Construction of [C4MIM]BF4 based in situ alkaline aqueous biphasic systems by NaOH for efficient extraction saponins from Xanthoceras sorbifolium Bunge leaves

In this study, a novel method for extraction saponins from Xanthoceras sorbifolium Bunge leaves (XLs) was developed using ultrasonic-assisted ionic liquid combined with in situ alkaline aqueous biphasic systems (UAE-IL-AABS). UAE-IL was firstly used to extract saponins from XLs, followed by removal of the phenolic impurities using in situ IL-AABS. A Box-Behnken Design (BBD) was used to analyze the [C 4 MIM]BF 4 concentration, time, liquid/solid ratio, and power on the saponins yield. Under the optimal conditions with [C 4 MIM]BF 4 concentration 2.3 M, time 19.9 min, liquid/solid ratio 24.9:1 (mL/g), and power 165 W, the saponins yield was 8.17%, which was 11.01% higher than ultrasonic assisted ethanol extraction method. The major compounds in UAE-IL were also identified using UPLC-MS/MS. Moreover, the optimized conditions of IL-AABS with recovery rate of saponins was 96.70%. Finally, a low extraction time, and favorable impurities removal efficiency and recyclability suggested UAE-IL-AABS is greener for production in the food, medicine, and chemical industry.