Perfil fitoquímico e avaliação da atividade antioxidante de extratos de Camellia sinensis (L.) Kuntze

Abstract

Green tea, produced from the leaves of Camellia sinensis (L.) Kuntze, is known for its high content of flavonoids, mainly catechins, which are associated with its antioxidant activity. In this work, the infusion of green tea, obtained in the local market, was carried out in water, both in the form of sachets and in bulk. The aqueous extract was treated with ethyl acetate to separate most of the phenolic compounds present in the teas. The characterization of the samples was carried out using the phenolic content methodologies from the Folin-Ciocalteau reagent and the flavonoid content using the ferric chloride colorimetric method. Spectroscopic characterizations were performed by mass and 1H NMR. With that, tests of antioxidant activity were carried out by the radical capture methodologies DPPH, ABTS and by reduction of the iron ion and cell viability test using fibroblast cells lineage 3T3, by the MTT method in 24 and 48 hours. Theoretical calculations were also performed for the conformational analysis of (+)-catechin, an important component of green tea. With the performance of the analyzes described, it was possible to observe the same phenolic content in both extracts, however, the flavonoid content of the green tea extract in sachet was higher than the bulk, in the characterization by mass spectrometry this was confirmed, being possible to identify all the catechins in the green tea extract in sachet, and in the bulk extract a greater number of phenolic acids was obtained. From the 1H NMR of tea extract in sachet, It was found signals of all compounds detected by mass spectrometry, confirming the presence of these components in tea. The antioxidant activity for the three methodologies tested was better for the green tea extract in sachet, being able to relate the greater number of flavonoids in this extract with the best antioxidant potential. Cell viability was tested for the green tea extract in sachet, and it was observed a decrease in viability at concentrations above 1mg/mL, at 24 and 48 hours, for the other tested concentrations the cells remained viable.