Formulation, structure, and applications of therapeutic and amino acid-based deep eutectic solvents: An overview

In the design of greener chemicals, deep eutectic solvents (DESs) are considered as one of the most versatile alternativemediawith widespread applications. DESs have the advantages of being nonflammable with negligible vapor pressure compared to the traditional solvents. They sharemany characteristics of ionic liquids, but DESs are cheaper to formulate, typically nontoxic, highly pure, recyclable, biodegradable, and are suitable for use with biological systems. In this article, the two emerging and unconventional types of DESs, therapeutic DES (THEDES) and amino acid-based DES (AADES) are reviewed. Based on the published literature, choline chloride and menthol are the two most common constituents to formulate THEDESs, while proline is the most common component to formulate AADESs. THEDESs have primarily been developed to enhance the efficacy of drugs, whereas AADESs have been explored for pharmaceuticals as well as for the extraction of phytochemicals, radioactive iodine capture, oil separation from ores, and to synthesize bioactive compounds. Since detailed knowledge of their structures, nonbonding interactions, formulations, and applications are yet to be explored, the aim of this review is to compile these details and provide a solid background for the future research. (C) 2020 Elsevier B.V. All rights reserved.