Effect of extraction conditions on total phenolic content and antioxidant capacity of pretreated wild Peumus boldus leaves from Chile

We studied the effect of both heat-drying and freeze-drying on the recovery of total phenolic compounds (TPCs) and antioxidant capacity from leaves of Peumus boldus Molina (Boldo), an endemic tree of Chile, using DPPH (2,2-diphenyl-1-picrylhydrazyl radical scavenging), FRAP (ferric reducing antioxidant power) and ORAC (oxygen radical absorbance capacity) methods. The results indicated that infusions prepared using commercial boldo tea bags had similar or higher TPCs, DPPH, FRAP and ORAC values in comparison with those of the infusions prepared using heat- or freeze-dried leaves. The extraction experiments showed that hydro-alcoholic mixtures are the best solvents to extract antioxidants from boldo leaves, favoring the use of freeze-dried leaves. Considering the alkaloid profile of the extracts of freeze-dried leaves and herbal tea bags, the latter exhibited higher amounts of the alkaloids tested, including boldine, which is well correlated with the results obtained using the ORAC method. These results indicate a great potential to develop commercial boldo extracts and could encourage improved applications of this endemic Chilean plant.