Thèses sur le sujet « Activité antimicrobiennes »
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Thiebault, Nicolas. « Propriétés antimicrobiennes et anti-inflammatoires de saccharides : étude structure / activité ». Amiens, 2008. http://www.theses.fr/2008AMIE0100.
Texte intégralThe aim of this work was to synthesize and characterize the carbohydrates derivatives modified in anomeric position or in primary position regioselectively. In the first time, a regioselective disubstitution of maltotriose (DP3) was carried out and optimized in only one step giving a key intermediary to the accesses of dialkylmaltotriosides derivatives. Then, we carried out the synthesis of S-alkylglycosides and O-alkylglycosides modified in anomeric position, with good yields, in order to undertake a study structure/activity. In the second time, we evaluated the antimicrobial properties of all these compounds. We observed that the S-alkylglycosides derivatives exhibit weak or no activity whereas the O-alkylmaltodextrines compounds alone or in mixture showed interesting antimicrobial activities. In the third time, an evaluation of the anti-inflammatory drug activity of all these compounds was carried out. Once again, the S-alkylglycosides derivatives presented weak or no activity, while the O-alkylmaltodextrines derivatives alone showed significative anti-inflammatory drug activities. Moreover, mixtures of the latter led to a synergy of action on the inhibition of IL8 never yet described in the literature
Andraud-Dieu, Amandine. « Recherche de molécules antimicrobiennes d'origine lichénique : Etude phytochimique de trois lichens & ; approche synthétique de deux composés actifs ». Thesis, Limoges, 2015. http://www.theses.fr/2015LIMO0029/document.
Texte intégralPhytochemical study of three lichens collected in Limousin, Usnea florida, Flavoparmelia caperata and Cladonia incrassata, led to the isolation and the structural identification of 16 secondary metabolites. First, these lichens were chosen after a preliminary screening performed on 17 species. Antimicrobial activity of acetone extracts was evaluated and bioassay-guided fractionation was performed. The two isomers of usnic acid, 3 dibenzofurans, 4 depsides, 3 depsidones, one aliphatic acid and one sterol were isolated. A trichlorinated xanthone, named cladoxanthone A, was extracted and identified for the first time in a natural source. A bioautographic protocol was used to evaluate antibacterial activities of these compounds on Staphylococcus aureus. MICs of the products obtained in sufficient amounts were determined by a broth microdilution method in parallel with Phenonip®, a preservative commonly used in cosmetic industry. Didymic and condidymic acids were found to be good candidates for use as preservatives. Secondly, owing to their potential industrial application, we explored synthetic routes for usnic acid and cladoxanthone A. Thus, the preparation of the key intermediate for access to usnic acid was optimized and the first coupling tests in the presence of a porphyrin were encouraging. Similarly, the proposed synthetic routes for cladoxanthone A are promising
Abbassi, Feten. « Caractérisation structurale et fonctionnelle des temporines-SH : de nouveaux peptides antimicrobiens isolés chez l'espèce de grenouille nord-africaine Pelophylax saharica ». Paris 6, 2009. http://www.theses.fr/2009PA066702.
Texte intégralAl, Hallak Mohamad. « Etude de la contamination fongique de l'air et des matériaux et de l'aérosolisation pour l'amélioration de la qualité de l'air intérieur ». Electronic Thesis or Diss., Université de Toulouse (2023-....), 2024. http://www.theses.fr/2024TLSES011.
Texte intégralIndoor air pollution is an important cause of diverse health problems for occupants including respiratory diseases, allergic symptoms, cancers, and cardiovascular problems. People spend 80-90% of their time indoors emphasizing the importance of understanding the main causes of indoor air pollution and finding suitable solutions to improve indoor air quality. The World Health Organization (WHO) reported in 2009 that biological pollution is one of the main causes of the degradation of indoor quality. In humid indoor environments, fungi can grow and develop on almost all building materials. Upon their development on surfaces, they produce particles such as spores, toxins or volatile organic compounds, and other metabolites that can be aerosolized. The release of particles from surfaces as well as their characteristics is dependent on different factors including the type and age of microorganisms on the surface, material properties, and environmental conditions (temperature, humidity, air velocity). Based on their sizes and their duration of availability in the indoor air, they can be inhaled by occupants, leading to serious health risks as they may penetrate different depths in the respiratory system. To respond to these issues, this work aimed to investigate the relations that may exist between microorganisms, especially fungi, present on surfaces and airborne particles contaminating the indoor air (In situ and in the lab). It would provide a clearer vision of fungal contamination in the indoor environment and would be helpful during investigating methods for controlling the growth of fungi indoors. In addition, investigations on the performances of selected photocatalysts and glycerol esters as antimicrobial products for reducing microbial contamination on surfaces in the laboratory were achieved. Initially, an In situ sampling campaign was held in a visibly contaminated house in Southern France. Surface sampling from contaminated materials and indoor airborne sampling were carried out. Then, DNA analysis for samples was carried out by Toulouse Biotechnology Institute (TBI). This part aimed to check the relationship, if any, between fungal contamination on surfaces and airborne contamination. Then, experiments on the antifungal and antibacterial activities of photocatalytic products and the antifungal activity of glycerol esters were carried out under different experimental conditions. This part aimed to test their efficiency as antibacterial/antifungal products that may be applied as additives in paints or coatings. The tests carried out in this part were preliminary tests in aqueous solutions and the impact of different conditions on the efficiency of each product was evaluated. The efficiency of three photocatalysts (TiO2, ZnO, Au-decorated ZnO) as antimicrobial products under light intensities close to real-life indoor conditions. The efficiencies of Undecylenic Acid (UA) and of three glycerol esters, formed upon esterification of Glycerols with UA, as antifungal products were evaluated. The last part of this study aimed to investigate the relationship between surface contamination and airborne contamination under controlled conditions (mainly airflow and relative humidity). A new experimental device was settled, design and validation of an experiment protocol that permit to determine the quantitative correlation between surface contamination and airborne contamination were carried out. The impact of different experimental parameters on the aerosolization of particles from contaminated surfaces into air was evaluated. The validation of this experimental protocol was important and brought attention to different tests that will be investigated in the near future
BOUCHIKHI, TOURIA. « Activite antimicrobienne de quelques huiles essentielles ». Clermont-Ferrand 2, 1994. http://www.theses.fr/1994CLF21670.
Texte intégralBoughougal, Amina. « Synthèse et caractérisation de composés de coordination antimicrobiens ». Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1260.
Texte intégralDevelopment of novel coordination complexes with diverse biological activities (antimicrobial, anti-inflammatory, antifungal, antioxidant and anticancer) is a rapidly evolving field of inorganic chemistry with potential direct impact on quality of life. Metal–drug complexes are of increasing interest in bioinorganic chemistry, leveraging the synergistic effect to lead to compounds with improved pharmacological activity. The recognition of the role of metal ions in biological systems and in treatment of various diseases calls attention to the benefits of studying the interaction of metal ions with organic drug molecules. In continuation with previous works of team, we focus here on the synthesis of new families of metal-antibiotic complexes associating, on one single-molecule, the antiseptic activity of a metal ion with the bioactivity of one or two type of bioactive molecules. Their additive actions have a synergetic effect and lead to more effective and shorter treatments and should strongly minimize the risks for appearance of bacteria mutants. In this work, we succeeded to synthesis the first metal-antibiotic complex associating two types of different antibiotic as ligands with Zn(II). The structure in the solid state of this new complex was established together with the studies of the chemical-physical properties. Comparative studies show it has a better antibacterial activity against (E.Coli, E,Aureus, E.Feacalis ) than parent antibiotics and complexes with only one of the antibiotic. This open a new concept named as Multi-Active Biomolecule Assembly. Moreover, the synthesis and characterisation of new trifluorométhylated antimicrobial ligands are described
Laurencin, Mathieu. « Peptides et pseudopeptides auto-assembleurs à activité antimicrobienne ». Rennes 1, 2008. http://www.theses.fr/2008REN1S142.
Texte intégralAntibiotic resistance of pathogens against conventional antibiotics increases at a rate which exceeds by far the speed of the development of new drugs. The antimicrobial peptides, both synthetic and from natural sources, have raised interest as potential useful drugs in the future. The use of peptides is however limited by a fast elimination in biological environment connected to their rapid degradation by proteases. The object of this work concerns the synthesis of no proteinogenic monomers, the aza-β3-aminoacids, in the goal to incorporate them into antimicrobial peptidic sequences. Aza-β3-aminoacid are analogues of α-aminoacids, which differ from β3-aminoacids by the presence of an extra nitrogen atom, with a non-fixed configuration, which carries the side chain. The introduction of these monomeric units within antimicrobial peptides gives access to antimicrobial pseudopeptides with an extended life cycle. The modification of a cuttlefish neuropeptide presenting antibacterial activities allowed us to obtain a peptidic analogue and two pseudopeptidic analogues more active than the natural peptide. On the other hand, we developed a peptide and a series of cyclopseudopeptides hybrids de novo which possess comparable activities to some common antibiotics. Now, we try to explain the mechanism of action of our peptides and pseudopeptides which act on the microbial membranes. The results, obtained by circular dichroism, light scattering and NMR, bring to light a phenomenon of auto-association which would play an essential role in the biological activity
Defer, Diane, Professeur Nathalie Bourgougnon et Mcf Yannick Fleury. « Recherche d'activités antimicrobiennes chez des mollusques marins. Purification et caractérisation partielle de peptides antimicrobiens isolés à partir de l'hémolymphe de Crassostrea gigas et de bactéries associées ». Phd thesis, Université de Bretagne Sud, 2009. http://tel.archives-ouvertes.fr/tel-00485008.
