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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Effect of Tannic Acid on the Protective Properties of the in situ Formed Pellicle

Hertel, Susann, Pötschke, Sandra, Basche, Sabine, Delius, Judith, Hoth-Hannig, Wiebke, Hannig, Matthias, Hannig, Christian 22 May 2020 (has links)
Objectives: In the present in situ/ex vivo study the impact of tannic acid on the erosion-protective properties of the enamel pellicle was tested. Additionally, the antiadherent and antibacterial effects of tannic acid were evaluated. Methods: The pellicle was formed in situ on bovine enamel samples fixed on individual splints worn by 6 subjects. Following 1 min of pellicle formation the volunteers rinsed for 10 min with tannic acid. After further oral exposure for 19 min, 109 min, and 8 h overnight, respectively, slabs were incubated in HCl ex vivo (pH 2.0, 2.3, 3.0) over 120 s. Subsequently, kinetics of calcium and phosphate release were measured photometrically. Samples after a 1-min fluoride mouth rinse as well as enamel samples with and without a 30-min in situ pellicle served as controls. Antiadherent effects were evaluated after a 1-min rinse with tannic acid and oral exposure of the slabs overnight. DAPI (4 ′ ,6-diamidino2-phenylindole) combined with concanavalin A staining and live/dead staining was used for fluorescence microscopic visualization and quantification of adherent bacteria and glucans. Modification of the pellicle’s ultrastructure by tannic acid was evaluated by transmission electron microscopy (TEM). Results: Tannic acid significantly improved the erosion-protective properties of the pellicle in a pH-dependent manner. Bacterial adherence and glucan formation on enamel were significantly reduced after rinses with tannic acid as investigated by fluorescence microscopy. TEM imaging indicated that rinsing with tannic acid yielded a sustainable modification of the pellicle; it was distinctly more electron dense. Conclusion: Tannic acid offers an effective and sustainable approach for the prevention of caries and erosion.
292

Extrakce antioxidantů z bezových květů a úchova extraktu pro další možné využití / Extraction of antioxidants from the elderberry blossom and preservation of the extract for further possible use

Krůzová, Sabina January 2018 (has links)
The thesis deals with the extraction of antioxidants from elder flowers and the way of storage obtained extract. The elder flowers which are obtained by cutting trees as a waste product and after their processing it could be used as an ingredient to cosmetics products for body and face skin or in a spa like additive to baths. In theoretical part are information about black elder, its botanical characteristics, utilization and about substances contained in it. There is also a chapter about lyophilization as a method which was used for concentration of extract. The last chapter describes theoretical information about liquid chromatography because this method was used for analysis of contents of extract. Experimental part describes optimalization steps in preparation of extract. It was found that the biggest content of polyphenolic compounds was when the proportion between flower and water was 1:10, optimal temperature of water for extraction is 100 °C and it was also found that the time of extraction don´t have any influence on content of polyphenols. Thanks to the lyophilization it was obtained dry light brown powder which is stable for long time. The lyophilizate was tested for some physical properties like pH, refractive index, solubility etc. There was also determined antioxidant activity by DPPH method and there was found quenching activity is 64,9 %. In determining of heavy metals in sample was found trace amounts of lead and chrome. By liquid chromatography was determined content of polyphenols, caffeic acid was in an amount 59,6 mgl1, chlorogenic acid 398 mgl1 and ferulic acid wasn´t detected. All of analysis was for 1% solution of extract because to cosmetic it could be just this amount to addition. In the last step was prepared a skin lotion with elder flower extract and it was tested for stability also was prepared an ointment from pork lard.
293

Optimalizace technologie výroby echinaceových kapek / Optimization of echinacea drops production technology

Boberová, Jana January 2020 (has links)
This diploma thesis deals with the production of herbal drops from Echinacea and the determination of the content of selected active substances. In the theoretical part, the taxonomic classification of echinacea, its botanical characteristics and growing conditions are mentioned. The history of cultivation and uses of this plant are also mentioned. An important chapter of the theoretical part is the chemical composition of the plant and differences in composition between individual cultivars of Echinacea. Methods for obtaining active substances and their determination are also mentioned. The last chapter is devoted to the technology of production of echinacea drops. In the experimental part, the extraction was optimized for dried flowers and roots of E. purpurea. The following extraction system was determined for the flowers: 40% ethanol, time 6 hours, weight to solvent ratio 1:10 and room temperature. For the roots, 20% ethanol and a time of 24 hours, a ratio of 1:10 and room temperature were evaluated as the best conditions. Furthermore, the best extracts were prepared, in which the content of total phenolic substances was set at 0.799-0.839 mg/ml, then the antioxidant activity was determined in the range from 116 to 242 µg T/ml, and finally the analysis of aromatic substances was performed by HS-SPME-GC-MS. Two commercial samples were also tested to compare the prepared extracts.
294

