NADES-based selective extraction of bioactive molecules: A case study with commercially important Himalayan medicinal plant Aconitum heterophyllum

Natural deep eutectic solvents (NADESs) are recognized as sustainable green media for extracting bioactive compounds from biomass. Herein, NADES-based green media was employed to extract bioactives from the Himalayan medicinal herb Aconitum heterophyllum Wall. Bioactive compounds such as aconitic acid (insecticidal, anti-bacterial, anti-fungal), atisinium (anti-plasmodial, anti-cancer, insecticidal), lappaconitine (analgesic, anti-cancer, anti-inflammatory), and 2-O-cinnamoyl hetisine (anti-plasmodial) were extracted by ultrasound-assisted methodology from the roots of A. heterophyllum. Twenty NADES-based solvent systems and four conventional solvents were screened to extract targeted bioactives. After performing the initial small-scale extraction, NADES-15 [lactic acid: glycerol (1:1)] was found to be the most effective extraction media compared to conventional solvents. The extraction efficiency of NADES-15 was further optimized by varying different parameters such as S: L (solid: liquid) ratio, extraction time, extraction temperature, and water content. The large-scale extraction was performed to validate the best-optimized parameters, and finally, solid-liquid extraction was utilized to recover NADES-15. Approximately 77.5% of NADES-15 was successfully recovered and reused. The extraction efficiency of recovered NADES-15 was found to be relatively lower than that of its fresh counterpart. DFT-based molecular mechanism studies revealed that higher exergonic stability and the presence of more hydrogen bond donor/acceptor species (which contributes to intermolecular hydrogen bond interactions) might be responsible for enhanced extraction efficiency of NADESs compared to conventional solvents.