Texte intégralKhoury, Madona. « Préparation, analyse et activités antimicrobiennes d'huiles essentielles de plantes libanaises ». Paris, Muséum national d'histoire naturelle, 2015. http://www.theses.fr/2015MNHN0024.
Texte intégral@Inspired by plant defenses, we undertook to evaluate the chemical diversity and antimicrobial activities of essential oils (EOs) from Lebanese plants. Following a metabolomic approach we were able to highlight the chemical diversity among the 32 studied oils and between the chemotypes of the same plant species. The screening led to the identification of several EOs with interesting antimicrobial activities. Hirtellina lobelii DC. EO was among the most active ones, alone or in combination with antimicrobial drugs. This oil holds remarkable antifungal potential against dermatophytic fungi by disrupting fungal membrane and ultimately leasing cells. We hypothesized that H. Lobelii EO should increase cell penetration of antifungal drugs and may also act through a specific mode of action. Altogether, these results lead us to believe that plant defense arsenal can inspire alternative ways of addressing the societal issue of multidrug resistant infections
Ngezahayo, Jeremie. « Plantes médicinales du Burundi et maladies infectieuses : enquête ethnobotanique et activités antibactériennes directe et indirecte de composés isolés de Platostoma rotundifolium (Briq.) A. J. Paton (Lamiaceae) ». Doctoral thesis, Universite Libre de Bruxelles, 2016. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/241022.
Texte intégralInfectious pathologies are diseases caused by the transmission of some pathogenic microorganisms among bacteria, viruses, fungi and protozoa. They drive the high mortality and morbidity rates recorded especially in developing countries, where the majority of the population cannot afford to access health care. The antimicrobial resistances currently observed in modern medical practice represent another major problem in the treatment of these diseases. These resistances are one of the most serious population health threats and can strike anyone in the world. It has thus become urgent to discover new antimicrobial agents that could possibly have novel mechanisms of action.Many plants used in traditional medicines against infections harbor useful antimicrobial components that can help in the fight against infectious diseases and antibiotic resistances. In this context, we conducted an ethnobotanical survey of medicinal plants used in Burundian traditional medicine to treat microbial infections. We inventoried 155 herbs from which 5 (Justicia subsessilis Oliv. (Acanthaceae); Platostoma rotundifolium (Briq.) A. J. Paton (Lamiaceae), Virectaria major (Schum.) Verdc. (Rubiaceae), Pavetta ternifolia (Oliv.) Hiern (Rubiaceae), and Stomatanthes africanus (Oliv. & Hiern) R. M. King & H. Rob. (Asteraceae) were selected for phytochemical screening and biological assays. The extracts of these plants were evaluated for their antibacterial effects, direct (bacteriostatic or bactericidal) and indirect (inhibition of resistance mechanisms by increasing or restoring the activity of antibiotics against resistant strains). All the selected plants species have shown antibacterial activity, justifying their use against microbial infections in Burundian traditional medicine, and more particularly Platostoma rotundifolium, whose extracts showed direct and indirect antibacterial effects on susceptible and resistant (MRSA) strains. The extracts from Platostoma rotundifolium also presented inhibitory effects on the expression of genes involved in quorum sensing, lasB and rhlA, as well as on biofilm formation by Pseudomonas aeruginosa PAO1.In order to isolate and identify the molecules responsible for these activities, the ethyl acetate extract (most active) from Platostoma rotundifolium was submitted to bioguided fractionation. This led to the isolation of nine compounds that were identified as ursolic acid, corosolic acid, tormentic acid, hyptadienic acid and 2α, 3α, 19β-trihydroxyurs-12-en-28-oic acid (isolated for the first time during this work and that was named jeremic acid), squalene, cassipourol, β-sitosterol and α-amyrin. All these molecules were isolated for the first time from Platostoma rotundifolium. The first three compounds showed a bactericidal effect on sensitive and resistant strains of bacteria, while the last three showed significant inhibitory effects on the expression of two QS genes (lasB and rhlA), and on biofilm formation by Pseudomonas aeruginosa PAO1. All these active molecules can be a lead in the fight against antibiotic resistance; and we can conclude that the data from an ethnobotanical survey of the knowledge and skills of traditional healers are very important, especially when they are exploited until the determination of the active ingredients responsible for a specific pharmacological activity.
Doctorat en Sciences biomédicales et pharmaceutiques (Pharmacie)
info:eu-repo/semantics/nonPublished
Hamdouna, Lama. « Caractérisation RMN et activité antimicrobienne de complexes organométalliques préparés par mécanosynthèse ». Electronic Thesis or Diss., Université de Lille (2022-....), 2023. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2023/2023ULILR048.pdf.
Texte intégralThe extensive use of solvents in modern chemical synthesis has posed significant economic and environmental challenges. To address these concerns, it is crucial to reduce solvent usage and embrace eco-friendly synthesis methods. One promising solution to these challenges is mechanochemical synthesis, which employs mechanical forces to drive chemical reactions without traditional solvents. However, many aspects of the reaction mechanisms involved in mechanochemistry remain poorly understood. Solid-state nuclear magnetic resonance (ssNMR) spectroscopy, capable of providing atomic-level resolution, holds great promise in unraveling the mechanisms of mechanochemical reactions. In this dissertation, we applied ssNMR spectroscopy to investigate the mechanochemical synthesis of transition metal-N-heterocyclic carbene (NHC) complexes through the weak base approach. These complexes, such as [Cu(Cl)(NHC)], [Ag(Cl)(NHC)], and [Rh(acac)(CO)(NHC)], have applications in catalysis and as anti-infective coatings for medical devices. Our research primarily focuses on exploring the impact of different workup protocols used during the preparation of these complexes. To explore these processes, we conducted a series of multinuclear ssNMR experiments, involving spin-1/2 (1H, 13C, 15N, 109Ag) and quadrupolar (35Cl, 63Cu) nuclei, at static magnetic field strengths of 9.4, 18.8, and 28.2 T. This approach allowed us to monitor the consumption of reactants and the formation of intermediate and final products across various synthetic routes and workup protocols. We leveraged the high resolution and sensitivity offered by a 1.2 GHz NMR magnet to observe isotopes subject to substantial quadrupolar interactions, such as 35Cl and 63Cu. Signal assignment in the NMR spectra was achieved through 2D heteronuclear correlation techniques in conjunction with Density Functional Theory (DFT) calculations of NMR parameters. Additionally, we complemented our ssNMR studies with techniques such as powder X-ray diffraction (XRD) and vibrational spectroscopy. Moreover, we extended our investigation to the mechanochemical synthesis of chalcogen-NHC derivatives, specifically thioureas (NHC=S) and selenoureas (NHC=Se), known for their unique electronic properties and biological activities. Using multinuclear ssNMR experiments, including spin-1/2 (1H, 13C, 15N, 77Se) and quadrupolar (33S) nuclei at static magnetic fields of 9.4 and 18.8T, along with DFT calculations of NMR parameters, we unveiled the mechanisms underlying these transformations. Our findings unequivocally confirm that the studied transition metal-NHC complexes and chalcogen-NHC derivatives are indeed formed in the solid state during ball milling, dispelling any doubts regarding solvent-driven reactions during subsequent workup or characterization. However, this assertion does not apply to the [Rh(acac)(CO)(NHC)] complexes, where mechanical forces during ball milling facilitated the reaction but necessitated the presence of solvents to complete it. Additionally, our study identified intermediate compounds, unreacted reagents, and by-products, providing a comprehensive understanding of the reaction outcomes. In conclusion, our research provides valuable insights into the mechanisms of mechanochemical processes and highlights the potential of ssNMR spectroscopy as a powerful technique for investigating and optimizing sustainable synthesis routes. This work contributes to the development of environmentally friendly and economically viable methods for chemical synthesis, addressing the pressing challenges posed by solvent usage in modern chemistry
Fassi, Fehri Lina. « Activité antimicrobienne de peptides membranotropes et mécanisme de résistance chez mycoplasma pulmonis ». Rennes 1, 2005. http://www.theses.fr/2005REN1S061.
Texte intégralDemers, Mathieu Véronique. « Activité antimicrobienne d'un extrait peptidique issus d'un hydrolysat trypsique de protéines de lactosérum ». Thesis, Université Laval, 2011. http://www.theses.ulaval.ca/2011/28671/28671.pdf.
Texte intégralFabre, Françoise. « Activité antimicrobienne d'huiles essentielles : comparaison de méthodes, détermination de l'activité de nouvelles huiles ». Clermont-Ferrand 1, 1991. http://www.theses.fr/1991CLF15004.
