Natural deep eutectic solvents-based selective extraction of saponins from Panax notoginseng: Process optimization, chemical profiling, and bioactivities evaluation

In this study, we employed ultrasound-assisted extraction in conjunction with natural deep eutectic solvents (NADES) to investigate an innovative and sustainable approach for the selective extraction of Panax notoginseng (PN) saponins. Fifteen NADES were prepared, of which choline chloride-urea (ChCl-Ur) was selected as the optimal solvent because of the higher solubility of PN saponins. Response surface methodology using Box-Behnken design was adopted to optimize the extraction process. According to the results, NADES with a water content of 45 % (v/v) and a ChCl/Ur ratio of 1:2 (mol/mol) exhibited superior efficacy as a solvent for extracting saponins from PN. The optimal extraction conditions include a liquid–solid ratio of 40 mL/g, an extraction temperature of 47 °C, and an extraction duration of 36 min. The extraction efficiency of NADES for saponins was superior to that of water and comparable to that of 70 % (v/v) methanol. Additionally, we assessed the anti-inflammatory and anticoagulant properties of the resulting extraction solution. The TNF-α and IL-1β inhibiting test showed that the NADES extract of saponins exhibited a stronger inhibitory effect on the mRNA expression of inflammatory cytokines TNF-α and IL-1β when compared to an aqueous extract. And a dose-dependent relationship was observed. In the anticoagulation activity assay, the NADES extract of saponins at a concentration of 25 mg/mL significantly prolonged the activated partial thromboplastin time (p < 0.05). Additionally, concentrations of 12.5 and 25 mg/mL exhibited significant prolongation of the prothrombin time (p < 0.01). These findings suggest that NADES can be used as a solvent to extract PN saponins in an efficient way, and the specific concentrations of the extract possess potent bioactivities.