An integrated green process for the extraction of triterpenic acids from Eucalyptus globulus leaves after hydrodistillation

Abstract

In this study the viability of the integrated exploitation of E. globulus leaf essential oil and triterpenic acids was evaluated through the development of a novel extraction process that can be implemented sequentially in a biorefinery context. Thus, essential oil (EO) collected by hydrodistillation was used for the first time as a bio-based solvent to recover triterpenic acids (TTAs) from the residue resulting from the EO recovery (from the hydrodistilled leaves). Ursolic, oleanolic, betulonic and betulinic acids were successfully extracted with EO with, for comparison purposes, its major component, 1,8-cineole (CO), showing TTAs extraction yields of 2.8 and 2.7% dw, respectively. Both EO and CO were particularly efficient in extracting ursolic (18.3 and 17.9 g kg⁻¹ dw) and oleanolic (6.0 and 5.7 g kg⁻¹ dw, respectively) acids, the major components of crude extracts. In addition, cytotoxicity evaluation showed that EO and CO crude extracts are non-toxic to macrophage cell lines at concentrations less than or equal to 0.04 and 0.08 mg mL⁻¹, respectively. Crude extracts dissolved in the EO and CO also showed higher anti-inflammatory activity than a synthetic mixture representative of the TTAs detected, demonstrating the synergistic effect between EO or CO and the extracted components. In summary, the EO is a potential bio-based solvent, which could be applied in biorefinery processes, replacing organic solvents such as n-hexane in the recovery of TTAs, without environmental side effects, and even with potential applications of the crude extracts themselves in the nutraceutical and pharmaceutical fields.