New Class of Tunable Choline Bromide-Based Hydrophobic Deep Eutectic Solvents for the Extraction of Bioactive Compounds of Varying Polarity from a Plant Matrix

Abstract

Deep eutectic solvents (DESs) are a class of sustainable solvents that have found numerous applications in different fields. One of their main attributes is the possibility of easily modifying their physicochemical properties by varying the type of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) that comprise them. Choline chloride ([Ch + ][Cl − ])-based hydrophilic DESs were among the first studied and the most used because of their capacity to easily create a hydrogen bonding network that lies in its unique chemical structure, characterized by a hydroxyl substituent within the ammonium headgroup. In this study, a new class of hydrophobic [Ch + ][Br − ]-modified salts were synthesized to produce HBAs with similar properties to choline for the preparation of hydrophobic DESs. Six different [Ch + ][Br − ]-based HDESs were prepared and characterized in terms of hydrophobicity, viscosity, and solvation properties (hydrogen bonding, dispersion, dipolarity/polarizability, n−π, and π−π interactions). They were employed as solvents in a microextraction method for the determination of phytochemicals in Cannabis sativa L. plant. The extraction performance of the [Ch + ][Br − ]-based HDESs was compared to eutectic mixtures based on conventional hydrophobic HBAs, and the results revealed that the unique properties of [Ch + ][Br − ]-modified salts allowed for the extraction of both hydrophilic (i.e., flavonoids) and hydrophobic compounds (i.e., cannabinoids).

A Comprehensive Review on Deep Eutectic Solvents and Its Use to Extract Bioactive Compounds of Pharmaceutical Interest

“…Hydrophobic DESs based on choline bromide with different chain lengths were synthesized to extract phytochemicals from Cannabis sativa . The hydrophobic and hydrophilic features of the DESs facilitated the interactions with polar and non-polar compounds present in the plant increasing the extraction efficiency [ 161 ].…”

Evolution of Green Sample Preparation: Fostering a Sustainable Tomorrow in Analytical Sciences

“…The DLLME employs minimal organic solvents, with only 200 μL of DES per sample, resulting in negligible waste generation. Another example available in the literature is devoted to the extraction of bioactive compounds (phytochemicals) from plant matrix ( Cannabis sativa L. ) by using tunable choline (Ch) bromide-based hydrophobic DES in dispersive liquid–solid microextraction (DSLME) . They synthesized six different [Ch + ]­[Br – ]-based hydrophobic DESs varying hydrophobicity, viscosity, and solvation properties, making the synthesis highly tailorable.…”

A Comprehensive Review on Deep Eutectic Solvents and Its Use to Extract Bioactive Compounds of Pharmaceutical Interest

“…Hydrophobic DESs based on choline bromide with different chain lengths were synthesized to extract phytochemicals from Cannabis sativa. The hydrophobic and hydrophilic features of the DESs facilitated the interactions with polar and non-polar compounds present in the plant increasing the extraction efficiency [166].…”