Glyceline (choline chloride-glycerol) (natural) deep eutectic solvents for bioactive compound extraction

Bioactive compounds are chemical molecules found in natural resources that provide various benefits. However, before they can be administered, they must first be extracted. This study looks at the extraction of bioactive compounds using a green solvent. Glyceline is commonly referred to as the deep eutectic solvent (DES) / the natural deep eutectic solvent (Na)DES, and it is composed of choline chloride (ChCl) acts as the hydrogen bond acceptor and glycerol (Gly) as the hydrogen bond donor. Glyceline formation outcomes in a significantly depressed melting point in comparison to its individual components. It aligns well with the principles of green chemistry, possessing highly desired characteristics such as low toxicity, high biodegradability, ease of preparation, and low cost. Glyceline is widely recognized as an efficient green solvent for the extraction of various bioactive compounds. Several bioactive compounds (BCs) such as phenols, terpenoids, alkaloids, etc. have been successfully extracted effectively by using glyceline in optimized conditions. Several factors such as temperature, molar ratio, water content, etc. affect its efficiency in extraction. On the way, glyceline has also shown limitation in extraction in several categories of compounds due to high viscosity, polarity mismatch, etc. Over the course, several techniques and strategies have been utilized to improve the efficiency of the ChCl:Gly either by changing conditions such as temperature increase, water addition, molar ratio, to improve properties such as viscosity, polarity, density, or by introducing additional ingredients that were recently used, named as catalyzed DES such as Lewis acid, heteropoly acid, or by introducing nanoparticles that either affect the acidity or composition. The incorporation of energy-intensive methods significantly compensates for low mass transfer rates by enhancing the physical process of extraction, often resulting in higher yields and shorter processing times. The applicability and usability in many domains, as well as their future prospects, are discussed. Additional research aimed at improving its selectivity and recovery methods is required for large-scale industrial use.