Made available in DSpace on 2014-08-20T13:33:01Z (GMT). No. of bitstreams: 1 dissertacao_cristian_kaefer.pdf: 618934 bytes, checksum: 3a187e51605cfbd7fbc2329acd8b0568 (MD5) Previous issue date: 2012-02-16 / The outer membrane of mammalian sperm is covered by the glycocalyx, a layer rich in carbohydrates which is crucial for the functions and interactions of male gametes with the extracellular environment. Several factors affect the motility and functional integrity of sperm, being the damage caused by excessive production of reactive oxygen species (ROS), an important factor. Lectins are proteins that bind specifically to carbohydrate residues. These proteins are useful tools for investigating the distribution and changes of membrane glycoconjugates. Studies have investigated the oxidative stress in sperm cells, however, to date, no studies have been conducted to evaluate the effect of plant lectins on oxidative stress in spermatozoa. The present study aimed to investigate the pattern of binding and the effects of lectins ConA, extracted from Canavalia ensiformis, ConBol, extracted from C. boliviana, and ConBr, extracted from C. brasiliensis, on motility, viability, lipid peroxidation, and ROS generation in bovine sperm. The three lectins bound to sperm, but with some differences. It was observed that the lectin ConA did not bind to the equatorial segment located between the acrosomal cap and post-acrosomal region. In 18% of sperm cells labeled with ConBol there was not binding in the acrosome region and 45% of ConBr labeled cells showed a fragmented binding to the sperm head. Sperm incubation with Canavalia lectins produced a decrease in motility. ConA and ConBr demonstrated a strong effect to decline motility soon after incubation (13.3 ± 3.3% in both lectins vs. 60 ± 5.7%) (P<0.05). The lowest motility values found was at the 15 µg/ml concentration after 2h incubation for ConBr (1.6 ±1.7%). The cell viability and lipid peroxidation were not affected by any lectin tested (P>0.05). However, ConA, ConBol and ConBr lectins showed similar behavior causing a increase of ROS production over time compared with control (P<0.05). In conclusion, this study demonstrates that sperm incubation with ConA, ConBol and ConBr lectins induce a decrease in motility and an increase generation of ROS that can led to a spermatozoon dysfunction. / A membrana externa dos espermatozoides de mamíferos é coberta pelo glicocálice, uma camada rica em carboidratos que é crucial para as funções e interações dos gametas masculinos com o ambiente extracelular. Vários fatores afetam a motilidade e a integridade funcional dos espermatozoides, sendo o dano causado pela produção excessiva de espécies reativas de oxigênio (ROS) um importante fator. Lectinas são proteínas que se ligam de forma especifica a resíduos de carboidratos. Essas proteínas são ferramentas úteis para a investigação da distribuição e alteração de glicoconjugados de membrana. Estudos investigaram o estresse oxidativo em células espermáticas, porém, até o momento, não foram realizados trabalhos para avaliar o efeito de lectinas vegetais no estresse oxidativo em espermatozoides. O presente estudo teve por objetivo investigar o padrão de ligação e os efeitos das lectinas ConA, extraída de Canavalia ensiformis, ConBol, extraída de C. boliviana, e ConBr, extraída de C. brasiliensis, na motilidade, viabilidade, peroxidação lipídica, e geração de ROS em espermatozoides bovinos. Foi observado que as três lectinas se ligaram aos espermatozóides, mas com algumas diferenças. A lectina ConA não se ligou ao segmento equatorial, localizado entre a capa acrossomal e a região pós-acrossomal. Em 18% dos espermatozoides marcados com ConBol não houve ligação da lectina na região do acrossoma. Já em 45% das células marcadas com ConBr houve uma ligação de aspecto fragmentado a cabeça do espermatozoide. A