Extraction of Bioactive Compounds from Haskap Leaves (Lonicera caerulea) Using Salt/Ethanol Aqueous Two-Phase Flotation

Aqueous two-phase flotation (ATPF) was used for the extraction and partial purification of bioactive compounds from haskap leaves. Two ATPF systems, ammonium sulfate/ethanol and sodium phosphate/ethanol, were compared. A Box-Behnken approach was used to investigate the operating parameters which included sample loading (5.0, 52.5, and 100.0 mg), flotation time (5, 62.5, 120 min), and air flow rate (11.4, 20.0, 28.6 mL/min). Response surface optimization was performed to maximize the yields of chlorogenic acid (CGA), flavonoids, and total phenolics (total phenolic content, TPC). At the optimized parameters for the ammonium sulfate/ethanol ATPF system (i.e., 5-mg leaves, 120-min flotation time, and air flow rate of 28.6 mL/min), the extraction efficiencies were 97.1%, 98.7%, and 99.6% for CGA, flavonoids, and TPC, respectively. The corresponding partition coefficients were 29.6 for CGA, 62.4 for flavonoids, and 231.4 for TPC. Quantitation of individual compounds using high-performance liquid chromatography showed that ATPF with ammonium sulfate/ethanol achieved yields of 0.031 mg CGA/mg dry mass leaves, 0.027-mg rutin/mg dry mass leaves, 0.006-mg luteolin-7-O-glucoside/mg dry mass leaves, and 0.007-mg diosmin/mg dry mass leaves. Based on the overall extraction performance, ammonium sulfate/ethanol ATPF is the preferred system in comparison to sodium phosphate/ethanol ATPF, for the extraction of bioactive compounds from haskap leaves.