Bioactivity-guided separation of potential α-glycosidase inhibitor from clerodendranthus spicatus based on HSCCC coupled with molecular docking

Clerodendranthus Spicatus is a traditional Dais medi-edible plant and it has been proven to have good blood glucose-lowering efficacy. However, the material basis of Clerodendranthus Spicatus has not been clarified yet and therefore needs to be determined. In this paper, the effective ingredients of this medicine were purified by high-speed counter-current chromatography. Alongside, their potential hypoglycemic activity was determined by α-glucosidase inhibitory activities in vitro and molecular docking. Finally, five compounds were purified and identified as 2-caffeoyl-L-tartaric acid (1), N-(E)-caffeoyldopamine (2), rosmarinc acid (3), methyl rosmarinate (4), 6,7,8,3′,4′-Pentamethoxyflavone (5). Examination of α-glucosidase inhibitory activity in vitro showed that 2-caffeoyl-L-tartaric acid and rosmarinic acid had a higher inhibitory activity than acarbose. Molecular docking indicated that the affinity energy of the identified compounds ranged from − 7.6 to − 8.6 kcal/mol, a more desirable result than acarbose (− 6.6 kcal/mol). Particularly, rosmarinc acid with the lowest affinity energy of − 8.6 kcal/mol was wrapped with 6 hydrogen bonds. Overall, α-glucosidase inhibitory activities and molecular docking suggested that rosmarinc acid was likely to be a promising hypoglycemic drug.

Bioactivity-Guided Separation of Potential α-glycosidase Inhibitor from Clerodendranthus Spicatus based on HSCCC with Molecular Docking

Clerodendranthus Spicatus is a traditional Dais medi-edible plant and it has been proven to have good blood glucose-lowering efficacy. However, the material basis of Clerodendranthus Spicatus has not been clarified yet. Therefore, in this paper, the compounds were purified by high-speed counter-current chromatography (HSCCC) and the potential activity of compounds were determined by molecular docking. In the separation process, the solvent system was determined by a 9 × 9 map-based solvent selection strategy and the solvent system hexane/ethyl acetate/methanol/water (3:5:3:5, v/v) was used for HSCCC. Finally, five compounds were purified and identified as 2-Caffeoyl-L-tartaric acid (1), N-(E)-caffeoyldopamine (2), rosmarinc acid (3), Methyl rosmarinate (4), 6,7,8,3',4'-Pentamethoxyflavone (5). Then, the identified compounds were individually docked with α-glycosidase. The affinity energies of the identified compounds ranged from -7.6 to -8.6 kcal/mol, which are all better than acarbose (-6.6 kcal/mol). In particularly, rosmarinc acid with the lowest affinity energy of -8.6 kcal/mol was wrapped by the active site of α-glycosidase. The docking results indicated that the target compounds have potential α-glycosidase inhibitory activity and may be responsible for the blood glucose-lowering activity of Clerodendranthus Spicatus. The results indicated that the bioactivity-guided method is practical for the effective separation of active compounds from natural resources.

Altering the inhibitory kinetics and molecular conformation of maltase by Tangzhiqing (TZQ), a natural α-glucosidase inhibitor

Background Tangzhiqing (TZQ), as a potential α-glycosidase inhibitor, possesses postprandial hypoglycaemic effects on maltose in humans. The aim of this study was to investigate the mechanisms by which TZQ attenuates postprandial glucose by interrupting the activity of maltase, including inhibitory kinetics and circular dichroism studies. Methods In this study, we determined the inhibitory effect of TZQ on maltase by kinetic analysis to determine the IC50 value and enzyme velocity studies and line weaver-burk plot generation to determine inhibition type. Acarbose was chosen as a standard control drug. After the interaction with TZQ and maltase, secondary structure analysis was conducted with a circular dichroism method. Results TZQ showed notable inhibition activity on maltase in a reversible and competitive manner with an IC50 value of 1.67 ± 0.09 μg/ml, which was weaker than that of acarbose (IC50 = 0.29 ± 0.01 μg/ml). The circular dichroism spectrum demonstrated that the binding of TZQ to maltase changed the conformation of maltase and varied with the concentration of TZQ in terms of the disappearance of β-sheets and an increase in the α-helix content of the enzyme, similar to acarbose. Conclusions This work provides useful information for the inhibitory effect of TZQ on maltase. TZQ has the potential to be an α-glycosidase inhibitor for the prevention and treatment of prediabetes or mild diabetes mellitus.

α-GLUCOSIDASE INHIBITION OF LACTONE INTERMEDIATES OF THE IMINOSUGAR DEOXYNOJIRIMYCIN

α-Glycosidase enzymes hydrolyse α-glycosidic linkages and are involved in bodily processes such as the catabolism of glycans, intestinal digestion, and the degradation of glycoproteins. Various types of diseases which are caused by the failure of this enzyme to function properly can be treated through enzyme inhibition. The hydroxyethyl derivative of DNJ (Miglitol) is a clinical drug for the treatment of type 2 diabetes. Although the iminosugar D-deoxynojirimisin (D-DNJ) is an excellent micromolar glycosidase inhibitor, the α-glucosidase inhibition activity of D-DNJ lactone intermediates has yet to be reported. Therefore, the scalable synthesis of the D-DNJ intermediates 1,2-O-isopropylidene-α-D-glucurono-3,6-lactone (2), 1,2-O-isopropylidene-β-L-idurono-3,6-lactone (3) and 5-azido-5-deoxy-1,2-O-isopropylidene-α-D-glucurono-3,6-lactone (4) was carried out using D-glucuronolactone (1) as the starting material based on the method reported by Best et al. 2010 with some modification and subsequently, evaluated for anti-α-glucosidase activity. All products were characterised and identified by HPLC-ELSD, mass spectrometry (DI-ESI-MS) and NMR spectroscopy (via comparison of 1D 1H and 13C data with previously reported values). The inhibitory activity of compounds 1-4 towards α-glucosidase from Saccharomyces cerevisiae was evaluated using the p-nitrophenyl α-D-glucopyranoside substrate. Compound 3 showed 29.5% inhibition followed by 2 (21.4%), 1 (15.8%) and 4 (15.7%) compared to the positive control, quercetin (72.7%).

α-d-Gal-cyclophellitol cyclosulfamidate is a Michaelis complex analog that stabilizes therapeutic lysosomal α-galactosidase A in Fabry disease

α-d-Gal-cyclophellitol cyclosulfamidate is a new class of neutral, conformationally-constrained competitive glycosidase inhibitor that stabilizes α-gal A and prevents its degradation both in vitro and in cellulo by mimicry of the Michaelis complex conformation.

Supramolecular azasugar clusters based on an amphiphilic fatty-acid-deoxynojirimycin derivative as multivalent glycosidase inhibitors

A novel supramolecular multivalent glycosidase inhibitor was constructed based on the amphiphilic deoxynojirimycin derivative FA-DNJ.