incubação com as lectinas do gênero Canavalia produziu um decréscimo na motilidade. ConA e ConBr demonstraram um grande efeito na diminuição da motilidade espermática logo após a incubação (13.3 ± 3.3% em ambas as lectinas vs. 60 ± 5.7%) (P<0.05). A motilidade mais baixa ocorreu com a concentração de 15 µg/ml de ConBr após 2h de incubação (1.6 ±1.7%). A viabilidade celular e a peroxidação lipídica não foram afetadas por nenhuma das lectinas testadas (P>0.05). No entanto, as lectinas ConA, ConBol e ConBr apresentaram comportamento similar causando um aumento na produção de ROS ao longo do tempo comparado com o controle (P<0.05). Em conclusão, este estudo demonstra que as lectinas ConA, ConBol e ConBr ligam-se aos carboidratos de membrana de espermatozoides bovinos e induzem uma diminuição da motilidade e aumento na geração de ROS, que pode levar a perda da função celular.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Oxidative stress is involved in several neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease and amyotrophic lateral sclerosis. Oxidative stress seems to be involved in the pathology of dementia/amnesia. It has been suggested that oxidative stress impairs the muscarinic cholinergic system triggering Alzheimer's disease. The muscarinic antagonist scopolamine has been used to induce amnesia in animals. This experimental model has been used in screening anti-amnesic drugs that could be useful for the treatment of dementia. The aim of this study was to evaluate the possible in vitro antioxidant effect of a series of pyrazoline derivatives newly synthesized: (1) 5-hydroxy-3-methyl-5-trifluoromethyl-4,5-dihydro-1H-carbaldehyde-pyrazole, (2) 5-hydroxy-3-methyl-5- trifluoromethyl-4,5-dihydro-1H-1-acetyl-pyrazole, (3) 5-hydroxy-3-methyl-5-trifluoromethyl-4,5-dihydro-1H-carboxyamide-pyrazole, (4) 5-hydroxy-3-methyl-5-trifluoromethyl-4,5-dihydro-1H-1-benzoyl-pyrazole, (5) 5-hydroxy-3-methyl-5-trifluoromethyl-4,5-dihydro-1H-1-(2- hydroxybenzoyl)-pyrazole and (6) 5-hydroxy-3-methyl-5-trifluoromethyl-4,5-dihydro-1H-1-(4-methoxybenzoyl)-pyrazole. Besides, considering the possible involvement of oxidative stress in dementia, the compound that was the most effective in vitro was assessed concerning to its ability to prevent the memory deficit and oxidative stress in a scopolamine-induced amnesia model. Compound (5) had the highest antioxidant capacity in vitro, since it reduced lipid peroxidation (TBARS) basal and stimulated by the pro-oxidants iron, hydrogen peroxide and sodium nitroprusside, having significant effects from 15 μM onwards (p<0.05). Compound (5) also protected against hydrogen peroxide-induced glutathione oxidation, with a significant effect at the concentration of 150 μM (p<0.05). This compound also had the highest total antioxidant activity, demonstrated by its ability to remove the radical 1,1-dyphenyl-2-pycrylhydrazyl (DPPH). Compounds (1) and (4) also reduced lipid peroxidation basal and stimulated by iron and sodium nitroprusside, having significant effects from 15 μM onwards (p<0.05). Compound (2) had the highest ability to reduce iron (p<0.05). Scopolamine administration 30 min before training session resulted in shorter latency to step-down during the test session of the inhibitory avoidance task (p<0.05). Pretreatment with pyrazole compound (5) had no effect per se on the step-down latency. However, pretreatment with compound (5) (100 μmol/kg) 30 min before scopolamine did prevent the amnesic effect of scopolamine (p<0.05). No significant effect of scopolamine or pyrazole treatment was observed on any of the oxidative stress markers evaluated (thiobarbituric acid reactive substances, non-protein sulfhydrylic groups content and activity of enzymes superoxide dismutase and catalase) suggesting that the protective effect of compound (5) was not related to a possible antioxidant activity. Results