Polygoni Vivipari Rhizoma (PVR), the dried root of
, has been used as herbal medicine in China for a long time. In the present study, a new method based on multi-step matrix solid-phase dispersion ...(MSPD), ultrafiltration and high performance liquid chromatography (HPLC) for screening alpha-glucosidase inhibitors (AGIs) from PVR was proposed. First, three different PVR extractions were prepared by multi-step MSPD with 15% methanol, 60% methanol and 100% methanol. Second, the alpha-glucosidase inhibition tests for the three extracts were carried out, and the 60% methanol extraction showed the best activity. Then, the AGIs screening experiment was performed with ultrafiltration and HPLC analysis using the 60% methanol extraction. Seven binding components (quercetin-3-
-vicianoside, quercetin 3-
-neohesperidoside, rutin, hyperoside, quercetin 3-
-glucuronide, luteolin-7-
-neohesperidoside, kaempferol 3-glucuronide) were found. These seven components were further validated as the AGIs by molecular docking analysis. The developed method was a rapid and efficient tool for screening AGIs from PVR, which provided scientific data for the bioactive components study of PVR.
The hypoglycaemic effects of two Ribes sp. i.e., anthocyanin-rich black currants (BC) were compared to green currants (GC), which are low in anthocyanins to establish which compounds are involved in ...the regulation of postprandial glycaemia. We determined the effect of the currants on inhibiting carbohydrate digestive enzymes (α-amylase, α-glucosidase), intestinal sugar absorption and transport across CaCo-2 cells. The digestion of these currants was modelled using in vitro gastrointestinal digestion (IVGD) to identify the metabolites present in the digested extracts by LC–MS/MS. Freeze-dried BC and IVDG extracts inhibited yeast α-glucosidase activity (P<.0001) at lower concentrations than acarbose, whereas GC and IVDG GC at the same concentrations showed no inhibition. BC and GC both showed significant inhibitory effects on salivary α-amylase (P<.0001), glucose uptake (P<.0001) and the mRNA expression of sugar transporters (P<.0001). Taken together this suggests that the anthocyanins which are high in BC have their greatest effect on postprandial hyperglycaemia by inhibiting α-glucosidase activity. Phytochemical analysis identified the phenolics in the currants and confirmed that freeze-dried BC contained higher concentrations of anthocyanins compared to GC (39.80 vs. 9.85 g/kg dry weight). Specific phenolics were also shown to inhibit salivary α-amylase, α-glucosidase, and glucose uptake. However, specific anthocyanins identified in BC which were low in GC were shown to inhibit α-glucosidase. In conclusion the anthocyanins in BC appear to regulate postprandial hyperglycaemia primarily but not solely by inhibiting α-glucosidase while other phenolics modulate salivary α-amylase, glucose uptake and sugar transporters which together could lower the associated risk of developing type-2 diabetes.
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Dietary inhibitors of fats and carbohydrates degrading enzymes can reduce obesity and type 2 diabetes. In this study, we screened crude extracts from 30 commonly consumed fruits to test their in ...vitro inhibitory effect against key enzymes relevant for obesity (pancreatic lipase) and type 2 diabetes (α-glucosidase and α-amylase), total phenolic content (Folin–Ciocalteu method), and antioxidant capacity (ABTS and FRAP). The IC50 values of the fruits tested varied from 39.91 to >400 mg/mL, from 1.04 to >80 mg/mL, and from 0.72 to 135.07 mg/mL against α-glucosidase, α-amylase, and pancreatic lipase, respectively. Antioxidant capacity ranged from 0.66 to 124.66 μmol of TE/g of fruit and strongly correlated with phenolic content, while the enzyme inhibition was poorly correlated with total phenolic and antioxidant capacity. Among fruits tested, blue honeysuckle and red gooseberry exhibited the highest inhibitory activity with respect to the carbohydrate degrading enzymes, while lingonberry had the strongest anti-lipase activity.
α‐glucosidase inhibitors (AGIs) are widely used for the treatment of type 2 diabetes, but their side effects have made it to develop novel and alternative AGIs immediately. In this study, the extract ...of Hypericum perforatum L. (HPE) has been confirmed to have α‐glucosidase inhibitory activity in vitro and in vivo. Seven active compounds, rutin, hyperoside, isoquercitrin, avicularin, quercitrin, quercetin, and biapigenin, were screened based on a bio‐affinity chromatography column with α‐glucosidase enzyme‐conjugated solid phase and UPLC/MS, which exhibited excellent α‐glycosidase inhibitory effects by the determined IC50 values. The mechanism of α‐glycosidase inhibitory activity of biapigenin was studied for the first time. The results showed that biapigenin was a high‐potential, reversible, and mixed enzyme inhibitor. Analysis by molecular docking further revealed that hydrophobic interactions were generated by interactions between biapigenin and amino acid residues LYS156, PHE303, PHE314, and LEU313. In addition, hydrogen bonding occurred between biapigenin and α‐glucosidase amino acid residues ASP307, SER241, and LYS156. This research identified that biapigenin could be a novel AGI and further applied to the development of potential anti‐diabetic drugs. Furthermore, our studies established a rapid in vitro screening method for AGIs from plants.
