This study evaluated olive leaves from three cultivars (Hojiblanca, Picual, and Arbequina) and olive pomace as complementary sources of bioactive compounds, comparing ultrasound-assisted extraction using organic solvents (UAE) with supercritical CO2 extraction (SFE). The aim was to determine how the plant matrix and extraction method influence phytochemical composition and functional properties, including antioxidant and antimicrobial activity. The results showed that both factors strongly affected extract composition and bioactivity. UAE favored the recovery of phenolic compounds associated with antioxidant activity, particularly in leaf extracts, while SFE promoted a distinct compositional profile enriched in flavonoids and lipophilic constituents, especially in olive pomace. Multivariate analysis confirmed a clear differentiation between matrices and extraction methods. Leaf extracts from Picual and Arbequina were mainly associated with phenolic compounds linked to antioxidant activity, including luteolin, ethyl vanillin, tyrosol, and isorhamnetin-3-O-glucoside. In contrast, olive pomace extracts were more strongly associated with flavonoids and lipophilic metabolites, such as triterpenes (oleanolic, maslinic, and ursolic acids) and lipid derivatives (oleic acid and lauric isopropanolamide). These compositional differences were reflected in biological activity: UAE extracts showed higher antioxidant activity, whereas SFE extracts, enriched in lipophilic and triterpenic compounds, exhibited stronger antimicrobial effects against Pseudomonas savastanoi and Hanseniaspora sp. Overall, these findings demonstrate that extraction-driven selectivity enables the production of olive-derived extracts with targeted functionalities, with UAE favoring antioxidant-oriented extracts and SFE promoting extracts enriched in lipophilic compounds with antimicrobial potential, particularly from olive pomace.
Gizaw et al. (Thu,) studied this question.