The effect of pH on horseradish peroxidase-catalyzed oxidation of melatonin: Production of N1-acetyl-N2-formyl-5- methoxykynuramine versus radical-mediated degradation

There is a growing body of evidence that melatonin and its oxidation product, N1-acetyl-N2-formyl-5-methoxykynuramine (AFMK), have anti-inflammatory properties. From a nutritional point of view, the discovery of melatonin in plant tissues emphasizes the importance of its relationship with plant peroxidases. Here we found that the pH of the reaction mixture has a profound influence in the reaction rate and products distribution when melatonin is oxidized by the plant enzyme horseradish peroxidase. At pH 5.5, 1 mm of melatonin was almost completely oxidized within 2 min, whereas only about 3% was consumed at pH 7.4. However, the relative yield of AFMK was higher in physiological pH. Radical-mediated oxidation products, including 2-hydroxymelatonin, a dimer of 2-hydroxymelatonin and O-demethylated dimer of melatonin account for the fast consumption of melatonin at pH 5.5. The higher production of AFMK at pH 7.4 was explained by the involvement of compound III of peroxidases as evidenced by spectral studies. On the other hand, the fast oxidative degradation at pH 5.5 was explained by the classic peroxidase cycle. © 2007 The Authors.

Antioxidant enzyme activity and hydrogen peroxide content during the drying of Arabica coffee beans

The development of the germination process and drought stress during the drying of coffee can generate reactive oxygen species, which can be neutralized by way of antioxidant mechanisms. No studies related to antioxidant enzymes during the drying of coffee were found in the literature, and considering their importance, the enzymatic activities of superoxide dismutase (SOD), guaiacol peroxidase (GPOX) and glutathione reductase (GR), and also the hydrogen peroxide content were evaluated during the drying of two types of coffee bean, one processed as natural coffee and the other as pulped natural coffee. The results showed a reduction in the SOD, GPOX and GR enzymatic activities of the natural coffee as compared to the pulped natural coffee during the drying period. Moreover, the hydrogen peroxide content of the natural coffee was greater than that of the pulped natural coffee. These results suggest the development of oxidative stress during the coffee drying process, controlled more efficiently in pulped natural coffee by the early action of GPOX during the drying process. Nevertheless, differential responses by SOD isoenzymes and possibly the role of other peroxidases also appear to be involved in the responses observed. © 2013 Springer-Verlag Berlin Heidelberg.

Caracterização do perfil da ação do ácido gálico e seus derivados sobre processos oxidativos in vitro e ex vivo

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Enxertia, atividade enzimática e orientação do tomateiro com quatro hastes

Pós-graduação em Agronomia (Produção Vegetal) - FCAV

Silicon in plant disease control

All essential nutrients can affect the incidence and severity of plant diseases. Although silicon (Si) is not considered as an essential nutrient for plants, it stands out for its potential to decrease disease intensity in many crops. The mechanism of Si action in plant resistance is still unclear. Si deposition in plant cell walls raised the hypothesis of a possible physical barrier to pathogen penetration. However, the increased activity of phenolic compounds, polyphenol oxidases and peroxidases in plants treated with Si demonstrates the involvement of this element in the induction of plant defense responses. The studies examined in this review address the role of Si in disease control and the possible mechanisms involved in the mode of Si action in disease resistance in plants.

Estudos bioquímicos de tegumento de soja brasileira: isolamento, purificação e caracterização de peroxidase com guaiacol como substrato

Pós-graduação em Biotecnologia - IQ

Apocinina e metóxi-catecóis correlatos: relação entre estrutura molecular e inibição da ativação do complexo NADPH oxidase

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudo bioquímico do efeito de alguns flavonóides de Pterogyne nitens Tulasne (Fabaceae) em processos oxidativos: sistema modelo quimicos, enzimáticos e celulares

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Oxidação de compostos β-dicarbonílicos por peroxidase

Pós-graduação em Biociências e Biotecnologia Aplicadas à Farmácia - FCFAR

Reguladores vegetais e bioestimulantes no desenvolvimento de Salvia officinalis L: avaliações fisológicas, bioquímicas e fitoquímicas

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo de dois genes de café (Coffea arabica) induzidos por estresse biótico e análise de suas regiões promotoras

Pós-graduação em Ciências Biológicas (Genética) - IBB

Efeito do L-Name na expressão de iNOS, MPO e na perda óssea alveolar em ratos diabéticos com periodontite experimental

Pós-graduação em Odontologia - FOAR

Efeito do tratamento periodontal não-cirúrgico em pacientes portadores de Diabetes mellitus tipo 2 com doença periodontal: análises clínica, enzimática e microbiológica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da indução de resistência no controle do crestamento bacteriano comum do feijão vagem

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Ação de indutores bióticos e abióticos no controle da ferrugem do eucalipto, atividade enzimática e expressão gênica durante o processo de infecção

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)