revealed that pyrazole compound (5) has in vitro antioxidant activity as well as neuroprotective activity in a model of amnesia. These findings suggest that compound (5) could be a promising drug for the treatment of Alzheimer´s disease. However, further studies are needed to elucidate the mechanisms involved in the antiamnesic effect of this compound, as well as its effect on other dementia models. / O estresse oxidativo está envolvido em diversas doenças neurodegenerativas importantes, tais como a doença de Alzheimer, a doença de Parkinson e a esclerose lateral amiotrófica. O estresse oxidativo parece estar envolvido na patologia da demência/amnésia, tendo sido sugerido que as alterações cerebrais decorrentes deste causam danos ao sistema colinérgico muscarínico e que desta forma desencadeiam a doença de Alzheimer. A escopolamina, um antagonista muscarínico, tem sido usado para induzir amnésia em animais, em um modelo experimental para a triagem de drogas que poderiam ser úteis no tratamento da demência. O principal objetivo deste estudo foi avaliar o possível efeito antioxidante in vitro de uma série de derivados pirazolínicos recém sintetizados: (1) 5-hidroxi-3-metil-5-trifluorometil-4,5-diidro-1H-carbaldeido-pirazol, (2) 5-hidroxi-3-metil-5- trifluorometil-4,5-diidro-1H-1-acetil-pirazol, (3) 5-hidroxi-3-metil-5-trifluorometil-4,5-diidro-1Hcarboxiamida- pirazol, (4) 5-hidroxi-3-metil-5-trifluorometil-4,5-diidro-1H-1-benzoil-pirazol, (5) 5-hidroxi-3-metil-5-trifluorometil-4,5-diidro-1H-1-(2-hidroxibenzoil)-pirazol e (6) 5-hidroxi-3-metil-5-trifluorometil-4,5-diidro-1H-1-(4-methoxibenzoil)-pirazol. Além disso, considerando o possível envolvimento do estresse oxidativo na demência, foi avaliada a capacidade do composto mais efetivo in vitro, em prevenir o déficit de memória e o estresse oxidativo em um modelo de amnésia induzida por escopolamina. O derivado pirazolínico (5) apresentou maior capacidade antioxidante in vitro, pois foi o mais efetivo para reduzir a lipoperoxidação (TBARS) basal e induzida pelos pró-oxidantes ferro, peróxido de hidrogênio e nitroprussiato de sódio, tendo efeitos significativos a partir de 15 μM (p<0,05). O composto (5) também protegeu a glutationa da oxidação induzida por peróxido de hidrogênio, tendo efeito significativo na concentração de 150 μM (p<0,05). Este composto também foi o que teve maior atividade antioxidante total, demonstrada pela sua capacidade de remover o radical 1,1-difenil-2-picrilhidrazil (DPPH). Os compostos (1) e (4) também reduziram a lipoperoxidação basal e induzida por ferro e nitroprussiato de sódio, tendo efeitos significativos a partir de 15 μM (p<0,05). O composto (2) apresentou a maior capacidade de redução de ferro (p<0,05). A administração de escopolamina 30 min antes do treino provocou amnésia, medida como a redução na latência para descer da plataforma no teste de esquiva inibitória (p<0.05). O pré-tratamento com o composto (5) 30 min antes da escopolamina não apresentou efeito per se na latência, mas preveniu o efeito amnésico da escopolamina, na dose de 100 μmol/kg (p<0.05). Não foi observado efeito significativo da escopolamina ou do composto (5) em qualquer dos marcadores de estresse oxidativo avaliados (substâncias reativas ao ácido tiobarbitúrico, grupos tiólicos não protéicos e atividade das enzimas superóxido dismutase e catalase), sugerindo que o efeito protetor do composto (5) não está relacionado à sua atividade antioxidante. Os resultados obtidos demonstram que o composto (5) apresenta atividade antioxidante in vitro e neuroprotetora em um modelo de amnésia, sugerindo que este composto pode ser promissor para o tratamento da doença de Alzheimer. No entanto, outros estudos são necessários para elucidar os mecanismos envolvidos na ação anti-amnésica deste composto, bem como o seu efeito em outros modelos de demência.