The Versatility of NADES Across Applications

Abstract

Natural deep eutectic solvents (NADES) are produced by combining natural compounds, such as sugars, amino acids, or organic acids, to form a liquid at room temperature. Compared to other solvents, NADES own several strengths, including cost-effectiveness, ease of preparation, tunable properties, biorenewability, and biodegradability, making them suitable for a wide range of industrial sectors. Research on NADES requires careful consideration of their composition and physicochemical properties, as these can significantly influence their range of applications. In this context, the main objective of this review is to provide insights into the application of NADES in different areas that go from enzymatic processes and extraction of bioactives to the formulation of pharmaceutical and cosmetic products. This review includes several case studies on the use of enzyme-NADES systems (lipase and laccase) to synthesize new materials and on the extraction of bioactives with NADES, highlighting their direct application in cosmetics and pharmaceutical formulations.

Keywords: Pharma-cosmetics; deep eutectic solvents; enzymatic processes; extraction; sustainable solvents.

Figure 1

Enzymatic synthesis of three polyesters using lipase, with NADES (1, 2, and 3) serving as both reagents and solvents: the initial and final pictures of the solution reactions and the maximum degrees of polymerization (DP_max) of the polyesters obtained (figure adapted from [17]).

Figure 2

Reactional scheme for the enzymatic synthesis of catechol or caffeic acid-based polyphenolic compounds using a laccase-NADES system (figure adapted from [16]).

Figure 3

Extraction yield using NADES as solvents and different extraction methods (a) and the NADES-extracts aspect after the extraction process (b). In (c), the extractive concentrations (g/L) obtained from cork are represented using a sealed extraction system with NADES (1, 5, 6, and 14), water, and 1,4-dioxane as extraction solvents. Note: Enfleurage method: cork 0.7 g; solvent 15 mL; room temperature; 3 days; 3 cycles; Ultrasound-assisted: cork 0.7 g; solvent 10 mL; 50 °C; 6 h; 3 cycles; Sealed system: cork 0.7 g; solvent 5 mL; 100 °C 6 h; 3 cycles (adapted from [13]).

Figure 4

Scheme illustrating the use of NADES 5—LA:GLY (1:1 and 1:4) and their NADES extracts to produce translucent NADES-in-oil (TE) emulsions for cosmetic and pharmaceutical applications. The figure shows the composition, appearance, and properties of TEs and the improvement in the melanization state of larvae (G. mellonella) (right image) (a); and the antimicrobial and antifungal results of TEs with NADES–eucalyptus and NADES–cork extracts (b) of TE composed of NADES (control), NADES–eucalyptus (TE-EL), and NADES–cork (TE-CP) extracts (adapted from [18]).

Figure 5

NADES’ applications across different sectors.