Pancreatic lipase and alpha-glucosidase inhibitors screening from Schisandra chinensis based on spectrum-effect relationship and ultra-high-performance liquid chromatography-tandem mass spectrometry.

As a traditional Chinese medicine, Schisandra chinensis has a potential weight-loss effect by delaying carbohydrate absorption and improving lipid metabolic disorders. However, its active components are still unclear and require in-depth research. In this study, the active components of Schisandra chinensis responsible for pancreatic lipase and alpha-glucosidase inhibitory activity were screened and identified based on a spectrum-effect relationship study in combination with ultra-performance liquid chromatography-tandem mass spectrometry analysis. The ultra-high-performance liquid chromatography fingerprints of 17 batches of Schisandra chinensis were established, and 14 common peaks were specified by similarity analysis. The half-maximal inhibition concentration values for pancreatic lipase and alpha-glucosidase inhibition were separately measured by enzymatic reactions. Using multivariate statistical methods including principal component analysis, partial least square analysis, and grey relational analysis, the correlation models between the peak areas of 14 common peaks and half-maximal inhibition concentration values were constructed, and the chromatographic peaks making a great contribution to efficacy were screened out. Peak1, Peak2, Peak4, Peak6, Peak9, Peak10, Peak11, and Peak13 were responsible for alpha-glucosidase inhibitory activity, while Peak1, Peak4, Peak6, Peak9, Peak10, and Peak11 for pancreatic lipase inhibitory activity. Finally, the 70% ethanol extracts of Schisandra chinensis were characterized by ultra-high-performance liquid chromatography-tandem mass spectrometry analysis, and 14 lignans were identified to further elucidate the active constituents of Schisandra chinensis. The positive results suggested the proposed strategy is simple and effective to screen active components from complex medicinal plants.

Screening and identification of acetylcholinesterase inhibitors from Terminalia chebula fruits by immobilized enzyme on cellulose filter paper coupled with ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry and molecular docking.

With the increasing demand of new drugs for the treatment of Alzheimer's disease (AD), screening acetylcholinesterase (AChE) inhibitors from traditional Chinese medicines (TCMs) has been proved to be an effective strategy for drug discovery. In present study, a novel strategy was developed to fish out AChE inhibitors from Terminalia chebula fruits based on immobilized AChE coupled with ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) and molecular docking. For AChE immobilization, cellulose filter paper (CFP) as the carrier was modified with chitosan to be introduced to amino groups, and then AChE was modified on the amino-modified CFP through a Schiff base reaction with glutaraldehyde as a cross-linking agent. The CPF-immobilized AChE possessed advantages of a wider range for pH and temperature endurance, better storage stability, excellent reproducibility and reusability. The CPF-immobilized AChE was incubated with the extract of T. chebula fruits, and then the active components would form complexes with immobilized AChE. The complexes were further conveniently separated with inactive components by virtue of the instantaneous separation characteristic of CFP. Eventually, 25 (1-11, 13-26) potential AChE inhibitors were fished out and their structures were further identified by UPLC-QTOF-MS. Moreover, molecular docking was performed to discriminate non-specific compounds to AChE and explore binding mechanisms between potential inhibitors and AChE, and 25 compounds could be well embedded into active sites of AChE with affinities ranging from -9.9 to -6.4 kcal/mol. Inhibitory activities of screened active components on AChE were evaluated in vitro, and punicalagin, 1,3,6-tri-O-galloyl-ß-D-glucose (1,3,6-TGG), chebulinic acid and geraniin exhibited excellent AChE-inhibitory properties with IC50 values of 0.43 ± 0.03, 0.46 ± 0.02, 0.50 ± 0.03 and 0.51 ± 0.03 mM, respectively. The results indicated that the developed method was simple and efficient, and could be utilized to screen and identify potential AChE inhibitors from TCMs.

α-Glucosidase inhibitors screening from Cyclocarya paliurus based on spectrum-effect relationship and UPLC-MS/MS.

Cyclocarya paliurus is an edible and medicinal plant exhibiting significant hypoglycemic effect. However, its active components are still unclear and need further elucidation. In this research, the active components of the leaves of C. paliurus responsible for the α-glucosidase inhibitory activity were screened and identified based on a spectrum-effect relationship study in combination with ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) analysis. The 70% ethanol eluate fraction of the leaves of C. paliurus with the strongest α-glucosidase inhibitory activity was obtained after extraction and purification with macroporous resin. Their chromatographic fingerprints (15 batches) were established by UPLC analysis and 32 common peaks were specified by similarity analysis. Their IC50 values for α-glucosidase inhibition were measured by an enzymatic reaction. Several multivariate statistical analysis methods including hierarchical cluster analysis, principal component analysis, partial least square analysis and gray relational analysis were applied to explore the spectrum-effect relationship between common peaks and IC50 values, and the chromatographic peaks making a large contribution to efficacy were screened out. To further elucidate the active components of leaves of C. paliurus, the 70% ethanol eluate fraction was characterized by UPLC-MS/MS analysis, and 10 compounds were identified. This study provides a valuable reference for further research and development of hypoglycemic active components of C. paliurus.

Dopamine-polyethyleneimine co-deposition of a capillary for α-glucosidase immobilization and its application in enzyme inhibitor screening.

An online method based on CE was established to screen α-glucosidase inhibitors from traditional Tibetan medicine extracts. First, the inner wall at the inlet of capillary column was simply and effectively functionalized by dopamine-polyethyleneimine co-deposition method, which combines the adhesion property of dopamine and easy cationization of polyethyleneimine. Then α-glucosidase was rapidly immobilized on the inner wall of the capillary column by electrostatic adsorption. The inter- and intraday repeatability of the peak area of the enzymatic reaction product (p-nitrophenol) in a capillary was evaluated, and RSD% (n = 3) was 0.94% and 1.09%, respectively. Good batch-to-batch reproducibility of the peak area between different capillaries (RSD = 2.1%, n = 5) shows that the preparation method has good reproducibility. The Michaelis-Menten constant of the immobilized α-glucosidase was measured to be 1.18 mM, and the capillary column enzyme reactor retained 85.9% of initial activity after 30 cycles. Finally, it was applied to the screening of enzyme inhibitors in 20 traditional Tibetan medicine extracts. Sixteen medicines with inhibitory activity were screened out, and Rheum australe had the strongest inhibitory effect with an inhibitory rate of 83.3 ± 0.4%. These results showed that this method is effective to find potential enzyme inhibitors.