This study investigates how solvent polarity and extraction technique influence the recovery of bioactive compounds from four Portuguese native plants: Geranium robertianum (herb Robert), Olea europaea (olive leaves), Salvia rosmarinus (rosemary) and Laurus nobilis (bay laurel). Maceration and Soxhlet extractions were performed using five solvents spanning a polarity range (methanol, ethanol, ethyl acetate, dichloromethane and hexane), followed by colorimetric phytochemical screening and extraction-yield comparison; aqueous infusion and water-based Soxhlet extraction were also assessed. Among the organic solvents tested, extraction yield increased with solvent polarity, with methanol consistently giving the highest recoveries; aqueous extraction showed species-dependent behavior. Phytochemical assays indicated a wide metabolite coverage in methanolic extracts, whereas tannins were not detected in ethanolic extracts and were only evidenced in bay laurel under less-polar conditions. GC–MS profiling of ethanolic extracts revealed distinct species-specific fingerprints dominated by fatty acids and terpenoid constituents, with Soxhlet generally enhancing late-eluting hydrophobic metabolites; rosemary was enriched in phenolic diterpenes, herb Robert and olive leaves showed a stronger contribution of carbohydrate-related compounds, and bay laurel displayed a comparatively simpler lipid/terpenoid profile. These results highlight the suitability of these Portuguese native plants as versatile sources of bioactive fractions whose composition can be selectively tuned through solvent polarity and extraction strategy.
Melro et al. (Thu,) studied this question.