Optimization of a Green Microwave-Assisted Extraction Method to Obtain Multifunctional Extracts of sp.

A microwave-assisted extraction (MAE) procedure has been optimized to simultaneously provide multifunctional extracts of sp. leaves with improved antioxidant properties and, for the first time, with optimal antimicrobial activity. Among the solvents evaluated, water was selected as the extractant in order to develop a green procedure and also for its improved bioactive properties (higher TPC and inhibition halo). MAE operating conditions were optimized by means of a 3-level factorial experimental design (100 °C, 14.7 min, 1 g of dry leaves/12 mL of water and 1 extraction cycle), and further applied to the extraction of bioactives from 6 different species. A comparative LC-Q MS and LC-QToF MS analysis of these MAE extracts was carried out for the first time in a single study, allowing the characterization of up to 40 phenolics and the quantitation of the most abundant. Antioxidant, antimicrobial (, and ) and antifungal () activities of MAE extracts depended on the species considered. In conclusion, the new MAE method developed here is shown as a green and efficient approach to provide multifunctional sp. extracts with an added value as natural food preservatives.