The broad objective of this study was to determine the effects of natural antioxidants and thermal treatment on quality of meat from Bonsmara and non-descript cattle. A survey was conducted among 222 consumers in Alice (Fort Hare University community), Eastern Cape Province to determine the level of their awareness on application of antioxidants as preservatives in meat and meat products during storage. Representative samples of Muscularis longissimuss thoracis et lumborum and liver were collected from each carcass of Bonsmara (n=40) and non-descript (n=40) cattle reared on natural pasture to determine the effect of natural antioxidants and thermal treatment on their quality. The results from the survey revealed that 51.35 percent of the respondents had not heard about the use of antioxidant as preservatives in meat products. However, among the remaining respondents (48.65 percent) that were aware of antioxidant and its use as preservative, about 19 percent knew of natural antioxidants, 35 percent synthetic antioxidants while 46 percent had knowledge of both. The results further revealed that the majority of the respondents (82 percent) that had knowledge of natural antioxidants were concerned about the use of synthetic antioxidants in meat and meat products due to their health consequences. The in vitro antioxidant and antibacterial analyses of Bidens pilosa and Moringa oleifera leaf extracts revealed that they contain rich bioactive compounds. Furthermore, the addition of leaf extracts from Moringa oleifera (ML, 0.05 and 0.1 percent w/w) and Biden pilosa (BP, 0.05 and 0.1 percent w/w) to ground raw beef as a natural antioxidant were found to improve the physicochemical, oxidative stability and microbiological qualities of meat compared to the control (meat without extract) and BHT treatment (0.02 percent w/w) during 6 days storage at 40 C. Cattle breed did not have much effect on colour parameters. However, the overall pH of ground beef treated with extracts showed lower values than control and BHT treated beef. Also, ground beef samples containing extracts exhibited (P < 0.05) better colour stability, especially higher redness (a* values), than the control. The formation of TBARS in beef samples treated with extracts was significantly (P < 0.05) lower than the control and BHT treatment. The antibacterial assay of the extracts revealed an appreciable broad spectrum activity against the tested bacteria and microbial counts in ground beef samples compared to control and BHT group. Ground beef treated with plant extracts exhibited lower microbial and lactic acid bacterial counts (P < 0.05) at day 0 and 3 than control samples. Moreover, it was observed that application of sous vides thermal method did not significantly affect the fatty acids and mineral loss in beef and liver across the treatments. However, the total concentration of MUFA was lower in raw liver (20.11±2.38 - 21.08±1.23 percent) than in beef (40.22±1.90 - 42.53±1.29 percent), while total PUFA content were higher in liver (30.73±2.60 - 31.11±1.19 percent) than in beef samples (10.13±3.36 - 11.02±2.74 percent) (p < 0.05). The results also revealed that liver samples from Bonsmara and non-descript cattle had a higher percentage of intramuscular fat content of 4.67 ± 0.53 percent and 4.44 ± 0.53 percent respectively, and fat free dry matter of 27.51 ± 1.05 percent and 25.73 ± 1.05 percent, respectively, than the beef samples (p < 0.05). The concentrations of Mg (52.80±0.22 - 53.70±0.02mg/100g) and Zn (8.90±0.15 - 19.60±0.15mg/100g) were higher in beef than liver samples. The level of Ca (17.00±0.17 - 17.50 ± 0.17mg/100g) in liver was higher than that of beef samples. It was concluded that most consumers preferred the use of natural antioxidants in meat products than synthetic antioxidants due to their health risk. The effectiveness of M. oleifera and B. pilosa leaf extracts on meat quality also revealed that these plants are promising candidates as natural preservatives and their application should be considered in the meat industry. Lastly, findings from this study showed that application of the sous vide technique could protect meat products from nutritional loss during thermal treatment.

