Counter-Current Fractionation-Assisted Bioassay-Guided Separation of Active Compound from Blueberry and the Interaction between the Active Compound and α-Glucosidase

Abstract

An efficient strategy for the selection of active compounds from blueberry based on counter-current fractionation and bioassay-guided separation was established in this study. Blueberry extract showed potential α-glucosidase inhibitory activity. After extraction by different solvents, the active components were enriched in water. The water extract was divided into six fractions via high-speed counter-current chromatography to further track the active components. Results indicated that the α-glucosidase inhibition rate of F4 was remarkable higher than the others. Cyanidin-3-glucoside (C3G) with a purity of 94.16% was successfully separated from F4 through column chromatography, and its structure was identified by ultraviolet spectral, Fourier-transformed infrared spectroscopy, high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry, 1H nuclear magnetic resonance (NMR), and 13C NMR. The interaction mechanism between C3G and α-glucosidase was clearly characterized and described by spectroscopic methods, including fluorescence and circular dichroism (CD) in combination with molecular docking techniques. C3G could spontaneously bind with α-glucosidase to form complexes by hydrogen bonds. The secondary structure of α-glucosidase changed in varying degrees after complexation with C3G. The α-helical and β-turn contents of α-glucosidase decreased, whereas the β-sheet content and the irregular coil structures increased. Molecular docking speculated that C3G could form hydrogen bonds with α-glucosidase by binding to the active sit (Leu 313, Ser 157, Tyr 158, Phe 314, Arg 315, and two Asp 307). These findings may be useful for the development of functional foods to tackle type 2 diabetes.

Ultrasonic-Assisted Aqueous Two-Phase Extraction and Properties of Water-Soluble Polysaccharides from Malus hupehensis

“…Moreover, the absorption peak of α-glucosidase (about 331 nm) gradually shifted to the right under different MHP concentrations (Figure 5B). The right shift phenomenon implied that the polarity of the microenvironment around Trp residues in α-glucosidase changed and became more hydrophilic after the addition of MHP [38]. Many studies showed that the polysaccharide with moderate molecular weight and high water solubility has the biological activity, while that with double helix or triple helix structure has better biological activity than other polysaccharides [14].…”

“…The antihyperglycemic activity of MHP in vitro was evaluated by α-glucosidase inhibition ability according to the method, that was slightly modified [38]. In short, 50 µL α-glucosidase (0.5 U/mL, dissolved in 0.2 M PBS, pH 6.9) was mixed with 50 µL MHP sample solution of different concentrations (0.2-3.0 mg/mL), and then incubated at 37 • C for 10 min.…”

Separation of principal component dihydromyricetin from Ampelopsis grossedentata by high‐speed counter‐current chromatography and its interaction with corn starch

“…The injection volume was 20 µl. The purity of component II was calculated by Equation (2) (Xue et al., 2021). $$\begin{equation}w_{i}\left(\%\right)= \frac{f_{i}A_{i}}{\sum f_{i}A_{i}}\end{equation}$$…”

“…The injection volume was 20 µl. The purity of component II was calculated by Equation (2) (Xue et al, 2021).…”

“…These methods cannot meet the demand for high‐purity DMY. High‐speed counter‐current chromatography (HSCCC) is a novel liquid–liquid separation method without a stationary phase acting as a carrier, and it effectively avoids the irreversible adsorption of active compounds on the solid phase (Xue et al., 2021). In addition, HSCCC can improve the loading capacity of samples and facilitate large‐scale separation and purification of bioactive compounds when compared with traditional chromatography.…”