Texte intégralMolero, Bondia Andrea. « Synthèse et activité antimicrobienne d’assemblages moléculaires basés sur les dendrimères greffés de lysine ». Thesis, Montpellier 2, 2013. http://www.theses.fr/2013MON20019.
Texte intégralL-Lysine dendrigrafts (DGLs) have various potential applications (antibacterial agents, antifungal agents…). These dendrigrafts are obtained according to an original procedure elaborated in our laboratory based on the polymerization of L-lysine N-carboxyanhydrides (Lys-NCA). The investigations carried out in the present dissertation are aimed at assessing (i) the feasibility of the different ways of modification of DGLs and (ii) the antibacterial activity of the synthesized conjugates. The manuscript begins by locating DGLs among the different categories of dendritic polymers reported in the literature. It also develops the applications of oligo- and poly-ethylene (OEG and PEG) as agents for the functionalization of bioactive molecules and for bioconjugate synthesis. An approach consisting in grafting third generation DGL (DGL-G3) with oligo-homoarginines (Har)n is then described. These entities have been synthesized from a first generation DGL (DGL-G1) using an innovative strategy for the elaboration of guanidinium-rich peptides in a straightforward and cheap strategy. The first part of this work is dedicated to the oligomer synthesis. The possibility of further grafting of the latter is conditioned by the preceding access to bifunctional spacers bearing an amino group on the one end and a masked aldehyde function on the other end. The amine will enable the initiation of Lys(Tfa)-NCA polymerization, whereas the aldehyde will serve for the covalent grafting to the DGL-G3 scaffold. The second part of this work is devoted to the DGL-G3 functionalization by the (Har)n oligomer through a reductive amination strategy that has been optimized and to the synthesis of new conjugates with hydrophobic side-chains. Among all the conjugates prepared, only those having hydrophobic chains lead to an increase in antibacterial activity
El-Ghaish, Shady Nabil Rashed. « Usage des bactéries lactiques issues de produits laitiers fermentés ou de fromages locaux obtenus en Egypte dans la protéolyse des protéines du lait afin de diminuer leurs propriétés allergéniques et dans l'obtention de produits antimicrobiens ». Nantes, 2011. http://archive.bu.univ-nantes.fr/pollux/show.action?id=b7546415-6795-4be6-8ea9-b7fbd47c219e.
Texte intégralThe strains used in this study were identified by 16s rDNA amplification and sequencing as : Lactobacillus fermentum IFO3956, Lactobacillus rhamnosus LMS2, Lactobacillus plantarum JDM1, Enterococcus faecium DO623, Enterococcus faecium E1162, Enterococcus faecium C68, Enterococcus faecalis HH22 and Enterococcus faecalis T8. All these strains showed a strong proteolytic activity. The strains Lactobacillus fermentum IFO3956 and Lactobacillus plantarum JDM1 included PrtP protease, while the strain Lactobacillus rhamnosus LMS2 contain PrtR protease. No presence of genes encoding proteases PrtB and PrtH has been detected in all strains tested. Proteases produces by Lactobacillus fermentum IFO3956, Lactobacillus rhamnosus LMS2 and Lactobacillus plantarum JDM1 may be classified as P III type, since they proteolysed s1-, s2 and -caseins. Depending on the reduced recognition and binding by IgE of s1-, and -caseins hydrolyzed by Lb. Fermentum IFO3956, Lactobacillus rhamnosus LMS2 and Lactobacilus plantarum JDM1 these straine may be used for the production of milk products with reduced s1-and - caseins immuno-reactivity. The active strains (Enterococcus faecium TX1330 and Enterococcus faecium E980) isolated from Egyptian dairy products were proved capable of producing a variety of bacteriocins (ent A, ent B, ent P and ent L50A) with considerable activity against Listeria monocytogenes. Analysis of Enterococcus faecium TX1330 and Enterococcus faecium E980 by the methods of molecular biology has revealed the absence of the virulence factor genes (asal, cyl A and cyl B, ace, efaAfs, and espfm) as compared with a positive strain (Enterococcus faecalis MM4594). Based on the obtained results showing that the two studied strains producers of enterocins were devoid of virulence factors and mostly sensitive to antibiotics, Enterococcus faecium TX1330 and Enterococcus faecium E980 may be used as safe and useful starter cultures or co-cultures
Salmi, Chanaz. « Conception et évaluation des activités antimicrobiennes de nouveaux dérivés aminostéroïdiens analogues de la squalamine ». Aix-Marseille 3, 2007. http://www.theses.fr/2007AIX30028.
Texte intégralExtensive use of antibiotics has raised a serious public health problem due to infections caused by multidrug-resistant bacterial pathogens. Consequently, there is a pressing need to develop new antibiotics to keep pace with bacterial resistance. Recently, a new cationic sterol, squalamine has been isolated from tissues of the dogfish shark Squalus Acanthias exhibiting potent antimicrobial activities. The synthesis of numerous squalamine analogues has been realized involving a diastereoselective titatium reductive amination reaction developed in our laboratory. A structure–activity relationships study has been conduced in order to determine the influence of polyamino, hydroxyl and sulfate moieties on the encountered antimicrobial activities
Okusa, Ndjolo Philippe. « Etude phytochimique et activité antimicrobienne directe et indirecte de Cordia gilletii De Wild, Boraginaceae ». Doctoral thesis, Universite Libre de Bruxelles, 2012. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209642.
Texte intégralLes extraits d’écorces de racines, doués d’activité antimicrobienne directe (extrait méthanolique) et indirecte (extrait n-hexanique) ont été soumis à une série de fractionnements dans le but d’isoler et d’identifier les composés actifs. Pour suivre l’activité lors des fractionnements, le milieu de culture utilisé pour la détection des composés actifs sur une plaque chromatographique (CCM-bioautographie) a été optimisé. Le composé férulaldéhyde, isolé de l’extrait méthanolique, a montré des propriétés antimicrobiennes, antioxydantes et antiplasmodiales. De l’extrait n-hexanique ont été isolés deux composés, l’un actif, le lupéol et l’autre inactif, la friedéline. Le lupéol a montré un effet antimicrobien indirect en réduisant la CMI de certains antibiotiques vis-à-vis d’une souche de MRSA. Ces trois composés, s’ils ont déjà été identifiés dans d’autres plantes, sont décrits pour la première fois dans l’espèce Cordia gilletii ;et ce travail constitue le premier rapport de l’effet antimicrobien indirect du lupéol.
Dans le but de s’assurer de l’innocuité des extraits de C. gilletii, une recherche d’alcaloïdes pyrrolizidiniques (APs) a été réalisée par GC-MS. Ces alcaloïdes présentent en effet un réel danger pour la santé humaine et la famille des Boraginaceae, à laquelle appartient l’espèce C. gilletii, est connue comme une des principales sources de ces composés. Aucun AP n’a pu être mis en évidence dans les extraits d’écorces de racines et de feuilles de cette plante jusqu’à une limite de détection de 2 ppm, suggérant ainsi une absence de risque toxicologique en relation avec ces alcaloïdes. Ces résultats rassurants restent à confirmer sur d'autres échantillons obtenus dans des lieux de récolte différents.
Le présent travail montre que C. gilletii peut agir contre les microorganismes pathogènes par :(i) son action antimicrobienne directe (due entre autre au férulaldéhyde); (ii) son effet antimicrobien indirect (dû au lupéol), effet permettant d’augmenter ou de restaurer l’activité des antibiotiques vis-à-vis des souches résistantes ;et (iii) son effet inhibiteur de l’expression des gènes du quorum sensing, effet permettant d’atténuer la virulence d’agents infectieux. Ces actions peuvent permettent de faire face aux infections dues notamment à des microorganismes résistants.
Infectious diseases remain a serious public health problem both in developing countries, where they are the main cause of the high mortality rates recorded, and in industrialized countries where there is an alarming incidence of antibiotic resistance. There is thus an increasing need for new compounds that can act by a direct antimicrobial effect or by an indirect effect, inhibiting resistance mechanisms of microorganisms. Medicinal plants, particularly those traditionally used against infectious diseases in developing countries, are a probable source for these types of compounds. In this context, Cordia gilletii De Wild (Boraginaceae), a medicinal plant from which root barks and leaves are traditionally used against infectious diseases in Democratic Republic of Congo, was investigated for biological activities and phytochemical composition. Root bark extracts showed interesting biological activities: (i) antimicrobial properties, acting directly (bactericid and bacteriostatic effects against gram positive and gram negative bacteria, respectively) or indirectly (enhancement or restoration of antibiotic activity on resistant strains); (ii) inhibitory effect on the expression of two Pseudomonas aeruginosa QS genes, lasB and rhlA; (iii) antiplasmodial effect against a chloroquine sensitive strain of Plasmodium falciparum; (iv) antioxidant effect determined by the free radical DPPH quenching. Leaves extracts showed only antiplasmodial activity.
