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The Methods for the Detection of Antioxidant Substances
TURKOVÁ, Kateřina
Antioxidants and free radicals are widely discussed in the clinical and nutritional literature. Various reactive oxygen species (ROS) may be produced from normal biochemical, essential metabolic processes or from external sources as exposure to a variety of agents presented in the environment. Lipids, proteins, carbohydrates and DNA are all capable of reacting with ROS and can be implicated in etiology of various human disorders. The antioxidant system protects the organism from the effects of free radicals by scavenging them and thus preventing structural damage of cells. Measuring the individual components of the antioxidant system has provided important information about the defences against free radical effect. During the last decade, many analytical methods have been developed to determine the antioxidant activity of natural compounds and their mixtures in vitro. Some procedures involve the methods based on the generation of various radical species and their elimination by treatment with potential antioxidant compounds. The tests used for the evalution of total antioxidant activity are: Trolox equivalent antioxidant capacity-TEAC, diphenylpicrylhydrazil - DPPH, oxygen radical absorbance capacity-ORAC and the methods testing the ability to prevent lipid peroxidation. The other group includes the procedures that are based on measurement of redox properties of compouds (ferric reducing antioxidant potential assay-FRAP, cyclic voltammetry, HPLC).
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Adipokinetic hormone counteracts oxidative stress elicited in insects by hydrogen peroxide: in vivo and in vitro study
BEDNÁŘOVÁ, Andrea
The involvement of members of Adipokinetic hormone (AKH) family in regulation of response to oxidative stress (OS) was investigated in the present study. OS was elicited in the insect body by exogenous application of hydrogen peroxide. In vivo experiments reveal that injection of hydrogen peroxide into the haemocoel of the firebug, Pyrrhocoris apterus, increases the level of AKH in the central nervous system (CNS) and in the haemolymph. The injection of hydrogen peroxide also increases the mortality of experimental bugs, whereas co-injection of hydrogen peroxide with Pyrap-AKH reduces mortality to control levels. Importantly, an increase in haemolymph protein carbonyl (an OS biomarker) levels is decreased to control levels when hydrogen peroxide is co-injected with Pyrap-AKH. Similar results were obtained using in vitro experiments. OS biomarkers such as malondialdehyde and protein carbonyls were significantly enhanced upon exposure of isolated CNS to hydrogen peroxide in vitro, whereas co-treatment of the CNS with hydrogen peroxide and Pyrap-AKH reduces their level significantly. Catalase activity was measured as well and the same pattern was observed. The results of the present study provide strong support on the feedback regulation between oxidative stressors and AKH action, and implicate AKH in counteracting OS.
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Effect of oxidative stress on antioxidant enzymes in \kur{Drosophila melanogaster}.
SZAKOSOVÁ, Klára
Oxidative stress reflects an imbalance between reactive oxygen species and antioxidant defense, which can result in cellular damage. The reactive radicals can interact with cell components, including proteins, lipids and nucleic acid. Antioxidant enzymes are the main defense against oxidative stress, representing by two the most important enzymes, catalase and superoxide dismutase. In this thesis I studied the effect of oxidative stress on activity of antioxidant enzymes in Drosophila melanogaster and Locusta migratoria, after exposure to the herbicide paraquat.
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Antioxidants in Food and Their Function in the Process of Defence Against the Free Radicals Effects
MOUDRÁ, Táňa
The thesis deals with antioxidants in food and their function in the process of defence against the effects of free radicals. At first, antioxidants are defined and their clasification is described in the theoretical part. Then this part deals with antioxidants in food, their effects on people´s health and antioxidants recommended daily doses. Possitive and negative effects of free radicals on people´s health and their relation to antioxidants are mentioned next. In the practical part, I concentrate on the survey focused on the investigation of the population awareness of antioxidants and their effects on health. One hundred and sixty respondents took part in the survey. They were devided into two groups; working people and pensioners. The questionnaire contained twelve questions which investigated the population awareness of the topic. The data collection took place in January 2013 and it was evaluated in February 2013. The collected data were evaluated according to basic statistical methods. The ascertained answers were put into unified tables and then they were compared. Especially, the general awareness was investigated and then the effect of education on the knoledge of the topic was considered.
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Functional analysis of Ssc1 and Iba57 proteins in \kur{Trypanosoma brucei}
SKALICKÝ, Tomáš
Aim of this thesis was to shed light on the function(s) of Iba57 and Ssc1 proteins in both life cycle stages of T. brucei using RNA interference. Depletion of Ssc1 resulted in severe grow phenotype, decrease in activities of iron-sulphur cluster-containing enzyme aconitase but no increase in oxidative stress sensitivity or accumulation of ROS in mitochondrion. Down regulation of Iba57, specialized maturation factor of aconitase and homoaconitase, lead to depletion of aconitase, destabilization of Isa1 and increased sensitivity to oxidative stress and accumulation of ROS in both stages.
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Contribution to the study of insect stress hormones
ALQUICER BARRERA, Glenda Paola
The present study considers the versatile role of adipokinetic hormones (AKHs). Using the firebug Pyrrhocoris apterus as a model insect, the hypothesis that AKHs mediate stress response mechanisms was explored. The outcome indicated that there is a positive feedback regulation between an oxidative stressor action and the level of AKH in insect body, and that AKHs might be involved in the activation of antioxidant protection mechanism. Further results revealed a functional homology between AKH and the mammalian hormone glucagon. The possible effects of glucagon on mobilisation of energy reserves and on elicitation of an antioxidant response to oxidative stress were investigated. As a result, glucagon-immunoreactive material was detected for the first time in the firebug central nervous system and gut. Antioxidant mechanisms are elicited after glucagon treatment but it did not involve mobilization of energy reserves or AKH level changes. As a complement, the existence of a feedback between juvenile hormone and AKH was investigated by topical application of the juvenile hormone analogue methoprene, which influenced the release of AKH from the central nervous system into the haemolymph and induced a partial reduction of lipid content in haemolymph.
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Identification and isolation gene encoding peroxiredoxin, detoxification enzyme involved in antioxidant defense of hard tick Ixodes ricinus.
HAVRAN, Jiří
Antioxidant enzymes play an important role in protection against the oxygen radicals generating during aerobic metabolism, as well as in defense against host immune responses. Peroxiredoxin isolated from the hard tick Ixodes ricinus belongs to 1CysPrx group of peroxiredoxins. It is expressed in all stages of hard tick (larva, nymph and adult) and in all tissues examined. The full gene (EU373821) is 756 nt long and consists of 251 amino acids, encoding 27.94 kDa protein. This is the first report of isolation of detoxification enzyme (peroxiredoxin) involved in antioxidant defense of hard tick Ixodes ricinus.
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Enhanced plant tolerance after ABA application
Pospíšilová, Jana ; Synková, Helena ; Baťková, Petra ; Haisel, Daniel ; Pešek, Bedřich
Critical period during micropropagation is often ex vitro transfer. The aim of this research was to determine whether exogenous abscisic acid (ABA) applied immediately after ex vitro transfer of in vitro grown tobacco regenerants can not only decrease transpiration rate and so partially eliminate their wilting but also ameliorate photoinhibition and oxidative stress. After ABA application, ABA content in tobacco leaves increased considerably, stomatal conductance and transpiration rate decreased more than in control plants and their wilting was limited. Chlorophyll and -carotene contents were higher in these plants, but the content of xanthophyll cycle pigments was not increased. However, the degree of xanthophyll cycle pigments deepoxidation was decreased what also suggested less stress in these plants. Applied ABA stimulated activities of some antioxidative enzymes but not immediately after ex vitro transfer.
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