Optimization of Extraction of Four Components from Radix Scrophulariae with Natural Deep Eutectic Solvents and Evaluation of Extract’s Antioxidant Activity

Abstract

Abstract In this research, eight natural deep eutectic solvents (NaDESs) consisting of food-grade ingredients were screened for the extraction of four bioactive compounds (acteoside, cinnamic acid, angoroside C and harpagoside) from radix scrophulariae (RS). Among these NaDESs, Proline-Glycerol NaDES with higher comprehensive score was selected. The Criteria Importance Through Intercriteria Correlation (CRITIC) was applied to calculate the information entropy and the weight of indexes, and figured out a comprehensive score. The weights of acteoside, cinnamic acid, angoroside C and harpagoside were 0.369, 0.172, 0.241 and 0.218, respectively. Response surface methodology (RSM) mathematical model was used to optimize the extraction parameters. The optimal extraction parameters were as follows: extraction time with 42.21 min, NaDES concentration with 52.89%, solid-to-liquid ratio with 1 : 37.05 g/mL and the predicted value of comprehensive score was 0.885. Under the optimal condition, the comprehensive score was 0.903 ± 0.005. Finally, the antioxidant activity experiment revealed that the 1,1-Diphenyl-2-picrylhydrazyl · radical scavenging activity and hydroxyl radical scavenging activity of the extract at 2.0 mg/mL and 1.5 mg/mL were approximately equal to those of ascorbic acid, respectively. The results showed that the extraction condition optimized by RSM combined with CRITIC was reasonable and dependable, and the extract of radix scrophulariae exhibited good antioxidant activity.