Identification of α-glucosidase inhibitors from Clinacanthus nutans leaf extract using liquid chromatography-mass spectrometry-based metabolomics and protein-ligand interaction with molecular docking / 药物分析学报

The present study used in vitro and in silico techniques, as well as the metabolomics approach to char-acterise α-glucosidase inhibitors from different fractions of Clinacanthus nutans. C. nutans is a medicinal plant belonging to the Acanthaceae family, and is traditionally used to treat diabetes in Malaysia. n-Hexane, n-hexane: ethyl acetate (1:1, v/v), ethyl acetate, ethyl acetate: methanol (1:1, v/v), and methanol fractions were obtained via partitioning of the 80％ methanolic crude extract. The in vitro α-glucosidase inhibitory activity was analyzed using all the fractions collected, followed by profiling of the metabolites using liquid chromatography combined with mass spectrometry. The partial least square (PLS) statistical model was developed using the SIMCA P +14.0 software and the following four inhibitors were obtained:(1) 4,6,8-Megastigmatrien-3-one; (2) N-Isobutyl-2-nonen-6,8-diynamide; (3) 1′,2′-bis(acetyloxy)-3′,4′-didehydro-2′-hydro-β, ψ-carotene; and (4) 22-acetate-3-hydroxy-21-(6-methyl-2,4-octadienoate)-olean-12-en-28-oic acid. The in silico study performed via molecular docking with the crystal structure of yeast isomaltase (PDB code: 3A4A) involved a hydrogen bond and some hydrophobic interactions be-tween the inhibitors and protein. The residues that interacted include ASN259, HID295, LYS156, ARG335, and GLY209 with a hydrogen bond, while TRP15, TYR158, VAL232, HIE280, ALA292, PRO312, LEU313, VAL313, PHE314, ARG315, TYR316, VAL319, and TRP343 with other forms of bonding.

Screening of α-glucosidase inhibitors from roots of Cichorium glundulosum by UF-LC-MS and molecular docking / 中草药

Objective To screen α-glucosidase inhibitors from root extract of Cichorium glundulosum (CGR) by UF-LC-MS and molecular docking. Methods The inhibitory activity of CGR extract was evaluated by establishing enzyme inhibitor model, Meanwhile, four active compounds from CGR extract were screened by UF-LC-MS and identified as α-glucosidase inhibitors, which were verified by using Autodock Software. Results The results showed that two compounds that combined with α-glucosidase well were screened out, including baicalin and lactupicrin, which showed significant α-glucosidase inhibitory activity in the concentration range of 0.1-2 mg/mL in a dose-dependent manner. Conclusion Our work provide theoretical basis for screening natural and high affinity enzyme inhibitors from CGR by using UF-LC-MS and molecular docking and further study of the hypoglycemic effect of C. glundulosum.

Screening of High-Affinity α-Glucosidase Inhibitors fromCichorium Glandulosum Boiss.et Hout Seed Based on UltrafiltrationLiquid Chromatography-Mass Spectrometry and Molecular Docking / 分析化学

High-affinity α-glucosidase inhibitors were screened from Cichorium glundulosum Boiss.et Hout seed (CGS) extract by ultra-filtration affinity-liquid chromatography-mass spectrometry (UF-LC-MS) and molecular docking.By taking 4-nitrobenzene-α-D-glucopyranoside (PNPG) as substrate and acarbose as positive control to evaluate the inhibitory activity of CGS extract, IC50 of acarbose and CGS extract were 0.003 mg/mL and 0.447 mg/mL, respectively.Meanwhile, 4 compounds from CGS extract by UF-LC-MS were screened and identified.Then by using autodock software, the compounds that combined with α-glucosidase were well screened out, including chlorogenic acid and isochlorogenic acid A.The inhibitory activity of chlorogenic acid and chlorogenic acid A against α-glucosidase was verified in vitro.The results showed that the inhibitory activity of the compounds toward α-glucosidase presented the sequence of acarbose>isochlorogenic acid A>chlorogenic acid.The inhibition rate of isochlorogenic acid A was close to acarbose.The experimental results illustrated that UF-LC-MS and molecular docking could be used to screen high affinity enzyme inhibitors from CGS.

Determination of α-glucosidase inhibitors from Scutellaria baicalensis using liquid chromatography with quadrupole time of flight tandem mass spectrometry coupled with centrifugal ultrafiltration / 中国天然药物

The present study aimed at identifying potential lead compounds for diabetes mellitus drug discovery. We developed a novel method involving centrifugal ultrafiltration separation subsequent liquid chromatography with quadrupole time of flight tandem mass spectrometry (LC-Q/TOF-MS/MS) determination to screen α-glucosidase inhibitors in complex Scutellaria baicalensis Georgi (SBG) extract. By adding a second filter to the screening process, the level of non-specific binding of Compounds 1, 3, 10 and 11 was significantly decreased, and the level of non-specific binding of Compounds 5 and 15 also was reduced. As a result, five flavonoids identified as baicalein, baicalein, wogonin, chrysin, and oroxylin A, were rapidly found to interact with α-glucosidase and possess potent anti-α-glucosidase activity in vitro. Specific binding of ligands to α-glucosidase was demonstrated though the proposed method and the ligands could be ranked in order of affinity for α-glucosidase, which were corresponded to the order of inhibitory activity in vitro. In conclusion, our results indicated that the developed method is a rapid and effective screening method for rat intestinal α-glucosidase inhibitors from complex herbal medicines such as SBG.