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1. Oliveira, Sandro de. Determinação da capacidade antirradicalar de produtos naturais utilizando-se a quimiluminescência do luminol e ensaios fotométricos com radicais estáveis.

Degree: Mestrado, Química, 2011, University of São Paulo

Os organismos vivos estão expostos à ação oxidativa de espécies reativas de oxigênio (ERO), causando uma série de doenças degenerativas como câncer, aterosclerose, diabetes, artrite e doenças do coração. Estudos têm demonstrado que o consumo de substâncias antioxidantes na dieta diária podem prevenir estes processos oxidativos que provocam o envelhecimento precoce do organismo. Nas últimas décadas tem se destacado o interesse em encontrar antioxidantes naturais para o emprego em produtos alimentícios ou farmacêuticos, com a finalidade de substituir antioxidantes sintéticos, os quais apresentam restrições devido ao seu potencial tóxico. Nesse trabalho, são comparados os resultados de medidas da capacidade antirradicalar de vários derivados fenólicos incluindo produtos naturais obtidos com os ensaios utilizando o radical estável DPPH• e o cátion radical ABTS•+, que apresentam vantagens em relação à simplicidade do método analítico e facilidade na coleta de dados, além da reprodutibilidade dos resultados. Além disso, desenvolveu-se um ensaio com DPPH• para avaliar a capacidade antirradicalar de compostos fenólicos em meio ácido, hidroalcoólico e tamponado, para possibilitar a obtenção de valores da capacidade antirradicalar de flavonoides e compostos análogos em meio aquoso em diferentes estados de ionização. Também, foi utilizado o ensaio quimiluminescente com luminol/hemina/H2O2, desenvolvido pelo nosso grupo de pesquisa, para a determinação da capacidade antirradicalar de extratos, fases e frações de Baccharis regnelli e proposto o novo parâmetro \"Porcentagem de Troloxp̈ara expressar adequadamente esta capacidade em misturas complexas. A sensibilidade do ensaio luminol comprovou ser maior que a de outros métodos e adequado para medir a capacidade antirradicalar de misturas complexas de produtos naturais, auxiliando no isolamento de novas substâncias com atividade antirradicalar.

Living organisms are exposed to the oxidative action of reactive oxygen species (ROS), causing a series of degenerative diseases such as cancer, atherosclerosis, diabetes, arthritis and heart disease. Studies have shown that consumption of antioxidant substances in the daily diet can prevent these oxidative processes that cause premature aging of the organism. Much attention has been paid in the last decades on the discovery of new natural antioxidants for its use in food or pharmaceutical industry, with the aim of replace synthetic antioxidants, which have restrictions due to their toxic potential. In this study, we compared the results from antiradical capacity determinations of several phenolic derivatives including natural products obtained by two different assays. One of them utilizes the stable radical DPPH• and the other the radical cation ABTS•+ as reagents and both have the advantage of a simple analytical method and ease in data collection as well as high data reproducibility. Furthermore, we have developed a method with DPPH• for the evaluation of the antirradicalar capacity of phenolic…

Advisors/Committee Members: Baader, Josef Wilhelm.

Subjects/Keywords: ABTS; ABTS; Anti-radical assay; Antioxidantes; Antioxidants; Chemiluminescence; DPPH; DPPH; Ensaio antirradicalar; Luminol; Luminol; Quimiluminescência

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Oliveira, S. d. (2011). Determinação da capacidade antirradicalar de produtos naturais utilizando-se a quimiluminescência do luminol e ensaios fotométricos com radicais estáveis. (Masters Thesis). University of São Paulo. Retrieved from http://www.teses.usp.br/teses/disponiveis/46/46136/tde-05122011-114158/ ;

Chicago Manual of Style (16th Edition):

Oliveira, Sandro de. “Determinação da capacidade antirradicalar de produtos naturais utilizando-se a quimiluminescência do luminol e ensaios fotométricos com radicais estáveis.” 2011. Masters Thesis, University of São Paulo. Accessed November 22, 2019. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-05122011-114158/ ;.

MLA Handbook (7th Edition):

Oliveira, Sandro de. “Determinação da capacidade antirradicalar de produtos naturais utilizando-se a quimiluminescência do luminol e ensaios fotométricos com radicais estáveis.” 2011. Web. 22 Nov 2019.

Vancouver:

Oliveira Sd. Determinação da capacidade antirradicalar de produtos naturais utilizando-se a quimiluminescência do luminol e ensaios fotométricos com radicais estáveis. [Internet] [Masters thesis]. University of São Paulo; 2011. [cited 2019 Nov 22]. Available from: http://www.teses.usp.br/teses/disponiveis/46/46136/tde-05122011-114158/ ;.