PURPOSE: Inhibitors of intestinal alpha-glucosidases are used therapeutically to treat type 2 diabetes mellitus. Bacteria such as Actinoplanes sp. naturally produce potent alpha-glucosidase inhibitor ...compounds, including the most widely available drug acarbose. It is not known whether lactic acid bacteria (LAB) colonising the human gut possess inhibitory potential against glucosidases. Hence, the study was undertaken to screen LABs having inherent alpha- and beta-glucosidase inhibitory potential. METHODS: This study isolated, screened, identified and extracted Lactobacillus strains (Lb1–15) from human infant faecal samples determining their inhibitory activity against intestinal maltase, sucrase, lactase and amylase. Lactobacillus reference strains (Ref1–7), a Gram positive control (Ctrl1) and two Gram negative controls (Ctrl2–3), were also analysed to compare activity. RESULTS: Faecal isolates were identified by DNA sequencing, with the majority identified as unique strains of Lactobacillus plantarum. Some strains (L. plantarum, L. fermentum, L. casei and L. rhamnosus) had potent and broad spectrum inhibitory activities (up to 89 %; p < 0.001; 500 mg/ml wet weight) comparable to acarbose (up to 88 %; p < 0.001; 30 mg/ml). Inhibitory activity was concentration-dependent and was freely available in the supernatant, and was not present in other bacterial genera (Bifidobacterium bifidum and Escherichia coli or Salmonella typhimurium). Interestingly, the potency and spectrum of inhibitory activity across strains of a single species (L. plantarum) differed substantially. Some Lactobacillus extracts had broader spectrum activities than acarbose, effectively inhibiting beta-glucosidase activity (lactase) as well as alpha-glucosidase activities (maltase, sucrase and amylase). Anti-diabetic potential was indicated by the fact that oral gavage with a L. rhamnosus extract (1 g/kg) was able to reduce glucose excursions (Area under curve; 22 %; p < 0.05) in rats during a carbohydrate challenge (starch; 2 g/kg). CONCLUSION: These results definitively demonstrate that Lactobacillus strains present in the human gut have alpha- and beta-glucosidase inhibitory activities and can reduce blood glucose responses in vivo. Although the potential use of LAB such as Lactobacillus as a dietary supplement, medicinal food or biotherapeutic for diabetes is uncertain, such an approach might offer advantages over drug therapies in terms of broader spectrum activities and fewer unpleasant side effects. Further characterisation of this bioactivity is warranted, and chronic studies should be undertaken in appropriate animal models or diabetic subjects.
For starch digestion to glucose, two luminal α-amylases and four gut mucosal α-glucosidase subunits are employed. The aim of this research was to investigate, for the first time, direct digestion ...capability of individual mucosal α-glucosidases on cooked (gelatinized) starch. Gelatinized normal maize starch was digested with N- and C-terminal subunits of recombinant mammalian maltase-glucoamylase (MGAM) and sucrase-isomaltase (SI) of varying amounts and digestion periods. Without the aid of α-amylase, Ct-MGAM demonstrated an unexpected rapid and high digestion degree near 80%, while other subunits showed 20 to 30% digestion. These findings suggest that Ct-MGAM assists α-amylase in digesting starch molecules and potentially may compensate for developmental or pathological amylase deficiencies.
Inhibitors of alpha glucosidase and pancreatic amylase play a vital role in the clinical management of postprandial hyperglycemia. Although, powerful synthetic inhibitors are available, natural ...inhibitors are potentially safer. Phenolic compounds from the millet seed coat were extracted with acidified methanol and characterised by HPLC and ESI-MS. These phenolics showed strong inhibition towards α-glucosidase and pancreatic amylase and the IC
50 values were 16.9 and 23.5
μg of phenolics, respectively. The enzyme kinetic studies, using Michaelis–Menton and Lineweaver–Burk equations, indicated that, in the presence of millet phenolics, the Michaelis–Menton constant (
K
m) remained constant but the maximal velocity (
V
max) decreased, revealing a non-competitive type of inhibition. The study indicated the therapeutic potentiality of millet phenolics in the management of postprandial hyperglycemia.
