A strategy based on liquid-liquid-refining extraction and high-speed counter-current chromatography for the...

The research of natural active substances is facing the problems of low separation efficiency and active component loss due to the complex composition of natural extracts. In this study, a strategy based on liquid-liquid-refining extraction and high-speed counter-current chromatography was established to solve this problem. Separation of an active compound with the α-amylase inhibitory activity from Taraxacum mongolicum Hand. -Mazz. was presented as an example. The ethyl acetate extract (FA) from T. mongolicum exhibited the potential effect on α-amylase and was divided into 8 fractions (FB-FI) by liquid-liquid-refining extraction. The results showed that the activity of FE was higher than the others. According to the results of liquid-liquid-refining extraction, a two-phase solvent system with a slightly higher polarity was selected to separate the fraction by HSCCC, and 110 mg of compound was separated from 900 mg FA using the model of consecutive separation. The compound was identified as luteolin by ¹H NMR and ¹³C NMR. The IC₅₀ of luteolin against α-amylase was 42.33±0.82 μg/mL. Then, molecular docking was introduced to study the relationship between the activity and the structure. The results showed that luteolin enfolded in the catalytic site of α-amylase through hydrogen bonds, van der Waals force and hydrophobic interaction, thus inhibiting the activity of the enzyme.