Ultrasonic-assisted extraction-synergistic deep eutectic solvents for green and efficient incremental extraction of Paris polyphylla saponins

Traditional Chinese medicine Paris polyphylla contains a multitude of bioactive chemicals, primarily saponins, that have been employed in the pharmaceutical sector for anti-cancer and anti-inflammatory functions. The low toxicity and exceptional dissolvability of deep eutectic solvents (DESs) make them a promising option in contrast to conventional organic reagents for extraction. This study reports ultrasonic-assisted extraction (UAE) approach was successfully applied for extracting P. polyphylla saponins employing ten DESs based on choline chloride. The chosen DES outperformed water and 80 % ethanol in terms of extraction performance. The maximum extraction yields of five target saponins in the pilot-scale application were 5.647, 5.984, 0.659, 0.653 and 0.613 mg/g under optimized conditions, which were 1.328–3.229 times higher than those obtained using conventional extraction media after statistical optimization using single-factor experiments and response surface methodology. A scanning electron microscope was used to examine the microstructure of samples before and after extraction. Additionally, five saponins were enriched and recovered with an acceptable recovery yield of 81.33–90.60 %, and at least four times the regenerating DES could be reused. The ultimate goal of this research was to devise a green, safe, high-efficiency and sustainable strategy to efficiently extract bioactive chemicals from plant matrices.