Optimization of Ultrasound-Assisted Extraction of Polyphenols from Myrtus communis L. Pericarp.

Response surface methodology (RSM) was used to optimize the extraction of phenolics from pericap of Myrtus communis using ultrasound-assisted extraction (UAE). The results were compared with those obtained by microwave-assisted extraction (MAE) and conventional solvent extraction (CSE) methods. The individual compounds of the optimized extract obtained by UAE were identified by ultra-high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (UHPLC-DAD-ESI-MSn). The yield of total phenolic compounds (TPC) was affected more significantly by ethanol concentration, irradiation time, liquid solvent-to-solid ratio (p < 0.0001) and amplitude (p = 0.0421) and optimal parameters conditions set by the RSM model were 70% (v/v), 7.5 min and 30%, respectively. The experimental yield of TPC (241.66 ± 12.77 mg gallic acid equivalent/g dry weight) confirmed the predicted value (235.52 ± 9.9 mg gallic acid equivalent/g dry weight), allowing also to confirm the model validity. Under optimized conditions, UAE was more efficient than MAE and CSE in extracting antioxidants, which comprised mostly myricetin glycosides. Globally, the present work demonstrated that, compared to MAE and CSE, UAE is an efficient method for phenolic extraction from M. communis pericarp, enabling to reduce the working time and the solvent consumption.

Phytochemical analysis of Myrtus communis plant: Conventional versus microwave assisted-extraction procedures.

Background Myrtle (Myrtus communis L) may constitute an interesting dietary source of health protective compounds. Microwave-assisted extraction (MAE) of total phenolic compounds (TPC) from myrtle leaf, stems, pericarp, and seeds was studied and the results were compared with those of the conventional method extraction (CME) in terms of extraction time. Methods Extraction yield/efficiency and antioxidant activity were measured using radical scavenging assay (DPPH•) and reducing power. Results The results show that the MAE was higher in terms of saving energy, extraction time (62 s) and extraction efficiency of bioactive compound compared to CME (2 h). Leaf presented the optimum content of total phenols (250 mg GAE.g-1 DW) and flavonoids (13.65 mg GAE.g-1 DW). However, the anthocyanin content was most important in pericarp extract (176.50±2.17 mg Cyd-3-glu g-1 DW). The antioxidant activity was important in all parts, mainly in leaves. The results indicated that appropriate microwave treatment could be an efficient process to phenolic compounds recovery and thus, better the antioxidant activity of myrtle extract. Conclusions Principal component analysis (PCA) applied to the experimental data shows that the distribution of the myrtle phenolic compounds depended on their plant part localization as well as the extraction method.