Studies on α-amylase inhibition by acarbose and quercetin using fluorescence, circular dichroism, docking, and dynamics simulations

This study looked at the effects of acarbose (ACA) and quercetin (QUE) on α-amylase activity, employing QUE and ACA to measure enzyme activity. The study observed that both drugs suppressed α-amylase activity, with greater inhibition reported at higher concentrations. The use of tryptophan residues as an intrinsic fluorescence probe permitted the observation of conformational changes in α-amylase, with CD measurements utilized to explore the secondary structure in the presence of QUE and ACA. Docking studies revealed an effective interaction between α-amylase, quercetin and acarbose, with a higher binding energy. Finally, a trajectory analysis was done to establish the stability and volatility of these complexes. These findings have potential significance for the development of new α-amylase-related therapeutics.

Novel molecular hybrids of EGCG and quinoxaline: Potent multi-targeting antidiabetic agents that inhibit α-glucosidase, α-amylase, and oxidative stress

Diabetes mellitus is a multifactorial disease and its effective therapy often demands several drugs with different modes of action. Herein, we report a rational design and synthesis of multi-targeting novel molecular hybrids comprised of EGCG and quinoxaline derivatives that can effectively inhibit α-glucosidase, α-amylase as well as control oxidative stress by scavenging ROS. The hybrids showed superior inhibition of α-glucosidase along with similar α-amylase inhibition as compared to standard drug, acarbose. Most potent compound, 15c showed an IC50 of 0.50 μM (IC50 of acarbose 190 μM) against α-glucosidase. Kinetics studies with 15c revealed a competitive inhibition against α-glucosidase. Binding affinity of 15c (-9.5 kcal/mol) towards α-glucosidase was significantly higher than acarbose (-7.7 kcal/mol). 15c exhibited remarkably high antioxidant activity (IC50 = 18.84 μM), much better than vitamin C (IC50 = 33.04 μM). Of note, acarbose shows no antioxidant activity. Furthermore, α-amylase activity was effectively inhibited by 15c with an IC50 value of 16.35 μM. No cytotoxicity was observed for 15c (up to 40 μM) in MCF-7 cells. Taken together, we report a series of multi-targeting molecular hybrids capable of inhibiting carbohydrate hydrolysing enzymes as well as reducing oxidative stress, thus representing an advancement towards effective and novel therapeutic approaches for diabetes.

Alpha-glucosidase inhibitory and hypoglycemic effects of imidazole-bearing thioquinoline derivatives with different substituents: In silico, in vitro, and in vivo evaluations

Type 2 diabetes mellitus (T2DM) is a chronic metabolic disorder characterized by high blood sugar levels. It was shown that modulating the activity of α-glucosidase, an enzyme involved in carbohydrate digestion and absorption, can improve blood sugar control and overall metabolic health in individuals with T2DM. As a result, in the current study, a series of imidazole bearing different substituted thioquinolines were designed and synthesized as α-glucosidase inhibitors. All derivatives exhibited significantly better potency (IC50 = 12.1 ± 0.2 to 102.1 ± 4.9 µM) compared to the standard drug acarbose (IC50 = 750.0 ± 5.0 µM). 8g as the most potent analog, indicating a competitive inhibition with Ki = 9.66 µM. Also, the most potent derivative was subjected to molecular docking and molecular dynamic simulation against α-glucosidase to determine its mode of action in the enzyme and study the complex's behavior over time. In vivo studies showed that 8g did not cause acute toxicity at 2000 mg/kg doses. Additionally, in a diabetic rat model, treatment with 8g significantly reduced fasting blood glucose levels and decreased blood glucose levels following sucrose loading compared to acarbose, a standard drug used for blood sugar control. The findings suggest that the synthesized compound 8g holds promise as an α-glucosidase inhibitor for improving blood sugar control and metabolic health.

In vitro inhibitory effect of five natural sweeteners on α-glucosidase and α-amylase

A promising and efficacious approach to manage diabetes is inhibiting α-glucosidase and α-amylase activity. Therefore, the inhibitory activities of five natural sweeteners (mogrosides (Mog), stevioside (Ste), glycyrrhizinic acid (GA), crude trilobatin (CT), and crude rubusoside (CR)) against α-glucosidase and α-amylase and their interactions were evaluated in vitro using enzyme kinetics, fluorescence spectroscopy, Fourier infrared spectroscopy, and molecular docking. The inhibitor sequence was CT > GA > Ste, as GA competitively inhibited α-glycosidase activity while CT and Ste exhibited mixed inhibitory effects. Compared to a positive control acarbose, the inhibitory activity of CT was higher. For α-amylase, the mixed inhibitors CT, CR, and Mog and the competitive inhibitor Ste effectively inhibited the enzyme, with the following order: CT > CR > Ste > Mog; nevertheless, the inhibitors were slightly inferior to acarbose. Three-dimensional fluorescence spectra depicted that GA, CT, and CR bound to the hydrophobic cavity of α-glucosidase or α-amylase and changed the polarity of the hydrophobic amino acid-based microenvironment and structure of the polypeptide chain backbone. Infrared spectroscopy revealed that GA, CT, and CR could disrupt the secondary structure of α-glucosidase or α-amylase, which decreased enzyme activity. GA, trilobatin and rubusoside bound to amino acid residues through hydrogen bonds and hydrophobic interactions, changing the conformation of enzyme molecules to decrease the enzymatic activity. Thus, CT, CR and GA exhibit promising inhibitory effects against α-glucosidase and α-amylase.

The effect of acarbose on inflammatory cytokines and adipokines in adults: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Although a large number of trials have observed an anti-inflammatory property of acarbose, the currently available research remains controversial regarding its beneficial health effects. Hence, the purpose of this study was to examine the effect of acarbose on inflammatory cytokines and adipokines in adults.

METHODS

PubMed, Web of Science, and Scopus were systematically searched until April 2023 using relevant keywords. The mean difference (MD) of any effect was calculated using a random-effects model. Weighted mean difference (WMD) and 95% confidence intervals (CIs) were calculated via the random-effects model.

RESULTS

The current meta-analysis of data comprised a total of 19 RCTs. Meta-analysis showed that acarbose significantly decreased tumor necrosis factor-alpha (TNF-α) (weighted mean difference [WMD]) = - 4.16 pg/ml, 95% confidence interval (CI) - 6.58, - 1.74; P = 0.001) while increasing adiponectin (WMD = 0.79 ng/ml, 95% CI 0.02, 1.55; P = 0.044). However, the effects of acarbose on TNF-α concentrations were observed in studies with intervention doses ≥ 300 mg/d (WMD = - 4.09; 95% CI - 7.00, - 1.18; P = 0.006), and the adiponectin concentrations were significantly higher (WMD = 1.03 ng/ml, 95%CI 0.19, 1.87; P = 0.016) in studies in which the duration of intervention was less than 24 weeks. No significant effect was seen for C-reactive protein (CRP; P = 0.134), interleukin-6 (IL-6; P = 0.204), and leptin (P = 0.576).

CONCLUSION

Acarbose had beneficial effects on reducing inflammation and increasing adiponectin. In this way, it may prevent the development of chronic diseases related to inflammation. However, more studies are needed.

