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Spectrophotometry of natural drugs - secondary metabolites of plants
Hořavová, Lenka ; Masařík, Michal (referee) ; Provazník, Ivo (advisor)
Plants are an important source of secondary metabolites, such as substances that have a beneficial biological effect on the health of humans and they are irreplaceable in the modern medicine. They may operate in prevention and in the treatment of civilization diseases. In terms of content substances, the phenolic come to fore, especially polyphenols, which have been related to a number of overview studies due to their wide distribution and high concentration in plants. They also represent an important part of substances with redox effects present in the human diet and have an important role for the plant itself. Currently, many laboratories are dedicated to pharmaceutical and biological testing of plants. Individual polyphenols in plant matrices are determined primarily by chromatography, electrophoresis methods, mass spectrometry and nuclear magnetic resonance. Valuable information on the content of polyphenols in plant extract can be obtained also by using spectrophotometric methods. The subject of this thesis is to provide information, characterization and comparison of conventional and modern techniques for the determination of natural substances – phenolic compounds using spectral techniques.
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Analysis of juices of selected blackcurrant varieties
Kaniová, Lenka ; Hrstka, Miroslav (referee) ; Vespalcová, Milena (advisor)
The work deals with the chemical analysis of juices selected varieties of black currant (Ribes nigrum L.). The theoretical part is divided into three main chapters. In the first chapter there are short botanical characteristics of black currants, content of biologically active substances in fruit and utilization of black currant fruit in food industry. In the second chapter there are characteristics, importance and methods of determination of phenolic compounds. Vitamin C is describe in the last chapter, its characteristics, importance and methods of determination. Experimental part describes determination of three chemical characteristic of black currant fruits: content of total phenolic compounds, content of total anthocyanins and content of vitamin C. Twelve modern varieties of black currant were selected for determination. Based on these results, it is possible to deduce the more important varieties. The content of total phenolic compounds was in the range of 326,7–641,4 mg•100 g-1 in all samples. The content of total anthocyanins was analysed in the range from 102,5 to 284,5 mg•100 g-1 in all samples. And content of vitamin C was in the range from 82,0 to 379,1 mg•100 g-1 in all samples. The overall comparison of the varieties of black currant was found, the varieties Ceres, Ben Hope, Ben Lomond, Démon and Ometa are the most promising varieties in terms of the content of the above mentioned compounds.
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Analysis of juices of selected red and white currant varieties
Černá, Anna ; Vítová, Eva (referee) ; Vespalcová, Milena (advisor)
Presented diploma thesis deals with the analysis of juices of selected red and white currant varieties. The theoretical part is dedicated to the characteristics of a currant, biologically active substances of its fruits, its growing proces and the utilization of currants in the food industry. The analyzed parameters of currants - phenolics, anthocyanins and vitamin C are also characterized in the theoretical part with possibůe methods of their determination. The experimental part is devoted to the preparation of samples and the working practices of individual analysis. Six selected varieties of white and eleven varieties of red currant from Research and Breeding Institute of Pomology Holovousy Ltd. and six varieties of white and ten varieties of red currant from private grower were used for the analysis. Total phenolics and anthocyanins were determined spectrophotometrically, the content of vitamin C was determined by HPLC. Higher values of these compounds were measured mainly in the varieties of Research and Breeding Institute of Pomology Holovousy Ltd. Varieties of red currants contained higher amounts of total phenolics and anthocyanins while white currants contained higher amounts of vitamin C.
