• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 827
  • 52
  • 19
  • 2
  • Tagged with
  • 900
  • 666
  • 249
  • 214
  • 176
  • 151
  • 132
  • 131
  • 123
  • 114
  • 110
  • 103
  • 102
  • 74
  • 63
  • 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.
301

Charakterizace bylin rodu Plectrantus pro využití v potravinářství / Characterization of the genus Plectrantus for use in the food industry

Chmelová, Nikola January 2021 (has links)
The aim of this diploma thesis was to determine the optimal extraction conditions for obtaining an extract from the plant Plectranthus amboinicus. Plectranthus amboinicus is an aromatic herb of the Lamiaceae family containing a large number of bioactive compounds. Because of this, it has a number of biological effects – antimicrobial, anti-inflammatory, antioxidant, analgesic, etc. To maintain the maximum of sensory and nutritionally valuable components of P. amboinicus, a simple maceration of fresh chopped herb was chosen. Maceration was performed under the following conditions: 40 minutes at 40 ° C, solvent 40% ethanol, weight 20 g of herb per 100 ml of solvent. The extract prepared under these optimal conditions was comprehensively characterized in terms of the content of total polyphenols, their concentration was determined to 0,08 ± 0,02 mgGEA·ml-1, which corresponds to 0,40 ± 0,07 mgGEA·g-1 of the plant. The antioxidant activity of the extract was 241,24 ± 29,24 µgTEAC·ml-1 and the radical scavenging activity of ABTS•+ was determined to be 49,29 ± 5,97 %. The antimicrobial activity was verified by the agar well diffusion method. Two types of bacteria were selected for the determination – gram-positive Bacillus cereus, gram-negative Escherichia coli and yeast Candida glabrata. The results showed that the extracts have the highest antimicrobial activity against B. cereus. There were 64 volatile aromatic compounds identified in the extract, with monoterpenes and sesquiterpenes dominating. The obtained results confirm that P. amboinicus, or its prepared extract, has a good potential for use as a new and non-traditional flavor in various foods and delicacies, which can also increase their nutritional value.
302

Stanovení antimikrobiální a antioxidační aktivity vybraných bylinných extraktů / Determination of antimicrobial and antioxidant activity of selected herbal extracts

Čaková, Adriana January 2021 (has links)
Tetradenia spp. is herb naturally growing in Africa and is part of family called Lamiaceae. The herb is used in traditional medicine to cure malaria, angina or as treatment for tropical skin diseases. Maceration was chosen from number of extraction methods, to obtain bioactive compounds from this plant. Optimization was performed with aim to retrieve as much of bioactive compounds as possible. Optimal conditions chosen were: temperature 60 °C, extraction time 40 minutes, solvent 40% ethanol and solid-solvent ratio 1:5. In total 63 aromatic active compounds were found in optimal extract. Terpenes were the most abundant (88,60 %), from them oxygenated monoterpenes (55,65 %) and monoterpenes (29,52 %). Compounds with highest percentage quantity were camphor (51,76 %), cis--ocimene (8,17 %), 3-octyl acetate (7,71 %), trans--ocimene (6,76 %), -terpinene (4,93 %), o-cymene (3,81 %), terpinolene (1,33 %), limonene (1,33 %), camphene (1,19 %) and borneol (1,20 %). Further, total phenolic content was 0,31 ± 0,02 mgGAEml-1, which equals 1,52 ± 0,11 mgGAEg-1 of plant. Antioxidant activity was 417,56 ± 32,84 gTEACml-1 and percentage of radical scavenging activity ABTS•+ was 88,99 ± 7,00 %. Finally antimicrobial activity was determined against bacteria Bacillus cereus, Escherichia coli and yeast Candida glabrata. Against E. coli and C. glabrata there was no inhibition exhibited. Against B. cereus there was seen mild inhibition activity. The results confirm that Tetradenia spp. contain a number of interesting aroma active compounds, which shows antioxidant and antimicrobial activity. The herb has a good potential as natural source of nutritious and sensory active compounds to be used into various foods.
303

Biologicky aktivní látky aronie (Aronia spp.) / Biologically active substances of chokeberry (Aronia spp.)

