O pequi caracteriza-se por possuir expressiva quantidade de compostos fenólicos, que por apresentarem propriedades antioxidantes estão associados com a prevenção da formação de radicais livres. Além de ser consumido in natura, é também comumente consumido na forma processada. No entanto, sabe-se que os antioxidantes presentes nos vegetais podem ser afetados pela forma de processamento e provocam alterações dos teores de fenólicos totais (FT) bem como da sua atividade antioxidante. Este trabalho objetivou avaliar o teor de FT e as propriedades antioxidantes da polpa do pequi processado e in natura. Foram obtidos os extratos alcoólicos (EALC) e aquosos (EAQ), a partir de amostras liofilizadas de diversas polpas de pequi processado (em conserva) e também do in natura, bem como as frações de ácidos fenólicos livres (AFL), ésteres solúveis de ácidos fenólicos (AFS) e ésteres insolúveis de ácidos fenólicos (AFI) de pequi processado (CB1). Os EALC e EAQ, além dos líquidos provenientes das conservas (LC), foram avaliados quanto aos teores de FT, onde se verificou que os EAQ do pequi in natura, principalmente, e do processado tiveram um maior conteúdo de FT quando comparados aos EALC. Os LC, por sua vez, apresentaram valores médios ainda maiores que os EAQ. Com relação ao teor de FT das frações, a AFL se destacou diante da AFS e AFI. Os extratos, LC e frações foram avaliados quanto à atividade antioxidante in vitro pelo sistema β-caroteno/ácido linoléico e também pelo ensaio do radical DPPH• (2,2 difenil-1-picril-hidrazila). No primeiro, verificou-se que os EAQ e LC do pequi apresentaram maior atividade que os EALC. Foi observada ainda atividade elevada em todas as frações analisadas. No segundo ensaio pelo método do radical DPPH•, pode-se observar que os extratos aquosos do pequi in natura apresentaram maior atividade, enquanto que, no pequi processado, os extratos alcoólicos e os líquidos das conservas tiveram melhores resultados. Verificou-se também que a AFL possui atividade superior às outras frações. De uma maneira geral, os resultados do pequi processado foram inferiores aos do pequi in natura tanto em relação aos teores de FT como na atividade antioxidante. Verificando-se ainda, que isto se deve principalmente à perda dos FT da polpa, indicando que houve lixiviação destes compostos para os LC. / Pequi characterized by having a significant amount of phenolic compounds, that are related with its antioxidant properties that are associated with the prevention of free radicals. Besides being eaten fresh, it is also widely consumed in processed form. However, it is known that the antioxidants present in plants can be affected by processing form and cause changes in the levels of total phenolic content (FT) and the antioxidant activity. The objective of this study was to evaluate the content of phenolic compounds and the antioxidant properties of the pequi pulp processed and fresh. Were obtained the alcoholic (EALC) and aqueous (EAQ) extracts from lyophilized samples of various pulps pequi processed (canned) and also in nature, as well as the fractions of free phenolic acids (AFL), soluble esters of phenolic acids (AFS) and insoluble esters of phenolic acids (AFI) of processed pequi (CB1). The EALC and EAq, besides the liquid from the canned (LC) were evaluated for the levels of FT, where it was found that the EAQ of the pequi in nature, mainly, and of the processed had, in general, a higher content of FT compared to EALC. The LC, in turn have showed that even greater EAQ. Regarding the content of FT of the fractions, the AFL stood in front of the AFS and AFI. The extracts, LC and fractions were also evaluated for their antioxidant activity in vitro by the system β-caroteno/ linoleic acid and by test DPPH• (2,2-diphenyl-1-picryl hydrazyl). At first, it was found that the LC and EAQ of the pequi showed greater activity than the EALC. Still high activity was observed in all fractions analyzed. In the second test, we can observe that the EAQ of the pequi in nature showed greater activity, whereas in pequi processed, the EALC and LC had better results. It was also noted that the AFL has superior activity to other fractions. In general, the results of pequi processed were lower than in fresh pequi both in relation to content of FT as antioxidant activity. Verifying also, that this is mainly due to the loss of FT of the pulp, indicating that there was leaching of these compounds to the LC.