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Harpagophytum procumbens, known as devil's claw, is an African plant with numerous therapeutic effects, among which stands out for its powerful anti-inflammatory action, but the mechanism by which exerts its effect is not well elucidated. It is known that reactive oxygen species and / or nitrogen are generated in acute and chronic inflammatory diseases causing high cytotoxicity that leads to tissue damage. Substances with antioxidant action can contribute to control and/or treat the inflammatory process.Thus, the goal of this study was to evaluate the effect of the infusion, the crude extract and fractions of H. procumbens on lipid peroxidation induced by different pro-oxidant agents (Iron or sodium nitroprusside). Furthermore, the effects of the ethyl acetate fraction was also tested on the antioxidant defenses (catalase activity and thiol protein and non-protein levels) and on cellular damage (cerebral cortex slices) induced by different pro-oxidant agents. All extracts prevented lipid peroxidation induced by Fe2+ and sodium nitroprusside. Ethyl acetate fraction of H. procumbens showed great power to protect against lipid peroxidation, prevention of cellular death, and shows ability to maintain the thiol levels and catalase activity in basal standarts. In conclusion, this study demonstrates that one of the possible mechanisms for therapeutic action presented by H. procumbens may be related to its antioxidant action, being was able to protect against oxidative stress and loss of cell viability. Once the relationship of inflammation process with oxidative stress is already well described in the literature, the antioxidant effect can also be found here related to potent anti-inflammatory effect exerted by H. procumbens. However more studies are needed on the mechanisms by which H. procumbens exerts its therapeutic effects. / O Harpagophytum procumbens, conhecido como garra do diabo, é uma planta de origem africana com inúmeros efeitos terapêuticos, entre os quais se destaca a sua potente ação anti-inflamatória, porém o mecanismo pelo qual exerce o seu efeito não está bem elucidado. Sabe-se que espécies reativas de oxigênio e/ou nitrogênio são geradas em doenças inflamatórias agudas e crônicas causando grande citotoxicidade, levando a danos teciduais. Substâncias com ação antioxidante podem contribuir para o controle e/ou tratamento de processos inflamatórios. Deste modo, o objetivo deste trabalho foi avaliar os efeitos da infusão, extrato bruto e frações de H. procumbens sobre a peroxidação lipídica induzida por diferentes agentes pró-oxidantes (Ferro ou Nitroprussiato de Sódio). Além disso, os efeitos da fração acetato de etila também foram testados sobre as defesas antioxidantes (atividade da catalase e níveis de tióis protéicos e não protéicos) e sobre o dano celular (fatias de córtex cerebral) induzido pelos diferentes agentes pró-oxidantes. Todos os extratos preveniram a peroxidação lipídica induzida pelo ferro e nitroprussiato de sódio. A fração acetato de etila de H. procumbens demonstrou maior potência em proteger contra a peroxidação lipídica, prevenir contra a morte celular, além de conseguir manter os níveis de tióis e da enzima catalase nos níveis basais. Em conclusão, este trabalho demonstra que um dos possíveis mecanismos de ação terapêutica apresentado pelo H. procumbens, pode estar relacionando a sua ação antioxidante, sendo este, capaz de proteger contra o estresse oxidativo e a perda da viabilidade celular. Uma vez que a relação do processo inflamatório com o estresse oxidativo já está bem descrita na literatura, o efeito antioxidante aqui encontrado pode estar também relacionado com o potente efeito anti-inflamatório exercido pelo H. procumbens. Porém mais estudos devem ser realizados acerca dos mecanismos pelo qual o H. procumbens exerce os seus efeitos terapêuticos.

