Optimization of an Ultrasound-Assisted Extraction Method Applied to the Extraction of Flavonoids from Moringa Leaves (Moringa oleífera Lam.)

Interest in phenolic compounds has recently increased due to their potential as antioxidant agents. Moringa leaves (Moringa oleifera) have a high content of phenolic compounds, which presents them as a promising source for the extraction of these compounds. However, it is necessary to use analytical techniques to identify and quantify their actual compound content to determine the quality of the raw material and the potential of the final product. Ultrasound assisted extraction is a green, rapid and environmentally friendly extraction technique that produces high quality extracts from natural products. Hence, the aim of this research is to optimize the variables of the ultrasound-assisted extraction (UAE) process for the extraction of moringa leaves using response surface methodology (RSM) to extract the main flavonoids using methanol as the extraction solvent. A Box–Behnken design (BBD) has been used to evaluate the effect of the ultrasound extraction process variables. Finally, the optimal extraction time in the range between 2 and 30 min was determined. The results revealed that the methanol concentration was the most influential variable. The optimal extraction time was established at 15 min. Six of the main flavonoids were quantified by UHPLC-DAD and identified by UHPLC-QToF-MS. The results confirmed that UAE is an efficient method for the extraction and subsequent analysis and quality control of the flavonoids that can be found in moringa leaves.