A vida útil do filé de salmão fresco é em grande parte limitada pela deterioração microbiana, proteolítica e oxidativa. Esse trabalho visou estudar o efeito do filme de quitosana adicionado ou não do extrato de resíduo agroindustrial de pimenta rosa (Schinus terebinthifolius Raddi) sobre a vida útil e qualidade de salmão do Atlântico (Salmo salar) fresco, embalado em atmosfera modificada (AM, 100% CO2), durante 28 dias. Os filés de salmão (± 300 g) com 11 dias post mortem sem pele e sem ossos foram embalados em 100% de dióxido de carbono (CO2), submetidos aos tratamentos: sem filme (TC), com filme de quitosana (TFQ) e com filme de quitosana adicionado do extrato de resíduo agroindustrial de pimenta rosa (TFQPR), armazenados a 2 ± 1° C e sem exposição à luz por 0 (11 dias), 7, 14, 21 e 28 dias. Após cada período de armazenamento, nove bandejas de cada tratamento foram analisadas de acordo com parâmetros físico-químicos (pH, cor, capacidade de retenção de água (CRA), perfil de textura (PT), bases voláteis totais (BVT), trimetilamina (TMA), estabilidade oxidativa, perfil de ácidos graxos (PAG), degradação de ATP e seus catabólitos), microbiológicas (microrganismos aeróbios mesófilos e psicrotróficos, bactérias láticas, coliformes totais e termotolerantes) e sensoriais. O estudo foi conduzido por um delineamento inteiramente casualizado com arranjo fatorial (3 tratamentos x 5 tempos de armazenamento), considerado como parcela o filé de salmão embalado em atmosfera modificada, com 3 repetições. Os dados foram analisados no ambiente R, a fim de verificar o efeito de tempo, tratamento e tempo x tratamento. Durante o armazenamento, o pH oscilou para os três tratamentos. Observou-se a descoloração dos filés de salmão devido à oxidação dos carotenoides astaxantina e cantaxantina, presentes no músculo do pescado. Ao longo do armazenamento, CRA foi reduzida, influenciando no perfil de textura das amostras. Os filés de salmão tornaram-se mais macios devido à proteólise muscular e a ação de microrganismos deteriorantes presentes. Os dados de oxidação lipídica foram baixos e não influenciou no PAG do salmão - considerando que o salmão é uma boa fonte de ácidos graxos poli-insaturados da série ômega-3. Os microrganismos deteriorantes analisados aumentaram ao longo do armazenamento, porém não ultrapassaram os limites recomendados pela ICMSF, bem como a contagem dos microrganismos patógenos. A análise sensorial permitiu verificar as mudanças nos filés de salmão ao longo do armazenamento, porém não houve diferença significativa entre os tratamentos. Em conclusão, o filme ativo foi eficiente na manutenção da qualidade e vida útil dos filés de salmão embalados com AM durante 28 dias de armazenamento, em comparação com o grupo controle (TC). / Shelf-life of the fillet of fresh salmon is greatly limited by microbial, proteolytic and oxidative deterioration. This research aimed to study the effect of chitosan active films and the addition of agro-industrial residue of pink pepper (Schinus terebinthifolius Raddi) on this film on fresh Atlantic salmon (Salmo salar) shelf-life and quality packaged in modified atmosphere packaging (MAP, 100% CO2) during 28 days. Skinless and boneless salmon fillets (± 300 g) with 11 days post mortem were packaged in 100% carbon dioxide (CO2) MAP according to three treatments: without chitosan film (TC), with chitosan film (TFQ) and with chitosan film added with agro-industrial residue of pink pepper (TFQPR), stored at 2 ± 1° C and under dark condition for 0 (11 days),7, 14, 21, and 28 days. After each retail day, 9 trays of each treatment were analyzed according to physical-chemical (pH, color, water holding capacity (WHC), texture profile (TP), total volatile basic nitrogen (TVB-N), trimethylamine (TMA), oxidative stability, fatty acid profile (FAP), and ATP and ATP-catabolites quantification), microbiological (the content of mesophilic, psychrotrophic, lactic, thermotolerant bacteria and total coliform), and sensory parameters. This research used Completely Randomized Design (CRD) with a factorial arrangement (3 treatments x 5 five storage time), considering the packaged salmon fillet as a research unity, with 3 repetitions. Data was analyzed on R environment, in order to verify time, treatment and time x treatment effects. During storage, pH oscillated for the three treatments. The salmon fillets discolored due to the carotenoids astaxanthin and canthaxanthin oxidation, which are present in fish muscle. Along storage time, WHC reduced, influencing on sample texture profile. Salmon fillets softened, which is possibly resulting from muscle proteolysis and from spoilage bacteria action. Lipid oxidation data were low and did not influence on salmon FAP - considering that salmon is a good source of omega-3 poly-unsaturated fatty acid. Fish spoilage bacteria increased along storage, but it was not higher than the legal limit established by ICMSF, as well as pathogen bacteria. Sensory analysis revealed overall changing on salmon fillets during storage. In conclusion, active film was efficient in the maintenance of quality and shelf-life of MAP-packaged salmon fillets during 28 days of storage, compared to control group (TC).

