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Doctoral Thesis
DOI
10.11606/T.6.2009.tde-10092009-092017
Document
Author
Full name
Silvio José Valadão Vicente
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Paulo, 2009
Supervisor
Committee
Torres, Elizabeth Aparecida Ferraz da Silva (President)
Areas, Jose Alfredo Gomes
Carvalho, João Ernesto de
Gotlieb, Sabina Lea Davidson
Ong, Thomas Prates
Title in Portuguese
Caracterização antioxidante do café (Coffea arabica, L.) e efeitos da sua administração oral em ratos
Keywords in Portuguese
Ácidos Fenólicos
Café
Capacidade Antioxidante
Enzimas Antioxidantes
Estresse Oxidativo
Abstract in Portuguese
Introdução: Um dos fatores de risco para doenças crônicas não-transmissíveis é o excesso de espécies reativas causado pelo estresse oxidativo. Ácidos fenólicos atuam na defesa contra estas espécies, agindo como antioxidantes e como fatores de transcrição para as enzimas antioxidantes fase II (superóxido dismutase, catalase e glutationa peroxidase). Vários alimentos possuem ácidos fenólicos na composição porém o café se destaca pelo alto conteúdo dos mesmos e por ser consumido mundialmente. Objetivos: a) Comparar a capacidade antioxidante e a estabilidade dos cafés regular e descafeinado ao longo de seis meses; b) Verificar o tempo de resposta e possíveis correlações dose-resposta do efeito antioxidante em ratos após dose única de café; c) Avaliar o efeito antioxidante e possíveis danos hepáticos em ratos submetidos a doses repetidas de café durante 30 dias. Métodos: na etapa in vitro, foram analisados os compostos fenólicos totais, os principais ácidos fenólicos, a capacidade antioxidante (ORAC e DPPH) e a estabilidade destes parâmetros nos cafés regular e descafeinado durante seis meses. Na etapa in vivo, foram utilizados ratos machos Wistar, sendo dosadas as enzimas fase II e o ORAC, além do exame histopatológico e biomarcadores. Resultados: o café regular apresentou capacidade antioxidante inicial superior ao descafeinado com compostos fenólicos totais iguais e maiores teores de ácido fenólicos (15,3% cafêico, 17,0% p-cumárico e 38,1% ferúlico), ORAC (20,8%) e DPPH (3,9%). Após 6 meses, as amostras fechadas à vácuo praticamente não sofreram perdas, as abertas mantidas a 4oC apresentaram perdas medianas (9,6% fenólicos totais, 4,5-8,2% ácidos fenólicos, 21,3-21,6% ORAC e 2,8-3,2% DPPH) e as mantidas abertas a 20oC exibiram perdas elevadas (14,4-19,8% fenólicos totais, 11,9-19,6% ácidos fenólicos, 38,8-49,9% ORAC e 2,1- 3,8% DPPH). Após dose única de café para os ratos, o tempo de resposta máxima para as enzimas fase II e ORAC foi de 1 hora, com significância estatística para as enzimas (p=0,015 SOD e Cat, p=0,007 GPx e p=0,403 ORAC). Após diferentes doses, foram obtidas correlações dose-resposta positivas e com significância estatística para as enzimas (p=0,050 SOD, p=0,033 Cat, p=0,008 GPx e p=0,113 ORAC). Após doses repetidas (30 dias), a atividade das enzimas antioxidantes e o ORAC apresentaram grandes aumentos (74,8% SOD, 59,4% Cat, 135,2% GPx e 25,1% ORAC), todos estatisticamente significativos (p<0,001 para todos). O tecido hepático e os biomarcadores não apresentaram alterações em relação ao grupo controle. Conclusões: o café regular apresentou capacidade antioxidante superior ao descafeinado, os dois cafés não apresentaram perdas das características antioxidantes após seis meses se mantidos selados à vácuo e a administração oral de café regular aumentou a condição antioxidante dos ratos de maneira significativa, sem causar danos hepáticos.
Title in English
Antioxidant characterization of coffee (Coffea arabica, L.) and the effects of its oral feed in rats
Keywords in English
Antioxidant Capacity
Antioxidant Enzymes
Coffee
Oxidative Stress
Phenolic Acids
Abstract in English
Introduction: A risk factor for several degenerative diseases is the excess of reactive species caused by oxidative stress. Phenolic acids share in the defense against those species, acting as antioxidants and as transcriptional factors for the phase II antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase). Several foods have phenolic acids in their composition but coffee stands out by the high contend of them and to be consumed worldwide. Objectives: a) Compare the antioxidant capacity and the stability of regular and decaffeinated coffees along six months; b) Verify the time of response and possible dose-response correlations of antioxidant effect in rats after a single dose of coffee; c) Evaluate the antioxidant effect and possible hepatic damages in rats submitted to repetitive doses along 30 days. Methods: in the in vitro step, it was analyzed the total phenolic compounds, main phenolic acids, antioxidant capacity (ORAC and DPPH) and the stability of these parameters in regular and decaffeinated coffees along six months. In the in vivo step, it was used male Wistar rats, being analyzed phase II enzymes and ORAC, besides histopathologic examination and biomarkers. Results: regular coffee presented a higher initial antioxidant capacity than decaffeinated coffee with equal total phenolic compounds and higher contend of phenolic acids (15.3% caffeic, 17.0% p-coumaric and 38.1% ferulic), ORAC (20.8%) and DPPH (3.9%). After six months, closed samples kept under vacuum practically did not show any losses, opened samples kept at 4oC presented regular losses (9.6% total phenolic compounds, 4.5-8.2% phenolic acids, 21.3-21.6% ORAC and 2.8-3.2% DPPH) and opened samples kept at 20oC exhibited big losses (14.4-19.8% total phenolic compounds, 11.9-19.6% phenolic acids, 38.8-49.9% ORAC and 2.1-3.8% DPPH). After a single dose of coffee for rats, time for maximum response of phase II enzymes and ORAC was 1 hour, with statistic significance for enzymes (p=0.015 SOD and Cat, p=0.007 GPx and p=0.403 ORAC). After different doses, it was obtained positive dose-response correlations, with statistic significance for enzymes (p=0.050 SOD, p=0.033 Cat, p=0.008 GPx and p=0.113 ORAC). After repetitive doses (30 days), the activity of antioxidant enzymes and ORAC showed big increases (74.8% SOD, 59.4% Cat, 135.2% GPx and 25.1% ORAC), all with statistic significance (p<0.001 for all). Hepatic tissue and biomarkers did not show any change compared to control group. Conclusions: regular coffee presented higher antioxidant capacity than decaffeinated coffee, both coffees did not show any antioxidant losses after six months if kept sealed under vacuum and the oral administration of regular coffee increased significantly the antioxidant condition of rats, without any hepatic damages.
 
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Publishing Date
2009-09-22
 
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