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, anticancer, 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 bestoptimized 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.

Automated summary

In this study, natural deep eutectic solvents (NADESs) were used to extract bioactive compounds from the Himalayan medicinal herb Aconitum heterophyllum Wall. The most effective NADES-based solvent system was found to be NADES-15 [lactic acid: glycerol (1:1)], which showed higher extraction efficiency compared to conventional solvents. The efficiency of NADES-15 extraction was further improved by optimizing parameters such as solid: liquid ratio, extraction time, temperature, and water content. The recovered NADES-15 showed relatively lower extraction efficiency than the fresh counterpart, and molecular mechanism studies suggested that higher exergonic stability and intermolecular hydrogen bond interactions might contribute to the enhanced extraction efficiency of NADESs compared to conventional solvents.