The enormous quantity of food wastes discarded annually forces a look into alternatives for this interesting feedstock.

The toxicity of ionic liquids, involving different classes of cations and different types of anions, was evaluated by a colorimetric assay with 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) in two colon carcinoma HT-29 and CaCo-2 cell lines. Confluent CaCo-2 cells can undergo spontaneously an enterocytic differentiation and represent a good in vitro model of normal human intestinal epithelium. Ionic liquids are highly promising due to their low vapour pressures, however, toxicity evaluation of these ionic liquids is of great importance to assess the risk of these ionic liquids to humans and the environment.

Novel ionic liquids (ILs) containing cholinium as a benign cation combined with anions based on five active pharmaceutical ingredients (APIs), namely, nalidixic acid, niflumic acid, 4-amino-salicylic acid, pyrazinoic acid and picolinic acid, were prepared via a simple and sustainable two-step anion exchange reaction. The solubility of the prepared pharmaceutically active ILs (API-ILs) in both water and simulated biological fluids at 25 °C and 37 °C, as well as the solubility of the parent APIs, were measured. Further, in vitro cytotoxicity levels for both cholinium-based API-ILs and parent APIs were established using two different human cells lines, namely Caco-2 colon carcinoma cells and HepG2 hepatocellular carcinoma cells. Herein, the dual nature of ILs is exploited by combining the cheap, available and essential nutrient cholinium cation with pharmaceutically active anions, upgrading the chemical, physical and biopharmaceutical properties, particularly melting point, aqueous solubility and the potential to penetrate cell membranes of the parent APIs, without impair their cytotoxicity response which prompt opportunities for creating further advances in pharmaceutical challenges.

The green and versatile character of deep eutectic solvents (DES) has turned them into significant tools in the development of green and sustainable technologies. For this purpose, their use in polymeric applications has been growing and expanding to new areas of development. The present review aims to summarize the progress in the field of DES applied to polymer science and engineering. It comprises fundamentals studies involving DES and polymers, recent applications of DES in polymer synthesis, extraction and modification, and the early developments on the formulation of DES–polymer products. The combination of DES and polymers is highly promising in the development of new and ‘greener’ materials. Still, there is plenty of room for future research in this field.