A new method for microwave assisted ethanolic extraction of Mentha rotundifolia bioactive terpenoids

Abstract

A new microwave-assisted extraction (MAE) method using ethanol as solvent has been optimized by means of a Box-Behnken experimental design for the enhanced extraction of bioactive terpenoids from Mentha rotundifolia leaves; 100°C, 5 min, 1.125 g dry sample: 10 mL solvent and a single extraction cycle were selected as optimal conditions. Improved performance of MAE method in terms of extraction yield and/or reproducibility over conventional solid-liquid extraction and ultrasound assisted extraction was also previously assessed. A comprehensive characterization of MAE extracts was carried out by GC-MS. A total of 46 compounds, mostly terpenoids, were identified; piperitenone oxide and piperitenone were the major compounds determined. Several neophytadiene isomers were also detected for the first time in MAE extracts. Different procedures (solid-phase extraction and activated charcoal (AC) treatment) were also evaluated for clean-up of MAE extracts, with AC providing the highest enrichment in bioactive terpenoids. Finally, the MAE method here developed is shown as a green, fast, efficient and reproducible liquid extraction methodology to obtain M. rotundifolia bioactive extracts for further application, among others, as food preservatives.

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

“…bioactives. Whereas the advantages associated with ohmic, microwave or ultrasound-assisted hydrodistillation to obtain essential oils rich in volatile bioactives have been described in a number of studies [13][14][15][16][17], literature regarding the development of procedures based on pressurized liquid extraction (PLE) [18], ultrasound-assisted extraction [19,20] or microwave-assisted extraction (MAE) [21][22][23][24][25] for the enhanced recovery of Mentha sp. bioactives is much more limited.…”

“…However, despite the fact that direct heating of the solvent by microwave irradiation has been shown to improve the speed and efficiency of bioactive extractions and the bioactivity of MAE extracts, previous applications of this advanced technique to Mentha sp. have commonly focused on a single Mentha species (Mentha piperita [21,24,25], M. pulegium [22], M. rotundifolia [23]), making the comparison of this effect difficult. Moreover, no previous study has addressed the optimization of an MAE method to obtain multifunctional extracts from different Mentha species, as the antimicrobial activity of MAE extracts of Mentha sp.…”

Green subcritical water extraction of Mentha x rotundifolia leaves collected in different annuities

“…of its essential oils, mainly obtained by distillation or hydrodistillation [5][6][7]. However, studies regarding the composition and bioactivity of extracts from this Mentha species obtained using polar solvents are scarce [8,9]. Moreover, no previous study has addressed the changes with harvesting year for extracts from M. rotundifolia samples collected at the same harvesting stage.…”

“…Although solid-liquid extraction (SLE) is the most widely used procedure to obtain bioactive extracts because of their undeniable advantages in terms of simplicity and affordability, advanced extraction techniques such as microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) and subcritical water extraction (SWE), are gaining importance as efficient alternatives for bioactive extraction [10]. While UAE [11][12][13][14] and MAE [8,11,15] have been previously described to provide improved performance for the extraction of Mentha bioactives, SWE has been scarcely applied for this purpose.…”

The Influence of Microwave Treatments on Bioactive Compounds and Antioxidant Capacity of Mentha piperita L.

“…Kohari et al, (2020) [ 14 ] applied solvent-free microwave extraction to Mentha arvensis L. in order to obtain essential oils and demonstrated that this method is more efficient than traditional hydrodistillation extraction. The fragrance components such as limonene and piperitone were found in a higher amount in microwave extraction compared with the traditional method [ 14 , 15 ]. A microwave-assisted extraction method has been optimized by using ethanol as a solvent to extract terpenoids from Mentha rotundifolia [ 6 ].…”