Root barks extracts with the highest direct (methanol extract) and indirect (n-hexane extract) antimicrobial properties were fractionated to isolate and to identify the active compounds. To bio-guide the fractionation, the culture medium for the detection of active compounds on chromatographic plates (TLC-bioautography) was optimized. The compound ferulaldehyde, isolated from the methanol extract, showed antimicrobial, antioxidant and antiplasmodial properties. From the n-hexane extract two compounds were isolated, lupeol and friedelin. Lupeol showed indirect antimicrobial effect by decreasing the MIC of some antibiotics against MRSA; whereas friedelin was inactive. Although these three compounds have already been described in other plant species, this is the first report of their occurence in Cordia gilletii; the indirect antimicrobial effect of lupeol is described for the first time in this work.
As it belongs to the family of Boraginaceae, a family well known as one of the most important sources of pyrrolizidine alkaloids (PAs), Cordia gilletii is susceptible to contain these toxic compounds that were consequently researched. A GC-MS analysis did not reveal the presence of PAs (detection limit, 2 ppm) in root barks and leaves extracts of C. gilletii, suggesting a lack of PA-related toxicity of this plant. This reassuring finding needs to be confirmed with samples harvested at different locations.
This work reveals that C. gilletii may act against pathogenic microorganisms by: (i) a direct antimicrobial effect (partly due to férulaldéhyde); (ii) the enhancement or restoration of antibiotic activity against resistant strains (effect of lupeol); and (iii) an inhibitory effect on the expression of quorum sensing regulator genes, decreasing the virulence of microorganisms. These actions could help to fight infections caused by resistant strains.
Doctorat en Sciences biomédicales et pharmaceutiques
info:eu-repo/semantics/nonPublished
Hatoum, Rima. « Levure laitières à activité antimicrobienne : une nouvelle génération de cultures protectrices et de probiotiques ». Thesis, Université Laval, 2013. http://www.theses.ulaval.ca/2013/30013/30013.pdf.
Texte intégralThe overall objective of this thesis was to isolate and identify new yeast strains from Quebec dairy products with antagonistic activity against food-borne pathogens such as Listeria sp. It also aims to evaluate the potential of these strains to be used as a natural food biopreservation. A total of 95 isolates of yeasts isolated from milk and cheese of Quebec were screened. Four yeasts, in particular, namely Candida tropicalis LMA-693, Debaryomyces hansenii LMA-916, Pichia fermentans LMA-256, and Wickerhamomyces anomalus LMA-827 selected for their inhibitory activity against Listeria monocytogenes. The inhibitory activity of these strains appears to be related to the production of an extracellular hydrophobic substances extracted from the culture supernatant. The evaluation of the inhibitory activity of these strains showed a strong inhibition against L. ivanovii HPB28 with microbial reduction of 97, 92, 84 and 78 %, respectively. Attempts to purify and characterize peptides produced by W. anomalus were conducted from the culture supernatant. Two protein HPLC peaks have demonstrated significant inhibition of L. ivanovii HPB28 were then identified and purified. In the second part of the thesis, the protective effect of D. hansenii LMA-916 and W. anomalus LMA-827 was analyzed as well as their acetone extracts concentrated against L. monocytogenes LMA-1045 in Camembert cheese model curd. Microbiological analyzes of different curds models showed significant inhibition of L. monocytogenes LMA-1045 in Camembert curd models containing the acetone extracts from the first day of ripening up to the fifth and ninth days. The electron microscopy observations revealed an extensive cell lysis, with the formation of pores. Finally, the survival of D. hansenii LMA-916 in a Camembert curd model under the gastrointestinal stress was studied using dynamic simulator in vitro gastrointestinal tract (TIM-1). The behavior of this strain showed a digestive stress tolerance and survival rate (number of CFU in the effluent from the TIM-1 / number of CFU input to the TIM-1 multiplied by 100) 2.08 % comparing with 1.85 % for Saccharomyces boulardii.
Manuel, Christian. « Les neuroleptiques phénothiaziniques peuvent-ils induire une activité antimicrobienne circulante chez des patients traités ? » Paris 5, 1994. http://www.theses.fr/1994PA05P227.
Texte intégralAllain, Philippe. « L'huile essentielle de Teucrium puechiae Greuter et Burdet : aspect botanique, composition chimique, activité antimicrobienne ». Montpellier 1, 1991. http://www.theses.fr/1991MON13521.
Texte intégralHatoum, Rima. « Levures laitières à activité antimicrobienne : une nouvelle génération de cultures protectrices et de probiotiques ». Doctoral thesis, Université Laval, 2013. http://hdl.handle.net/20.500.11794/24261.
Texte intégralThe overall objective of this thesis was to isolate and identify new yeast strains from Quebec dairy products with antagonistic activity against food-borne pathogens such as Listeria sp. It also aims to evaluate the potential of these strains to be used as a natural food biopreservation. A total of 95 isolates of yeasts isolated from milk and cheese of Quebec were screened. Four yeasts, in particular, namely Candida tropicalis LMA-693, Debaryomyces hansenii LMA-916, Pichia fermentans LMA-256, and Wickerhamomyces anomalus LMA-827 selected for their inhibitory activity against Listeria monocytogenes. The inhibitory activity of these strains appears to be related to the production of an extracellular hydrophobic substances extracted from the culture supernatant. The evaluation of the inhibitory activity of these strains showed a strong inhibition against L. ivanovii HPB28 with microbial reduction of 97, 92, 84 and 78 %, respectively. Attempts to purify and characterize peptides produced by W. anomalus were conducted from the culture supernatant. Two protein HPLC peaks have demonstrated significant inhibition of L. ivanovii HPB28 were then identified and purified. In the second part of the thesis, the protective effect of D. hansenii LMA-916 and W. anomalus LMA-827 was analyzed as well as their acetone extracts concentrated against L. monocytogenes LMA-1045 in Camembert cheese model curd. Microbiological analyzes of different curds models showed significant inhibition of L. monocytogenes LMA-1045 in Camembert curd models containing the acetone extracts from the first day of ripening up to the fifth and ninth days. The electron microscopy observations revealed an extensive cell lysis, with the formation of pores. Finally, the survival of D. hansenii LMA-916 in a Camembert curd model under the gastrointestinal stress was studied using dynamic simulator in vitro gastrointestinal tract (TIM-1). The behavior of this strain showed a digestive stress tolerance and survival rate (number of CFU in the effluent from the TIM-1 / number of CFU input to the TIM-1 multiplied by 100) 2.08 % comparing with 1.85 % for Saccharomyces boulardii.
Barreteau, Hélène. « Recherche de molécules à activité antimicrobienne dans des coproduits végétaux issus des industries agroalimentaires ». Amiens, 2004. http://www.theses.fr/2004AMIE0417.
Texte intégralRémy, Benjamin. « Développement d'une nouvelle génération de pansements antimicrobiens à base d'enzyme à activité lactonase ». Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0391.
Texte intégralBacteria use a communication system, or quorum sensing (QS), to synchronize group behaviors according to population density. Some pathogens use QS to coordinate virulence and biofilm formation. Interfering with QS, or quorum quenching, represents a target to extent antibacterial drug resources. Along this PhD project, SsoPox, a hyperstable lactonase, hydrolyzing acyl homoserine lactones (AHL) involved in the QS of Gram-negative pathogen bacteria like Pseudomonas aeruginosa was studied. SsoPox was studied and characterized for its use in wound dressing against P. aeruginosa infection. The enzyme resistance to industrial constraints encountered during wound dressings manufacturing processes was estimated. SsoPox demonstrated a high tolerance to heat, organic solvents, ambient temperature storage and to sterilization processes. The enzyme efficiency was shown on 2 model strains and 51 clinical isolates of P. aeruginosa. SsoPox was also more efficient than 2 well characterized QS inhibitors. The enzyme kept its efficiency even when immobilized. A last part was dedicated to phenotypical and molecular study of enzymatic QQ of P. aeruginosa. SsoPox and another lactonase GcL, having distinct AHL specificities, were compared. In vitro experiments highlighted different impacts between the enzymes on virulence factors and biofilm. An in vivo study showed that SsoPox, unlike GcL, was able to reduce P. aeruginosa virulence. QS gene expression and proteome study confirmed distinct impacts between each enzyme treatment s. Thus, SsoPox seems to be a prime candidate for development of innovative medical devices
Ahmadova, Aynur. « L' activité protéolytique et antimicrobienne des bactéries lactiques isolées de produits laitiers fermentés traditionnels d'Azerbaïdjan ». Nantes, 2012. http://www.theses.fr/2012NANT2026.
