in sensitive tumor cell lines via inhibition of key cellular processes such as cell motility, proliferation, and cell cycle regulation across different indications. Orthogonal functional in vitro assays confirmed the association of the OMX-0407-mediated anti-tumor efficacy with the arrest of G1/S transition and corresponding downregulation of cell cycle associated proteins PAK1/2 and ARHGAP35. The profound impact of OMX-0407 on fundamental regulatory mechanisms of cell division and cancer cell apoptosis translates into dose-dependent single-agent, anti-tumor efficacy in various pre-clinical tumor models of selected indications. Combination with Axitinib, a selective orally available inhibitor of vascular endothelial growth factor receptor 2, significantly enhanced anti-tumor efficacy and pharmacodynamic inhibition of cell growth as well as angiogenesis. These data further strengthen the potential of OMX-0407 in the treatment of RCC as well as other indications. In summary, OMX-0407 is a novel spectrum selective kinase inhibitor, currently under evaluation in a clinical Phase I trial (NCT05826600). OMX-0407 demonstrates strong anti-tumor efficacy in monotherapy in selected sensitive indications through a dual-pronged MoA, by modulating the tumor microenvironment and exerting direct anti-tumor activity in solid tumor indications with high unmet medical need. Citation Format: Ilona-Petra Maser, Marisa Stebegg-Wagner, Bettina Bauer, Filippos Konstantinidis, Andreas Schirmer, Moritz Zulley, Sonja Lacher, Barbara Kracher, Parastou Kohvaei, Murray Yule, Hannes Loferer, Stefan Bissinger. Salt-inducible kinase inhibitor OMX-0407 drives cell-cycle arrest in vitro and in vivo: An in-depth MoA analysis by phospho-proteomics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 514.

ENHANCER OF SHOOT REGENERATION1 promotes de novo root organogenesis after wounding in Arabidopsis leaf explants.

Plants have an astonishing ability to regenerate new organs after wounding. Here, we report that the wound-inducible transcription factor ENHANCER OF SHOOT REGENERATION1 (ESR1) has a dual mode of action in activating ANTHRANILATE SYNTHASE ALPHA SUBUNIT1 (ASA1) expression to ensure auxin-dependent de novo root organogenesis locally at wound sites of Arabidopsis (Arabidopsis thaliana) leaf explants. In the first mode, ESR1 interacts with HISTONE DEACETYLASE6 (HDA6), and the ESR1-HDA6 complex directly binds to the JASMONATE-ZIM DOMAIN5 (JAZ5) locus, inhibiting JAZ5 expression through histone H3 deacetylation. As JAZ5 interferes with the action of ETHYLENE RESPONSE FACTOR109 (ERF109), the transcriptional repression of JAZ5 at the wound site allows ERF109 to activate ASA1 expression. In the second mode, the ESR1 transcriptional activator directly binds to the ASA1 promoter to enhance its expression. Overall, our findings indicate that the dual biochemical function of ESR1, which specifically occurs near wound sites of leaf explants, maximizes local auxin biosynthesis and de novo root organogenesis in Arabidopsis.

Formulated hydroxy fatty acids from fruit pomaces reduce apple scab development caused by Venturia inaequalis through a dual mode of action.

The outermost hydrophobic layer of plants, i.e. the cuticle, is mainly composed of cutin, a polyester of hydroxy fatty acids with reported eliciting and/or antimicrobial activities for some of them. By-products of the fruit processing industry (fruit pomaces), often strongly enriched in cuticular material, are therefore a potential source of bioactive compounds for crop protection against pathogen attack. We investigated the utilization of tomato and apple pomaces in the development of a cutin-based biocontrol solution against apple scab, a major apple disease caused by Venturia inaequalis. Several cutin monomer extracts obtained through different strategies of depolymerization and purification were first compared for their ability to induce a targeted set of defense genes in apple seedlings after foliar application. After a step of formulation, some extracts were chosen for further investigation in planta and in vitro. Our results show that formulated cutin monomers could trigger a significant transcriptome reprogramming in apple plants and exhibit an antifungal effect on V. inaequalis. Cutin monomers-treated apple seedlings were significantly protected against infection by the apple scab agent. Altogether, our findings suggest that water-dispersed cutin monomers extracted from pomaces are potential new bio-based solutions for the control of apple scab.

Structural engineering of antimicrobials for optimal broad-spectrum activity

Antimicrobial materials are a crucial component in eradicating and managing the spread of infectious diseases. They are expected to act on a broad-spectrum of microbes, including emerging pathogens which could cause the next Disease X. Herein, we reassessed a series of antimicrobial imidazolium polymers on our shelves and uncovered extended functionality through dual modes of action. By redesigning their structures, a truly broad-spectrum antimicrobial material with optimized activity against bacteria (G ​+ve, G -ve) and fungi, as well as enveloped and non-enveloped viruses was developed. We demonstrated that the imidazolium polymer exhibits dual modes of function against microbes: targeting the microbial membrane and binding DNA. The latter DNA binding affinity was found to be key against non-enveloped viruses. With this insight, we designed small molecule compounds that exhibited optimum broad-spectrum antimicrobial activity and excellent efficacy against ESKAPE group of pathogens that are responsible for some of the deadliest nosocomial infections worldwide. Our results could also shed light on the design of broad-spectrum antimicrobial compounds against Disease X.