Palkovská, Kateřina January 2021 (has links)
This master thesis deals with preparation of extracts from fruits of aronia, optimization of conditions for extraction and subsequent characteristics of the obtained optimal extract. In the theoretical part information about the botanical characteristics of Aronia melanocarpa and about its utilization are mentioned. Furthermore, the chemical composition of aronia fruits is described and the main biologically active substances contained in the plant are described. At the end of the theoretical part extraction and separation techniques, determination methods of antioxidant, antimicrobial activity and determination of aromatic active compounds are described. The experimental part describes the optimization of maceration so that the macerate contains as much polyphenolic substances as possible, as well as aromatic active substances. 40% ethanol, at a temperature of 60 ° C, with a weight solvent ratio of 1: 5, for 40 minutes proved to be optimal for the maceration of aronia fruits. The total polyphenol content of the optimal extract was determined to be 5237.2 ± 40.7 mgGAEkg-1 and the antioxidant activity by TEAC to be 512.5 ± 5.04 gml-1. 24 aromatic active compounds were identified in the extract, with the largest percentage being monoterpenes and aldehydes. Furthermore, it was found that the extract did not show antimicrobial activity against the microorganisms used (Bacillus cereus, Escherichia coli and Candida glabrata). The obtained results confirm that aronia extracts are an important source of many biologically active compounds and can be used in food as a natural source of nutritionally and sensory valuable substances.
304

Syntéza derivátů haemanthaminu a jejich biologická aktivita / Synthesis of haemanthaminy derivatives and their biological activity

Bodoríková, Viera January 2019 (has links)
4 ABSTRACT Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany Candidate: Viera Bodoríková Supervisor: doc. Ing. Lucie Cahlíková, Ph.D. Title of Diploma thesis: Synthesis of haemanthamine derivatives and their biological activity Haemanthamine, an isoquinoline Amarillidaceae alkaloid, exhibits a wide and important range of biological activities, including antitumor, antiviral, antioxidant, antimalarial and anticonvulsant. Biological activity of haemanthamine relatives closely with its structure. By modifying the different parts of the molecule, we can identify some structure-activity relationships. With this aim, the thirteen semisynthetic analogues of alkaloid haemathamine were prepared and purified using analytic and preparative TLC methods. The obtained substances were then subjected to structural analysis, specifically, there were used MS, HRMS, 1D and 2D NMR spectroscopic techniques. Prepared compounds were tested on its possibility to inhibit human erythrocytic acetylcholinesterase (HuAChE) and human serum butyrylcholinesterase (HuBuChE). The most promising biological activities have been shown by aromatic esters labelled as LC- 70 (IC50 HuAChE = 0,12 ± 0,01 µM) and LC-73 (IC50 HuAChE =0,17 ± 0,01 µM). The cytotoxic activity of prepared compounds has been...
305

Sušení organických materiálů / Drying of the organic materials

Fialová, Gabriela January 2018 (has links)
This master’s thesis deals with the general characteristics of drying processes, types of moisture and bonds in the material. The following describes the drying process and selected drying equipment. It also includes a chapter on proteins, their changes in the air with increasing temperature. This thesis also describes denaturation of proteins as well as activity of water and it‘s dependence on microbial reactions in food. The practical part is focused on experimental measurement of the drying curves of crushed larvae, their construction and subsequent evaluation. The last part is devoted to measuring the activity of water samples of crushed larvae of different moisture.
306

Analýza beta-glukanů ve vybraných druzích hub / Analysis of beta-glucans in some fungi

Phan, Huong Tra January 2018 (has links)
The main goal of this thesis was to analyse the amount of beta glucans in selected mushroom species. The overall characterization of the composition and content of bioactive compounds in mushrooms was studied too. The theoretical part was focused on description of Fungi, especially the Basidiomycota phyla. The overview of fungal morphology and chemical composition was elaborated. Further, theoretical basis of analytical methods used was introduced. In the experimental part, extracts from selected species of mushrooms (shiitake, oyster mushroom, white champignon, brown champignon and jew’s ear) were prepared. Overall group parameters such as polyphenols, flavonoids, antioxidant activity were determined by spectrophotometry. The amount of beta-glucans in the fungi was measured after enzyme hydrolysis using commercial kit. The content and composition of fatty acids was measured by gas spectrometry. Using emission spectrometry (ICP/OES) the presence of heavy metals was analysed in fungal extracts. Cytotoxicity was tested by MTT test on human cell lines. In the last part the antimicrobial activity against Gram-positive bacterium Micrococcus luteus, Gram-negative Serratia marcescens and yeast Candida labrata was tested. In the thesis, a complex characterization of composition and biological effect of some mushrooms was given.
307

Izolace antibakteriálních sloučenin z kávové sedliny / Isolation of antimicrobial compounds from spent coffee grounds

