Aqueous two-phase extraction of bioactive compounds from haskap leaves (Lonicera caerulea): Comparison of salt/ethanol and sugar/propanol systems

Abstract

Aqueous two-phase extraction (ATPE) was used to extract bioactive compounds from haskap leaves (Lonicera caerulea) using salt/ethanol and sugar/propanol-based systems. The systems consisted of components that are generally recognized as safe (GRAS): ammonium sulphate/ethanol, sodium dihydrogen phosphate/ethanol, glucose/1-propanol, and maltose/1-propanol. The factors investigated were extraction time (5, 62.5, 120 min), sample loading (0.1, 0.55, 1 wt%), and tie line length (TLL) (low, medium, high) to represent different aqueous two-phase system (ATPS) compositions of salt or sugar and alcohol. Multi-response optimization was conducted to maximize the yield of chlorogenic acid, flavonoids, and total phenolic content. The results show that salt/ethanol ATPE systems had higher extraction efficiency than sugar/propanol ATPE. Among these four systems, sodium dihydrogen phosphate (NaH2PO4)/ethanol ATPE had the maximum extraction efficiency of 93.9% for chlorogenic acid, 96.8% for flavonoids, and 97.8% for total phenolic content. The corresponding partition coefficients were 1.73 for chlorogenic acid, 3.50 for flavonoids, and 6.59 for total phenolic content. Further analysis using high-performance liquid chromatography (HPLC) revealed that the extracts from ATPE were more refined in comparison to conventional solvent extracts. Additionally, nuclear magnetic resonance (NMR) spectra showed preliminary qualitative profiling of the extracts. This work demonstrates that ATPE using GRAS components is a green alternative to conventional extraction with organic solvents for the recovery of high-value bioactive compounds from haskap leaves.