Texte intégralThis thesis was devoted for the study of proteolytic and antimicrobial activities of LAB isolated from traditional Azerbaijani fermented dairy products. LAB isolation was done from 46 samples of traditional fermented dairy products obtained from different regions of Azerbaijan. As a result of the screening 10 new LAB strains were isolated, from which 8 were proteolytic and belong to the species Lactobacillus helveticus (1 strain), Lactobacillus paracasei subsp. рaracasei (1 strain) and Enterococcus faecalis (6 strains). Two strains were producers of bacteriocins and belong to species Enterococcus faecium and Lactobacillus curvatus. Specificity of proteolytic activities of studied LAB strains depended on the substrate cleaved and on bacterial growth phase. Found proteolytic activities were mainly directed against caseins. The optimal hydrolysis of substrates by studied strains was observed at 37-45 ºС and at neutral pH range. The studied strains produced several proteases, mainly metallo- and serine- proteases. The proteolysis of caseins by strains Lactobacillus helveticus А75 and Enterococcus faecalis AN1 decreased their immunoreactivity as a result of lytic destruction of IgE binding linear epitopes. The studied bacteriocinogenic strains inhibited the growth of closely related LAB strains and also pathogens such as Listeria monocytogenes, Bacillus cereus. Lactobacillus curvatus A61 also displayed antifungal activity. The mode of action of found bacteriocins was dependent on the test-organism used and was bacteriostatic or bactericidal. Enterococcus faecium AQ71 possesses genes coding enterocins Р, L50A/B and A. Lactobacillus curvatus A61 possesses the structural gene of curvacin A. Antimicrobial substances produced by the studied LAB strains are heat stable and active in broad pH range. The studied Azerbaijani LAB do not possess the virulence factors and multi-resistance to antibiotics. Thus they are safe for industrial application. Moreover, the studied Azerbaijani LAB strains are resistant to physiological concentrations of bile salts, what is one of the main characteristics of probiotic strains. All these results suggest that the studied bacteriocinogenic and proteolytic strains could be used safely as starter and co-cultures for the food industry
Myint, Aung. « Criblage de souches d'actinomycètes productrices d'antifongiques nonpolyéniques : production, extraction, purification et caractérisation des composés antimicrobiens biosynthétisés ». Vandoeuvre-les-Nancy, INPL, 1997. http://www.theses.fr/1997INPL049N.
Texte intégralDjouhri, Bouktab Lamia. « Synthèse et évaluation des activités antimicrobiennes de nouveaux dérivés 3,20-bis (pollyaminostéroïdiens). Applications en thérapeutique humaine ». Thesis, Aix-Marseille 2, 2011. http://www.theses.fr/2011AIX22957/document.
Texte intégralAminosterol derivatives analogues of squalamine possess a broad spectrum activity against multidrug resistant bacteria and fungi. We synthesized a new series of 3,20-bis(polyaminosteroïd) analogues involving a titanium reductive amination possessing numerous positives charges due to the presence of nitrogen groups. The study of relation structure-activity demonstrates that the nature of the amino group attached to the sterol plays a crucial role on antimicrobial activity of these compounds. We had also determined the mechanism of action of bis(polyaminosteroïd) on Gram negative and Gram positive bacteria. The study of antifungal activity of squalamine and aminosterol derivative ASD-1 show a good activity against various yeast responsible of fungal infections, minimal inhibitrice concentration ranging from 1 to 16 μg/mL. We studied a potential application of these compounds in human therapeutic. We evaluated squalamine and related parent-derived ointments (1%) as potential new compounds for S. aureus decolonization in a new mouse model. Using this model we found that squalamine ointment (1%) was able to reduce efficiently S. aureus colonization. Squalamine and bis(polyaminosteroïd) derivatives were actives against multidrug resistant bacteria and fungi isolated from cystic fibrosis patients. We investigated the potential use of squalamine compound in vitro in a nebulizer disinfection model. A formulation of squalamine disinfecting soluble tablets at 2.5 % (W/W) was developed and successfully applied for rapid nebulizer disinfection
Kieffer, Anne-Estelle. « Implication de l'ubiquitine dans l'immunité innée : Activité antimicrobienne des fragments N-et C-terminaux de l'ubiquitine ». Université Louis Pasteur (Strasbourg) (1971-2008), 2003. http://www.theses.fr/2003STR13146.
Texte intégralUbiquitin (Ub) is a multifunctionnal highly converved protein, which is implicated in protein degradation. Our results integrate Ub into the concept of Neuroimmunity. Ub is stored in secretory granules of chromaffin cells and released during stress into the circulation with catecholamines and antimicrobial peptides derived from chromogranins and proenkephalin-A during stress. The C-terminal fragment Ub65-76 displays a potent antifungal activity, crosses the cell wall of fungi and inhibits calmodulin-dependent calcineurin, an enzyme crucial for fungal growth. Ub65-76 and the N-terminal peptide (residues 1-34) could be generated during an infection with S. Aureus and act synergistically to kill fungi. Furthermore, they don't display any toxicity towards mammalian cells. The Ub C-terminal-derived peptide (Ub65-76) could be used with the N-terminal peptide (Ub1-34) and antimicrobial peptides derived from chromogranins as new antifungal agents
Kondracki, Marie-Lise. « Étude chimique et biologique de quinones sesquiterpéniques isolées de l'éponge Sménospongia sp ». Paris 11, 1988. http://www.theses.fr/1988PA112008.
Texte intégralEl, khawand Toni. « Extraction et hémisynthèse de stilbènes de la vigne et du vin pour une application en santé humaine et végétale ». Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0402.
Texte intégralStilbenes are a group of defence molecules produced by grapevine to fight against pathogens. They are consequently found in wine, where they acquire an added value through their proven positive effects on human health. Knowing that the efficacy of stilbenes against some oomycetes and fungus pathogens that attack grapevine increases with their oligomerization degree, the first objective of this thesis was to optimize and proceed to oxidative coupling reactions of resveratrol and ɛ-viniférine extracted from grapevine canes, in the presence of metal salts, in order to produce stilbene oligomers. On the one hand, these hemisynthesis reactions led to the formation of stilbenes with high molecular weight, and to the production of extracts with high antifungal activity against two major grapevine pathogens, Plasmopara viticola and Botrytis cinerea. On the other hand, these oxidative coupling reactions carried out on wine helped study the mechanisms of the oxidative transformation of resveratrol in wine, identify the resulting oligomers and determine the conditions conducive to their formation. Finally, the potential effects of these oligomers on human health were studied, by evaluating the level of their anti-inflammatory activity
Benabdelkader, Tarek. « Biodiversité, bioactivité et biosynthèse des composés terpéniques volatils des lavandes ailées, Lavandula stoechas sensu lato, un complexe d'espèces méditerranéennes d'intérêt pharmacologique ». Phd thesis, Université Jean Monnet - Saint-Etienne, 2012. http://tel.archives-ouvertes.fr/tel-00952695.
Texte intégralBirck, Cécile. « Conception et caractérisation de films antimicrobiens à base de poly(alcool vinylique) pour l’emballage à contact alimentaire ». Thesis, Lille 1, 2014. http://www.theses.fr/2014LIL10074/document.
Texte intégralThe aim of this work was to develop antimicrobial films based on polyvinyl alcohol (PVOH) crosslinked by citric acid (CTR). In our approach, sodium benzoate (NaBz) was introduced in polymer, alone or in complex form with hydroxypropyl-β-cyclodextrin (HPβCD). Both CTR residual functions grafted on polymer and free NaBz are expected to provide antimicrobial effects by contact and diffusion. Films were elaborated by casting from aqueous solutions and crosslinked by heat treatment. Crosslinking reaction has been highlighted and followed through the study of residual reagents, the evolution of Tg and residual COOH functions according to crosslinking time. From this investigation, a compromise between sufficient crosslinking and preserved film ductility has been found for a CTR concentration between 20 and 30 wt%. The time required to bind all of the reagents decreases with the increase of temperature or amount of CTR. The crosslinking reaction was not modified by the presence of HPβCD. With the addition of CTR or HPβCD and the crosslinking step, the films remain slightly permeable to O2 and highly permeable to water vapor. Considering the NaBz release in water, kinetics is slowed from 360 min of crosslinking and 20 wt% CTR. HPβCD has no major influence on the kinetics of release but allow to double released amount. Antimicrobial activity by contact and diffusion has been demonstrated for the majority of films against all studied microorganisms
Naimi, Sabrine. « Stabilité gastro-intestinale, activité antimicrobienne et impact sur le microbiote colique de la microcine J25 : approches métagénomiques et métabolomiques ». Doctoral thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/30724.
