Ultrasonic assisted extraction of coumarins from Angelicae Pubescentis Radix by betaine-based natural deep eutectic solvents

This study focused on extracting coumarins from Angelicae Pubescentis Radix (APR) using deep eutectic solvents (DES). The process parameters were optimized using response surface methodology and characterized by projected scanning electron microscopy analysis. Methods: Eighteen types of DESs based on Choline chloride, Betaine, Sodium acetate, and Ammonium acetate were synthesized. The ultrasonic-assisted effect of these DESs on the yield of coumarins was investigated using high-performance liquid chromatography (HPLC). We studied and optimized the technological conditions for extracting coumarins from APR using a one-factor-at-a-time method and response surface methodology. Additionally, scanning electron microscopy was employed to observe the degree of fragmentation of APR powder before and after extraction with methanol solvent and DESs. The biological activity of DESs extract was evaluated using the free radical scavenging model of 1,1-diphenyl-2-picrylhydrazide (DPPH), while the molecular docking approach was used to explore the binding potential between the coumarins and superoxide dismutase (SOD) enzymes. The results indicated that the natural deep eutectic system with a molar ratio of betaine to ethylene glycol of 1:4 exhibited the most effective extraction. The optimum extraction conditions included a water content of 16.11% in the DESs, a temperature of 43.52 °C, an extraction time of 59.61 minutes, and an extraction yield of 3.37%. Furthermore, scanning electron microscopy revealed that the cells of APR powder obtained through ultrasonically assisted treatment with DESs exhibited the most severe breakage. The experiment demonstrated that the DESs extract exhibited a high scavenging capacity for DPPH free radicals. Conclusion: DESs present as an environmentally friendly solvent option for effectively extracting coumarins from APR, indicating promising potential for substitution of organic solvents.