Synergistic effect of potential alpha-amylase inhibitors from Egyptian propolis with acarbose using in silico and in vitro combination analysis

BACKGROUND

Type 2 Diabetes mellitus (DM) is an affliction impacting the quality of life of millions of people worldwide. An approach used in the management of Type 2 DM involves the use of the carbohydrate-hydrolyzing enzyme inhibitor, acarbose. Although acarbose has long been the go-to drug in this key approach, it has become apparent that its side effects negatively impact patient adherence and subsequently, therapeutic outcomes. Similar to acarbose in its mechanism of action, bee propolis, a unique natural adhesive biomass consisting of biologically active metabolites, has been found to have antidiabetic potential through its inhibition of α-amylase. To minimize the need for ultimately novel agents while simultaneously aiming to decrease the side effects of acarbose and enhance its efficacy, combination drug therapy has become a promising pharmacotherapeutic strategy and a focal point of this study.

METHODS

Computer-aided molecular docking and molecular dynamics (MD) simulations accompanied by in vitro testing were used to mine novel, pharmacologically active chemical entities from Egyptian propolis to combat Type 2 DM. Glide docking was utilized for a structure-based virtual screening of the largest in-house library of Egyptian propolis metabolites gathered from literature, in addition to GC-MS analysis of the propolis sample under investigation. Thereafter, combination analysis by means of fixed-ratio combinations of acarbose with propolis and the top chosen propolis-derived phytoligand was implemented.

RESULTS

Aucubin, identified for the first time in propolis worldwide and kaempferol were the most promising virtual hits. Subsequent in vitro α-amylase inhibitory assay demonstrated the ability of these hits to significantly inhibit the enzyme in a dose-dependent manner with an IC50 of 2.37 ± 0.02 mM and 4.84 ± 0.14 mM, respectively. The binary combination of acarbose with each of propolis and kaempferol displayed maximal synergy at lower effect levels. Molecular docking and MD simulations revealed a cooperative binding mode between kaempferol and acarbose within the active site.

CONCLUSION

The suggested strategy seems imperative to ensure a steady supply of new therapeutic entities sourced from Egyptian propolis to regress the development of DM. Further pharmacological in vivo investigations are required to confirm the potent antidiabetic potential of the studied combination.

Inhibitory effect of acarbose on tyrosinase: application of molecular dynamics integrating inhibition kinetics

Due to its clinical and cosmetic applications, investigators have paid attention to tyrosinase (TYR) inhibitor development. In this study, a TYR inhibition study with acarbose was investigated to gain insights into the regulation of the catalytic function. Biochemical assay results indicated that acarbose was turned to be an inhibitor of TYR in a reversible binding manner and probed as a distinctive mixed-type inhibitor via measurement of double-reciprocal kinetic (Ki = 18.70 ± 4.12 mM). Time-interval kinetic measurement indicated that TYR catalytic function was gradually inactivated by acarbose in a time-dependent behavior displaying with a monophase process that was evaluated by semi-logarithmic plotting. Spectrofluorimetric measurement by integrating with a hydrophobic residue detector (1-anilinonaphthalene-8-sulfonate) showed that the high dose of acarbose derived a conspicuous local structural deformation of the TYR catalytic site pocket. Computational docking simulation showed that acarbose bound to key residues such as HIS61, TYR65, ASN81, HIS244, and HIS259. Our study extends an understanding of the functional application of acarbose and proposes that acarbose is an alternative candidate drug for a whitening agent via direct retardation of TYR catalytic function and it would be applicable for the relevant skin hyperpigmentation disorders concerning the dermatologic clinical purpose.Communicated by Ramaswamy H. Sarma.

Acarbose reduces Pseudomonas aeruginosa respiratory tract infection in type 2 diabetic mice

BACKGROUND

Type 2 diabetes mellitus (T2DM) is widely prevalent worldwide, and respiratory tract infections (RTIs) have become the primary cause of death for T2DM patients who develop concurrent infections. Among these, Pseudomonas aeruginosa infection has been found to exhibit a high mortality rate and poor prognosis and is frequently observed in bacterial infections that are concurrent with COVID-19. Studies have suggested that acarbose can be used to treat T2DM and reduce inflammation. Our objective was to explore the effect of acarbose on P. aeruginosa RTI in T2DM individuals and elucidate its underlying mechanism.

METHODS

High-fat diet (HFD) induction and P. aeruginosa inhalation were used to establish a RTI model in T2DM mice. The effect and mechanism of acarbose administered by gavage on P. aeruginosa RTI were investigated in T2DM and nondiabetic mice using survival curves, pathological examination, and transcriptomics.

RESULTS

We found that P. aeruginosa RTI was more severe in T2DM mice than in nondiabetic individuals, which could be attributed to the activation of the NF-κB and TREM-1 signaling pathways. When acarbose alleviated P. aeruginosa RTI in T2DM mice, both HIF-1α and NF-κB signaling pathways were inhibited. Furthermore, inhibition of the calcium ion signaling pathway and NF-κB signaling pathway contributed to the attenuation of P. aeruginosa RTI by acarbose in nondiabetic mice.

CONCLUSIONS

This study confirmed the attenuating effect of acarbose on P. aeruginosa RTIs in T2DM and nondiabetic mice and investigated its mechanism, providing novel support for its clinical application in related diseases.

Indole Diterpene Derivatives from the Aspergillus flavus GZWMJZ-288, an Endophytic Fungus from Garcinia multiflora

A new indole diterpene, 26-dihydroxyaflavininyl acetate (1), along with five known analogs (2-6) were isolated from the liquid fermentation of Aspergillus flavus GZWMJZ-288, an endophyte from Garcinia multiflora. The structures of these compounds were identified through NMR, MS, chemical reaction, and X-ray diffraction experiments. Enzyme inhibition activity screening found that compounds 1, 4, and 6 have a good binding affinity with NPC1L1, among which compound 6 exhibited a stronger binding ability than ezetimibe at a concentration of 10 µM. Moreover, compound 5 showed inhibitory activity against α-glucosidase with an IC50 value of 29.22 ± 0.83 µM, which is 13 times stronger than that of acarbose. The results suggest that these aflavinine analogs may serve as lead compounds for the development of drugs targeting NPC1L1 and α-glucosidase. The binding modes of the bioactive compounds with NPC1L1 and α-glucosidase were also performed through in silico docking studies.

Discovery of novel 4,5-diphenyl-imidazol-α-aminophosphonate hybrids as promising anti-diabetic agents: Design, synthesis, in vitro, and in silico enzymatic studies

Herein, a novel series of 4,5-diphenyl-imidazol-α-aminophosphonate hybrids 4a-m was designed, synthesized, and evaluated as new anti-diabetic agents. These compounds were evaluated against two important target enzymes in the diabetes treatment: α-glucosidase and α-amylase. These new compounds were synthesized in three steps and characterized by different spectroscopic techniques. The in vitro evaluations demonstrated that all the synthesized compounds 4a-m were more potent that standard inhibitor acarbose against studied enzymes. Among these compound, the most potent compound against both studied enzymes was 3-bromo derivative 4l. The latter compound with IC50 = 5.96 nM was 18-times more potent than acarbose (IC50 = 106.63 nM) against α-glucosidase. Moreover, compound 4l with IC50 = 1.62 nM was 27-times more potent than acarbose (IC50 = 44.16 nM) against α-amylase. Molecular docking analysis revealed that this compound well accommodated in the binding site of α-glucosidase and α-amylase enzymes with notably more favorable binding energy as compared to acarbose.

