RESUMEN
Coffee production is one of the main agricultural activities in Brazil, and several coffee cultivars with disease resistance have already been developed. The secondary metabolites produced by plants are closely associated with defense strategies, and the resistance of coffee cultivars to bacterial halo blight (BHB) can be related to these compounds. Therefore, this study aims to compare a partially resistant coffee cultivar (Iapar-59) and a susceptible cultivar (Mundo Novo 376/4) to BHB (Pseudomonas syringae pv. garcae) in relation to the chemical composition and antioxidant activity of the leaf extracts. In addition, this study determined the total phenolic and flavonoid contents and phenolic profiles of the Iapar-59 leaf extracts of plants inoculated with P. syringae pv. garcae. The Iapar-59 extract showed a higher content of phenolic compounds and flavonoids than the Mundo Novo 376/4 extract. Both cultivars contained gallic, chlorogenic and caffeic acids; however, the highest contents were quantified in the Iapar-59 cultivar. The leaf extracts from the Iapar-59 cultivar exhibited higher antioxidant activity. Higher concentrations of gallic, caffeic and chlorogenic acids and the presence of vanillin were detected in the extract of cultivar Iapar-59 inoculated with P. syringae pv. garcae.
RESUMEN
The radish (Raphanus sativus L.) is a vegetable of the Brassicaceae family cultivated worldwide and has several medicinal properties. Its biological activities are related to various secondary metabolites present in the species, especially phenolics. Thus, the objectives of this study were the chemical analysis and evaluation of the antioxidant and antimicrobial activities of the dry extract and fractions of the fodder turnip leaves (R. sativus var. oleiferus Metzg.). Samples were analyzed by mass spectrometry and the antioxidant activity was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical method and the reducing power method. Antimicrobial activity was determined by the agar diffusion and microdilution methods. The total phenols were concentrated in the butanol fraction (121.27 mg GAE/g) and the flavonoids were concentrated in the ethyl acetate fraction (98.02 mg EQ/g). The ethyl acetate fraction showed the best antioxidants results, with 83.45% of free radical scavenging and 11.34% of ferric ions reduction. The analysis of antimicrobial activity showed that the dry extract had the highest average zone of inhibition against Bacillus subtilis (18.67 mm). Smaller values of the minimum inhibitory concentration for Micrococcus luteus were, and the ethyl acetate fraction showed a lower minimum inhibitory concentration (0.1 mg/ml) for that microorganism. There was a strong correlation between the antioxidant activity and the content of phenols and flavonoids. The results showed the potential antioxidant and antimicrobial activities of this extract with the ethyl acetate fraction being most promising for further studies.
O rabanete(Raphanus sativus L.) é um vegetal da família Brassicaceae cultivado em todo o mundo e possui diversas propriedades medicinais. Suas atividades biológicas estão relacionadas aos vários metabólitos secundários presentes na espécie, especialmente os compostos fenólicos. Desta forma, os objetivos deste estudo foram realizar análises químicas e avaliar as atividades antioxidante e antimicrobiana do extrato seco e das frações das folhas de R. sativus var. oleiferus Metzg. As amostras foram analisadas em espectrômetro de massas e o potencial antioxidante foi avaliado pelos métodos do radical DPPH (2,2-difenil-1-picrilhidrazila) e do poder redutor. A atividade antimicrobiana foi determinada pelos métodos de difusão em ágar e da microdiluição. Observou-se que os fenóis totais se concentraram na fração butanólica (121,27 mg EAG/g), enquanto que e os teores de flavonoides concentraram-se na fração acetato de etila (98,02 mg EQ/g). A fração acetato de etila apresentou os melhores resultados antioxidantes, com porcentagem de sequestro dos radicais DPPH de 83,45% e com porcentagem de redução dos íons férrico de 11,34%. A análise da atividade antimicrobiana revelou que o extrato seco teve maior média de halos de inibição frente ao Bacillus subtilis(18,67 mm). Os menores valores da concentração inibitória mínima foram para Micrococcus luteus, sendo que a fração acetato de etila demonstrou menor concentração inibitória mínima (0,1 mg/mL) para esse micro-organismo. Houve uma forte correlação entre a atividade antioxidante e o teor de fenóis e de flavonoides. Os resultados demonstraram potenciais ações antioxidante e antimicrobiana do extrato e das frações avaliados, sendo a fração acetato de etila promissora para estudos posteriores.
Asunto(s)
Raphanus , Antiinfecciosos , Antioxidantes , Plantas Medicinales , Bacillus subtilis , Micrococcus luteus , Brassicaceae , Compuestos Fenólicos , Fenómenos QuímicosRESUMEN
The extraction of mechanically separated meat has emerged as an attractive process. However, it increases the incorporation of oxygen and, consequently, of flavors due to rancidity. Thus, preservatives must be added. The objective of this study was to evaluate the shelf life of minced tilapia to replace synthetic preservatives with Hijiki and Nori seaweeds extracts. The application of the extracts had no effect on the chemical composition of the minced tilapia. The seaweed extracts had inhibitory effect on total volatile base nitrogen. The minced tilapia complied with the microbiological standard set by Brazilin law. The panelists detected no differences in the rancid aroma and only minor differences were detected in the color of the products. It can be concluded that the minced tilapia with added seaweed extracts were within quality standards during frozen storage.