Kurzová, Pavlína January 2020 (has links)
Coffee grounds are one of the very valuable lignocellulosic wastes that have been able to be processed and used for isolated phenolic substances. Many phenolic substances isolated from lignocellulosic wastes have antimicrobial properties. Aim of this thesis is isolation phenolic substances from spent coffee grounds extract and their available antimicrobial properties. Two isolation ways were applied to receive phenolic substances from spent coffee grounds: 1) solvent extraction (hexane, 75% ethanol, 70% acetone, diethyl ether, and ethyl acetate) and 2) release of active substances by alcoholic fermentation. All isolated materials were characterized by the viewpoint of concentration of reducing sugars, polyphenols and flavonoids. Subsequently, their antimicrobial activity was determined by using agar diffusion and broth dilution methods. Two gram-positive bacteria (Bacillus subtilis and Micrococcus luteus), one gram-negative bacteria (Serratia marcescens) and two yeasts (Candida glabrata and Saccharomyces cerevisiae) were used for antimicrobial testing. High-performance liquid chromatography (HPLC) was used to identify phenolic substances in the extracts. First, the results showed that the isolated sample with the highest antimicrobial activity was 70% acetone extract. This extract contained chlorogenic acid, gallic acid, caffeic acid and coumaric acid according to HPLC. The ethyl acetate extract showed the lowest antimicrobial activity. Second, after lyophilization, the isolated materials also revealed high antimicrobial activity. The highest antimicrobial activity displayed the materials obtained by the extraction with 70% ethanol. This sample contained chlorogenic acid, gallic acid and caffeic acids. Next, samples with phenolic compounds were obtained by the alcoholic fermentation of spent coffee grounds. These samples showed similarly to the previous solution extracts significant antimicrobial activity. Interestingly, the unfiltered samples received directly after alcoholic fermentation also showed antifungal properties. The characterization of phenolic compounds by HPLC showed similarly as in previous examples that chlorogenic, caffeic and gallic acids were present in these samples.
308

Využití cvičebního programu Drums Alive u seniorů / The use of Drums Alive exercise program in older people

Ančerlová, Marie January 2021 (has links)
Title: Use of the DRUMS ALIVE program (drumming on gymnastic balls) for seniors. Objectives: The aim of the thesis was to find out whether there will be a change in functional fitness after three months of application of the "Drums Alive" program for seniors. Methods: Ten women with an average age of 75 years were tested. Functional fitness was evaluated using the measurement of batteries "Senior Fitness Test" before and after the three-month intervention program. A custom inteview survey was used for evaluation of subjective feelings of the participants. The exercises took place once a week for three months and each lesson lasted 40 minutes. Results: Fitness Drums Alive applied for a duration of 3 months mainly improved the strength of the upper and lower extremities. The flexibility of the joints of the upper and lower extremities, aerobic fitness and agility did not show any major changes. The training program was assessed positively overall by the participants. Keywords: physical activity, fitness, rythm, health, aging
309

Efekt pravidelně aplikované severské chůze na vybrané kardiorespirační parametry u dospělých jedinců po operaci srdeční chlopně / Effect of regularly applied nordic walking on selected cardiorespiratory parameters in adults after heart valve surgery

Tejnecká, Michaela January 2021 (has links)
Author: Bc. Michaela Tejnecká Title: The effect of regularly applied Nordic walking on selected cardiorespiratory parameters in adults after heart valve surgery. Aim: The aim of this work was to analyze the effect of six months of Nordic walking intervention on selected casrdiorespiratory parameters in adults after heart valve surgery. Methods: The study included ten individuals (mean age 62 years) who were at least five years apart after heart valve surgery. Blood pressure (BP) was measured using a pulsed wrist tonometer, blood oxygen saturation (BOS) and heart rate (HR) were measured using a pulse oximeter, and the ejection fraction of the heart (EF) was evaluated echocardiographically. Nordic walking training units took plaxe once a week for 6 months. During this intervention, the level of training gradually increased both in distance and elevation of the terrain. Results: In all probands there was an average reduction in systolic blood pressure during exercise by an average of 10,3 mmHg and a reductionin heart rate during exercise by an average of 24 beats per minute. The resting ejection fraction increased by an average of 5,5% after six month intervention. These changes were statistically significant (p<0,01). The results of the work point to the benefits of Nordic walking for cardiac...
310

Obezita v českých médiích / Obesity in the Czech media

Burdová, Lucie January 2021 (has links)
The growing prevalence of obesity, both in adults and children, not only in developed countries, is perceived as a global problem due to the associated health risks. This study quantifies the media content in the selected period 01.07.2019-30.06.2020, it identifies which media and with what reach communicates the obesity most often, as well as verifies whether this finding correlates with the sources of information most often used by obese people. In addition, it finds a correlation between the use of the term obesity in the title and the complexity of the information contained therein. The aim of this study is to analyze media content as a source of information on obesity and to verify in this context whether media content supports the stereotype in terms of depicting obesity as a disease and health risk associated with individual responsibility at the level of etiology and therapy, including appropriate stigmatizing visualization. Furthermore to verify, whether the authors of media content related to obesity, as this is perceived as a disease, most often mediate the views and perspectives of doctors, respectively obesitologists, and are a means for government communication of strategies in the field of health and health literacy of the Czech Republic's population. There was used quantitative...

Page generated in 0.1644 seconds