Short-term effects of etifoxine on human gut microbiome in healthy men

BackgroundNeurosteroids have recently gained in interest as a treatment strategy for affective disorders. Etifoxine is known for its dual mode of action, one of which is to stimulate endogenous neurosteroid synthesis. The gut microbiome has been studied in affective disorders, but it has not been investigated in the context of human etifoxine or neurosteroid interventions.MethodsWe performed a crossover study with 36 healthy male volunteers who received etifoxine versus alprazolam and placebo in a balanced Williams design. Participants were randomized into six sequences and went through three 5-day treatments followed by wash-out phases of 9 days. Bacterial compositions in stool samples were determined by high-throughput 16S rRNA amplicon sequencing.ResultsGut microbiome analyses revealed no relevant effects between treatments with respect to alpha and beta diversity. Differential abundance analyses yielded etifoxine treatment as the only effect related to changes in microbial features with reductions of Faecalibacterium duncaniae, Roseburia hominis and Lactobacillus rogosae (i.e., Bacteroides galacturonicus).ConclusionHere we report on the first human investigation of the gut microbiome with short-term etifoxine intervention. Differences in diversity and compositional structure of the microbiome were more likely due to between- subject effects rather than medication. However, five-day treatment with etifoxine reduced the abundance of a few bacterial species. These species are currently seen as beneficial components of a healthy intestinal microbiome. This reduction in abundances may be related to elevated endogenous neurosteroids.

Development of High-Loading Trastuzumab PLGA Nanoparticles: A Powerful Tool Against HER2 Positive Breast Cancer Cells.

Trastuzumab, a therapeutic monoclonal antibody directed against HER2, is routinely used to treat HER2-positive breast cancer with a good response rate. However, concerns have arisen in the clinical practice due to adverse side effects. One way to overcome these limitations is to encapsulate trastuzumab in nanoparticles to improve cytotoxic activity, increase intracellular drug concentrations, escape the immune system and avoid systemic degradation of the drug in vivo. A double emulsion method was used to encapsulate trastuzumab into poly(lactic-co-glycolic) nanoparticles, effective for their biocompatibility and biodegradability. These nanocarriers, hereafter referred to as TZPs, were characterised in terms of size, homogeneity, zeta potential and tested for their stability and drug release kinetics. Finally, the TZPs cytotoxicity was assessed in vitro on the HER2 positive SKBR3 breast cancer cell line and compared to free trastuzumab. The TZPs were stable, homogeneous in size, with a reduced zeta potential. They showed higher encapsulation efficiency and drug loading, a prolonged trastuzumab release kinetics that retained its physicochemical properties and functionality. TZPs showed a stronger cytotoxicity and increased apoptosis than similar doses of free trastuzumab in the cell line analysed. Confocal microscopy and flow cytometry assessed TZPs and trastuzumab cellular uptake while Western blot evaluated downstream signalling, overall HER2 content and shedding. TZPs exert more robust effects than free trastuzumab via a dual mode of action: TZPs are taken up by cells through an endocytosis mechanism and release the drug intracellularly for longer time. Additionally, the TZPs that remain in the extracellular space release trastuzumab which binds to the cognate receptor and impairs downstream signalling. This is the sole modality used by free trastuzumab. Remarkably, half dose of TZPs is as efficacious as the highest dose of free drug supporting their possible use for drug delivery in vivo.

Rational design and characterization of cell-selective antimicrobial peptides based on a bioactive peptide from Crocodylus siamensis hemoglobin

Antimicrobial resistance is a growing health concern. Antimicrobial peptides are a potential solution because they bypass conventional drug resistance mechanisms. Previously, we isolated a peptide from Crocodylus siamensis hemoglobin hydrolysate, which has antimicrobial activity and identified the main peptide from this mixture (QL17). The objective of this work was to evaluate and rationally modify QL17 in order to: (1) control its mechanism of action through bacterial membrane disruption; (2) improve its antimicrobial activity; and (3) ensure it has low cytotoxicity against normal eukaryotic cells. QL17 was rationally designed using physicochemical and template-based methods. These new peptide variants were assessed for: (1) their in vitro inhibition of microbial growth, (2) their cytotoxicity against normal cells, (3) their selectivity for microbes, and (4) the mode of action against bacteria using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and confocal microscopy. The results indicate that all designed peptides have more potent antimicrobial efficacy than QL17 and IL15 peptides. However, only the most rationally modified peptides showed strong antimicrobial activity and minimal toxicity against normal cells. In particular, IL15.3 (hydrophobicity of 47% and net charge of + 6) was a potent antimicrobial agent (MIC = 4–12 μg/mL; MBC = 6–25 μg/mL) and displayed excellent selectivity for microbes (cf. human cells) via FACS assays. Microscopy confirmed that IL15.3 acts against bacteria by disrupting the cell membrane integrity and penetrating into the membrane. This causes the release of intracellular content into the outer environment leading to the death of bacteria. Moreover, IL15.3 can also interact with DNA suggesting it could have dual mode of action. Overall, a novel variant of QL17 is described that increases antimicrobial activity by over 1000-fold (~ 5 μg/mL MIC) and has minimal cytotoxicity. It may have applications in clinical use to treat and safeguard against bacteria.

Common-sense combination therapy in refractory immune thrombocytopaenia.

Common-sense combination therapy in refractory immune thrombocytopaenia.