Made available in DSpace on 2015-12-10T14:22:29Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-06-26. Added 1 bitstream(s) on 2015-12-10T14:28:30Z : No. of bitstreams: 1 000852081_20170626.pdf: 422935 bytes, checksum: e1874f683ced5ed4bd3fcc07e1fbb4f0 (MD5) Bitstreams deleted on 2017-06-30T13:45:03Z: 000852081_20170626.pdf,. Added 1 bitstream(s) on 2017-06-30T13:45:55Z : No. of bitstreams: 1 000852081.pdf: 836873 bytes, checksum: 08e748581ea59d72c9d85ea816d769e3 (MD5) Bitstreams deleted on 2017-08-24T16:17:02Z: 000852081.pdf,. Added 1 bitstream(s) on 2017-08-24T16:17:48Z : No. of bitstreams: 1 000852081.pdf: 836873 bytes, checksum: 08e748581ea59d72c9d85ea816d769e3 (MD5) / O desenvolvimento de novos fármacos com ação antioxidante tem sido um importante objeto de estudo, uma vez que a terapêutica farmacológica atual para o tratamento de doenças como Alzheimer, Parkinson, esclerose múltipla, doença de Huntington, epilepsia e alguns tipos de neoplasias pode ser realizada devido às propriedades antioxidantes de muitos compostos naturais e/ou sintéticos. Dessa forma, a busca por novos agentes antioxidantes é extremamente necessária e atualmente é objeto de interesse em novas pesquisas pela indústria cosmética, farmacêutica e nutricional. Neste contexto, este trabalho irá permitir o aumento do conhecimento sobre Moringa oleifera por meio da avaliação do potencial antioxidante, fotoprotetor e antiglicação dos extratos desta espécie, além de elucidar relatos etnobotânicos de sua utilização e enriquecer o conhecimento científico desta espécie amplamente empregada como planta medicinal. Além disso, porque são reduzidas as informações científicas sobre as atividades que serão avaliadas neste projeto / The development of new drugs with antioxidant action has been an important subject of study, since the current drug therapy for the treatment of diseases such as Alzheimer's, Parkinson's, multiple sclerosis, Huntington's disease, epilepsy and some types of cancer can be performed because the antioxidant properties of many natural and / or synthetic compounds. Thus, the search for new antioxidants is extremely necessary and is currently the subject of interest in new research by the cosmetic, pharmaceutical and nutritional industry. In this context, this work will enable increased knowledge on Moringa oleifera by evaluating the antioxidant potential, sunscreen and anti-glycation of the extracts of this species, besides elucidating ethnobotanical reports of its use and enrich the scientific knowledge of this widely used species with medicinal plant. In addition they are reduced scientific information on the activities to be evaluated in this project

Made available in DSpace on 2014-06-11T19:35:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-02-22Bitstream added on 2014-06-13T21:07:18Z : No. of bitstreams: 1 arwa_ps_dr_araiq_parcial.pdf: 140184 bytes, checksum: f2d411778c9b9af9eb7533d4fc96e1e8 (MD5) Bitstreams deleted on 2015-06-25T13:01:05Z: arwa_ps_dr_araiq_parcial.pdf,. Added 1 bitstream(s) on 2015-06-25T13:03:24Z : No. of bitstreams: 1 000718879_20160222.pdf: 127126 bytes, checksum: 8a2ae7d96951ff36a34f967d8659d0d8 (MD5) Bitstreams deleted on 2016-02-22T11:12:48Z: 000718879_20160222.pdf,. Added 1 bitstream(s) on 2016-02-22T11:13:42Z : No. of bitstreams: 1 000718879.pdf: 2745649 bytes, checksum: a0fd20904df0ddfc1ca542753185938c (MD5) / A investigação fitoquímica de espécies vegetais contribui para a conservação e uso sustentável da diversidade vegetal no Estado de São Paulo através de estudos sobre diversidade química e busca de drogas potenciais, que incluem as atividades de bioprospecção e fiazem parte da estratégia de exploração racional de nossa biodiversidade. A planta selecionada para este estudo, Garcinia brasiliensis (família Clusiaceae), apresentou perfil químico com expressiva ocorrência de benzofenonas, conhecidas por seu potencial antimalárico, antioxidante, antibacteriano e antinflamatório. Os objetivos deste trabalho incluíram o estudo químico/biológico dos caules e folhas de Garcinia brasiliensis, com o isolamento e determinação estrutural de metabólitos secundários e avaliação de sua bioatividade. Apesar das plantas medicinais serem raramente utilizadas como antioxidantes na medicina popular, suas propriedades terapêuticas podem ser devidas a sua capacidade de sequestrar radicais livres de oxigênio, envolvidos em diversas patologias decorrentes do estresse oxidativo em sistemas biológicos. A ação antioxidante tem sido também apontada como forte indicativo de ação quimiopreventiva, associada à indução de enzimas destoxificantes do organismo como a quinona redutase, que pode evitar eventos iniciais da geração de tumores. O estudo fitoquímico dos extratos de folhas e galhos de G. brasiliensis resultou no isolamento ou identificação de diversas substâncias polifenólicas a partir de frações polares: os biflavonoides amentoflavona, podocarpusflavona, fukugetina, além de procianidina e seus trímeros e da benzofenona garcinol através do uso de técnicas cromatográficas e espetrométricas como CLAE-DAD, CLAE-EM, UV, IV e RMN. Os extratos de baixa polaridade foram analisados por CG-EM... / The phytochemical investigation of plant species contributes to conservation and sustainable use of São Paulo biodiversity. This project has addressed the phytochemical investigation of stems and leaves of Garcinia brasiliensis, with isolation, structural determination of secondary metabolites as well as evaluation of bioactivity. G. brasiliensis is a member of the Clusiaceae family with interesting secondary metabolites such as benzophenones which have potent antimalarial, antioxidant, antitumoral, antibacterial, antiinflamatory and chemoprevention capacity. Whereas medicinal plants are not used as antioxidants in popular medicine their therapeutic properties are derived from capacity to scavenge free radicals involved in oxidative stress. The antioxidant activity is indicative of chemoprevention associated with toxic enzymes such as quinone reductase that is associated with inhibition of tumor development. The phytochemical study of extracts from leaves and stems of G. brasiliensis led to the isolation or identification of several polyphenols from polar fractions: biflavonoids amenthoflavone, podocarpusflavone, fukugetin, in addition to procyanidin and its trimers and the benzophenone garcinol through chromatographic and spectrometric techniques as HPLC-DAD, HPLC MS, UV, IR and NMR. Low polarity extracts were analyzed by GC-FID and evidenced the presence of triterpenes and steroids, including stigmasterol,  -amirinone,  -amirin, taraxerol and lupeol, as major compounds. Metabolite target analysis was carried out using thin layer chromatographic tests with  -carotene and anisaldehyde as revealing agents aiming the detection of antioxidant compounds, in addition to inhibitory activity against T. cruzi, human and plant pathogenic fungi, malaria, acetylcholinesterase, and HIV protease. Best results were obtained for... (Complete abstract click electronic access below)

