In silico identification of two peptides with antibacterial activity against multidrug-resistant Staphylococcus aureus

Here we report two antimicrobial peptides (AMPs), HG2 and HG4 identified from a rumen microbiome metagenomic dataset, with activity against multidrug-resistant (MDR) bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA) strains, a major hospital and community-acquired pathogen. We employed the classifier model design to analyse, visualise, and interpret AMP activities. This approach allowed in silico discrimination of promising lead AMP candidates for experimental evaluation. The lead AMPs, HG2 and HG4, are fast-acting and show anti-biofilm and anti-inflammatory activities in vitro and demonstrated little toxicity to human primary cell lines. The peptides were effective in vivo within a Galleria mellonella model of MRSA USA300 infection. In terms of mechanism of action, HG2 and HG4 appear to interact with the cytoplasmic membrane of target cells and may inhibit other cellular processes, whilst preferentially binding to bacterial lipids over human cell lipids. Therefore, these AMPs may offer additional therapeutic templates for MDR bacterial infections

In silico identification of two peptides with antibacterial activity against multidrug-resistant Staphylococcus aureus

Here we report two antimicrobial peptides (AMPs), HG2 and HG4 identified from a rumen microbiome metagenomic dataset, with activity against multidrug-resistant (MDR) bacteria, especially methicillin-resistant Staphylococcus aureus (MRSA) strains, a major hospital and community-acquired pathogen. We employed the classifier model design to analyse, visualise, and interpret AMP activities. This approach allowed in silico discrimination of promising lead AMP candidates for experimental evaluation. The lead AMPs, HG2 and HG4, are fast-acting and show anti-biofilm and anti-inflammatory activities in vitro and demonstrated little toxicity to human primary cell lines. The peptides were effective in vivo within a Galleria mellonella model of MRSA USA300 infection. In terms of mechanism of action, HG2 and HG4 appear to interact with the cytoplasmic membrane of target cells and may inhibit other cellular processes, whilst preferentially binding to bacterial lipids over human cell lipids. Therefore, these AMPs may offer additional therapeutic templates for MDR bacterial infections

In silico identification of novel peptides with antibacterial activity against multidrug resistant Staphylococcus aureus

Herein we report the identification and characterisation of two linear antimicrobial peptides (AMPs), HG2 and HG4, with activity against a wide range of multidrug resistant (MDR) bacteria, especially methicillin resistant Staphylococcus aureus (MRSA) strains, a highly problematic group of Gram-positive bacteria in the hospital and community environment. To identify the novel AMPs presented here, we employed the classifier model design, a feature extraction method using molecular descriptors for amino acids for the analysis, visualization, and interpretation of AMP activities from a rumen metagenomic dataset. This allowed for the in silico discrimination of active and inactive peptides in order to define a small number of promising novel lead AMP test candidates for chemical synthesis and experimental evaluation. In vitro data suggest that the chosen AMPs are fast acting, show strong biofilm inhibition and dispersal activity and are efficacious in an in vivo model of MRSA USA300 infection, whilst showing little toxicity to human erythrocytes and human primary cell lines ex vivo. Observations from biophysical AMP-lipid-interactions and electron microscopy suggest that the newly identified peptides interact with the cell membrane and may be involved in the inhibition of other cellular processes. Amphiphilic conformations associated with membrane disruption are also observed in 3D molecular modelling of the peptides. HG2 and HG4 both preferentially bind to MRSA total lipids rather than with human cell lipids indicating that HG4 may form superior templates for safer therapeutic candidates for MDR bacterial infections

Identification et caractérisation de nouvelles molécules antibactériennes efficaces contre les bactéries multi-résistantes dont Helicobacter pylori