Philosophiae Doctor - PhD / This study explores the roles of exogenously applied nitric oxide, exogenously applied caffeic acid and salt stress on the ontioxidant system in cereal (exemplified by maize) and legume (using soybean as an example) plants together with their influence on membrane integrity and cell death. This study investigates changes in H₂O₂ content, root lipid peroxidation, root cell death and antioxidant enzymatic activity in maize roots in response to exogenously applied nitric oxide (NO) and salt stress. This part of the study is based on the partially understood interaction between NO and reactive oxygen species (ROS) such as H₂O₂ and the role of antioxidant enzymes in plant salt stress responses. The results show that application of salt (NaCl) results in elevated levels of H₂O₂ and an increase in lipid peroxidation, consequently leading to increased cell death. The study also shows that by regulating the production and detoxification of ROS through modulation of antioxidant enzymatic activities, NO plays a pivotal role in maize responses to salt stress. The study argues for NO as a regulator of redox homeostasis that prevents excessive ROS accumulation during exposure of maize to salinity stress that would otherwise be deleterious to maize. This study extends the role of exogenously applied NO to improve salt stress tolerance in cereals crops (maize) further to its role in enhancing salt stress tolerance in legumes. The effect of long-term exposure of soybean to NO and salt stress on root nodule antioxidant activity was investigated to demonstrate the role of NO in salt stress tolerance. The results show that ROS scavenging antioxidative enzymes like SOD, GPX and GR are differentially regulated in response to exogenous application of NO and salt stress. It remains to be determined if the NO induced changes in antioxidant enzyme activity under salt stress are sufficient to efficiently reduce ROS accumulation in soybean root nodules to levels close to those of unstressed soybean root nodules. Furthermore, this study investigates the effect of long-term exposure of soybean to exogenous caffeic acid (CA) and salt stress, on the basis of the established role of CA as an antioxidant and the involvement of antioxidant enzymes in plant salt stress responses. The effect of CA on soybean nodule number, biomass (determined on the basis of nodule dry weight, root dry weight and shoot dry weight), nodule NO content, and nodule cyclic guanosine monophosphate (cGMP) content in response to salt stress was investigated. Additionally, CA-induced changes in nodule ROS content, cell viability, lipid peroxidation and antioxidant enzyme activity as well as some genes that encode antioxidant enzymes were investigated in the presence or absence of salt stress. The study shows that long-term exposure of soybean to salt stress results in reduced biomass associated with accumulation of ROS, elevated levels of lipid peroxidation and elevated levels of cell death. However, exogenously applied CA reversed the negative effects of salt stress on soybean biomass, lipid peroxidation and cell death. CA reduced the salt stress-induced accumulation of ROS by mediating changes in root nodule antioxidant enzyme activity and gene expression. These CA-responsive antioxidant enzymes were found to be superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), and glutathione reductase (GR), which contributed to the scavenging of ROS in soybean nodules under salt stress. The work reported in Chapter 2 has been published in a peer-reviewed journal [Keyster M, Klein A, Ludidi N (2012) Caspase-like enzymatic activity and the ascorbate-glutathione cycle participate in salt stress tolerance of maize conferred by exogenously applied nitric oxide. Plant Signaling and Behavior 7: 349-360]. My contribution to the published paper was all the work that is presented in Chapter 2, whereas the rest of the work in the paper (which is not included in Chapter 2) was contributed by Dr Marshall Keyster.

Philosophiae Doctor - PhD

Chronic pancreatitis (CP) is a heterogeneous disease defined as chronic inflammatory changes of the pancreatic tissue caused by variety of aetiologies. Oxidative stress accompanying the inflammatory processes has been suggested as an important factor contributing to CP development. The aim of this study was to determine levels of lipid peroxidation products malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), together with nitrites, the total antioxidant capacity, cytokines, biochemical and haematological parameters in the plasma of patients with CP and control subjects. Levels of MDA and 4-HNE were analyzed using high-performance liquid chromatography. The total antioxidant capacity of plasma against peroxyl radicals was evaluated using chemiluminescence determination. Nitrites were determined using Griess reaction. Cytokines - TNF-alfa; TNF RI; PDGF-AB; TGF-beta, together with myeloperoxidase and hyaluronan were determined using ELISA Kits. Biochemical and haematological parameters were measured by standard methods.