Texte intégralAntibiotics have long been used in animal husbandry practices as feed additives to improve animal growth as well as to treat bacterial infections, including those caused by Escherichia coli and Salmonella. However, this practice has largely contributed to the emergence of antibiotic resistance in commensal and pathogenic bacteria, which has led to a real public health problem. The increased incidence of infections caused by antibiotic-resistant pathogenic bacteria, has promoted the search for new alternatives and natural antimicrobial peptides (AMPs), including bacteriocins are among the promising alternatives that have been proposed. Microcin J25 (MccJ25) is an antimicrobial peptide produced by Escherichia coli and known to exert a potent inhibitory activity against Enterobacteriaceae, including Salmonella. Thanks to its lasso structure, MccJ25 has a low sensitivity to proteases and to denaturing conditions suggesting a higher stability in the gastrointestinal tract (GI) conditions. These characteristics make MccJ25 a molecule with high potential for use as an alternative to antibiotics in the veterinary field. The general objective of this thesis was to evaluate the potential of MccJ25 as an alternative to antibiotics for the inhibition of Salmonella in the physiological conditions of the digestive tract of piglet. In the first part of this study, the stability and the inhibitory activity of MccJ25 were evaluated in the different compartments of the GI tract using the dynamic simulator TIM-1. MccJ25 demonstrated higher stability in the stomach compartment; however, a moderate degradation was observed when the peptide entered the duodenum. Degradation products of MccJ25 in duodenal conditions and in the presence of different proteolytic enzymes were further analyzed using LC-MS/MS and subsequent molecular networking analysis using the Global Natural Product Social Molecular Networking platform (GNPS). Thus, the enzymes responsible for the degradation of MccJ25 have been identified. In the second part of the present study, the minimal inhibitory (MIC) and bactericidal (MBC) concentrations of MccJ25 were determined in vitro against Salmonella enterica subsp. enterica serovar Newport ATCC6962 in LB medium as well as in MacFarlane medium that simulates the swine colonic conditions. This inhibitory activity was also compared to that of two other antimicrobials namely reuterin and rifampicin. Finally, the activity of MccJ25 against Salmonella Newport and its impact on the composition and the metabolic activity of the swine colonic microbiota were evaluated using the in vitro continuous fermentation model PolyFermS that simulates the swine proximal colon conditions. The inhibitory activity against Salmonella Newport was evaluated using the agar diffusion assay, while the impact on the different bacterial groups of the swine colonic microbiota was quantified by qPCRPMA method and Illumina MiSeq sequencing. Interestly, MccJ25 did not induce any significant modification of the composition of the colonic microbiota, whereas it strongly inhibited the growth of Salmonella Newport, unlike reuterin and rifampicin. However, the analysis of the metabolic activity of the colonic microbiota using the R software and the LC-MS data, demonstrated a significant effect of MccJ25 on the intracellular metabolome. No significant effect was obtained with extracellular metabolome. In conclusion, the application of very original, varied and complementary microbiological, metagenomic and metabolomic approaches allowed us to confirm the potential of MccJ25 for use as an alternative to antibiotics in the veterinary sector. Its stability in the early stages of digestion, its specificity with regard to Salmonella and the fact that its addition into the intestinal microbiota does not cause any dysbiosis, suggested it as a good candidate as an anti-Salmonella. However, additional studies remain necessary to confirm these results in vivo under real animal use conditions.
El, Omari Khaled. « Etude de l’activité antimicrobienne et antioxidante des huiles essentielles extraites de plantes Libanaises ». Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10233.
Texte intégralAntibiotic resistance has become a real concern. Thus, the research of antimicrobial compounds is more relevant than ever. The aromatic plants are a potential source of these compounds. The thesis presents an advanced study of the chemical composition and describes the antimicrobial activity of essential oils from three plants: Micromeria barbata (M.barbata), Eucalyptus spp. and Juniperus excelsa (J.excelca). The influence of several parameters such as organ type, elevation of plant growth,duration of extraction, and drying method has been discussed .The results reveal that non – flowering of M..barbata has the maximum percentage (99.54%) of the oil is collected at the altitude (1700 m). However, the percentage of Pulgeone, the main component of the essential oil gradually decreases with increasing altitude. Furthermore, the activity of essential oils extracted from plants in three different altitudes is similar for the different microbial strains tested.The essential antibacterial and antifungal oil M. barbata is also highlighted against different bacterial species, including those resistant to carbapenems, for opportunistic fungi and dermatophytesThe antimicrobial activity of three essential oils is evaluated against two strains of Mycobacterium tuberculosis (including XDR), two atypical species: Mycobacterium kansasii and Mycobacterium gordonae well as Paenibacillus larvae ,the causative agent of American foulbrood disease that infect the honey bees larvae . Results show that three oils have a significant anti-mycobacterial activity
El, Omari Khaled. « Etude de l’activité antimicrobienne et antioxidante des huiles essentielles extraites de plantes Libanaises ». Electronic Thesis or Diss., Lille 1, 2016. http://www.theses.fr/2016LIL10233.
Texte intégralAntibiotic resistance has become a real concern. Thus, the research of antimicrobial compounds is more relevant than ever. The aromatic plants are a potential source of these compounds. The thesis presents an advanced study of the chemical composition and describes the antimicrobial activity of essential oils from three plants: Micromeria barbata (M.barbata), Eucalyptus spp. and Juniperus excelsa (J.excelca). The influence of several parameters such as organ type, elevation of plant growth,duration of extraction, and drying method has been discussed .The results reveal that non – flowering of M..barbata has the maximum percentage (99.54%) of the oil is collected at the altitude (1700 m). However, the percentage of Pulgeone, the main component of the essential oil gradually decreases with increasing altitude. Furthermore, the activity of essential oils extracted from plants in three different altitudes is similar for the different microbial strains tested.The essential antibacterial and antifungal oil M. barbata is also highlighted against different bacterial species, including those resistant to carbapenems, for opportunistic fungi and dermatophytesThe antimicrobial activity of three essential oils is evaluated against two strains of Mycobacterium tuberculosis (including XDR), two atypical species: Mycobacterium kansasii and Mycobacterium gordonae well as Paenibacillus larvae ,the causative agent of American foulbrood disease that infect the honey bees larvae . Results show that three oils have a significant anti-mycobacterial activity
Blond, Alain. « Les microcines C51 et J25, peptides antimicrobiens d'Entérobactéries : études structurales par RMN et modélisation moléculaire : relations structure/activité ». Paris 6, 2002. http://www.theses.fr/2002PA066040.
Texte intégralMnayer, Dima. « Eco-Extraction des huiles essentielles et des arômes alimentaires en vue d'une application comme agents antioxydants et antimicrobiens ». Thesis, Avignon, 2014. http://www.theses.fr/2014AVIG0257/document.
Texte intégralPlant essential oils and aromas are a real potential for the industry to substitute the synthetic compounds that might have harmful effects on the human health and the environment. In order to contribute to the green chemistry principles, this study focuses on the “eco-extraction” and valorization of natural plant extracts and the development of a new «green» technology for the extraction of aromatic compounds. The first part of this manuscript highlights the biological properties of the essential oils and aromas and the importance of their applications in various sectors especially in the food industry. In the second part, studies on the biological properties of the essential oils from plants of the Alliaceae family show their good antioxidant and antimicrobial activities. These encouraging results have allowed in the third part to evaluate the onion by-products resulting from the turbo hydrodistillation, which are normally considered as waste. The technique offers a good extraction of flavonoids and phenols using water as natural solvent. The fourth and final part of this work deals with the optimization and the development of a «green» technology using ultrasound and sunflower oil as a natural solvent for the extraction of aromatic compounds from thyme. This new ecological approach allows the extraction of absolutes free from waxes and petroleum solvent residues, having the highest content in thymol and exerting the strongest antioxidant activity
Ephrem, Elissa. « Évaluation de l’efficacité des antimicrobiens naturels libres et encapsulés contre la colonisation du jus d’orange par des bactéries lactiques : comparaison entre quatre systèmes d'encapsulation ». Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1328.
Texte intégralFresh orange juice is widely appreciated by consumers due to its pleasant taste and high nutritional value. Fresh orange juice is rapidly altered during storage, especially by microorganisms. The addition of plant-derived antimicrobials to orange juice may increase its shelf life during storage at 4 °C. Many of these natural antimicrobials are sensitive to environmental factors which reduce their effectiveness in food products. Therefore, their incorporation into encapsulation systems is required. Although this strategy is promising, the evaluation of the activity of encapsulated antimicrobials in fruit juices remains limited. In this study, we searched for a natural molecule active against Lactobacillus fermentum, a bacterium involved in the deterioration of orange juice, in the culture medium. Nerolidol (Ner), a sesquiterpene alcohol, was selected among 28 natural molecules (terpenes and phenols) and showed a potent activity against L. fermentum (minimum inhibitory concentration (MIC) = 25 μM and minimal bactericidal concentration (CMB) = 50 μM) in culture medium at 37 °C. Ner was incorporated into hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex, conventional liposomes (CLs), dug-in-cyclodextrin-in liposome (DCL) and bicelles. HPLC analysis showed a Ner content of 40, 30 and 15 μg per mg powder of HP-β-CD/Ner inclusion complex, LCs, and DCL system, respectively. In addition, the systems were characterized in terms of morphology, size, homogeneity, and zeta potential. Ner was incorporated in bicelles at a phospholipids to Ner molar ratio of 100:1 without altering the structural characteristics of the system (size, homogeneity, zeta potential, morphology). This formulation showed a high encapsulation efficiency of Ner, a high phospholipid incorporation rate, and a molar percentage of Ner in bicelles of 0.86%. At higher concentrations, Ner altered the physical (size, homogeneity, morphology) and the thermodynamic parameters of the bicelles membrane in addition to the increase in membrane fluidity. The HP-β-CD/Ner inclusion complex (MIC = 100 μM and CMB = 200 μM) showed good efficacy against L. fermentum in the culture medium at 37 C. The efficacy of free Ner and HP-β-CD/Ner inclusion complex was greatly reduced in refrigerated orange juice, as a total bactericidal activity was observed after 8 and 17 days of incubation, respectively, at a Ner concentration of 2000 μM. Whereas, liposomes blocked this activity for at least 20 days and altered the appearance of the juice. At 4000 μMof free Ner or Ner incorporated into the inclusion complex, a total bacterial death was observed after 5 and 6 days, respectively. In addition, the presence of the inclusion complex did not alter the pH and the titratable acidity of the juice, while a slight increase in the Brix degree value was observed. Subsequent studies on the antibacterial activity of bicelles incorporating Ner may be considered to determine the effectiveness of the prepared system. This system could also be characterized in terms of release rate and Ner stability
Beaugendre, Camille. « Caractérisation des résines de Calophyllum inophyllum L. : approches déréplicatives pour la recherche de composés antimicrobiens ». Thesis, Université Paris Cité, 2019. http://www.theses.fr/2019UNIP5067.
