Influence of temperature, solvent and extraction procedure on the content of phenolic compounds and antioxidant activity of <i>Aloysia citriodora</i> Palau leaves

Introduction: The leaves of Aloysia citriodora Palau are a source of phenolic compounds that have antioxidant properties. Objective: The objective of this study was to compare the effects of temperature, type of solvent, maceration, and ultrasound processes in the extraction of phenolic compounds from A. citriodora Palau leaves that allow for maintaining the highest antioxidant capacity. Methods: In this study, phenolic compounds were extracted from A. citriodora by two methods, maceration, and ultrasonic treatment, using water and 80% ethanol as solvents and extraction temperatures of 25 °C, 45 °C, and 65 °C. Total phenolic compounds (TPhen), total flavonoid compounds (TFlav), and antioxidant capacity, evaluated by DPPH and ABTS assay, were characterized and reported as inhibition concentration (IC50). Results: The highest CPhen content was obtained with ethanolic extract using the ultrasonic method at 65 °C, with a value of 15.32 mg EAG/mL at 65 °C. For TFlav, the highest value was obtained with the ultrasonic treatment at 45 °C using ethanol as solvent, obtaining a value of 6.52 mg EQ/mL. The best antioxidant capacity was shown by the sonication with ethanol at 65 and 45 °C, with IC50 values of 27.10 µg/mL and 20.40 µg/mL, respectively. Conclusion: Ultrasound extraction at higher temperatures (45°C and 65°C) proved more effective than maceration, yielding greater amounts of phenolic and flavonoid compounds and exhibiting better antioxidant capacity.”. Keywords: Aloysia citrodora, phenolic compounds, antioxidant activity, inhibitory concentration IC50.