Magister Scientiae (Biodiversity and Conservation Biology) / Wheat is a key global commodity in terms of acreage and tradeable value and as a staple in household diets. Many factors including biotic stress conditions have detrimental effects on global wheat production and yield. The increasing prevalence of biotic stress inflicted by fungal species such as Fusarium has significantly reduced yield and quality of cereal crops thus, threatening sustainable agriculture and food security. Interactions between wheat and Fusarium spp. such as Fusarium proliferatum triggers the accumulation of reactive oxygen species (ROS) to levels toxic to the plant thus leading to oxidative damage and ultimate cellular death. In order to maintain redox homeostasis, plants rely on ROS-scavenging antioxidants (enzymatic and non-enzymatic) to control ROS molecules to levels less toxic to plants. This study investigated the impact of F. proliferatum on the physio-biochemical responses of two wheat cultivars (SST 015 and SST 088). Changes in seed germination, growth, biomass, chlorophyll and mineral contents were monitored. Furthermore, changes in ROS accumulation and antioxidant enzyme activity was measured in the shoots of both wheat cultivars.

>Magister Scientiae - MSc / Biotic stress is one of the main causes for agricultural loss of economically important cereal crops. The increasing prevalence of biotic stress inflicted by fungal species such as Fusarium has significantly reduced yields and quality of cereals, threatening sustainable agriculture and food security worldwide. Interactions between wheat and Fusarium spp. such as Fusarium oxysporum promotes the accumulation of reactive oxygen species (ROS). Overproduction of ROS can become toxic to plants depending on the scavenging ability of antioxidant systems to maintain redox homeostasis. This study investigated the effects of F. oxysporum on the physiological and biochemical response of three wheat cultivars namely, SST 056, SST 088 and SST 015. Physiological responses were monitored by measuring changes observed in plant growth parameters including shoot and root growth and biomass, relative water content as well as photosynthetic metabolism and osmolyte content in all three wheat cultivars. Downstream biochemical analysis involved monitoring the accumulation of ROS biomarkers (superoxide and hydrogen peroxide) as well as the detection of enzymatic activity of superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POD). These biochemical responses were only monitored on the two wheat cultivars which presented contrasting responses to F. oxysporum infection. Results showed that F. oxysporum significantly reduced plant growth, biomass, chlorophyll pigments and relative water content of all three cultivars, with the highest reduction observed for SST 088 relative to SST 015 and SST056. On the other hand, proline content was significantly enhanced in all three wheat cultivars, with the highest increase observed for SST 015 relative to SST 056 and SST 088. Based on the contrasting physiological results observed for these three cultivars, downstream biochemical analysis was focused on SST 015 and SST 088. F. oxysporum trigged an increased in superoxide and hydrogen peroxide contents in both cultivars, with the highest increase observed for SST 088. A similar trend was observed for the extent of lipid peroxidation, manifested as enhanced MDA levels. Furthermore, F. oxysporum differentially altered antioxidant enzyme activity relative to the control of both wheat cultivars. A Significant increase in SOD activity was observed for both cultivars in response to F. oxysporum. However, contrasting responses in APX and POD activity (as seen for the band intensities of individual isoforms) was observed in these wheat cultivars in response to F. oxysporum. Based on the results obtained in this study we suggest that F. oxysporum infection has varying degrees of severity in different wheat cultivars. In light of the significant reduction of plant development coupled with enhanced ROS accumulation and differential antioxidant capacity for SST 015 relative SST 088, we suggest that SST 015 is more resilient to F. oxysporum. We thus conclude that a direct relationship exists between ROS accumulation and antioxidant scavenging in regulating plant tolerance against F. oxysporum pathogens.

