Anthocyanins, Phenolic Compounds, and Antioxidants from Extractions of Six Eucalyptus Species

Abstract

The leaves of Eucalyptus have multiple biological activities such as antimicrobial, antiseptic, antioxidant, and antifungal. A Soxhlet extraction, SLE, and HD were used to obtain extracts from the leaves of six Eucalyptus species, E. globulus, E. oblicua, E. pavaflora, E. camaldulensis, E. viminalis, and E. nitens, and to study their antioxidant capacity. Solvents such as acetone, dichloromethane, ethanol, hexane, methanol, and water were used to study how polarity influences extraction yields. The SLE method achieved higher or similar yields, depending on the species and its composition, than the Soxlet method at a temperature of 50 °C. The highest yields were obtained with E. viminalis with methanol (42.5 wt.%), the highest phenolic content was obtained with E. nitens with methanol (124.17 mg GAE/g of extract), and the highest anthocyanin levels obtained were with E. nitens with hexane (5.05 mg CC/g of extract). E. nitens obtained almost five times more phenolic content than E. globulus; therefore, it is the most promising species. The high content of the compounds analysed confirm the good potential of these species to obtain value-added compounds. Our results demonstrate that the differences in the extract contents depend on the polarity of the solvents used. In addition, the use of these species will reduce the residue in the forest, which is greatly beneficial.