O crescimento da produção e comercialização de pescado gera um aumento considerável na quantidade de resíduos. A escassez de reutilização e as formas incorretas de descarte tem sido preocupação constante das indústrias e dos pesquisadores, que buscam soluções para a melhor destinação dos mesmos. Buscando o conceito de empresa eco eficiente, são propostos tratamentos que levem à obtenção de coprodutos. A produção de \"farinha de peixe\" é a forma de aproveitamento do resíduo mais utilizada, porém apresenta baixo valor comercial. A elaboração de hidrolisados proteicos apresenta-se como uma alternativa de maior valor agregado. A clivagem proteica realizada por enzimas específicas pode gerar peptídeos biologicamente ativos, que apresentam propriedades funcionais e medicinais, bem como atividade antioxidante. O objetivo deste trabalho foi a elaboração e caracterização de hidrolisados proteicos de cabeças de tilápia (Oreochromis niloticus), a aferição da atividade antioxidante destes e sua relação com o tamanho de peptídeos, como forma de se obter e disponibilizar coprodutos, visando a sustentabilidade da cadeia produtiva desta espécie. O hidrolisado proteico de tilápia (HPT) foi obtido por hidrólise enzimática e empregando as enzimas Neutrase (Protemax NP-800), Papaína (Brauzyn-100) e Pepsina nos tempos 30, 60 e 120 minutos. O grau de hidrólise foi determinado através da metodologia com utilização do o-ftaldialdeído. A atividade antioxidante foi avaliada pelos ensaios do DPPH e ABTS+. O perfil de peptídeos foi avaliado através da separação por cromatografia em gel com coluna Superdex peptide. O grau de hidrólise para os tratamentos com a neutrase (30 min, 60 min, 120min) variou de 11,3% a 14,1%. No tratamento com a papaína (30 min, 60 min, 120 min) o grau de hidrólise foi superior ao observado com a enzima neutrase, apresentando variação de 21,14%a 25,28%. A variação para o tratamento com a pepsina (30 min, 60 min e 120 min) foi de 10,18% a 14,97% Todos os hidrolisados apresentaram propriedade antioxidante através da inibição de radicais livres, mesmo a concentrações baixas de hidrolisado. A inibição de 50% (EC50) dos radicais na metodologia de DPPH ocorreu com concentrações inferiores a 3mg/mL para todos os tratamentos, sendo a menor concentração 1,36 mg/mL (pepsina 120 min) e a maior 2,70 mg/mL (neutrase 30 min). Na metodologia de ABTS, concentrações superiores foram necessárias para a inibição de 50% dos radicais, porém ainda assim foram inferiores a 5%. A menor concentração foi 3,58 mg/mL (pepsina 120 min) e a maior foi de 4,49 mg/mL (neutrase 60 min). O tamanho das cadeias de peptídeos para a maioria dos tratamentos se situou entre cadeias de 1000 a 10000Da, sendo que o tratamento com pepsina promoveu porcentagem de peptídeos com maior peso molecular seguido pela neutrase. A papaína foi a enzima que promoveu maior clivagem de proteína e menores tamanhos de peptídeos, localizados na faixa de 100 a 1000 Da, valor relacionado ao seu maior grau de hidrólise. As propriedades observadas nos hidrolisados elaborados indicam que este pode ser um potencial suplemento alimentício devido ao seu elevado valor proteico, aditivos para conservação de alimentos e ainda aplicados na indústria farmacêutica. / The growth in production and marketing of fish generates a considerable increase in the amount of waste. The scarcity of re-used products and incorrect disposal forms has been a constant concern of industries and researchers who seek solutions for better allocation thereof. Seeking an efficient eco company concept, proposed treatments are leading to obtaining co-products. The production of \"fish meal\" with the residues is the most common use for the waste, but has a low commercial value. The preparation of protein hydrolysates is presented as an alternative with higher added value. The protein