Texte intégralNavarri, Marion. « Métabolites secondaires de champignons de sédiments marins profonds : criblages génétique et fonctionnel et caractérisation structurale de molécules antimicrobiennes ». Thesis, Brest, 2016. http://www.theses.fr/2016BRES0127/document.
Texte intégralThe spreading of antimicrobial resistant microorganisms jeopardizes global health caresystem. To counteract this threat the renewal of antibiotic molecules is a global priority. Antibioticcompounds are mainly originated from microorganisms, so microorganisms and their secondarymetabolites received an increasing interest. The search for new natural antimicrobial compoundsfrom microorganisms gained untapped ecosystems as marine biosphere.We investigated the antimicrobial properties of a fungal collection. The 183 fungal isolateswere collected from deep subseafloor sediment and isolated between 4 and 1,884 meters belowthe seafloor. Secondary metabolites production potential was studied for all isolates in thecollection by screening genes coding PolyKetide Synthase (PKS), Non-Ribosomal Peptide Synthetase(NRPS), TerPene Synthase (TPS) and hybrid PKS-NRPS. After isolates dereplication according to theirMSP-PCR fingerprinting, an antimicrobial screening was performed for 110 isolates, highlighting ahigh proportion of filamentous fungi with antimicrobial properties (32%).After extraction and bio-guided fractionation bioactive metabolites isolated from 3 strains,were characterized in a structural and functional manner: O. griseum UBOCC-A-114129 producedfuscin, dihydrofuscin, secofuscin and dihydrosecofuscine, P. bialowiezense UBOCC-A-114097synthetized mycophenolic acid and Penicillium sp. UBOCC-A-114109 produced rugulosin.In the meantime, LC-HRMS analysis, performed on fungal extracts, showed a great proportionof metabolites not detected in interrogated databases. So, deep subseafloor fungi, represent anuntapped reservoir of original structures to explore
Claveau, David. « Activités antimicrobiennes de différentes préparations de ZnO, CaO et MgO et leur potentiel comme agents de conservation dans les jus de fruit ». Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26675/26675.pdf.
Texte intégralBirck, Cécile. « Conception et caractérisation de films antimicrobiens à base de poly(alcool vinylique) pour l’emballage à contact alimentaire ». Electronic Thesis or Diss., Lille 1, 2014. http://www.theses.fr/2014LIL10074.
Texte intégralThe aim of this work was to develop antimicrobial films based on polyvinyl alcohol (PVOH) crosslinked by citric acid (CTR). In our approach, sodium benzoate (NaBz) was introduced in polymer, alone or in complex form with hydroxypropyl-β-cyclodextrin (HPβCD). Both CTR residual functions grafted on polymer and free NaBz are expected to provide antimicrobial effects by contact and diffusion. Films were elaborated by casting from aqueous solutions and crosslinked by heat treatment. Crosslinking reaction has been highlighted and followed through the study of residual reagents, the evolution of Tg and residual COOH functions according to crosslinking time. From this investigation, a compromise between sufficient crosslinking and preserved film ductility has been found for a CTR concentration between 20 and 30 wt%. The time required to bind all of the reagents decreases with the increase of temperature or amount of CTR. The crosslinking reaction was not modified by the presence of HPβCD. With the addition of CTR or HPβCD and the crosslinking step, the films remain slightly permeable to O2 and highly permeable to water vapor. Considering the NaBz release in water, kinetics is slowed from 360 min of crosslinking and 20 wt% CTR. HPβCD has no major influence on the kinetics of release but allow to double released amount. Antimicrobial activity by contact and diffusion has been demonstrated for the majority of films against all studied microorganisms
Hammami, Riadh. « Approches biochimiques et bioinformatiques pour l'étude de la relation structure/fonction des peptides antimicrobiens d'origine végétale ». Electronic Thesis or Diss., Lille 1, 2009. http://www.theses.fr/2009LIL10044.
Texte intégralDifferent approaches but complementary in bioinformatics and biochemistry have been used during this study to identify, investigate and characterize new plant antimicrobial peptides. At first, and given the wide diversity of antimicrobial peptides uncovered so far, we have set the first goal to develop a platform that includes software, Scientific DataBase Maker (SciDBMaker) and a database PhytAMP. This platform allows the extraction, analysis and sorting of data on proteins from the Swiss-Prot database. It can also gather taxonomic, microbiological and physicochemical information on plant antimicrobial peptides. Thus the development of this platform opens up new informative prospects, particularly those relating to the prediction of structure / function in relation to the target organisms and thus their mode of action. In a second time, an experimental approach was used to evaluate the antimicrobial potential of some spontaneous plants from arid regions of Tunisia. Thus, the antimicrobial activity of Oudneya africana R. Br (Brassicaceae), Juniperus phoenicea L. (Cupressaceae) and Pistacia atlantica Desf. (Anacardiaceae), three spontaneous plant species used for medicinal purposes in the arid areas of Tunisia, as well as their physicochemical properties have been evaluated. The results showed the presence of antimicrobial activity in the three studied plants. This study has clearly established the potential of medicinal plants growing wild in arid regions of Tunisia as a source of antimicrobial agents. A study conducted on an active extract of one of three plants, Oudneya africana, showed the presence of peptide molecule of low molecular weight with a very broad spectrum antimicrobial action. The study of the extract was performed and revealed the potential of such bioactive natural molecules for exploitation in both the food and pharmaceutical industries. Our work is an important contribution to the study of plant antimicrobial peptides. Very original scientific informations have been generated throughout our study. The generated fundamental and applied knowledge open multiple perspectives for further exploration of this field of activity which still untapped
Bouarab, Lynda. « Évaluation du potentiel et de voies innovantes de mise en oeuvre de composés phénoliques antimicrobiens d’origine végétale pour la conservation des aliments ». Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1084.
Texte intégralThe plant kingdom is a renewable resource of a wide range of biologically active secondary metabolites. This thesis proposes a multidisciplinary strategy for evaluating the potential of plant-derived antimicrobial phenolic compounds for food preservation. A screening of the antimicrobial activity in vitro against 8 strains of foodborne pathogenic and spoilage microorganisms of a hundred pure molecules and about sixty plant extracts allowed to select the most active. Different mechanisms of action with respect to S. aureus could be demonstrated by flow cytometry coupled with the use of probes of the physiological state of the bacteria for some of the selected active compounds. For application to beef, the antibacterial activity of the most active phenolic compounds or plant extracts has been re-evaluated in more complex culture media mimicking their protein and fat content. The results of this screening and a microbiological monitoring of minced beef with 1% (m / m) of added extract made it possible to observe that the observed losses of antibacterial activity were in particular correlated with the interactions of the phenolic compounds with the proteins or fat. Incorporation of phenolic compounds or plant extracts into packaging materials in contact with food constituted was the second proposed route of implementation. Plastic films that retain antibacterial activity have thus been able to be prepared by melting
Chessa, Céline. « Activités antivirales et immunomodulatrices des peptides antimicrobiens au cours de l'infection de kératinocytes primaires humains par le virus West Nile ». Thesis, Poitiers, 2022. http://www.theses.fr/2022POIT1401.
Texte intégralWest Nile Virus (WNV) is an emerging neurotropic flavivirus for which there is no treatment nor vaccine. Transmitted to humans during the blood meal of the vector mosquito, the virus is inoculated into the skin where it infects the keratinocytes of the epidermis. The defensive arsenal of the human keratinocyte includes the synthesis of 9 antimicrobial peptides whose activity against WNV has never been studied so far. In this work, we evaluated the antiviral and immunomodulatory properties of human cathelicidin LL-37, human beta-defensin type 3 (hBD-3), and two S100 family peptides, psoriasin S100A7 and calprotectin S100A8/A9. Our results showed a direct antiviral activity of LL-37, at high concentration (10 µg/mL), resulting in a reduction of the viral load in the supernatant of the infected keratinocytes and of the infectious titer of a viral inoculum incubated in presence of the peptide. In contrast, hBD-3 treatment did not have a significant impact on WNV infection at the concentrations tested. In addition, a significant increase in the expression of several inflammatory markers at the transcriptomic and protein levels was observed in the presence of each of the two peptides compared to cells stimulated by a synthetic double-stranded RNA, poly (I:C), or infected with WNV in their absence. In the second part of this work, the experiments carried out with the S100A7 and S100A8/A9 peptides proved to be disappointing. Addition of the peptides during the infection of keratinocytes or the use of genetically modified cells to overexpress the peptides of interest showed no significant impact on the replication of WNV. Moreover, no virucidal effect of S100 peptides at a concentration of 10 µg/mL nor immunomodulatory properties was observed. In conclusion, these results suggest an indirect antiviral effect of LL-37 and hBD-3 by potentiation of the innate immune response of the keratinocyte to infection. These immunomodulatory properties would be added, for LL-37, to a direct action by altering the viral particle. In contrast, S100 family peptides do not appear to have a major antiviral role in the keratinocyte antiviral response to WNV infection. In general, this work underlines the still little-known antiviral potential of molecules produced by the skin and keratinocytes at the entry point and initial site of replication of WNV and arboviruses in the organism
Hammami, Riadh. « Approches biochimiques et bioinformatiques pour l'étude de la relation structure/fonction des peptides antimicrobiens d'origine végétale ». Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10044/document.
