Methylxanthines, phenolic composition, and antioxidant activity of bark from residues from mate tree harvesting (Ilex paraguariensis A. St. Hil.)

Leaves and products made from them are the major focus of research on bioactive compounds of mate (Ilex paraguariensis). However, studies on other parts of the plant, are scarce. The aim of this study was to determine the methylxanthines, phenolic compounds, and antioxidant activity of mate bark (residual biomass) and compare with those of mate leaves. The high antioxidant activity of mate bark and its high concentration of total polyphenols were apparent in both the aqueous and the methanolic extracts, the values of which were greater than those detected in the leaves. Of the phenolic acids identified, the levels of chlorogenic acid and 4,5-dicaffeoylquinic acid in the samples were significantly higher in the methanolic bark extract. With regard to methylxanthines, considerable concentrations were detected in the samples. The results obtained contribute to the viability of exploiting this residue, broadening the use of the mate plant.