Theoretical and experimental evidence for the use of natural deep eutectic solvents to increase the solubility and extractability of curcumin

Natural Deep Eutectic Solvents (NADESs) are a novel class of environmentally friendly liquids that can replace traditional organic solvents in industrial applications due to their ecologically beneficial features. These novel organic solvents are formed via weak interactions (mostly H-bonds) between two or more naturally existing substances. Even though they were recently found and recognized, NADESs have been the subject of significant and exciting research due to their unique properties. This study aims to determine the thermodynamic properties of eight NADESs and their solubility towards curcumin, a naturally occurring substance with significant medicinal properties. This study used a dual in-vitro and in-silico strategy: first, NADESs were characterized using Fourier transform infrared spectroscopy; second, various combinations and mixes were simulated using the Turbomole and COSMOThermX tools. Additionally, it was discovered that the curcumin activity coefficient in the NADES1 is −0.31 higher than that of the other NADESs (0.23–3.4) or the individual components (2.4–5.4) and water 8.9. The findings demonstrated that the studied NADESs had critical structural features in H-bonding and curcumin solubilization capabilities.