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.

Carotenoid composition of Brazilian fruits and vegetables

Brazil has a wide diversity of food sources of carotenoids. The updated Brazilian database consists of more than 270 items of fruits, vegetables and their prepared and processed products. The database demonstrates variations due to variety, maturity, production technique, climate and processing. Many of these foods are not found in the US and European databases. Good to rich sources (>20 μg/g) of β-carotene are: acerola, bocaiúva, mango 'Extreme' and tucumã. Sources of both α-carotene and β-carotene are buriti, carrot, Cucurbita moschata 'Menina Brasileira', 'Baianinha' and 'Goianinha', and red palm oil. Commercially produced and uncultivated or semi-cultivated leafy vegetables, C. maxima 'Jerimum Caboclo' and the hybrid Tetsukabuto, cooked broccoli are sources of lutein and β-carotene. The edible Tropaeolum majus flower is especially rich in lutein. Although many fruits have β-cryptoxanthin as principal carotenoid (e.g. caja, nectarine, peach, orange-fleshed papaya, tree tomato), the levels are below 20 μg/g. Good to rich sources of lycopene are guava and guava products, papaya, pitanga and pitanga juice, tomato and tomato products, and watermelon. Sources of zeaxanthin are rare; although the principal carotenoid of piqui, the amount is low, lower than that found in buriti.

Effect of fungicides on the mite fauna of prunus persica L. cultivars in Presidente Prudente, SP, Brazil

The objective of this study was to characterize the diversity of phytophagous and predatory mites on peach cultivars either with or without fungicide treatment, in the city of Presidente Prudente, State of São Paulo, Brazil. In order to evaluate the effect of fungicides, leaf samples were colleted at random from treated and untreated plants of the Tropical, Aurora 1 and Aurora 2 cultivars, from June 2004 to February 2006. From the results obtained it can be concluded that: plants with or without treatment showed high populations of predatory mites, indicating that the treatments were innocuous on the mite populations. A diversified composition of the mite community was observed. The Phytoseiidae family had the highest richness in numbers and species of mites. Euseius citrifolius and E. concordis were the most abundant species. Plants with or without treatment had high abundances of predatory mites, with a predominance of E. citrifolius.

Morphological alterations on human radicular dentin after exposure to different fruit juice drinks

Purpose: This in vitro study aimed to evaluate the effect of different fruit juice drinks available in the Brazilian market on smear layer removal and dentinal tubules opening, as well as to verify the effect of toothbrushing subsequently to the juices exposure. Methods: Dentin specimens were prepared and randomly distributed into the control group (distilled water) and twelve types of fruit juice drinks (cashew, orange, mandarin, apple, passion fruit, guava, strawberry, grape, mango, pear, peach, pineapple). The following treatments were applied: immersion or immersion + brushing. After preparation for SEM, photomicrographs were assessed using an index of smear layer removal. Results: No significant differences regarding smear layer removal and dentinal tubules exposure could be observed between the groups after both treatments (Kruskal-Wallis, post-hoc paired comparisons, P>0.05). The control solution and the fruit juice drinks were not able to remove smear layer and to open dentinal tubules. Significant difference between the applied treatments was detected only for the mango juice group (Mann-Whitney, P<0.05). Conclusion: Under the experimental conditions, the different fruit juice drinks did not promote significant alterations on human radicular dentin morphology regardless of the subsequent application of brushing procedures. Copyright: © 2011 Zandim et al.

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.

Polyphenoloxidase activity in peaches after vibration

The vibration during transportation is one of the main causes of fruit damage. The actual methodologies used for damage evaluation in fruits seem to be subjective, since most of them are based on visual evaluation. In this study the effect of vibration, for one and two hours, on polyphenoloxidase (PPO) activity in peach pulp was investigated. The relation among PPO activity variation, postharvest time and resting time were also considered. Results showed that vibration affects PPO activity. However, it was not possible to correlate PPO activity variation and vibration.

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)

Painéis alternativos produzidos a partir de resíduos termoplásticos e da pupunheira (Bactris gasipaes Kunth)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Viabilidade de uso de um misturador para a análise de propriedades reológicas de produtos alimentícios

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Análise isotópica da variabilidade natural do carbono-13 e avaliação energética em néctares de pêssego – Prunus persica (L.) Batsch

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Influência do tipo de ensacamento no controle de pragas do pessegueiro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Fenologia, produção e qualidade dos frutos de cultivares de pessegueiro (Prunus Persica L. Bastch) em São Manuel – SP

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

Conservação de pêssegos 'Biuti irradiados e armazenados com e sem refrigeração

Pós-graduação em Agronomia (Horticultura) - FCA

Teores de carboidratos em pessegueiros cultivados em clima subtropical

Pós-graduação em Agronomia (Horticultura) - FCA

Avaliação de cultivares e épocas de poda para o pessegueiro na região de Botucatu/SP

Pós-graduação em Agronomia (Horticultura) - FCA