Texte intégralDifferent approaches but complementary in bioinformatics and biochemistry have been used during this study to identify, investigate and characterize new plant antimicrobial peptides. At first, and given the wide diversity of antimicrobial peptides uncovered so far, we have set the first goal to develop a platform that includes software, Scientific DataBase Maker (SciDBMaker) and a database PhytAMP. This platform allows the extraction, analysis and sorting of data on proteins from the Swiss-Prot database. It can also gather taxonomic, microbiological and physicochemical information on plant antimicrobial peptides. Thus the development of this platform opens up new informative prospects, particularly those relating to the prediction of structure / function in relation to the target organisms and thus their mode of action. In a second time, an experimental approach was used to evaluate the antimicrobial potential of some spontaneous plants from arid regions of Tunisia. Thus, the antimicrobial activity of Oudneya africana R. Br (Brassicaceae), Juniperus phoenicea L. (Cupressaceae) and Pistacia atlantica Desf. (Anacardiaceae), three spontaneous plant species used for medicinal purposes in the arid areas of Tunisia, as well as their physicochemical properties have been evaluated. The results showed the presence of antimicrobial activity in the three studied plants. This study has clearly established the potential of medicinal plants growing wild in arid regions of Tunisia as a source of antimicrobial agents. A study conducted on an active extract of one of three plants, Oudneya africana, showed the presence of peptide molecule of low molecular weight with a very broad spectrum antimicrobial action. The study of the extract was performed and revealed the potential of such bioactive natural molecules for exploitation in both the food and pharmaceutical industries. Our work is an important contribution to the study of plant antimicrobial peptides. Very original scientific informations have been generated throughout our study. The generated fundamental and applied knowledge open multiple perspectives for further exploration of this field of activity which still untapped
Nyegue, Maximilienne Ascension. « Propriétés chimiques et biologiques des huiles essentielles de quelques plantes aromatiques et/ou médicinales du Cameroun : évaluation de leurs activités antiradiculaires, anti-inflammatoires et antimicrobiennes ». Montpellier 2, 2006. http://www.theses.fr/2006MON20010.
Texte intégralDhouioui, Mouna. « Contribution à l’étude phytochimique d’espèces végétales de la flore tunisienne (Aristolochia longa L. et Bryonia dioïca Jacq.) : évaluation des activités antioxydante et antimicrobienne ». Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1212.
Texte intégralComposition of essential oil is known to depend on intrinsic and extrinsic factors. Experiments were conducted to study the variation in the essential oil composition of Aristolochia longa (Aristolacheae) harvested at different period (August, 2009; September, 2011; March, 2012; and April, 2013). The essential oil composition was assessed by GC–FID and GC–MS analyses. Hence, oxygenated sesquiterpenes (50.2–81.1%) and oxygenated monoterpenes (5.9–28.0%) are the major chemical groups. The antimicrobial properties of essential oils were evaluated against six microorganisms by the disc diffusion method. Increasingly, the essential oil isolated from roots collected in September (2011), exhibited the highest antimicrobial activity against Streptococcus agalactiae (G+) and Enterococcus faecium (G+). The composition of the fatty acids of the roots and aerial parts of A. longa and Bryonia dioïca (Cucurbutaceae) was analyzed by GC-FID and GC-MS. The oils extracted from the aerial parts of both species were rich in polyunsaturated fatty acids with the essential linolenic and linoleic acids being the most prominent compounds. Oleic and linoleic acids were the majors fatty acids in the roots of both species. The antibacterial activity, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the lipid extracts were determined against a panel of five bacterial strains. The antibacterial activity of the root lipid extracts was particularly important against Enterococcus feacium (G+) (CMI value of 125 μg/mL; CMB values > 250 μg/mL) and Streptococcus agalactiae (G+) (CMI value of 125 μg/mL; CMB values 250 μg/mL for A. longa roots). These results indicate that A. longa and B. dioïca could be considered as good sources of essential fatty acids which can act as natural antibacterial agents. An experimental design is an experimental set-up to simultaneously evaluate several factors at given numbers of levels in a predefined number of experiments, and also to provide maximum chemical information by analysing chemical data. So, Plackett–Burman (PB) experimental was used to appreciate the stability of DPPH and to estimate antioxidant activity of ferulic acid and the plant extracts. Hence, to increase DPPH absorbance at 190μM the buffer type, pH medium, solvent type and reaction time should be maintained at its lower level while buffer concentration, temperature, buffer ratio should be kept at its high level. While, to increase DPPH absorbance at 50 μM is obtained with buffer acetate, lower temperature and short reaction time. Further, the radical scavenging activity of the plant extracts and ferulic acid as a pure compound is examined in the selected conditions by PB design
Darpentigny, Clémentine. « Fonctionnalisation de structures de nanocellulose en fluide supercritique pour des applications de pansements antimicrobiens Ice-templated freeze-dried cryogels from tunicate cellulose nanocrystals with high specific surface area and anisotropic morphological and mechanical properties Highly Absorbent Cellulose Nanofibrils Aerogels Prepared by Supercritical Drying ». Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAV052.
Texte intégralIn a context where the need for innovative medical devices is increasing and the environmental issue is becoming a major concern, the objective of the project the aim of the project was to prepare antimicrobial wound dressings using the greenest possible way. For this purpose, nanocelluloses have been chosen as bio-based and biocompatible building blocks for the design of porous architectures and their functionalization with antimicrobial agents was then undertaken in supercritical CO2 medium (CO2sc) used as an alternative to organic solvents and by taking advantage of its specificities such as high diffusivity, easy removal of solvent and residual reagents and compatibility with fragile materials. Thus, 2D and 3D structures, nanopapers, cryogels and aerogels, were prepared from cellulose nanofibrils (CNFs) and nanocrystals (CNCs), and exhibited various properties in terms of morphology, porosity and specific surface area. In order to introduce antibacterial functionality, cryogels prepared from nanocellulose with varied surface chemistries were impregnated in scCO2 with a synthetic antibiotic, ciprofloxacin. Impregnated cryogels exhibited antibacterial activity against both gram-negative and gram-positive bacterial strains. Then, four materials of increasing specific surface area, all prepared from CNFs, were impregnated with an essential oil molecule, thymol. Results show a direct relationship between of the amount of impregnated molecules and the specific surface that leads in the case of cryo- and aerogels to good antimicrobial properties against two types of bacteria and yeast. In a second strategy, covalent grafting of CNFs structures in supercritical CO2 was investigated with a novel antibacterial aminosilane. Surface analysis characterizations methods (X-ray photoelectron spectroscopy, contact angle and surface zeta potential analysis) confirmed the successful grafting on nanopapers. The contact active properties of grafted nanopapers and cryogels were assessed. These results are very promising for the design of antimicrobial bio-based and biocompatible medical devices using supercritical conditions
Shyam, Radhe. « Cationic amphipathic peptoid oligomers as antimicrobial peptide mimics ». Thesis, Université Clermont Auvergne (2017-2020), 2018. http://www.theses.fr/2018CLFAC048/document.
Texte intégralLiving organisms produce antimicrobial peptides (AMPs) to protect themselves against microbes.The growing problem of antimicrobial resistance calls for new therapeutic strategies and the natural AMPs have shown ground-breaking potential to address that issue. They show broad-spectrum activity and their main mechanism of action by bacterial cell membrane disruption implies low emergence of resistance which makes them potent candidates for replacing conventional antibiotics. Nevertheless, few hurdles are impeding their use, notably poor bioavailability profile. Some of these limitations can be overcome by developing peptidomimetics of AMPs which exhibit antibacterial activities together with enhanced therapeutic potential. Peptoids (i.e. N-alkyl glycine oligomers) adopting cationic amphipathic helical structures are mostly competent AMP mimetics. From a conformational point of view, peptoids are fundamentally more flexible than peptides primarily due to the cis/trans isomerism of N,N-disubstituted amides but studies in this area have shown that cis amide conformation can be controlled by careful choice of side-chain to set a PolyProline I-type helical structure of peptoids. In this thesis, the genesis of novel amphipathic cationic peptoids carrying cis-directing tert-butyl and/or triazolium-type side-chains and their untapped potential to act against bacteria will be discussed comprehensively. First, the solutionphase synthesis of tert-butyl-based oligomers was developed. Second, novel method of solid-phase submonomer synthesis was optimised to access 1,2,3-triazolium-based oligomers. Then, the synthesised cationic oligomers were evaluated for their antibacterial potential, followed by antibiofilm activity and cell selectivity assays. In the end, to have insights on the mode of action of amphipathic peptoids, microscopy was carried out