cleavage performed by specific enzymes can generate biologically active peptides which exhibit functional and medicinal properties as well as antioxidant activity. The objective of this work was the preparation and characterization of protein hydrolysates of tilapia (Oreochromis niloticus) , the measurement of antioxidant activity of these and its relation to the size of peptides as a way to obtain and provide co-products , aimed at the sustainability of the chain production of this species. The protein hydrolyzate of tilapia (HPT) was obtained by enzymatic hydrolysis and employing the enzyme Neutrase (Protemax NP- 800), Papain (Brauzyn - 100) and Pepsin at 30, 60 and 120 minutes. The degree of hydrolysis was determined using o- phthaldialdehyde . In the treatment with papain (30 min, 60 min, 120 min) the degree of hydrolysis was higher than that observed with Neutrase enzyme, showing variation of 21.14% to 25.28%. The variation for treatment with pepsin (30 min, 60 min and 120 min) was 10.18% and 14.97% hydrolyzed. All samples showed antioxidant properties through inhibition of free radicals, even at low concentrations hydrolyzate. The 50% inhibition (EC50) of the DPPH radical methodology occurred at concentrations below 3 mg / ml for all treatments, being the lowest concentration 1.36 mg / ml (lot 120 min) and the largest 2.70 mg / ml (Neutrase 30 min). In the ABTS method, higher concentrations were required for 50% inhibition of the radical, but still was less than 5%. The lowest concentration was 3.58 mg / mL (120 pepsin min) and the largest was 4.49 mg / mL (Neutrase 60 min). The size of the peptide chains to most treatments ranged from 1000 to 10000Da chains, whereas treatment with pepsin promoted percentage of peptides of higher molecular weight followed by Neutrase. The papain was the enzyme cleavage that generated more protein and peptides of smaller size, situated in the range from 100 to 1000 Da, which is related to the higher degree of hydrolysis. The properties observed in hydrolysates produced indicate that this is a potential food supplement because of its high protein value for food preservation additives, and applied in the pharmaceutical industry.

Magister Pharmaceuticae - MPharm / Hypertension is by far the most common risk factor for cardiovascular disease (CVD), which has been identified as the leading cause of death worldwide and a major economic burden in developing countries. Over the years, there has been an increased interest in isolating and identifying bioactive compounds from medicinal plant, with the aim of finding alternative sources of therapy to some of the problematic synthetic drugs and to validate the therapeutic use of some traditional plants. The renin angiotensin aldosterone system is a key regulator of blood pressure, on which ACE (Angiotensin Converting Enzyme) inhibitors act and have been at the forefront of therapeutic strategy for treatment and management of hypertension and CVD. But despite the success of ACEI’s, their long term use has been associated with side- effects coupled with its contraindication in pregnancy. The plant of interest, Centella asiatica is a widely known medicinal plant, used in treatment of a variety of conditions including hypertension. There is currently no scientific evidence validating its claimed use in hypertension. This study therefore, investigated the ACE inhibitory effects of Centella asiatica. Crude methanol, ethanol and aqueous extracts of Centella asiatica were assayed for ACE inhibition activity. Methanol and ethanol crude extract(s) was subjected to a bioassay guided fractionation process to isolate and identify the active compounds. A fluorescence based ACE assay was utilized at various stages of the process including HPLC purification stage to screen the fractions and compounds for ACE inhibition activity.