Council of Science Editors:

Oliveira Sd. Determinação da capacidade antirradicalar de produtos naturais utilizando-se a quimiluminescência do luminol e ensaios fotométricos com radicais estáveis. [Masters Thesis]. University of São Paulo; 2011. Available from: http://www.teses.usp.br/teses/disponiveis/46/46136/tde-05122011-114158/ ;


North-West University

2. Pretorius, Corlea. Antioxidant properties of Lippia javanica (Burm.f.) Spreng. / C. Pretorius .

Degree: 2010, North-West University

The evolution of aerobic metabolic processes unavoidably led to the production of reactive oxygen species (ROS). ROS have the ability to cause harmful oxidative damage to biomolecules. Increased ROS generation and subsequent oxidative stress have been associated with aging and neurodegenerative disorders such as Parkinson’s and Alzheimer’s diseases as a result of the extreme sensitivity of the central nervous system to damage from ROS. Antioxidant defence systems have co–evolved with aerobic metabolic processes to counteract oxidative damage inflicted by ROS. The impact of neurodegenerative disorders on society is increasing rapidly as the life expectancy of the global population increases. In this day and age, a much younger group of the population is also experiencing neurodegenerative symptoms as a result of the harmful effect of the human immunodeficiency virus (HIV) on the central nervous system. Plants are an invaluable source of medicinal compounds. The use of plants for their healing properties is rooted in ancient times. The aim of this study was to select from twenty one plants, the plant with the most promising antioxidant activity and to determine whether extracts of this plant could act as free radical scavengers, comparing the results to Trolox, a known free radical scavenger. The next step was to isolate and characterize a compound from an extract exhibiting promising antioxidant activity. Bioassay–guided fractionation was followed to achieve this. During screening trials, twenty one plants, namely Berula erecta, Heteromorpha arborescens, Tarchonanthus camphoratus, Vernonia oligocephala, Gymnosporia buxifolia, Acacia karroo, Elephantorrhiza elephantina, Erythrina zeyheri, Leonotis leonurus, Plectranthus ecklonii, P. rehmanii, P. venteri, Salvia auretia, S. runcinata, Solenostemon latifolius, S. rotundifolius, Plumbago auriculata, Clematis brachiata, Vangueria infausta, Physalis peruviana and Lippia javanica were selected from literature, based on reported antioxidant activity within the plant families, for screening of their antioxidant activity. One hundred and ten extracts were prepared from the leaves, using Soxhlet extraction and the solvents petroleum ether (PE), dichloromethane (DCM), ethyl acetate (EtOAc) and ethanol (EtOH), consecutively. The focus during initial screening trials was on chemistry–based assays. The oxygen radical absorbance capacity (ORAC) and ferric reducing antioxidant power (FRAP) assays were employed for the primary screening of the one hundred and ten leaf extracts. The ORAC assay was used to determine whether the plant extracts were able to scavenge peroxyl radicals and the FRAP assay was used to determine the reducing abilities of the extracts. Quantification of the peroxyl radical scavenging activity by the ORAC assay revealed that activity was observed for most of the extracts, with the ethyl acetate and ethanol extracts of L. javanica exhibiting the most promising activity. This pattern of activity was also found with the reducing capacity evaluated by the FRAP assay…

Subjects/Keywords: Verbenaceae; Lippia javanica; Antioxidant; Neurodegeneration; Oxygen radical absorbance capacity (ORAC); Ferric reducing antioxidant power (FRAP); Nitro-blue tetrazolium assay (NBT); Thiobarbituric acid reactive substances assay (TBARS); Anti-oksidant; Neurodegenerasie; Suurstofradikaal-opruimings aktiwiteit (ORAC); Yster-reduserende antioksidant aktiwiteit (FRAP); Nitrobloutetrasolium toets (NBT); Tiobarbituursuur reaktiewe substanse toets (TBARS)

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Pretorius, C. (2010). Antioxidant properties of Lippia javanica (Burm.f.) Spreng. / C. Pretorius . (Thesis). North-West University. Retrieved from http://hdl.handle.net/10394/4726

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Pretorius, Corlea. “Antioxidant properties of Lippia javanica (Burm.f.) Spreng. / C. Pretorius .” 2010. Thesis, North-West University. Accessed November 22, 2019. http://hdl.handle.net/10394/4726.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Pretorius, Corlea. “Antioxidant properties of Lippia javanica (Burm.f.) Spreng. / C. Pretorius .” 2010. Web. 22 Nov 2019.

Vancouver:

Pretorius C. Antioxidant properties of Lippia javanica (Burm.f.) Spreng. / C. Pretorius . [Internet] [Thesis]. North-West University; 2010. [cited 2019 Nov 22]. Available from: http://hdl.handle.net/10394/4726.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Pretorius C. Antioxidant properties of Lippia javanica (Burm.f.) Spreng. / C. Pretorius . [Thesis]. North-West University; 2010. Available from: http://hdl.handle.net/10394/4726

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.