The effect of acarbose on lipid profiles in adults: a systematic review and meta-analysis of randomized clinical trials

PURPOSE

Dyslipidemia, characterized by elevated levels of triglycerides (TG), low-density lipoprotein (LDL), total cholesterol (TC), and reduced levels of high-density lipoprotein (HDL), is a major risk factor for cardiovascular diseases (CVD). Several studies have shown the potential of acarbose in improving serum lipid markers. However, there have been conflicting results on the topic in adults. Therefore, a comprehensive systematic review and meta-analysis was conducted to assess the impact of acarbose on lipid profiles.

METHODS

The random-effects approach was used to combine the data, and the results were provided as weighted mean difference (WMD) with 95% confidence intervals (CI).

RESULTS

Our meta-analysis included a total of 74 studies with a combined sample size of 7046 participants. The results of the analysis showed that acarbose resulted in a reduction in levels of TG (WMD = - 13.43 mg/dl, 95% CI: - 19.20, - 7.67; P < 0.001) and TC (WMD = - 1.93 mg/dl, 95% CI: - 3.71, - 0.15; P = 0.033), but did not affect other lipid markers. When conducting a nonlinear dose-response analysis, we found that acarbose was associated with an increase in levels of HDL (coefficients = 0.50, P = 0.012), with the highest increase observed at a dosage of 400 mg/d. Furthermore, our findings suggested a non-linear relationship between the duration of the intervention and TC (coefficients = - 18.00, P = 0.032), with a decline observed after 50 weeks of treatment.

CONCLUSION

The findings of this study suggest that acarbose can reduce serum levels of TG and TC. However, no significant effects were observed on LDL or HDL levels.

Phytochemical analysis, in vitro and in silico effects from Alstonia boonei De Wild stem bark on selected digestive enzymes and adipogenesis in 3T3-L1 preadipocytes

BACKGROUND

Obesity is a global health issue arising from the unhealthy accumulation of fat. Medicinal plants such as Alstonia boonei stem bark has been reported to possess body weight reducing effect in obese rats. Thus, this study sought to investigate the in vitro and in silico effects of fractions from Alstonia boonei stem bark on selected obesity-related digestive enzymes and adipogenesis in 3T3-L1 preadipocytes.

METHOD

Two fractions were prepared from A. boonei: crude alkaloid fraction (CAF) and crude saponin fraction (CSF), and their phytochemical compounds were profiled using Liquid chromatography with tandem mass spectrometry (LCMS/MS). The fractions were assayed for inhibitory activity against lipase, α-amylase and α-glucosidase, likewise their antiadipogenic effect in 3T3-L1 adipocytes. The binding properties with the 3 enzymes were also assessed using in silico tools.

RESULTS

Eleven alkaloids and six saponin phytochemical compounds were identified in the CAF and CSF using LCMS/MS. The CAF and CSF revealed good inhibitory activity against pancreatic lipase enzyme, but weak and good activity against amylase respectively while only CSF had inhibitory activity against α-glucosidase. Both fractions showed antiadipogenic effect in the clearance of adipocytes and reduction of lipid content in 3T3-L1 adipocytes. The LCMS/MS identified compounds (41) from both fractions demonstrated good binding properties with the 3 enzymes, with at least the top ten compounds having higher binding energies than the reference inhibitors (acarbose and orlistat). The best two docked compounds to the three enzymes were firmly anchored in the substrate binding pockets of the enzymes. In a similar binding pattern as the reference acarbose, Estradiol-17-phenylpropionate (-11.0 kcal/mol) and 3α-O-trans-Feruloyl-2 α -hydroxy-12-ursen-28-oic acid (-10.0 kcal/mol) interacted with Asp197 a catalytic nucleophile of pancreatic amylase. Estradiol-17-phenylpropionate (-10.8 kcal/mol) and 10-Hydroxyyohimbine (-10.4 kcal/mol) interacted with the catalytic triad (Ser152-Asp176-His263) of pancreatic lipase while Estradiol-17-phenylpropionate (-10.1 kcal/mol) and 10-Hydroxyyohimbine (-9.9 kcal/mol) interacted with Asp616 and Asp518 the acid/base and nucleophilic residues of modelled α-glucosidase.

CONCLUSION

The antiobesity effect of A. boonei was displayed by both the alkaloid and saponin fractions of the plant via inhibition of pancreatic lipase and adipogenesis.

Do antidiabetic drugs prevent the transformation of Acanthamoeba trophozoite into cyst form?

This study examines the effects of three different drugs with metformin, acarbose and pioglitazone active ingredients used for antidiabetic purposes on Acanthamoeba cysts and trophozoites. Cultures of A. castellanii trophozoites and cysts were prepared to test the anti-amoebic activity of metformin, acarbose and pioglitazone. Cultures were then prepared for A. castellanii cyst and trophozoite forms and parasites were exposed to different concentrations (0.750 mg/mL, 0.375 mg/mL, 0.186 mg/mL and 0.093 mg/mL) of metformin, acarbose and pioglitazone. As a result of the study, the reproductive potential suppressive effects and conversion from trophozoite form to cyst form of all three substances on A. castellanii trophozoites and cysts were determined. Parasites were counted at 12, 24 and 48 hours in the cell counter after staining with trypan blue. In comparison of the effects of metformin, acarbose and pioglitazone used in the study on A. castellanii trophozoites and cysts, it was observed that all three substances were statistically effective against cysts and trophozoites at a concentration of 0.750 mg/mL. Furthermore, it was determined that all concentrations of the three active substances included in the study significantly decreased the rate of cyst formation even at the end of the 7th day. In this context, it was determined that all three substances have amebicidal effects, and they significantly inhibit the transformation of A. castellanii trophozoites to cyst form. It is thought that these active substances, which are currently used as anti-diabetic, can be used in combination with other drugs in A. castellanii infections based on our study findings.

Physicochemical characterizations, α-amylase inhibitory activities and inhibitory mechanisms of five bacterial exopolysaccharides

Inhibiting pancreatic α-amylase activity can decrease the release rate of glucose, thereby delaying postprandial blood glucose. This study aimed to investigate the physicochemical properties and porcine pancreatic α-amylase (PPA) inhibitory activities of five bacterial exopolysaccharides (EPSs). We also aimed to analyze the differences of their inhibitory activities, exploring the inhibition mechanism between EPSs and PPA. Five EPSs had a low molecular weight (55-66 kDa), which were mainly composed of mannose and glucose with total content exceeding 86 %. The IC50 values of five EPSs (0.162-0.431 mg/mL) were significantly lower than that of acarbose (0.763 mg/mL), indicating that the inhibitory effects of five EPSs on PPA were stronger than acarbose, especially the EPS from Bacillus subtilis STB22 (BS-EPS). Moreover, BS-EPS was a mixed-type inhibitor, whereas other EPSs were noncompetitive inhibitors of PPA. Five EPSs quenched the fluorophore of PPA by the mixed quenching or apparent static quenching. Interestingly, BS-EPS showed stronger binding affinity to PPA than other EPSs. It can be speculated that EPSs with low molecular weight, high carboxylic acid content, and α-glycosidic bond exhibited high PPA inhibitory activity. These results suggest that BS-EPS can effectively inhibit PPA activity and has potential applications in reducing postprandial hyperglycemia.