Phospholipids can regenerate oxidized tocopherols and help delay lipid oxidation. The impact of emulsifier type, tocopherol homologue and phospholipid head group on tocopherol-phospholipid interaction was investigated in this study. Three µmol tocopherol/kg emulsion and 15.0µmol/kg emulsion of PE or PS were dissolved in oil and emulsions were prepared. Tween 20 or bovine serum albumin(BSA) was used as emulsifier and the continuous phase contained 10mM imidazole/acetate buffer at pH 7. Lipid hydroperoxides and hexanal were measured as lipid oxidation products and the lag phase was determined. With Tween 20 as the emulsifier, α and δ-tocopherol had a hexanal lag phase of 2 and 4 days respectively. PE and PS both extended the lag phase to 7 and 10 days respectively in presence of δ-tocopherol. Whereas, PS extended the lag phase to 6 days and PE could not exhibit any synergism with α-tocopherol. With BSA as the emulsifier, α and δ-tocopherol had a lag phase of 4 days. PE and PS extended the lag phase to 11 days and 10 days respectively in presence of δ-tocopherol and to 7 and 8 days respectively in presence of α-tocopherol. PE and PS both exhibited synergism with mixed tocopherol and the extent of synergism was in less than δ-tocopherol but more than α-tocopherol. Phospholipids could potentially be used with tocopherols to improve the oxidative stability of emulsions. PE was more effective with BSA whereas PS was equally effective with both emulsifiers.

Neurodegenerative diseases occur as a result of the breakdown and deterioration of the neurons of the central nervous system (CNS). They are commonly found in elderly people and are a major cause of morbidity and mortality, thereby imposing severe strains on the social welfare systems. Alzheimer’s disease (AD) is the most common age-related neurodegenerative disorder. Cholinergic deficit, senile plaque/amyloid-β peptide deposition and oxidative stress have been identified as three main pathogenic pathways which contribute to the progression of AD. The current therapeutic options cause several side-effects and have problems associated with bioavailability. Therefore, the need arises to search for new compounds from natural products with potential to treat AD. Seventeen plants were selected for this study based on their documented ethno-medicinal use in improving memory, to treat insomnia, calm agitated people, and other neurological disorders. The plants were screened for inhibition of acetylcholinesterase (AChE) using the TLC and microtiter plate method. A dose-dependent inhibition of the enzyme was observed and 4.5% of all the plants showed low (<30% inhibition) AChE inhibition. The ethyl acetate extracts of the roots of Crinum bulbispermum, Xysmalobium undulatum, Lannea schweinfurthii, Scadoxus puniceus and bulbs of Boophane disticha had the best AChE inhibition. Although the IC50 of these plant extracts were higher than that of the positive control, galanthamine (0.00053 mg/ml), they showed good AChE inhibitory activity considering they are still mixtures containing various compounds. The antioxidant activity of the plant extracts was determined by their ability to scavenge ABTS (2,2´-azinobis-3-ethylbenzothiazoline-6-sulfonic acid) and DPPH (1,1-diphenyl-2-picryl- hydrazyl) radicals. The dichloromethane/methanol (1:1) extracts of Chamaecrista mimosoides (root), Buddleja salviifolia (whole plant), Schotia brachypetala (root and bark), water extracts of Chamaecrista mimosoides (root), Buddleja salviifolia (whole plant), Schotia brachypetala (root and bark) and methanol extracts of the roots of Crinum bulbispermum, Piper capense, Terminalia sericea, Lannea schweinfurthii and Ziziphus mucronata all showed good antioxidant activity (>50%), in both assays. B. disticha contained very promising AChE inhibition and was subjected to isolation of active compounds using thin layer chromatography, column chromatography and preparative thin layer chromatography. Two compounds, 6-hydroxycrinamine (a crinine-type alkaloid) and cycloeucalenol (a cycloartane triterpene), were isolated for the first time from the bulbs of this plant. 6-Hydroxycrinamine, and two fractions, EAM 17-21 21,22 and EAE 11 (which could not be purified further due to low yield), were found to inhibit AChE with IC50 values of 0.445 ± 0.030 mM, 0.067 ± 0.005 mg/ml and 0.122 ± 0.013 mg/ml, respectively. Cytotoxicity of the isolated compounds and two active fractions was determined on human neuroblastoma (SH-SY5Y) cells using the MTT and neutral red uptake assays. 