Deep eutectic solvents for sustainable extraction of polyphenols and saponins from plant sources: assessment of the impact of influencing factors

With the requirement to increase the safety and sustainability of the separation processes, there has been a shift toward the utilization of green solvents in the extraction processes. Deep eutectic solvents (DESs) are neoteric solvents with several advantages over conventional organic solvents or ionic liquids (ILs). They are nontoxic, nonflammable, biodegradable, and less costly. Moreover, they can be regenerated and reused in the extraction process in repeated cycles. The extraction yield using DESs can be improved through the employment of ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), ultrahigh pressure extraction (UHPE), or negative pressure cavitation extraction (NPCE). These techniques not only shorten the processing time but also intensify the mass transfer and facilitate the diffusion and extraction of bioactive ingredients. With the raised interest in the separation and purification of polyphenol and saponin compounds with several therapeutic properties, DESs have found their applications as alternative solvents. This review aims to highlight recent applications of DESs for the extraction of flavonoids, curcuminoids, and saponins from plant sources and discuss and compare the factors that should be considered for enhancing the extraction efficiency of these bioactive ingredients. The discussed works lay the foundations for further development of the extraction processes using these solvents. [GRAPHICS]