Imidazo[1,2-c]quinazolines as a novel and potent scaffold of α-glucosidase inhibitors: design, synthesis, biological evaluations, and in silico studies

α-Glucosidase inhibition is an approved treatment for type 2 diabetes mellitus (T2DM). In an attempt to develop novel anti-α-glucosidase agents, two series of substituted imidazo[1,2-c]quinazolines, namely 6a-c and 11a-o, were synthesized using a simple, straightforward synthetic routes. These compounds were thoroughly characterized by IR, 1H and 13C NMR spectroscopy, as well as mass spectrometry and elemental analysis. Subsequently, the inhibitory activities of these compounds were evaluated against Saccharomyces cerevisiae α-glucosidase. In present study, acarbose was utilized as a positive control. These imidazoquinazolines exhibited excellent to great inhibitory potencies with IC50 values ranging from 12.44 ± 0.38 μM to 308.33 ± 0.06 μM, which were several times more potent than standard drug with IC50 value of 750.0 ± 1.5 μM. Representatively, compound 11j showed remarkable anti-α-glucosidase potency with IC50 = 12.44 ± 0.38 μM, which was 60.3 times more potent than positive control acarbose. To explore the potential inhibition mechanism, further evaluations including kinetic analysis, circular dichroism, fluorescence spectroscopy, and thermodynamic profile were carried out for the most potent compound 11j. Moreover, molecular docking studies and in silico ADME prediction for all imidazoquinazolines 6a-c and 11a-o were performed to reveal their important binding interactions, as well as their physicochemical and drug-likeness properties, respectively.

Chromogenic Assay Is More Efficient in Identifying α-Amylase Inhibitory Properties of Anthocyanin-Rich Samples When Compared to the 3,5-Dinitrosalicylic Acid (DNS) Assay

The inhibition of carbohydrate digestion by plant bioactive compounds is a potential dietary strategy to counteract type 2 diabetes. Indeed, inhibition of α-amylase, a key enzyme that carries out the bulk of starch digestion, has been demonstrated for a range of bioactive compounds including anthocyanins; however, sample pigmentation often interferes with measurements, affecting colorimetric assay outcomes. Therefore, the present study compared the performance of a direct chromogenic assay, using 2-chloro-4 nitrophenyl α-D-maltotrioside (CNPG3) as a substrate, with the commonly used 3,5-dinitrosalicylic acid (DNS) assay. The direct chromogenic assay demonstrated a 5-10-fold higher sensitivity to determine α-amylase inhibition in various samples, including acarbose as a reference, pure anthocyanins, and anthocyanin-rich samples. The IC50 values of acarbose presented as 37.6 μg/mL and 3.72 μg/mL for the DNS assay and the direct chromogenic assay, respectively, whereas purified anthocyanins from blackcurrant showed IC50 values of 227.4 µg/mL and 35.0 µg/mL. The direct chromogenic assay is easy to perform, fast, reproducible, and suitable for high-throughput screening of pigmented α-amylase inhibitors.

Exploring the interactive mechanism of acarbose with the amylase SusG in the starch utilization system of the human gut symbiont Bacteroides thetaiotaomicron through molecular modeling

The α-amylase, SusG, is a principal component of the Bacteroides thetaiotaomicron (Bt) starch utilization system (Sus) used to metabolize complex starch molecules in the human gastrointestinal (GI) tract. We previously reported the non-microbicidal growth inhibition of Bt by the acarbose-mediated arrest of the Sus as a potential therapeutic strategy. Herein, we report a computational approach using density functional theory (DFT), molecular docking, and molecular dynamics (MD) simulation to explore the interactive mechanism between acarbose and SusG at the atomic level in an effort to understand how acarbose shuts down the Bt Sus. The docking analysis reveals that acarbose binds orthosterically to SusG with a binding affinity of -8.3 kcal/mol. The MD simulation provides evidence of conformational variability of acarbose at the active site of SusG and also suggests that acarbose interacts with the main catalytic residues via a general acid-base double-displacement catalytic mechanism. These results suggest that small molecule competitive inhibition against the SusG protein could impact the entire Bt Sus and eliminate or reduce the system's ability to metabolize starch. This computational strategy could serve as a potential avenue for structure-based drug design to discover other small molecules capable of inhibiting the Sus of Bt with high potency, thus providing a holistic approach for selective modulation of the GI microbiota.

Acarbose Mitigates Age-Dependent Alterations in Erythrocyte Membrane Transporters During Aging in Rats

Acarbose (ACA), a well-studied and effective inhibitor of α-amylase and α-glucosidase, is a postprandial-acting antidiabetic medicine. The membrane of the erythrocyte is an excellent tool for analyzing different physiological and biochemical activities since it experiences a range of metabolic alterations throughout aging. It is uncertain if ACA modulates erythrocyte membrane activities in an age-dependent manner. As a result, the current study was conducted to explore the influence of ACA on age-dependent deteriorated functions of transporters/exchangers, disrupted levels of various biomarkers such as lipid hydroperoxides (LHs), protein carbonyl (PCO), sialic acid (SA), total thiol (-SH), and erythrocyte membrane osmotic fragility. In addition to a concurrent increase in Na+/H+ exchanger activity and concentration of LH, PCO, and osmotic fragility, we also detected a considerable decrease in membrane-linked activities of Ca2+-ATPase (PMCA) and Na+/K+-ATPase (NKA), as well as concentrations of SA and -SH in old-aged rats. The aging-induced impairment of the activities of membrane-bound ATPases and the changed levels of redox biomarkers were shown to be effectively restored by ACA treatment.

Acarbose diminishes postprandial suppression of bone resorption in patients with type 2 diabetes

AIMS

The alpha-glucosidase inhibitor acarbose is an antidiabetic drug delaying assimilation of carbohydrates and, thus, increasing the amount of carbohydrates in the distal parts of the intestines, which in turn increases circulating levels of the gut-derived incretin hormone glucagon-like peptide 1 (GLP-1). As GLP-1 may suppress bone resorption, acarbose has been proposed to potentiate meal-induced suppression of bone resorption. We investigated the effect of acarbose treatment on postprandial bone resorption in patients with type 2 diabetes and used the GLP-1 receptor antagonist exendin(9-39)NH₂ to disclose contributory effect of acarbose-induced GLP-1 secretion.

METHODS

In a randomised, placebo-controlled, double-blind, crossover study, 15 participants with metformin-treated type 2 diabetes (2 women/13 men, age 71 (57-85 years), BMI 29.7 (23.6-34.6 kg/m²), HbA1c 48 (40-74 mmol/mol)/6.5 (5.8-11.6 %) (median and range)) were subjected to two 14-day treatment periods with acarbose and placebo, respectively, separated by a six-week wash-out period. At the end of each period, circulating bone formation and resorption markers were assessed during two randomised 4-h liquid mixed meal tests (MMT) with infusions of exendin(9-39)NH₂ and saline, respectively. Glucagon-like peptide 2 (GLP-2) was also assessed.

