Ultrasound-Assisted Extraction: Effect of Extraction Time and Solvent Power on the Levels of Polyphenols and Antioxidant Activity of Mesembryanthemum edule L. Aizoaceae Shoots

Purpose: To investigate the influence of extraction conditions assisted by ultrasound on the quality of extracts obtained from Mesembryanthemum edule shoots. Methods: The extraction procedure was carried out in an ultrasonic bath. The effect of two solvents (methanol and ethanol) and two extraction times (5 and 10 min) were evaluated on the basis of the phenolic content and antioxidant activity of the plant extract. Results: Significant variability in phenolic content and antioxidant activity, depending on the solvent (S), and to a lesser degree, extraction duration (D) and their interaction (S/D) were found. Methanol extract was significantly richer in total polyphenols than ethanol extract, their levels being 104.7 and 74.2 mg GAE.g-1DW, respectively. For the two solvents used, longer extraction duration yielded higher polyphenol content. The ethanol extract exhibited higher antioxidant activity than the methanol extract. Moreover, Also, the longer sonication duration (10 min) yielded extracts with higher antioxidant activities. Conclusion: The antioxidant capacity of M. edule is strongly influenced by the nature of the extracting solvent and the duration of sonication extraction.