Vvoj energetickch npoj nov©ho typu s obsahem p­rodn­ch aktivn­ch sloek / Development of a new type of energy drinks containing natural active components

Vysok, Marie January 2017 (has links)
The aim of this thesis is the development and preparation of a new energy drink. The theoretical part of the thesis focuses on the comparison of the drinks available in market, the presentation of the main active ingredients and the proposal of enriching the new energy drink. It also describes the possibility of using an encapsulation and the method used to determine specific compound in energy drink or encapsulated particles. In the experimental part of the work, at the beginning, the main content of energy drinks were characterized, for instance caffeine, sugar, polyphenol and vitamin C. Subsequently the energy drink based on selected types of loose teas that were enriched with the encapsulated extract of acai, acerola, maca, goji and ginseng was designed. All extracts contained large amounts of polyphenols and antioxidants. In addition, acerola extracts contained very high amounts of vitamin C. Two types of particles, alginate particles and liposomes were prepared for encapsulation. For all particles, encapsulation efficiency, size, stability, and antioxidant activity were determined. Long-term stability was then monitored within three months. The particles were also exposed to artificial gastric, pancreatic and bile juice. All tested particles showed very good encapsulation efficiency. In terms of long-term storage stability in an aqueous environment. Particularly liposome particles, which also showed high stability by zeta potential measurement, were suitable. On the contrary, in case of alginate particles, when stored in an aqueous medium, the release of active substances occurred. Finally, an energy drink was created and subjected to sensory analysis. The best energy drink was based on black or green tea with alginate particles acai, goji and ginseng.
295

Studium bioaktivních látek růže šípkové / Study of rose hip bioactive compounds

Konderla, Patrik January 2017 (has links)
Purpose of this thesis was research the content of biologically active substances in herbal rosehip extracts and also determination of antimicrobial and antioxidant activity of these extracts. Teoretical part describes informations about Rosa canina L., detailed specification of biologically active substances, specification of antioxidation and overview of methods determine antioxidant compound and antimicrobial activity. In the practical part was by combination of different solvents, procedures and herbal materials, made 21 extracts of Rosa canina L.. From measuring of these extracts, was made extraction curves and also was determined antimicrobial efficiency against bacterial strains Serratia marcescesns, Bacillus subtilis, Bacillus cereus and Micrococcus luteus. Results shows, that also all extracts has some antimicrobial activity, but only against microorganisms Micrococcus luteus and Bacillus cereus. Also was found that bud extracts contains more bioactive compounds soluble in ethanol, meanwhile rose hip extracts contains more bioactive compounds soluble in water.
296

Etude phytochimique et activité biologique du produit Gencix® extrait des feuilles de papayer / Phytochemical study and biological activity of the Gencix® product extracted from papaya leaves