RESULTS

Compared to placebo, acarbose impaired the MMT-induced suppression of CTX as assessed by baseline-subtracted area under curve (P = 0.0037) and nadir of CTX (P = 0.0128). During acarbose treatment, exendin(9-39)NH₂ infusion lowered nadir of CTX compared to saline (P = 0.0344). Neither parathyroid hormone or the bone formation marker procollagen 1 intact N-terminal propeptide were affected by acarbose or GLP-1 receptor antagonism. Acarbose treatment induced a greater postprandial GLP-2 response than placebo treatment (P = 0.0479) and exendin(9-39)NH₂ infusion exacerbated this (P = 0.0002).

CONCLUSIONS

In patients with type 2 diabetes, treatment with acarbose reduced postprandial suppression of bone resorption. Acarbose-induced GLP-1 secretion may contribute to this phenomenon as the impairment was partially reversed by GLP-1 receptor antagonism. Also, acarbose-induced reductions in other factors reducing bone resorption, e.g. glucose-dependent insulinotropic polypeptide, may contribute.

Synthetic α-glucosidase inhibitors as promising anti-diabetic agents: Recent developments and future challenges

Diabetes mellitus is one of the biggest challenges for the scientific community in the 21st century. It is a well-recognized multifactorial health problem contributes significantly to high mortality rates by causing serious health complications mainly related to cardiovascular diseases, kidney damage and neuropathy. The inhibition of α-glucosidase (enzyme that catalyses starch hydrolysis in the intestine) is an effective therapeutic approach for controlling hyperglycemia associated with type-2 diabetes. However, the presently approved drugs/inhibitors such as acarbose, miglitol and voglibose have several undesirable gastrointestinal side effects impeding their applications. Therefore, search for novel and more effective inhibitors with reduced side effects and less cost remains a fascinating area of research. In this context, a large variety of α-glucosidase inhibitors have been identified in recent years that demands attention from drug development community. This review is therefore an effort to summarize and highlight the promising α-glucosidase inhibitors especially those which are primarily based on aromatic heterocyclic scaffolds such as coumarin, imidazole, isatin, pyrimidine, quinazoline, triazine, thiazole etc, having improved safety and pharmacological profiles.

Early or Late-Life Treatment With Acarbose or Rapamycin Improves Physical Performance and Affects Cardiac Structure in Aging Mice

Pharmacological treatments can extend the life span of mice. For optimal translation in humans, treatments should improve health during aging, and demonstrate efficacy when started later in life. Acarbose (ACA) and rapamycin (RAP) extend life span in mice when treatment is started early or later in life. Both drugs can also improve some indices of healthy aging, although there has been little systematic study of whether health benefits accrue differently depending on the age at which treatment is started. Here we compare the effects of early (4 months) versus late (16 months) onset ACA or RAP treatment on physical function and cardiac structure in genetically heterogeneous aged mice. ACA or RAP treatment improve rotarod acceleration and endurance capacity compared to controls, with effects that are largely similar in mice starting treatment from early or late in life. Compared to controls, cardiac hypertrophy is reduced by ACA or RAP in both sexes regardless of age at treatment onset. ACA has a greater effect on the cardiac lipidome than RAP, and the effects of early-life treatment are recapitulated by late-life treatment. These results indicate that late-life treatment with these drugs provide at least some of the benefits of life long treatment, although some of the benefits occur only in males, which could lead to sex differences in health outcomes later in life.

Characterizing the Effect of Amylase Inhibitors on Maltodextrin Metabolism by Gut Bacteria Using Fluorescent Glycan Labeling

Diet-derived polysaccharides are an important carbon source for gut bacteria and shape the human gut microbiome. Acarbose, a compound used clinically to treat type 2 diabetes, is known to inhibit the growth of some bacteria on starches based on its activity as an inhibitor of α-glucosidases and α-amylases. In contrast to acarbose, montbretin A, a new drug candidate for the treatment of type 2 diabetes, has been reported to be more specific for the inhibition of α-amylase, notably human pancreatic α-amylase. However, the effects of both molecules on glycan metabolism across a larger diversity of human gut bacteria remain to be characterized. Here, we used ex vivo metabolic labeling of a human microbiota sample with fluorescent maltodextrin to identify gut bacteria affected by amylase inhibitors. Metabolic labeling was performed in the presence and absence of amylase inhibitors, and the fluorescently labeled bacteria were identified by fluorescence-activated cell sorting coupled with 16S rDNA amplicon sequencing. We validated the labeling results in cultured isolates and identified four gut bacteria species whose metabolism of maltodextrin is inhibited by acarbose. In contrast, montbretin A slowed the growth of only one species, supporting the fact that it is more selective. Metabolic labeling is a valuable tool to characterize glycan metabolism in microbiota samples and could help understand the untargeted impact of drugs on the human gut microbiota.

Acarbose Protects Glucolipotoxicity-Induced Diabetic Nephropathy by Inhibiting Ras Expression in High-Fat Diet-Fed db/db Mice

Diabetic nephropathy (DN) exacerbates renal tissue damage and is a major cause of end-stage renal disease. Reactive oxygen species play a vital role in hyperglycemia-induced renal injury. This study examined whether the oral hypoglycemic drug acarbose (Ab) could attenuate the progression of DN in type 2 diabetes mellitus mice. In this study, 50 mg/kg body weight of Ab was administered to high-fat diet (HFD)-fed db/db mice. Their body weight was recorded every week, and the serum glucose concentration was monitored every 2 weeks. Following their euthanasia, the kidneys of mice were analyzed through hematoxylin and eosin, periodic acid Schiff, Masson's trichrome, and immunohistochemistry (IHC) staining. The results revealed that Ab stabilized the plasma glucose and indirectly improved the insulin sensitivity and renal functional biomarkers in diabetic mice. In addition, diabetes-induced glomerular hypertrophy, the saccharide accumulation, and formation of collagen fiber were reduced in diabetic mice receiving Ab. Although the dosages of Ab cannot decrease the blood sugar in db/db mice, our results indicate that Ab alleviates glucolipotoxicity-induced DN by inhibiting kidney fibrosis-related proteins through the Ras/ERK pathway.

Synthesis, Conformational Analysis and Evaluation of the 2-aryl-4-(4-bromo-2-hydroxyphenyl)benzo[1,5]thiazepines as Potential α-Glucosidase and/or α-Amylase Inhibitors

The ambident electrophilic character of the 5-bromo-2-hydroxychalcones and the binucleophilic nature of 2-aminothiophenol were exploited to construct the 2-aryl-4-(4-bromo-2-hydroxyphenyl)benzo[1,5]thiazepines. The structures and conformation of these 2-aryl-4-(4-bromo-2-hydroxyphenyl)benzo[1,5]thiazepines were established with the use of spectroscopic techniques complemented with a single crystal X-ray diffraction method. Both ¹H-NMR and IR spectroscopic techniques confirmed participation of the hydroxyl group in the intramolecular hydrogen-bonding interaction with a nitrogen atom. SC-XRD confirmed the presence of a six-membered intramolecularly hydrogen-bonded pseudo-aromatic ring, which was corroborated by the DFT method on 2b as a representative example in the gas phase. Compounds 2a (Ar = -C₆H₅), 2c (Ar = -C₆H₄(4-Cl)) and 2f (Ar = -C₆H₄(4-CH(CH₃)₂) exhibited increased inhibitory activity against α-glucosidase compared to acarbose (IC₅₀ = 7.56 ± 0.42 µM), with IC₅₀ values of 6.70 ± 0.15 µM, 2.69 ± 0.27 µM and 6.54 ± 0.11 µM, respectively. Compound 2f, which exhibited increased activity against α-glucosidase, also exhibited a significant inhibitory effect against α-amylase (IC₅₀ = 9.71 ± 0.50 µM). The results of some computational approaches on aspects such as noncovalent interactions, calculated binding energies for α-glucosidase and α-amylase, ADME (absorption, distribution, metabolism and excretion) and bioavailability properties, gastrointestinal absorption and blood-brain barrier permeability are also presented.