6- hydroxycrinamine and fraction EAM 17-21 21,22 were found to be toxic with IC50 values of 54.5 μM and 21.5 μg/ml as determined by the MTT assay. The isolated compounds and fractions did not show any protective effect against cell death induced by Aβ25-35 possibly due to the poor antioxidant activity of B. disticha bulbs. Cytotoxicity was also determined for the methanol extracts of the roots of C. bulbispermum, T. sericea, L. schweinfurthii and Z. mucronata, as they contained promising antioxidant activity. C. bulbispermum was the most toxic, reducing cell viability by <40% at the highest concentration tested. Z. mucronata and L. schweinfurthii were the least toxic with IC50 values exceeding 100 μg/ml, the highest concentration tested. Three concentrations of the plant extracts that were not toxic, or presented low toxicity, were selected to evaluate their possible protective effect against cell death induced by Aβ25-35. Pretreatment with Z. mucronata and T. sericea roots showed a dose dependent inhibition of cell death caused by Aβ25-35. Pre-treatment with L. schweinfurthii roots resulted in an optimum dose for inhibition of Aβ25-35 induced cell death at 25 μg/ml, while still maintaining 80% viability. The roots of C. bulbispermum at non-toxic dose still maintained >50% viability. This study confirms the neuroprotective potential of some of the plants which had AChE inhibitory and antioxidant activity. In addition, four of the plants were shown to prevent cell death caused by Aβ25-35. These plants can serve as potential leads in developing drugs relevant to treatment of AD. Furthermore, two new compounds present in the bulbs of B. disticha were identified. Additional investigations need to be carried out by applying QSAR studies to modify the structure of the alkaloid with the aim of reducing its observed toxicity. / Thesis (PhD)--University of Pretoria, 2012. / Pharmacology / unrestricted

Antimicrobial peptides (AMPs) have been identified as important therapeutic agents that can be developed as new multifunctional antibiotic compounds, which may address antibiotic resistance. AMPs have a wide range of bioactivities, including antimicrobial, antioxidant, anti-inflammatory and anticancer properties. Os and Os-C (a derivative of Os, lacking cysteine residues) are two synthetic AMPs derived from the tick defensin OsDef2 which have been shown to have antibacterial, antioxidant and anti-inflammatory activity. Differences in bacterial killing times between these peptides indicate differences in the modes of bacterial killing. For the further development of Os and Os-C for therapeutic application, the aim of this study was to establish the mode of bacterial killing, to determine if these peptides are cytotoxic to human erythrocytes and leukocytes. Lastly, to determine if these peptides have additional beneficial cellular effects such as antioxidant activity. Ultrastructural analysis with electron microscopy techniques revealed that both peptides adversely affected the membranes and intracellular structures of both Gram-negative Escherichia coli and Gram-positive Bacillus subtilis bacteria. Effects included membrane ruffling, cytoplasmic retraction, intracellular granulation and the formation of dense fibres. At the minimum bactericidal concentrations (MBCs) of 0.77 μM for Os and 1.74 μM for Os-C membrane permeabilisation measured with the SYTOX green assay was found not to be the principle mode of action. In stationary phase bacteria, fluorescent triple staining showed that both peptides caused permeabilisation. Studies using fluorescently labelled peptides revealed that the membrane penetrating activities of Os and Os-C were similar to buforin II, a cell-penetrating peptide. Os was able to enter stationary phase E. coli and B. subtilis while Os-C was unable to enter E. coli cells and accumulated on B. subtilis septa. Using plasmid binding and fluorescence displacement assays both peptides could bind DNA, while a dosage effect was only observed for Os. Evaluation of cytotoxicity revealed that Os and Os-C caused no erythrocyte haemolysis or changes to erythrocyte morphology. Only the highest concentration of Os (100 μM), which is 130 fold greater than the MBC for E. coli and B. subtilis, caused cellular damage to peripheral mononuclear (MN) and polymorphonuclear (PMN) cells. In contrast, Os-C caused leukocyte activation identified by associated morphological features and reactive oxygen species (ROS) formation. Chemical and erythrocyte antioxidant assays indicated that both Os and Os-C had antioxidant activity. Both peptides provided extracellular protection of erythrocytes against 2,2'-azobis(2-amidinopropane) dihydrochloride induced oxidative damage. In MN and PMN cells Os showed low levels of antioxidant activity while Os-C had minimal activity. In conclusion, both peptides showed a dual mechanism of bacterial killing, targeting both the membrane and intracellular elements. Os had a predominant membrane effect while Os-C targeted the septa of B. subtilis and had a higher affinity for DNA. Cytotoxicity in erythrocytes and leukocytes was minimal. In addition, Os exhibited antioxidant properties while Os-C caused leukocyte activation. Both peptides have been identified as promising therapeutic agents although activity in plasma and the effect on coagulation must still be determined. / Thesis (PhD)--University of Pretoria, 2017. / Anatomy / PhD / Unrestricted