Dejoie, Stéphane 08 December 2017 (has links)
Utilisé dans l’entretien et le soin des gencives et des dents, le produit Gencix® (SAS Esprit d’éthique) a montré, d’après les observations cliniques des dentistes, une action anti-inflammatoire et nettoyante des dents. Ce dentifrice incorpore un extrait aqueux de feuilles de papayer. Afin d’en comprendre le mécanisme d’action en termes de métabolites actifs, un fractionnement bioguidé et une étude déréplicative associant LCUV- MSn et RMN du 13C ont été menés. L’activité relevée en clinique ne semble pas liée à un effet antibiofilm. Une activité anti-inflammatoire (anti-TNF-alpha) serait liée aux flavonoïdes plus ou moins glycosylés présents dans l’extraits. Nous avons en effet pu identifier quelques-uns des actifs comme la quercétine et le kaempferol, déjà décrits comme inhibiteurs de la libération du TNF- alpha. D'autres flavonols libres ou conjugués tels que la rutine, identifiés dans les fractions actives, peuvent également contribuer à l'activité anti-inflammatoire globale. Plus notablement, au cours de ce travail, des esters des acide malique et hydroxycinnamique ont pour la première fois été associés à une activité anticalcaire, en particulier l’acide caféoylmalique. Ce dernier agit sans doute en synergie avec d’autres composés analogues. Les différents groupements acides carboxyliques et hydroxyles présents dans ces dérivés agissent vraisemblablement en complexant les ions Ca2+. Au-delà de ces résultats, ces anticalcaires nouvellement identifiés apparaissent comme des actifs « verts » (non toxiques, n’entraînant pas de bioaccumulation et biodégradables), respectueux de l'environnement. Cette activité anticalcaire remarquable a fait l’objet d’un dépôt de brevet. / Gencix® (SAS Esprit d’Ethique) is used for the maintenance and care of gums and teeth. Clinical observations reported from dentists showed that this product-integrating anaqueous Carica papaya leaf extract- showed teeth cleaning and anti-inflammatory properties. In order to understand the mechanism of action and the role of the metabolites of the plant extract, a bioguided fractionation and a dereplicative study associating LC-UV-MSn and 13C NMR were conducted. Clinical activity does not appear to be related to an antibiofilm effect. The anti-inflammatory (anti-TNF-alpha) activity is most probably associated with glycosylated flavonoids. We have been able to identify some of the active ingredients such as quercetin and kaempferol which are already known to inhibit the release of TNF-α. Other free or conjugated flavonols such as rutin, identified in the active fractions, may also contribute to the overall anti-inflammatory activity. Most notably, esters of malic and hydroxycinnamic acids were described for the first time as scaling inhibitors, particularly caffeoyl malate. This compounds probably acts in synergy with other analog compounds. The various hydroxyl and carboxylic groups present in these compounds are probably responsible for this activity by complexing Ca2+ ions. Beyond these results, these metabolites, which are newly identified as anti-scalant, appear as "green" (i. e. non-toxic, non-bioaccumulative and biodegradable) as well as environmentally friendly. Therefore, this outstanding scaling inhibition property was subjected to patent application.
297

Étude phytochimique des extraits de deux Euphorbiaceae : Ricinus communis et Jatropha curcas. Évaluation de leur propriété anti-oxydante et de leur action inhibitrice sur l’activité de l'acétylcholinestérase / Phytochemical study of extracts from two Euphorbiaceae : Ricinus communis and Jatropha curcas. Evaluation of their anti-oxidant property and their inhibitory action of the acetylcholinesterase enzyme

