Extraction of Plant and Algal Polyphenols Using Eutectic Solvents

Natural ingredients are currently attracting growing interest for industrial applications such as functional food, nutraceuticals, cosmetics, and pharmaceuticals. A key point is the societal acceptance for the naturally occurring compounds which are believed to be safer to humans and environment than artificial compounds. Polyphenols are one of the most interesting plant substances which are carrying many biological activities. Thousands of phenolic compounds have been identified, isolated, and selected from the plant kingdom including terrestrial and marine sources. A challenge concerns the development of efficient and green technologies for the extraction of plant and algal polyphenols. Ionic liquids have been successfully evaluated, but they are facing strong issues related to their cost, sourcing, and green nature, precluding any industrial development. Being cheaper and eco-friendly, deep eutectic and natural deep eutectic solvents have a great potential as solvents for the extraction of polyphenols. The ability of deep eutectics to form hydrogen bonds is particularly of interest for the selective extraction of polyphenols since these compounds are generally rich in hydrogen bond donor groups.