Bioactive compounds and antioxidant activity of leaves from olive trees grown in Paraná, Brazil

Abstract

The objective of this work was to evaluate the bromatological composition, bioactive compounds, antioxidant activities, and color of the leaves of olive cultivars Arbosana, Arbequina, Frantoio, Manzanilla, and Koroneiki in northwestern Paraná, Brazil. Leaves of each cultivar were collected for the experiment, which was carried out in a completely randomized design. The dry matter (DM) of olive leaves contains mostly carbohydrates (56.15 to 59.42 g 100 g^-1 DM) and fibers (17.37 to 19.73 g 100 g^-1 DM) in its bromatological composition. The total polyphenol content ranges from 13.27 to 22.81 mg GAE g^-1, with cultivar Manzanilla standing out, and the flavonoid content from 6.50 to 7.65 mg QE g^-1. Manzanilla shows the highest antioxidant activity of 93.56 and 78.15% in the DPPH and ABTS assays, respectively. When compared with the other cultivars, Manzanilla and Koroneiki have leaves with a higher green intensity and total chlorophyll content of 0.958 and 0.833 mg 100 mL^-1, respectively. In the ABTS assay, there is a correlation both between total polyphenol content and antioxidant activity and between chlorophyll content and antioxidant activity. Olive leaves have characteristics that allow their application as an additive or ingredient for the development of food products with satisfactory antioxidant activity.