Orientador: Dulce Helena Siqueira Silva / Banca: Ana Helena Januário / Banca: Patrícia Sartorelli / Banca: Lourdes Campaner dos Santos / Banca: Alberto José Cavalheiro / Resumo: A investigação fitoquímica de espécies vegetais contribui para a conservação e uso sustentável da diversidade vegetal no Estado de São Paulo através de estudos sobre diversidade química e busca de drogas potenciais, que incluem as atividades de bioprospecção e fiazem parte da estratégia de exploração racional de nossa biodiversidade. A planta selecionada para este estudo, Garcinia brasiliensis (família Clusiaceae), apresentou perfil químico com expressiva ocorrência de benzofenonas, conhecidas por seu potencial antimalárico, antioxidante, antibacteriano e antinflamatório. Os objetivos deste trabalho incluíram o estudo químico/biológico dos caules e folhas de Garcinia brasiliensis, com o isolamento e determinação estrutural de metabólitos secundários e avaliação de sua bioatividade. Apesar das plantas medicinais serem raramente utilizadas como antioxidantes na medicina popular, suas propriedades terapêuticas podem ser devidas a sua capacidade de sequestrar radicais livres de oxigênio, envolvidos em diversas patologias decorrentes do estresse oxidativo em sistemas biológicos. A ação antioxidante tem sido também apontada como forte indicativo de ação quimiopreventiva, associada à indução de enzimas destoxificantes do organismo como a quinona redutase, que pode evitar eventos iniciais da geração de tumores. O estudo fitoquímico dos extratos de folhas e galhos de G. brasiliensis resultou no isolamento ou identificação de diversas substâncias polifenólicas a partir de frações polares: os biflavonoides amentoflavona, podocarpusflavona, fukugetina, além de procianidina e seus trímeros e da benzofenona garcinol através do uso de técnicas cromatográficas e espetrométricas como CLAE-DAD, CLAE-EM, UV, IV e RMN. Os extratos de baixa polaridade foram analisados por CG-EM... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The phytochemical investigation of plant species contributes to conservation and sustainable use of São Paulo biodiversity. This project has addressed the phytochemical investigation of stems and leaves of Garcinia brasiliensis, with isolation, structural determination of secondary metabolites as well as evaluation of bioactivity. G. brasiliensis is a member of the Clusiaceae family with interesting secondary metabolites such as benzophenones which have potent antimalarial, antioxidant, antitumoral, antibacterial, antiinflamatory and chemoprevention capacity. Whereas medicinal plants are not used as antioxidants in popular medicine their therapeutic properties are derived from capacity to scavenge free radicals involved in oxidative stress. The antioxidant activity is indicative of chemoprevention associated with toxic enzymes such as quinone reductase that is associated with inhibition of tumor development. The phytochemical study of extracts from leaves and stems of G. brasiliensis led to the isolation or identification of several polyphenols from polar fractions: biflavonoids amenthoflavone, podocarpusflavone, fukugetin, in addition to procyanidin and its trimers and the benzophenone garcinol through chromatographic and spectrometric techniques as HPLC-DAD, HPLC MS, UV, IR and NMR. Low polarity extracts were analyzed by GC-FID and evidenced the presence of triterpenes and steroids, including stigmasterol,  -amirinone,  -amirin, taraxerol and lupeol, as major compounds. Metabolite target analysis was carried out using thin layer chromatographic tests with  -carotene and anisaldehyde as revealing agents aiming the detection of antioxidant compounds, in addition to inhibitory activity against T. cruzi, human and plant pathogenic fungi, malaria, acetylcholinesterase, and HIV protease. Best results were obtained for... (Complete abstract click electronic access below) / Doutor