Ghnimi, Wafa 05 January 2015 (has links)
Ce travail de recherche est centré sur la valorisation de deux Euphorbiacées : Ricinus communis et Jatropha curcas. La première est une espèce autochtone connue comme plante dont l’huile des graines est utilisée pour ses vertus cosmétiques quant à la deuxième, c’est une espèce allochtone récemment introduite à titre expérimental en Tunisie et connue comme plante bioénergetique. Pour le ricin huit populations Tunisiennes ont été étudiées: Riadh Andalous, Nefza, Béja, Nabeul, Hammamet, Bouficha, Khanguet Hajej et Aouled Amer. Quant au jatropha, le matériel végétal est récolté dans la station expérimentale de Nabeul (Tunisie). Il s’agit de huit populations qui proviennent d’Arusha en Tanzanie, de Mozambique, de Suriname et de Brésil à partir de cinq provenances à savoir : Paranà, Norte de Minas, Mato Grosso, Regiao sudeste et Vale do Jequitinhonha. Le travail comprend une première partie consacrée à une étude bibliographique. Une deuxième partie est consacrée aux matériels et méthodes utilisés et une dernière partie qui montre l’ensemble des résultats obtenues. Ainsi, les résultats montrent que les extraits des feuilles des populations des deux espèces étudiées sont plus riches en composés phénoliques que les extraits des racines. L’étude phytochimique a montré que le ricin contient surtout de l’acide gentisique. Quant au jatropha, il contient surtout de l’épicatechine et de la naringine. L’étude chimique des huiles fixes des deux espèces montrent que l’huile de ricin renferme essentiellement d’acide ricinoléique. Quant à l’huile de jatropha, elle contient deux acides gras en proportions majeures qui sont l’acide oléique et l’acide linoléique. L’évaluation des activités anti-oxydantes des extraits des deux espèces indique une corrélation positive entre ces activités et les teneurs en composés phénoliques. Par ailleurs, l’étude de l’activité anti-acétylcholinestérase des extraits testés montrent que ces extraits sont des inhibiteurs de l’AChE plus puissants que la galanthamine utilisée comme contrôle positif. Notre étude a confirmé que les différents extraits de ricin et de jatropha, autres que les huiles fixes, peuvent donc être exploités pour d’autres activités biologiques, parmi les quelles l’action inhibitrice de l’AChE une des principales cibles des traitements contre la maladie l’Alzheimer et le piégeage des radicaux libres, en raison de leur richesse en composés phénoliques / The aim of this study is to promote two Euphorbiaceae plants the Ricinus communis and the Jatropha curcas, the first one is known for its oil used in the cosmetic products, whereas the second one is known especially for its seeds used in the production of biodiesel. For the castor plant, eight Tunisian populations are studied: Riadh Andalous, Nefza, Beja, Nabeul, Hammamet, Bouficha, Khanguet Hajej and Aouled Amer. For the jatropha, recently introduced in Tunisia, the plant material is collected from the Nabeul station (Tunisia). Eight populations coming from Arusha in Tanzania, Mozambique, Suriname and Brazil from regions of Paraná, Minas Norte, Mato Grosso, Regiao sudeste and Vale do Jequitinhonha are studied. In first, a bibliographic study is made. In second, the used materials and methods are cited. Fanilly, all the results are mentioned. The study shows that the phenolic compounds are higher in the leaves extracts than in the roots extracts for both species. The phytochemical study shows that the gentisic acid is the major phenolic compound identified in the castor plant extracts. In contrast, the epicatechin and the naringin are the most important phenolic compounds identified in the jatropha extracts. The GC-MS analysis reveals that the castor oil contains mainly the ricinoleic acid. For the jatropha oil, two major fatty acids are identified: the oleic and the linoleic acids. Results of the antioxidant properties of leaves and roots of both species indicate a positive correlation between the leaves and the roots activities and their contents of phenolic compounds. Furthermore, the anti-acetylcholinesterase activity of the tested extracts shows for the first time that some tested extracts are more active than the galantamine used as a positive control. Our study confirmed that, in addition to their oils, different extracts of the castor plant and the jatropha can be used for biological activities such as the scavenging free radicals and the inhibitory action of AChE enzyme, which is a major target for treatments against the Alzheimer's disease due to their high levels of phenolic compounds. Owing to the activities of the leaves and the roots extracts confirmed by this study, the agricultural exploitation of the castor plant and the jatropha can be economically more profitable
298

Medicinal Chemistry of ATP Synthase: A Potential Drug Target of Dietary Polyphenols and Amphibian Antimicrobial Peptides

Ahmad, Zulfiqar, Laughlin, Thomas F. 20 August 2010 (has links)
In this review we discuss the inhibitory effects of dietary polyphenols and amphibian antimicrobial/antitumor peptides on ATP synthase. In the beginning general structural features highlighting catalytic and motor functions of ATP synthase will be described. Some details on the presence of ATP synthase on the surface of several animal cell types, where it is associated with multiple cellular processes making it an interesting drug target with respect to dietary polyphenols and amphibian antimicrobial peptides will also be reviewed. ATP synthase is known to have distinct polyphenol and peptide binding sites at the interface of α/β subunits. Molecular interaction of polyphenols and peptides with ATP synthase at their respective binding sites will be discussed. Binding and inhibition of other proteins or enzymes will also be covered so as to understand the therapeutic roles of both types of molecules. Lastly, the effects of polyphenols and peptides on the inhibition of Escherichia coli cell growth through their action on ATP synthase will also be presented.
299

Stanovení vybraných chemických parametrů v plodech nových odrůd rybízů / Determination of selected chemical parameters of fruit of new currant varieties

Pelikánová, Blanka January 2014 (has links)
Presented diploma thesis is dedicated to the determination of selected chemical parameters of fruits of new currant varieties. The theoretical part is focused on the characteristics of currant, the biologically active substances of its fruits and also the utilization of current in the food industry. Further part of the theory deals with the main chemical parameters which were examined: polyphenols, anthocyanins, ascorbic acid and antioxidant activity. In the practical part there were determined selected chemical parameters in six white, twelve red and thirteen black varieties of currant. Anthocyanins and polyphenols have been determined spectrophotometrically. The content of ascorbic acid in selected varieties of currant was determined by HPLC. As a technique for the determinationof the antioxidant activity was selected the method of free radical DPPH.
300

Polyphenol intake by food group in the ulcerative colitis population

Kleinman, Joshua 19 June 2019 (has links)
No description available.

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