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Fortification of selected cereal products
Hurtová, Jana ; RNDr.Renata Mikulíková, Ph.D. (referee) ; Márová, Ivana (advisor)
Present diploma thesis describes the study of bioactive compounds in the cereals. The work is focused on possible fortification of cereal products in order to increase nutritional value of final products which is reduced during the food processing and storage. Cereal grains are rich in several phenolic compounds, vitamins and minerals that reduce the risk of chronic diseases. The aim of this study was the preparation and analysis of model fortified cereals using lyophilized fruit originating from Czech Republic. A comparative analysis of content of bioactive substances in commercial and fortified products for children was performed too. The experimental part deals with a content of individual flavonoids by RP-HPLC/UV/VIS method, spectrophotometric determination of total and reducing saccharides and analysis of mono- and disaccharides by the HPLC/RI method as well. Differences in the content of individual flavonoids and saccharides after the application of acid hydrolysis of samples were investigated. The content of these compounds increased in most products because of their release from glycosidic forms. Presence of phenolics was confirmed in all analyzed cereals. Addition of 10% of lyophilized fruit/vegetable preparative (carrot, berries, apples) caused several fold increase of phenolics content in model mixtures. In commercially available cereal products there are relatively high differences in total phenolics content, proportionally to fruit component amount. The work included the spectrophotometric analysis of total polyphenols and flavonoids in a model physiological environment (artificial stomach juice) in which the hydrolysis of bound phenolic compounds occurred. The results of this study show that addition of lyophilized fruit seems to be a good way to increase the nutritional value and maintain the content of bioactive compounds in cereal products.
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Analysis of some active substances in different products from rice
Valentová, Radka ; Melounová, Jitka (referee) ; Márová, Ivana (advisor)
Presented diploma thesis is focused on analysis of selected biologically active substances in different kinds of natural and peeled rice. In rice samples phenolic compounds, antioxidant activity, content of saccharides and vitamin C were analysed. Active substances and saccharides were analysed by UV-VIS spectrophotometry and RP-HPLC-UV/VIS. Content of phenolic compounds and saccharides was measured before and after acid hydrolysis. The content of these compounds increased several times because of release of active substances from glycosides. As a part of diploma thesis basic sensory analysis was performed and consumer questionnaires were evaluated. The highest level of antioxidant activity was detected in Indian Wild rice. The highest content of total polyphenols and flavonoids was detected in Red Rice Natural before acid hydrolysis. After acid hydrolysis the highest content was detected in Indian Wild rice. The highest content of individual flavonoids, phenolic acids and catechins was detected in natural rice Indian Wild, Rice Three colours and in two samples of rice parboiled. The highest content of total and reducing saccharides was found in rice Indian Wild before hydrolysis, while after hydrolysis the content was very similar in all rice samples. The amount of individual monosaccharides after acid hydrolysis increased, while total content of disaccharides decreased. The highest value of simple sugars was detected in rice parboiled and Indian Wild rice. The content of vitamin C was detected only in four rice kinds - in two samples of rice parboiled, Rice Three colours and rice Indian Wild.
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Analysis of active phenolics in some cereal products
Vondráčková, Hedvika ; Vávrová, Milada (referee) ; Márová, Ivana (advisor)
Presented diploma thesis was focused on study of phenolic substances in various cereal products. Flours, brans and germs from various cereals, flakes and extruded cereals were chosen as samples. Phenolic substances were analyzed by spectrophotometry, RP-HPLC/UV-VIS and RP-HPLC/PDA/ESI-MS. Studies of saccharide content which were analyzed by spectrophotometry and HPLC/RI was incorporated to this thesis. Differences in the content of phenolic substances released from glycosides after acid hydrolysis of samples and differences in saccharide content determined after acid and enzymatic hydrolysis of samples were investigated. Simple sensory analysis of extruded cereal products of different flavour (cocoa, honey, chocolate) was carried out too. In analyzed samples the highest content of total phenolics and total flavonoids was measured in wheat germs. Especially in wheat germs and also in buckwheat and oat flakes, maize brans and cereals products Teddy (cereal balls with cocoa) and Ferda (cereal grains with honey) high levels of individual catechins, phenolic acids and flavonoids were determined too. The quantity of phenolic substances increased for several times in samples processed by acid hydrolysis in comparison to non-hydrolyzed samples. The high content of total saccharides, reduced saccharides and individual mono- and disaccharides was found mainly in extruded products. Concentration of monosaccharides increased in acid hydrolyzed samples in spite of disaccharides concentration that was higher only in some of hydrolyzed samples. In several cases final disaccharide concentrations were lower in hydrolyzed samples than in non-hydrolyzed ones.