M.Sc. / The main objective of this study was to perform active biomonitoring in the Rietlvlei Wetland System. Active biomonitoring, which can be defined as “the translocation of organisms from one place to another and quantifying their biochemical, physiological and/or organismal responses for the purpose of water quality monitoring” (De Kock and Kramer, 1994), has several advantages over the chemical monitoring system. Effluents often are complex and poorly characterized mixtures of a large number of chemicals. A combination of many chemicals being present in very small amounts (even below detection limits) can have a substantial impact on organisms, and a chemical-based approach may not identify the source of pollution nor will effect of synergism or antagonism be taken into account (Smolders et al., 2003). A suite of biomarkers of oxidative stress and histopathology were investigated in the fish Oreochromis mossambicus and the mollusk Melanoides tuberculata. The organisms were bred under laboratory conditions. They were deployed during the high-flow and low-flow periods, in cages at three sites down the flow gradient of the Rietvlei wetland system, to determine spatial and temporal variations in biomarker responses and general water chemistry in the system. The oxidative stress biomarkers analyzed were catalase (CAT), superoxide dismutase (SOD), peroxidase (GPx), as well as levels of reduced glutathione (GSH) and lipid peroxidation as malondialdehyde (MDA). There was evidence of presence of chemicals inducing oxidative stress in the organisms as indicated by the high levels of MDA, GSH and GPx. Induction of CAT and SOD was not substantial due to possible inhibitory factors. This study established that organism transplantation is a feasible strategy for biomonitoring. Overall, no distinct variations were observed in the spatial and temporal comparisons in all the biomarker responses. The findings of this investigation also provide a basis for further investigation into the application of these biomarkers in ecological risk assessment. / Dr. V. Wepener

The amino acid, tryptophan, obtained through dietary means, is metabolised by the enzymes tryptophan 2,3-dioxygenase (TDO), indoleamine 2,3-dioxygenase (IDO) and tryptophan hydroxylase. All the enzymes have an effect on circulating tryptophan levels, especially TDO, since it is the major site of tryptophan catabolism in the liver and results in the production of kynurenine metabolites, viz. kynurenine, kynurenic acid, 3-hydroxyanthranilic acid and quinolinic acid. Extrahepatically, IDO is responsible for the synthesis of the kynurenine metabolites. Tryptophan 2,3-dioxygenase and IDO activity is increased by hormones or substrates such as tryptophan, and inflammation, in the case of IDO. Tryptophan availability for serotonin (5-HT) synthesis by the enzyme tryptophan hydroxylase is primarily dependent on TDO activity. A study was attempted in order to ascertain whether any of the endogenous metabolites of the kynurenine and serotonergic pathways would be able to inhibit TDO activity. Results showed that although the kynurenines had no effect, the indoleamines, except for the indoleacetic acids, were able to reduce TDO activity. 6-Methoxy-2-benzoxazolinone (6-MBOA), a structural analogue to melatonin, was the most potent inhibitor with a reduction in activity of 55 % compared with the control. The pineal gland in the rat brain has been shown to have the highest IDO activity. With induction, the kynurenine metabolite concentrations of kynurenic acid and quinolinic acid are increased. The effects of both compounds were determined on the serotonergic pathway. Although kynurenic acid produced no significant effect, quinolinic acid significantly reduced N-acetylserotonin and melatonin synthesis at concentrations of lOJLM and 100 JLM respectively. Many authors have implicated oxygen derived species as causative agents in the important neurodegenerative disorders such as Parkinson's and Huntington's disease. Increased radical generation and lipid peroxidation have been suggested to be responsible for the toxic destruction of neurons, especially in the brain because of its high lipid content and oxygen demand. The brain is therefore vulnerable to oxidative attack. During inflammatory diseases, IDO is induced with a resultant increase in kynurenines. This study was also an attempt at determining the effect of kynurenines on lipid peroxidation. All metabolites of the kynurenine pathway were able to induce lipid peroxidation significantly. The antioxidative potential of various tryptophan analogues, viz. serotonin, melatonin and 6-methoxy-2-benzoxazolinone, was determined using quinolinic acid-induced lipid peroxidation. Serotonin, melatonin and 6-MBOA were able to significantly reduce quinolinic acid-induced lipid peroxidation.