Critical Assessment of In Vitro Screening of α-Glucosidase Inhibitors from Plants with Acarbose as a Reference Standard

Postprandial hyperglycemia is treated with the oral antidiabetic drug acarbose, an intestinal α-glucosidase inhibitor. Side effects of acarbose motivated a growing number of screening studies to identify novel α-glucosidase inhibitors derived from plant extracts and other natural sources. As "gold standard", acarbose is frequently included as the reference standard to assess the potency of these candidate α-glucosidase inhibitors, with many outperforming acarbose by several orders of magnitude. The results are subsequently used to identify suitable compounds/products with strong potential for in vivo efficacy. However, most α-glucosidase inhibitor screening studies use enzyme preparations obtained from nonmammalian sources (typically Saccharomyces cerevisiae), despite strong evidence that inhibition data obtained using nonmammalian α-glucosidase may hold limited value in terms of identifying α-glucosidase inhibitors with actual in vivo hypoglycemic potential. The aim was to critically discuss the screening of novel α-glucosidase inhibitors from plant sources, emphasizing inconsistencies and pitfalls, specifically where acarbose was included as the reference standard. An assessment of the available literature emphasized the cruciality of stating the biological source of α-glucosidase in such screening studies to allow for unambiguous and rational interpretation of the data. The review also highlights the lack of a universally adopted screening assay for novel α-glucosidase inhibitors and the commercial availability of a standardized preparation of mammalian α-glucosidase.

Exploring Active Ingredients, Beneficial Effects, and Potential Mechanism of Allium tenuissimum L. Flower for Treating T2DM Mice Based on Network Pharmacology and Gut Microbiota

Forty compounds were isolated and characterized from A. tenuissimum flower. Among them, twelve flavonoids showed higher α−glucosidase inhibition activities in vitro than acarbose, especially kaempferol. The molecular docking results showed that the binding of kaempferol to α−glucosidase (GAA) could reduce the hydrolysis of substrates by GAA and reduce the glucose produced by hydrolysis, thus exhibiting α−glucosidase inhibition activities. The in vivo experiment results showed that flavonoids−rich A. tenuissimum flower could decrease blood glucose and reduce lipid accumulation. The protein expression levels of RAC−alpha serine/threonine−protein kinase (AKT1), peroxisome proliferator activated receptor gamma (PPARG), and prostaglandin G/H synthase 2 (PTGS2) in liver tissue were increased. In addition, the Firmicutes/Bacteroidetes (F/B) ratio was increased, the level of gut probiotics Bifidobacterium was increased, and the levels of Enterobacteriaceae and Staphylococcus were decreased. The carbohydrate metabolism, lipid metabolism, and other pathways related to type 2 diabetes mellitus were activated. This study indicating flavonoids−rich A. tenuissimum flower could improve glycolipid metabolic disorders and inflammation in diabetic mice by modulating the protein expression and gut microbiota.

Isolation of Chalcomoracin as a Potential α-Glycosidase Inhibitor from Mulberry Leaves and Its Binding Mechanism

Diabetes is a chronic metabolic disease, whereas α-glucosidases are key enzymes involved in the metabolism of starch and glycogen. There is a long history of the use of mulberry leaf (the leaf of Morus alba) as an antidiabetic herb in China, and we found that chalcomoracin, one of the specific Diels–Alder adducts in mulberry leaf, had prominent α-glucosidase inhibitory activity and has the potential to be a substitute for current hypoglycemic drugs such as acarbose, which have severe gastrointestinal side effects. In this study, chalcomoracin was effectively isolated from mulberry leaves, and its α-glucosidase inhibition was studied via enzymatic kinetics, isothermal titration (ITC) and molecular docking. The results showed that chalcomoracin inhibited α-glucosidase through both competitive and non-competitive manners, and its inhibitory activity was stronger than that of 1-doxymycin (1-DNJ) but slightly weaker than that of acarbose. ITC analysis revealed that the combination of chalcomoracin and α-glucosidase was an entropy-driven spontaneous reaction, and the molecular docking results also verified this conclusion. During the binding process, chalcomoracin went into the “pocket” of α-glucosidase via hydrophobic interactions, and it is linked with residues Val544, Asp95, Ala93, Gly119, Arg275 and Pro287 by hydrogen bonds. This study provided a potential compound for the prevention and treatment of diabetes and a theoretical basis for the discovery of novel candidates for α-glycosidase inhibitors.

Reducing the intestinal side effects of acarbose by baicalein through the regulation of gut microbiota: An in vitro study

Combination of dietary flavonoid-baicalein and acarbose reduces the risk that prediabetes will develop into type 2 diabetes mellitus; however, the mechanism underlying this effect has not been clarified. In this study, the in vitro culture conditions of intestinal microorganisms from prediabetic mice were optimized to increase over 30% similarity between in vitro cultured and fecal samples. Baicalein and acarbose alone and in combination, and their corresponding starch hydrolysate were assayed by the in vitro model. The results indicated that the combination of baicalein with acarbose decreased gas production by reducing the residual starch ratio in starch hydrolysate and decreasing the dosage of acarbose, and that reducing the relative abundance of gut bacteria correlated with gas production is the main mechanism. This study provided a theoretical foundation for the development of flavonoid dietary supplements to enhance the efficacy of oral hypoglycemic agents with fewer side effects and higher efficacy.

Can gallic acid potentiate the antihyperglycemic effect of acarbose and metformin? Evidence from streptozotocin-induced diabetic rat model

This study investigated the influence of dietary phenolic acid- Gallic acid (GA) on the antihyperglycemic properties of acarbose (ACA) and metformin (MET). Streptozotocin-induced diabetic rats were treated (p.o) with ACA, MET, GA and their combinations for 14 days. The effects of the treatments on blood glucose and insulin levels, pancreas α-amylase and intestinal α-glucosidase activities, as well as thiobarbituric acid reactive species (TBARS), thiol and reactive oxygen species (ROS) levels, including antioxidant enzyme activities were investigated. A significant increase in blood glucose, insulin, ROS and TBARS levels, and impaired antioxidant status, as well as elevation in the activities of α-amylase and α-glucosidase observed in diabetic rats were ameliorated in the treatment groups. Hpwever, GA had varying effects on the antidiabetic properties of the drugs. Nevertheless, GA showed more potentiating effects on the antidiabetic effect of MET and these effects were better observed at the lower dose of GA.