Charles University in Prague, Faculty of Science Department of Experimetnal Plant Biology Ph.D. study program: Plant physiology and anatomy Abstract Antioxidant enzymes response to abiotic stress. Impact of decreased cytokinin level. Zuzana Lubovská Supervisor: RNDr. Naďa Wilhelmová, CSc. Supervisor-consultant: RNDr. Helena Štorchová, CSc. Praha, 2015 The response of the antioxidant enzyme system to drought, heat and a combination of these stresses was followed in tobacco plants overexpressing cytokinin oxidase/dehydrogenase1 (CKX1) under the root-specific WRKY6 promoter (W6:CKX1 plants) and under the constitutive 35S promoter (35S:CKX1 plants) and in the corresponding wild type (WT). CKX1 over-producing lines developed a bigger root system, which contributed to their stress tolerance. The high stress tolerance of 35S:CKX1 plants was also associated with a dwarf shoot phenotype and changed leaf morphology. The genes for chloroplastic antioxidant enzymes, stroma ascorbate peroxidase (sAPX), thylakoid ascorbate peroxidase (tAPX) and chloroplastic superoxide dismutase (FeSOD), which are responsible for scavenging of reactive oxygen species produced via electron transfer during photosynthesis, were all strongly transcribed in control conditions. All the tested stresses down-regulated expression of these genes...

The thesis deals with monitoring of ascorbic acid and other substances in selected fruit drinks. The theoretical part begins with a summary of knowledge about the occurrence and importance of ascorbic acid and their physiological effects. Furthermore, the content of vitamin C in individual fruits is compared. The following part deals with the division of soft drinks and raw materials, used for the production of soft fruit drinks. Part of the thesis is focused on the technology of fruit juice production obtained by direct pressing of fruit material and technology of fruit drinks production from fruit concentrates. The practical part is focused on determination of vitamin C concentration as well as vitamins of group B (B1, B2, B3, B5, B6) and organic acids (citramic acid, citric acid, malic acid, pyruvic acid and succinic acid) in samples of direct fruit juices and juice from concentrate. Mass spectrometer-coupled high-performance liquid chromatography (HPLC-MS) was used to detect vitamin C and other substances.

Purpose: To investigate the influence of intensity versus total energy expenditure on neutrophilia and blood oxidative stress to acute exercise. Methods: Nine males (18-30 yr) completed one maximal (Max) and three submaximal exercise sessions: 1) 45 min at 10% above (LT+) lactate threshold (LT), 2) 45 min at 10% below (LT-) LT, and 3) 10% below LT until caloric expenditure equaled the 10%+ trial (LT-kcal). Blood was sampled before (PRE), immediately (POST), 1 h, and 2 h after exercise to measure neutrophils, myeloperoxidase, superoxide (O2-), neutrophil activation (O2-/neutrophils), ascorbic acid, uric acid, malondialdehyde, and lipid hydroperoxides. Results: Intensity-dependent neutrophilia occurred POST exercise with significant increases (P ≤ 0.05) after Max and LT+. A second neutrophilia wave occurred 2 h postexercise. Superoxide was elevated POST (Max) and 2 h post (Max and LT+). In contrast, O2-/neutrophils was increased at 2 h only (Max and LT +). These data indicate that immediately postexercise, total neutrophil number rather than activation best represents neutrophil-generated reactive species within blood. POST Max, ascorbic acid and uric acid were decreased indicating a blood oxidative stress occurred. Alternately, total energy expenditure was not related to any marker of neutrophilia or oxidative stress. Conclusion: Exercise intensity plays a major role in postexercise blood oxidative stress, whereas total exercise energy expenditure does not. Further, neutrophils recruited into circulation during exercise may impose a threshold dependent oxidative stress in blood plasma after exercise.