Plants are exposed to diverse environmental stresses, which can lead to the accumulation of harmful reactive oxygen species (ROS). To prevent cellular damage, plants have evolved diverse antioxidant compounds and mechanisms to scavenge and remove ROS. My research aimed to determine if condensed tannins (CTs) function as in vivo antioxidants in plants. CTs are abundant plant secondary metabolites and are well-known for their strong in vitro antioxidant activity, but their function as antioxidants in planta has not previously been investigated. I used transgenic hybrid poplar (Populus tremula x tremuloides) with high (MYB134- and MYB115-overexpressing) and low (MYB134-RNAi) leaf CT content. Three different abiotic stresses were used to induce oxidative stress in the plants: methyl viologen (MV), drought, or UV-B stress. Oxidative stress can damage the plant's photosystems, and this damage was assessed using chlorophyll fluorescence. I employed light-adapted (Fq’/Fm’) and dark-adapted (Fv/Fm) parameters of chlorophyll fluorescence and monitored photosystem II function during each stress. Under all three stresses, the high-CT transgenics retained greater chlorophyll fluorescence, demonstrating reduced photosystem II damage, compared to wild-type plants. Oxidative damage was measured by quantifying malondialdehyde (MDA), and hydrogen peroxide (H2O2) was quantified as a measure of ROS accumulation. High-CT plants consistently accumulated less H2O2 and MDA than wild-type plants before and after each stress. MYB134-RNAi plants showed the converse effects, as predicted by lower CT concentrations, with reduced photosystem function and increased levels of H2O2 and MDA compared to wild-type following each stress. Overall, this work demonstrates that CTs can function as in planta antioxidants and can aid in protection against oxidative damage. My work provides the first evidence for an antioxidant function of CTs in living plants exposed to stress. / Graduate / 2020-12-18

A dissertation submitted to the Faculty of Medicine, University of the Witwatersrand, Johannesburg. in fulfilment of the requirements for the degree of Doctor of Philosophy / This thesis describes and discusses oxidants and anti-oxidants and their relation to human disease. Cigarette smoking is used as the model for the study of chronic inflammatory processes, firstly, to establish a causative link between oxidants and disease viz. lung function abnormalities in smokers, secondly to evaluate the interaction between hyperactive phagocytes and anti-oxidant defences and thirdly, to investigate the possibility that intervention with anti-oxidants may ameliorate the effects of chronic inflammation. / IT2018

The objective was to examine effects of melatonin supplementation during late gestation on uterine artery hemodynamics, offspring growth, and endocrine profiles. Prior to day 170 of gestation, heifers were trained to the Calan feeding system. On day 190 of gestation, heifers (n = 20) were blocked by BW and then randomly assigned to one of two dietary treatments: 1) 20 mg of dietary melatonin per day (MEL) or 2) no melatonin supplementation (CON). Supplementation ceased on day 262 of gestation. A main effect (P < 0.01) of treatment was observed for total uterine artery blood flow with it being increased in MEL vs. CON. An interaction (P = 0.008) was observed in calf body weight increasing at weeks 8 and 9 in MEL vs. CON. Dietary melatonin could be used to potentially increase uterine blood flow and calf body weight.

No description available.