L’infection gastrique par Helicobacter pylori (bactérie à Gram négatif) touchant plus de 50 % des humains est la seconde cause d’infection bactérienne dans le Monde après les carries. A long terme, les complications causées par cette infection (ulcères et cancers) sont responsables de plus de 700,000 décès par an. Les antibiotiques “conventionnels” utilisés en médecine ont permis de traiter les patients infectés par H. pylori mais ont également malheureusement conduit à l’apparition de souches résistantes aux traitements responsables d’échecs thérapeutiques observés chez 20-30 % des patients. L’augmentation constante de l’incidence de souches résistantes d’H. pylori a motivée la recherche de nouvelles molecules ayant comme caractéristiques: i) d’être actives contre H. pylori, notamment les souches déjà résistantes aux antibiotiques conventionnels, ii) d’être peu ou pas toxiques et iii) de ne pas causer / sélectionner de résistance. Durant ma thèse, plusieurs molécules naturelles ou synthétiques pouvant remplir ces critères ont été évaluées : i) les Aurones et les Berbérines qui sont des molécules issues de plantes, ii) les peptides antimicrobiens (PAM) issus de champignons (les cyclodepsipeptides), de grenouilles (Temporine SHa et ses dérivés) ou d’estomac de vache (les Lynronnes). Les résultats obtenus montrent que plusieurs de ces pistes peuvent être considérées comme prometteuses dans l’éradication d’H. pylori, particulièrement celle des PAM de type Temporine SHa et Lynronnes qui sont peu toxiques et actifs même contre les souches résistantes aux antibiotiques conventionnels responsables d’échecs thérapeutiques.Helicobacter pylori, a gram-negative bacterium infecting the stomach, is the second cause of bacterial infection (after caries) in the world with 50 % of the human beings chronically infected. Long term infection by H. pylori leads to gastric ulcer and eventually to gastric cancer, with around 700,000 deaths per year. Although antibiotics were successfully used to treat patients, they are also responsible for the selection of resistant strains accounting for the 20-30 % treatment failure observed. For that reason, new molecules should be considered to treat H. pylori, ideally ones that are: i) active on H. pylori, including strains already resistant to conventional antibiotics, ii) not or poorly toxic and iii) not able to cause significant resistance. Few options were considered during my thesis that we thought could fulfill those purposes: i) Aurones and Berberines that are plant molecules and ii) antimicrobial peptides (AMP) originated from fungi (cyclodepsipeptides), from frog’s skin (Temporin-SHa and its derivatives), or present in the stomach of cow (Lynronnes). Taken together, my results demonstrated that among the different options we tested to treat H. pylori, Temporin-SHa and Lynronnes are the best candidates, particularly in the case of resistant strains responsible for treatment failure

Antioxidant Activity and Biocompatibility of Fructo-Polysaccharides Extracted from a Wild Species of Ornithogalum from Lebanon

International audienceThe present study aims to investigate the properties of biopolymers extracted from a Lebanese onion non edible plant. The extraction was performed under mild conditions by varying the percentage of ultra-sound (US) treatment duration to a total extraction time of 30 min (0, 50, 100% US). The extracts were characterized using FTIR, SEC, GC-MS, TGA, and DSC analyses. The composition of the extracts was determined from the total carbohydrate content and protein content measurements. The thermal analyses indicate that all samples have high thermal stability. The antioxidant activities of the extracts were investigated, using β-carotene bleaching, scavenging activity of ABTS, metal chelating ability, and total antioxidant activity tests. The results indicate that the 50% US treatment leads to the best antioxidant activity. Biocompatibility of the extracts was evaluated using hemolysis and cytotoxicity assays. The results showed that 0 and 50% US samples are not toxic to human cells, in contrary to 100% U

Resorcinol-based hemiindigoid derivatives as human tyrosinase inhibitors and melanogenesis suppressors in human melanoma cells

International audienceHuman tyrosinase (hsTYR) catalyzes the key steps of melanogenesis, making it a privileged target for reducing melanin production in vivo. However, very few hsTYR inhibitors have been reported so far in the literature, whereas thousands of mushroom tyrosinase (abTYR) inhibitors are known. Yet, as these enzymes are actually very different, including at their active sites, there is an urgent need for new true hsTYR inhibitors in order to enable human-directed pharmacological and dermocosmetic applications without encountering the inefficiency and toxicity issues currently triggered by kojic acid or hydroquinone. Starting from the two most active compounds reported to date, i.e. a 2-hydroxypyridine-embedded aurone and thiamidol, we combined herein key structural elements and developed new nanomolar hsTYR inhibitors with cell-based activity. From a complete series of thirty-eight synthesized derivatives, excellent inhibition values were obtained for two compounds in both human melanoma cell lysates and purified hsTYR assays, and a promising improvement was observed in whole cell experiments

