Natural deep eutectic solvents (NADES) for the extraction of bioactive compounds from quinoa (Chenopodium quinoa Willd.) leaves

Natural deep eutectic solvents (NADES) have emerged as a promising, eco-friendly alternative to petrochemicals to extract plant metabolites. As the demand for sustainable, “green” ingredients for industrial applications is growing, those solvents are purported to develop extracts with interesting phytochemical fingerprints and biological activities. Given the interest of flavonoids from Chenopodium quinoa Willd. leaves, an efficient “green” extraction method was developed by investigating eight NADES with defined molar ratios, i.e. malic acid-choline chloride (chcl)-water (w) (1:1:2, N1), chcl-glucose-w (5:2:5, N2), proline-malic acid-w (1:1:3, N3), glucose-fructose-sucrose-w (1:1:1:11, N4), 1,2-propanediol-chcl-w (1:1:1, N5), lactic acid-glucose-w (5:1:3, N6), glycerol-chcl-w (2:1:1, N7) and xylitol-chcl-w (1:2:3, N8). Rheological measurements of all NADES confirmed their pseudoplastic behaviors. To improve the extraction processes through lowering NADES viscosity without disturbance of eutectic properties, differential scanning calorimetry (DSC) was applied to determine the maximum amount of water that could be added to NADES (N1, N2, N3 and N4; 17.5%, 20%, 10% and 10% w/w, respectively). The phytochemical compositions of NADES extracts were analyzed by high-performance thin-layer chromatography (HPTLC) and their free radical scavenging and α-amylase inhibitory properties were assessed by HPTLC-bioautography. N2, diluted with 20% of water, and N7 presented the best potential for replacing methanol for an eco-friendly extraction of flavonoids, radical scavengers, and α-amylase inhibitors from quinoa leaves. Their biological properties, combined with a good understanding of both thermal behavior and viscosity, make the obtained quinoa leaves NADES extracts good candidates for direct incorporation in nutraceutical formulations. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany