Perfil metabolômico de folhas de cultivares de oliveiras nas diferentes estações do ano

Abstract

Considered a millenary culture, the olive tree (Olea europaea L.) has besides its fruit, the leaves, which contain appreciable amounts of bioactive compounds, which are related to the system of defense of plants and with various actions in the human organism. The abiotic stresses act as mechanisms of activation of the routes of synthesis of these compounds, due to the increase of the oxidative level in the plants by the production of free radicals. Commonly cultivated in the Mediterranean region, several breeding programs were responsible for the modification and creation of new olive cultivars, so that they could be cultivated throughout the world. Therefore, the objective of this study was to evaluate the metabolic profile of leaves of olive cultivars (Arbequina, Manzanilla and Picual) collected in the different seasons of the year (autumn, winter, spring and summer) in Pinheiro Machado / RS during 2016/17. The determination of phenolic compounds, flavonoids, tannins, carotenoids and chlorophylls were performed by spectrophotometry, while the identification and quantification of individual phenolics was performed by high performance liquid chromatography coupled to mass spectrometry. Antioxidant potential tests were also carried out using DPPH, FRAP and ABTS methods. As results it was possible to observe that the leaves of the cultivar Manzanilla presented the highest contents of phenolic compounds and that the leaves collected in the summer presented a quantity of these compounds significantly higher than those collected in the other seasons. Consequently, the potential antioxidants of the polar extracts of these leaves showed high correlation with these compounds, being observed greater potentials in the same treatments in which the content of phenolic compounds excelled. Polar and nonpolar compounds behaved differently, raising questions about how the synthesis pathways of these compounds interact or whether they are independent. The relationship between the purpose of the cultivar (oil production or table olives) and the bioactive compounds in leaves still needs to be better studied, due to the higher levels of phenolic compounds and hydrolysable tannins found in Manzanilla in this work. Finally, it was possible to conclude that the cultivar and the collection season have a significant relationship with the metabolic profile of olive leaves.