Synthesis and in vitro evaluation of chlorogenic acid amides as potential hypoglycemic agents and their synergistic effect with acarbose

Type 2 Diabetes mellitus is a chronic disease considered one of the most severe global health emergencies. Chlorogenic acid (1) has been shown to delay intestinal glucose absorption by inhibiting the activity of α-glucosidase (α-Glu) and α-amylase (α-Amy). In the present work, eleven chlorogenic acid amides have been synthesized and evaluated for their antioxidant properties (as DPPH and ORAC) and inhibition activity towards the two enzymes and, with the aim to obtain dual-action antidiabetic agents. The two most promising hypoglycemic compounds, bearing a tertiary amine function on an alkyl chain (8) and a benzothiazole scaffold (11), showed IC₅₀ values lower than that of (1) (45.5 µM α-Glu; 105.2 µM α-Amy). Amides 8 and 11 were by far more potent α-Glu inhibitors than the antidiabetic drug acarbose (IC₅₀ = 268.4 µM) and about twice less active toward α-Amy than acarbose (IC₅₀ = 34.4 µM). Kinetics experiments on amides 8 and 11 indicated these compounds as mixed-type inhibitors of α-Glu with K'_i values of 13.3 and 6.3 µM, respectively. The amylase inhibition occurred with a competitive mechanism in the presence of 8 (K_i = 79.7 µM) and with a mixed-type mechanism with 11 (K_i = 19.1 µM; K'_i = 93.6 µM). Molecular docking analyses supported these results, highlighting the presence of additional binding sites in both enzymes. Fluorescence experiments confirmed the grater affinity of amides 8 and 11 towards the two enzymes respect to (1). Moreover, a significant enhancement in acarbose efficacy was observed when inhibition assays were performed adding acarbose and amide 11. The above outcomes pinpointed the benzothiazole-based amide 11 as a promising candidate for further studies on type 2 diabetes treatment, both alone or combined with acarbose.

Inhibition Mechanism of α-Amylase/α-Glucosidase by Silibinin, Its Synergism with Acarbose, and the Effect of Milk Proteins

As a natural flavonolignan, silibinin is reported to possess multiple biological activities, while the inhibitory potential of silibinin on carbohydrate-hydrolyzing enzymes is still unclear. Therefore, in this study, the inhibitory effect and underlying mechanism of silibinin against α-amylase/α-glucosidase were investigated. The results indicated that silibinin showed a strong inhibitory efficiency against α-amylase/α-glucosidase in noncompetitive manners and exhibited synergistic inhibition against α-glucosidase with acarbose. However, interestingly, the inhibitory effect of silibinin was significantly hindered in various milk protein-rich environments, but this phenomenon disappeared after simulated gastrointestinal digestion of milk proteins in vitro. Furthermore, silibinin could combine with the inactive site of α-amylase/α-glucosidase and change the microenvironment and secondary structure of the enzymes, thereby influencing the catalytic efficiency of enzymes. This research suggested that silibinin could be used as a novel carbohydrate-hydrolyzing enzyme inhibitor, and milk beverages rich in silibinin had the potential for further application in antidiabetic dietary or medicine.

Synthesis and α-glucosidase inhibition studies of norfloxacin-acetanilide hybrids

α-Glucosidase inhibitors occupy a prominent position among the various treatments of type-2 diabetes mellitus (DM2). In this study, a series of new norfloxacin-acetanilide hybrid molecules were synthesized and screened for α-glucosidase inhibition activity. The synthetic methodology involves the synthesis of a series of α-bromoacetanilides by condensing bromoacetyl bromide with various substituted anilines. These α-bromoacetanilides were coupled with norfloxacin in DMF to get the titled hybrids. The structure elucidation of synthesized compounds were characterized by ¹H NMR, ¹³C NMR and LC-MS. Finally, the compounds were screened for their α-glucosidase inhibition activity using acarbose as a reference drug (IC₅₀ =58 μM). Among the tested compounds, 3i and 3j displayed potent α-glucosidase inhibition activity with IC₅₀ values of 7.81±0.038 and 5.55±0.012 μM respectively. In-addition, 3m, 3f and 3k were demonstrated moderate alpha-glucosidase inhibition activities with IC₅₀ values of 52.905±0.041, 23.79± 0.087 and 23.06±0.026 μM respectively. The structure-activity relationship was established with the help of molecular docking by using Molecular Operating Environment software (MOE 2014).

Potential for Gut Peptide-Based Therapy in Postprandial Hypotension

Postprandial hypotension (PPH) is an important and under-recognised disorder resulting from inadequate compensatory cardiovascular responses to meal-induced splanchnic blood pooling. Current approaches to management are suboptimal. Recent studies have established that the cardiovascular response to a meal is modulated profoundly by gastrointestinal factors, including the type and caloric content of ingested meals, rate of gastric emptying, and small intestinal transit and absorption of nutrients. The small intestine represents the major site of nutrient-gut interactions and associated neurohormonal responses, including secretion of glucagon-like peptide-1, glucose-dependent insulinotropic peptide and somatostatin, which exert pleotropic actions relevant to the postprandial haemodynamic profile. This review summarises knowledge relating to the role of these gut peptides in the cardiovascular response to a meal and their potential application to the management of PPH.

Personal Glucose Meter for α-Glucosidase Inhibitor Screening Based on the Hydrolysis of Maltose

As a key enzyme regulating postprandial blood glucose, α-Glucosidase is considered to be an effective target for the treatment of diabetes mellitus. In this study, a simple, rapid, and effective method for enzyme inhibitors screening assay was established based on α-glucosidase catalyzes reactions in a personal glucose meter (PGM). α-glucosidase catalyzes the hydrolysis of maltose to produce glucose, which triggers the reduction of ferricyanide (K₃[Fe(CN)₆]) to ferrocyanide (K₄[Fe(CN)₆]) and generates the PGM detectable signals. When the α-glucosidase inhibitor (such as acarbose) is added, the yield of glucose and the readout of PGM decreased accordingly. This method can achieve the direct determination of α-glucosidase activity by the PGM as simple as the blood glucose tests. Under the optimal experimental conditions, the developed method was applied to evaluate the inhibitory activity of thirty-four small-molecule compounds and eighteen medicinal plants extracts on α-glucosidase. The results exhibit that lithospermic acid (52.5 ± 3.0%) and protocatechualdehyde (36.8 ± 2.8%) have higher inhibitory activity than that of positive control acarbose (31.5 ± 2.5%) at the same final concentration of 5.0 mM. Besides, the lemon extract has a good inhibitory effect on α-glucosidase with a percentage of inhibition of 43.3 ± 3.5%. Finally, the binding sites and modes of four active small-molecule compounds to α-glucosidase were investigated by molecular docking analysis. These results indicate that the PGM method is feasible to screening inhibitors from natural products with simple and rapid operations.

