Inhibition of α-glucosidase and α-amylase by flavonoid glycosides from Lu'an GuaPian tea: molecular docking and interaction mechanism

Abstract

Green tea may favorably modulate blood glucose homeostasis, and regular consumption of green tea can prevent the development of type 2 diabetes mellitus. In this study, α-glucosidase and α-amylase inhibitory effects of the novel acylated flavonol tetraglycoside (camellikaempferoside C, 1) and 14 other flavone and flavone glycosides (FGs) isolated from Lu'an GuaPian (Camellia sinensis L.O. Kuntze) were evaluated. The kaempferol monoglycoside (15) showed inhibitory activity against α-glucosidase with IC50 at 40.02 ± 4.61 μM, and kaempferol diglycoside (13) showed α-amylase inhibition with IC50 at 0.09 ± 0.02 μM. Further, inhibitory mechanisms of FGs 15 and 13 were studied by molecular docking analysis and fluorescence spectrometry. Molecular docking suggested that FG 15 interacted with α-glucosidase mainly by hydrogen bonding, which was the same interaction force between FG 13 and α-amylase. Intrinsic fluorescence of α-glucosidase and α-amylase was quenched by 15 and 13, respectively, through a static quenching mechanism. The spontaneous formation of 15-α-glucosidase and 13-α-amylase complexes was driven by van der Waals forces and hydrogen bonding. The present study provides new insight into the potential application of Lu'an GuaPian green tea as a functional food ingredient to regulate postprandial hyperglycemia through inhibition of α-glucosidase/α-amylase by FGs, particularly the mono- and di- glycosides of kaempferol.

HPLC-ESI-qTOF-MS/MS Characterization, Antioxidant Activities and Inhibitory Ability of Digestive Enzymes with Molecular Docking Analysis of Various Parts of Raspberry (Rubus ideaus L.)

“…Many reports have confirmed that the amino acid residues Asp 197 and His 305 played critical roles in the catalytic reaction of α-amylase [40,41]. The mechanisms of the digestive enzymes inhibitory activities of these compounds possibly involve the binding of compounds with the catalytic sites of digestive enzymes [37]. The results demonstrated that the hydrogen bonds and the binding residues with active sites have important effects on these digestive enzymes activities.…”

“…EA also interacted with the amino acid residue Glu 411 of α-glucosidase. Some researchers have confirmed that some active sites (Glu 411) of α-glucosidase may inhibit the catalytic activity of this enzyme [37]. Consequently, ellagic acid showed the weakest α-glucosidase inhibitory effect.…”

“…At least three investigated molecules formed H-bonds with the amino acid residues of Asp 69, Asp 215, and Asp 352, which may exert its α-glucosidase inhibitory effect. Hua et al (2018) have also reported that Asp 69, Asp 215, and Arg 442 were the important residues involved in H-bond formation during the binding with α-glucosidase [37]. also reported that the binding active sites (Asp 215 and Asp 352) in between the ligands and α-glucosidase played important roles in exert its α-glucosidase inhibitory effect [23].…”

“…The correlation analysis results between the TPC and two digestive enzymes inhibition potency clearly verified that there was a good positive correlation between these two parameters (α-glucosidase inhibition potency vs. TPC, r = 0.781, p < 0.05; α-amylase inhibition potency vs. TPC, r = 0.854, p < 0.01). Many researches have confirmed that phenolic-rich extracts from leaf-tea, edible fruits, and natural products possess good inhibitory ability on digestive enzymes [23,37]. have confirmed that procyanidin C3 possessed strong α-glucosidase inhibitory capacity [38].…”

Inhibitory mechanism of lactoferrin on antibacterial activity of oenothein B: isothermal titration calorimetry and computational docking simulation

“…The mechanisms of fluorescence quenching can either be dynamic or static resulting in collisional encounters or formation of non‐fluorescing complexes, respectively . The data of fluorescence quenching was analyzed according to the Stern–Volmer equation where F 0 and F are the fluorescence intensities before and after the addition of the quencher, respectively; K q is the bimolecular quenching constant; γ 0 is the lifetime of the fluorophore in the absence of the quencher, and the average lifetime of biological macromolecules is approximately 10 −8 s; [ Q ] is the concentration of the quencher (in this case OeB), and K SV is the Stern–Volmer quenching constant.…”