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Amount of selected biologically active compounds in Stevia rebaudiana
Porubčanová, Vladimíra ; Jurečková, Zuzana (referee) ; Vespalcová, Milena (advisor)
This bachelor thesis deals with plant, called stevia rebaudiana and analysis of phenolic compounds in the extracts from it. The theoretical part describes its botanical characteristics, chemical constitution and effect on humans health. This thesis is interested in sweetener, produced from stevia, comercionally used as E 960: steviol-glykosides, too. There is listed register of companies producing this sweetener and food products, where stevia is used in. The experimental part of thesis is focused to analysis of total phenolic content in stevia extracts, because leaves of stevia are primary used for sweetening of tea. The main aim of the thesis was find out, how is total phenolic content changed during extraction of leaves in time, in water with different temperature and in different samples.
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Analysis of phenolics in different kinds of coffee
Jašková, Martina ; Halienová, Andrea (referee) ; Márová, Ivana (advisor)
The aim of this bachelor thesis was examining the quantity of biologically significant substances in selected types of roasted ground coffee, instant coffee and coffee extract. The particular kinds of coffee differed in technological processing, degree of roasting and composition. In the practical part total phenolics and flavonoids by using spectrophotometry methods. The total antioxidant activity in the individual coffee extracts was determined by ABTS method. Qualitative and quantitative analysis of some individual antioxidants and caffeine was performed using RP-HLPC with spectrophotometric detection. As a part of the work sensory analysis of all coffee samples was realized and consumer questionnaires were completed.
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Analysis of biologically active substances in some cereal products
Valentová, Radka ; Starečková, Terezie (referee) ; Márová, Ivana (advisor)
Presented bachelor thesis is focused on study of biologically active substances in cereal products. In theoretical part over view of cereal active substances, predominantly phenolic compounds were introduced. In practical part 15 kinds of cereal products were analyzed. In these materials some group parameters - total phenolics, total flavonoids and total antioxidant activity were measured by spectrophotometry. RP-HPLC/UV-VIS method was performed for analysis of selected individual flavonids. The highest content of phenolic compounds was measured in cereals containing fruits (raspberries, blueberries, tropical and red fruit), cacao, crusty fruits (hazel nuts, sunflower seeds) and buckwheat. All cereal products contain catechine, epicatechine, catechin gallate, epicatechin gallate, chlorogenic and ferulic acid. As a part of bachelor thesis simple sensory analysis was performed and consumer questionnaires were evaluated.
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The content of selected phenolic compounds in representatives of Chenopodium L and Atriplex L genera.
DĚKANOVÁ, Zdeňka
The thesis deals with measuring the content of chosen phenolic substances in some specimen of the genera Chenopodium L. and Atriplex L. Two independent analytical methods were used to determine the content of phenolic substances, namely the Micellar Electrokinetic Capillary Chromatography (MECC) method and the High - Performance Liquid Chromatography (HPLC) method. Two cultured species of the genera Spinacia and Atriplex, three freely growing specimen of the genus Chenopodium and three freely growing species of the genus Atriplex were analysed. The analysis concerned the leaves and the inflorescence of these species.The total content of quercetin and rutin was determined by the MECC method. The highest total content of quercetin was found in the leaves of the Garden Orache (4240 mg/kg of dry matter), the lowest total content of quercetin was found in the inflorescence of the Atriplex prostrata DC. (19.6 mg/kg of dry matter). Rutin was only found in four samples, the rest of the samples contained rutin in quantities below the limit of quantification. The highest content of rutin was found in the leaves of the Lamb´s Quarters (868 mg/kg of dry matter).
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