Masters of Science / In this study, we observed that phosphate (P) deficiency stunted plant growth and produced plants with poor morphological characteristics (yellow and small leaves). Furthermore, we treated plants with 0.8 mM (control) and 0.02 mM P (deficient) in addition to 6 μM methylglyoxal (MG) and we observed that the plants treated with MG had a higher germination, and better morphological characteristics (the leaves were more dark green and bigger in size) compared to the P deficient plants. However, we also observed that the P deficient plants treated with MG had low levels of both O2- and H2O2 and this could be a possible reason for the improved growth and morphological characteristics. In contrast, the P deficient plants not treated with MG had high levels of O2- and H2O2 which could be the possible reason for the observed cell death. We also performed biochemical assays including superoxide dismutase, ascorbate peroxidase, malondialdehyde content, ascorbic acid content, catalase, and most of the assays showed high levels of reactive oxygen species (ROS) and low levels of antioxidant activities in plants not treated with MG while high levels of antioxidant activities and low levels of ROS were observed in plants treated with exogenous MG. Since nitric oxide (NO) is also known to be a signalling molecule, we did a NO assay and observed that NO content increased under low exogenous doses of MG. From our findings we came to a hypothesis that MG modulates P deficiency stress in P. vulgaris through NO signalling or it might be that NO and MG work in tandem to modulate signalling pathways under P deficiency. Finally, we looked at the nutrient profile and the results showed that while there was a poor nutrient profile generally under P deficiency, there was an improvement in nutrient profile when MG was administered at low doses.

<p><strong>Apstrakt je obrađen tehnologijama za optičko prepoznavanje teksta (OCR).</strong></p><p>Ispitan je uticaj heksanskih, etanolnih i etil-acetanih ekstrakata zrna soje i punomasnih hraniva od zrna soje, ekstrudiranog sojinog griza i hidrotermički tretiranog zrna soje, na termičku i katalitičku oksidaciju metil-linoleata primenom ESR spektroskopije i &quot;spin- traping&quot; tehnike. Utvrđeno je da ispitivani ekstrakti inhibiraju termičku i katalitičku oksidaciju metil-linoleata različitim mehanizmima antioksidativnog delovanja. Ustanovljeni antioksidativni efekti dovedeni su u vezu sa vrstama i sadržajem liposolubilnih (a-tokoferol, P-karotin, ukupni ksantofili) i neliposolubilnih antioksidanata (izoflavoni i fitinska kiselina) soje, odnosno u vezu sa termičkim tretmanima primenjenim u proizvodnji ovih hraniva. Ispitani su i uticaji primene različitih rastvarača (etil-acetat, etanol, acetonitril) na antioksidativne efekte ekstrakata neliposolubilnih antioksidanata punomasnih hraniva od zrna soje tokom termičke i katalitičke oksidacije sojinog ulja primenom ESR.</p> / <p><strong>Abstract was processed by technology for Optical character recognition (OCR).</strong></p><p>The influence of hexane, ethanol and ethyl acetate extracts of soybean grain and full-fat feeds of soybean grain, fullfat extruded soybean grits and hydrothermal treated soybean grain on the thermal and catalytic oxidation of methyl linoleate has been studied by ESR spectroscopy and spin-trapping method. It has been found that the investigated extracts inhibit the thermal and catalytic oxidation of methyl linoleate through different mechanisms of antioxidation action. The antioxidative effects found were related to the kinds and contents of soybean liposolubile (a-tocopherol, P-carotene, total xanthophyls) and nonliposolibile antioxidants (isoflavones, phytic acid), that is, they were put in relation to thermal treatments used in production of these feeds. The effects of the application of different solvents on the antioxidative actions of the extracts of nonliposolubile antioxidants of full-fat soybean feeds during thermal and catalytic oxidation of soybean oil have been studied by ESR.</p>