Tailor-made hydrophobic deep eutectic solvents for cleaner extraction of polyprenyl acetates from Ginkgo biloba leaves

Deep eutectic solvents (DESs), especially hydrophilic DESs, have been considered green substitutes to conventional organic solvents for bioactive compounds extraction. This study provided a practical example demonstrating the efficiency of hydrophobic DESs as designer solvent to extract polyprenyl acetates from Ginkgo biloba leaves. A hydrophobic ternary DES named as MCO gave the highest extraction yield for polyprenyl acetates during the initial screening. It was tailor-made from methyl trioctyl ammonium chloride, capryl alcohol and octylic acid at a molar ratio of 1:2:3 by systematically optimizing the DES component type, molar ratio and number. With MCO-based extraction, the operational factors influencing the extraction yield were further optimized by statistical method. The model for the extraction of polyprenyl acetates was well established and verified. Extraction yield of 84.11 ± 0.7366 was obtained at the optimal conditions, which was much higher than those of conventional hydrophobic organic solvents (petroleum ether and n-hexane). Moreover, excellent recovery of polyprenyl acetates from MCO extraction solution was obtained by macroporous resin AB-8 or DM130 adsorption. This study demonstrated that not only hydrophilic DESs but also hydrophobic DESs can be adopted as solvents for bioactive compounds extraction from biomass.