Alpha-glucosidase (maltase, sucrase, isomaltase and glucoamylase) activities which are involved in carbohydrate metabolism are present in human intestinal maltase-glucoamylase (MGAM) and ...sucrase-isomaltase (SI). Hence, these proteins are important targets to identify drugs against postprandial hyperglycemia thereby for diabetes. To find natural-based drugs against MGAM and SI, Artocarpus heterophyllus leaf was explored for MGAM and SI inhibition in in vitro and in silico. A. heterophyllus leaf aqueous active fraction (AHL-AAF) was prepared using Soxhlet extraction followed by silica column chromatography. The phytoconstituents of AHL-AAF were determined using LC-ESI-MS/MS. AHL-AAF showed dose-dependent and mixed inhibition against maltase (IC50 = 460 µg/ml; Ki = 300 µg/ml), glucoamylase (IC50 = 780 µg/ml; Ki = 480 µg/ml), sucrase (IC50 = 900 µg/ml, Ki = 504 µg/ml) and isomaltase (IC50 = 860 µg/ml, Ki = 400 µg/ml). AHL-AAF phytoconstituents interaction with N-terminal (Nt) and C-terminal (Ct) subunits of human MGAM and SI was analyzed using induced-fit docking, molecular dynamics (MD), and binding free energy calculation. In docking studies, rhamnosyl hexosyl methyl quercetin (RHMQ), P-coumaryl-O-16-hydroxy palmitic acid (PCHP), and spirostanol interacted with active site amino acids of human MGAM and SI. Among these RHMQ stably interacted with all the subunits (Nt-MGAM, Ct-MGAM, Nt-SI and Ct-SI) whereas PCHP with Ct-MGAM and Nt-SI during MD analysis. In molecular docking, the docking score of RHMQ with NtMGAM, CtMGAM, NtSI and CtSI was −8.48, −12.88, −11.98 and −11.37 kcal/mol. The docking score of PCHP for CtMGAM and NtSI was −8.59 and −8.4 kcal/mol, respectively. After MD simulation, the root mean square deviation (RMSD) and root mean square fluctuation (RMSF) values further confirmed the stable protein-ligand interaction. The RMSD value of all the complexes were around 2.5 Å and the corresponding RMSF values were also quite low. In MM/GBSA analysis, the involvement of Van der Waals and lipophilic energy in the protein/ligand interactions are understood. Further binding free energy for Nt-MGAM-PCHP, Nt-MGAM-RHMQ, Nt-SI-PCHP, Nt-SI-RHMQ, Ct-MGAM-PCHP, Ct-MGAM-RHMQ and Ct-SI-RHMQ complexes was found to be −24.94, −46.60, −46.56, −44.48, −40.3, −41.86 and −19.39 kcal/mol, respectively. Altogether, AHL-AAF showed inhibition of α-glucosidase activities of MGAM and SI. AHL-AAF could be further studied for its effect on diabetes in in vivo.
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•Artocarpus heterophyllus leaf aqueous active fraction (AHL-AAF) subjected to LC-ESI-MS/MS.•AHL-AAF inhibited mammalian glucosidases activities.•AHL-AAF active molecules interacted with human glucosidase in silico .•MD simulation described the stability of protein-ligand complexes.
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•ERT has been ineffective for Pompe disease patients who form high, sustained antibody titers.•AAV-mediated liver-specific expression induced tolerance to ERT through activation of ...Tregs.•The liver depot of GAA is more efficient than the direct transduction of muscle.
Pompe disease is caused by mutations in acid alpha glucosidase (GAA) that causes accumulation of lysosomal glycogen affecting the heart and skeletal muscles, and can be fatal. Enzyme replacement therapy (ERT) with recombinant human GAA (rhGAA) improves muscle function by reducing glycogen accumulation. Limitations of ERT include a short half-life and the formation of antibodies that result in reduced efficacy. By harnessing the immune tolerance induction properties of the liver, liver-targeted gene delivery (with an adeno-associated virus vector containing a liver specific promoter), suppresses immunity against the GAA introduced by gene therapy. This induces immune tolerance to rhGAA by activating regulatory T cells and simultaneously, corrects GAA deficiency. Potentially, liver-targeted gene therapy can be performed once with lasting effects, by administering a relatively low dose of an adeno-associated virus type 8 vector to replace and induce immune tolerance to GAA.
In the Philippines, medicinal plants still provide the first line of therapeutic remedies and their reported efficacy in traditional treatments provides an opportunity for drug discovery and ...development. The study aimed to evaluate in vitro commonly used Philippine medicinal plants for their alpha-amylase and alpha-glucosidase inhibitory activities as potential sources of antidiabetic agents. The study emphasised the inhibitory activities of 54 medicinal plants against α-amylase and α-glucosidase enzymes. The findings revealed 7 medicinal plants with the highest alpha-glucosidase inhibitory activity of ≥ 50% and 3 with alpha-amylase inhibitory activity of ≥ 20%. Ethyl acetate extract of Cycas sp. exhibited the highest α-glucosidase inhibitory activity with 83.87% ± 1.52 followed by the aqueous extract of cf. Calyptranthera sp. With 82.07% ± 0.14 with Acarbose as the reference standard (99.71% ± 0.63) at 10µg/mL (w/v) concentration. For the alpha-amylase inhibitory assay, the highest bioactivity was observed in ethyl acetate extract of Curcuma longa L. (39.44% ± 1.56) with Acarbose as the reference standard (51.59% ± 0.98) at 10µg/mL (w/v) concentration. These findings suggest the potential of the above-mentioned plants as sources of alpha-amylase and alpha-glucosidase inhibitors that may be used as antidiabetic agents.
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