Resorcinol-based hemiindigoid derivatives as human tyrosinase inhibitors and melanogenesis suppressors in human melanoma cells

Human tyrosinase (hsTYR) catalyzes the key steps of melanogenesis, making it a privileged target for reducing melanin production in vivo. However, very few hsTYR inhibitors have been reported so far in the literature, whereas thousands of mushroom tyrosinase (abTYR) inhibitors are known. Yet, as these enzymes are actually very different, including at their active sites, there is an urgent need for new true hsTYR inhibitors in order to enable human-directed pharmacological and dermocosmetic applications without encountering the inefficiency and toxicity issues currently triggered by kojic acid or hydroquinone. Starting from the two most active compounds reported to date, i.e. a 2-hydroxypyridine-embedded aurone and thiamidol, we combined herein key structural elements and developed new nanomolar hsTYR inhibitors with cell-based activity. From a complete series of thirty-eight synthesized derivatives, excellent inhibition values were obtained for two compounds in both human melanoma cell lysates and purified hsTYR assays, and a promising improvement was observed in whole cell experiments

Elaboration of antimicrobial polymeric materials by dispersion of well-defined amphiphilic methacrylic SG1-based copolymers

WOS:000439140100012Bacterial resistance to antibiotics is a major public health problem and there is an urgent need to find new antimicrobial materials to circumvent the development of resistant pathogens. The aim of this work is to propose an efficient and versatile method for the elaboration of antimicrobial polymeric materials based on the simple dispersion of a low amount of high molecular weight (M-n \textgreater 20 000 g mol(-1)) amphiphilic methacrylic copolymers prepared by nitroxide-mediated polymerization in different common organic matrices (here PS and PMMA). More precisely, after studying the influence of different copolymer parameters on their biological activity (the amount and type of comonomer (styrene or acrylonitrile), the architecture (random or diblock), and the type of cationic charge (permanent or not)), some selected candidates were dispersed in PS and PMMA matrices and were shown to efficiently turn these inactive materials into antibacterial ones with out a significant hemolytic character. In particular, only 0.02 wt% of antimicrobial copolymers were sufficient to confer an activity against both Gram positive (B. subtilis) and Gram negative (E. coli) bacteria

Furan-Conjugated Tripeptides as Potent Antitumor Drugs

Cervical cancer is among the leading causes of death in women. Chemotherapy options available for cervical cancer include highly cytotoxic drugs such as taxol, cisplatin, 5-florouracil, and doxorubicin, which are not specific. In the current study, we have identified a new peptide conjugate (Fur4-2-Nal3-Ala2-Phe1-CONH2) (conjugate 4), from screening of a small library of tripeptide-conjugates of furan, as highly potent anticancer compound against human cervical cancer cells (HeLa cells) (IC50 = 0.15 ± 0.05 µg/mL or 0.28 +/− 0.09 µM). Peptides were constructed on Rink amide resin from C- to N-terminus followed by capping by α-furoic acid moiety. The synthesized peptides were purified by recycling RP-HPLC, and structures of all the peptides were confirmed by using FABMS/ESIMS, 1H- NMR, 13C-NMR, and HR-FABMS. Conjugate 4 was furthermore found to be specifically active against human cervical cancer cells since it did not inhibit the proliferation of other human normal cells (HUVEC (human umbilical vein endothelial cells) and IMR-90 (normal human fibroblasts)), and cancer cells tested (HUVEC, MCF-7, and MDA-MB-231 cells), as well as in mice 3T3 cells (normal fibroblasts). This study revealed a good structure activity relationship of various peptide conjugates. Conjugate 4 in branched forms (4a and 4b) were also synthesized and evaluated against HeLa cells, and results revealed that both were inactive. Atomic force microscopy (AFM) studies and staining with rhodamine 123 and propidium iodide (PI) revealed that conjugate 4 possesses a membranolytic effect and causes the loss of mitochondrial membrane potential