Reusable Fluorescent Nanobiosensor Integrated in a Multiwell Plate for Screening and Quantification of Antidiabetic Drugs

A highly stable and reusable fluorescent multisample nanobiosensor for the detection of α-glucosidase inhibitors has been developed by coupling fluorescent liposomal nanoparticles based on conjugated polymers (L-CPNs) to the enzyme α-glucosidase, one of the main target enzymes in the treatment of type 2 diabetes. The mechanism of sensing is based on the fluorescence "turn-on" of L-CPNs by p-nitrophenol (PNP), the end product of the enzymatic hydrolysis of p-nitrophenyl-α-d-glucopyranoside. L-CPNs, composed of lipid vesicles coated with a blue-emitting cationic polyfluorene, were designed and characterized to obtain a good response to PNP. Two nanobiosensor configurations were developed in this study. In the first step, a single-sample nanobiosensor composed of L-CPNs and α-glucosidase entrapped in a sol-gel glass was developed in order to characterize and optimize the device. In the second part, the nanobiosensor was integrated and adapted to a multiwell microplate and the possibility of reusing it and performing multiple measurements simultaneously with samples containing different α-glucosidase inhibitors was investigated. Using super-resolution confocal microscopy, L-CPNs could be visualized within the sol-gel matrix, and the quenching of their fluorescence, induced by the substrate, was directly observed in situ. The device was also shown to be useful not only as a platform for screening of antidiabetic drugs but also for quantifying their presence. The latter application was successfully tested with the currently available drug, acarbose.

The role of GLP-1 in the postprandial effects of acarbose in type 2 diabetes

AIMS

The alpha-glucosidase inhibitor acarbose is believed to reduce plasma glucose by delaying hydrolysis of carbohydrates. Acarbose-induced transfer of carbohydrates to the distal parts of the intestine increases circulating glucagon-like peptide 1 (GLP-1). Using the GLP-1 receptor antagonist exendin(9-39)NH2, we investigated the effect of acarbose-induced GLP-1 secretion on postprandial glucose metabolism in patients with type 2 diabetes.

METHODS

In a double-blinded, placebo-controlled, randomized, crossover study, 15 participants with metformin-treated type 2 diabetes (age: 57-85 years, HbA1c: 40-74 mmol/mol) were subjected to two 14-day treatment periods with acarbose or placebo, respectively, separated by a 6-week wash-out period. At the end of each period, two randomized 4-h liquid mixed meal tests with concomitant infusion of exendin(9-39)NH2 and saline, respectively, were performed.

RESULTS

Compared to placebo, acarbose increased postprandial GLP-1 concentrations and decreased postprandial glucose. We observed no absolute difference in the exendin(9-39)NH2-induced increase in postprandial glucose excursions between placebo and acarbose periods, but relatively, postprandial glucose was increased by 119 ± 116% (mean ± s.d.) during exendin(9-39)NH2 infusion in the acarbose period vs a 39 ± 27% increase during the placebo period (P = 0.0163).

CONCLUSIONS

We confirm that acarbose treatment stimulates postprandial GLP-1 secretion in patients with type 2 diabetes. Using exendin(9-39)NH2, we did not see an impact of acarbose-induced GLP-1 secretion on absolute measures of postprandial glucose tolerance, but relatively, the effect of exendin(9-39)NH2 was most pronounced during acarbose treatment.

Sargassum fusiforme polysaccharide partly replaces acarbose against type 2 diabetes in rats

The objective of present research was to explore whether Sargassum fusiforme polysaccharide (SFP) could partly replace acarbose against type 2 diabetes in rats. Results indicated that SFP co-administered with low-dose acarbose intervention typically mitigated diabetic symptoms and serum profiles and exhibited better anti-diabetic effects than single acarbose treatment in controlling fasting blood glucose, improving insulin resistance and mitigating kidney injuries. The RT-qPCR analysis indicated that SFP co-administered with low-dose acarbose administration distinctly activated the IRS/PI3K/AKT signaling pathway compared with single acarbose treatment. Moreover, the co-administration also restrained liver fat accumulation via affecting the expression of HMGCR and SREBP-1c genes. In addition, the 16S rRNA gene sequencing analysis indicated that SFP co-administered with low-dose acarbose significantly restored beneficial composition of gut flora in diabetic rats, such as the increase of Muribaculaceae, Lachnospiraceae, Bifidobacterium, Ruminococcaceae_UCG-014, Ruminococcus_1, Romboutsia, Eggerthellaceae, Alistipes and Faecalibaculum, and the decrease of Escherichia-Shigella. These results suggested that SFP, the novel natural adjuvant of acarbose, displayed the desirable benefits in minimizing the dose of drug, while improving the anti-diabetic efficiency.

Hepatic and cardiovascular safety of acarbose among type 2 diabetes patients with end-stage renal disease: A nationwide population-based longitudinal study

AIM

To assess the relationship between acarbose and hepatotoxicity, cardiovascular disease (CVD), and mortality among type 2 diabetes (T2D) patients with end-stage renal disease (ESRD).

METHODS

32,531 T2D patients with ESRD were identified from Taiwan's National Health Insurance Research Database in 2000~∼2012 and followed up until 2013. 19.3% of subjects were newly initiated with acarbose during the follow-up. The use of acarbose was quantified as the numbers of the 30-day drug's supplies and dosages (measured by defined daily doses; DDDs), respectively. Time-varying Cox models were applied to evaluate the association of acarbose use with hepatic, cardiovascular and mortality outcomes, with adjustment for patients' demographics, comorbidities, diabetes severity, and co-medications.

RESULTS

For each 30-day supply increase in acarbose exposure, the risks of hepatic injury, composite CVD events, and all-cause mortality were significantly lowered by 9% (95% confidence interval: 6-12%), 7% (6-7%) and 7% (7-8%), respectively, while for each 30-day DDD increase in acarbose exposure, the risks for three aforementioned outcomes were significantly reduced by 45% (33-54%), 33% (29-36%) and 35% (32-39%), respectively. In subgroup analyses, the favorable study outcomes of acarbose use were more apparent among patients with more severe diabetes, a longer diabetes duration, or absence of established CVD at baseline.

CONCLUSION

Acarbose used in real-world T2D patients with ESRD may have hepatic and cardiovascular safety.

High-Fiber Diet or Combined With Acarbose Alleviates Heterogeneous Phenotypes of Polycystic Ovary Syndrome by Regulating Gut Microbiota

OBJECTIVE

Gut microbial dysbiosis is associated with high heterogeneity of polycystic ovary syndrome (PCOS); however, studies about gut microbiota targeted clinical intervention in PCOS are limited. Our study aimed to evaluate the effects of high-fiber diet or combined with acarbose on the clinical phenotypes of PCOS, focusing on the possible influence of gut microbiota in this process.

METHODS

Twenty-five patients with PCOS were recruited and randomly divided into two groups, W group (n = 14) received the WTP diet (a high-fiber diet composed of whole grains, traditional Chinese medicinal foods, and prebiotics), and A group (n = 11) received the WTP diet combined with acarbose. The follow-up time was 12 weeks. The sex hormonal and glycolipid metabolic parameters, inflammatory factors, brain-gut peptides, and alteration of gut microbiota were evaluated.

RESULTS

The PCOS clinical phenotypes, inflammatory state, and brain-gut peptides secretion were all alleviated in both groups, while the hyperandrogenism, insulin resistance, and brain-gut peptides secretion were better improved in the A group. Alpha and beta diversities were altered more significantly in the A group. Amplicon sequence variants (ASVs) were clustered into 14 co-abundant groups (CAGs) as potential functional groups that may respond to the intervention. The CAGs predominantly comprised of Bifidobacterium and Lactobacillus were more enriched, while the CAGs predominantly comprised of Bacteroides vulgatus, Alistipes, Blautia, Lachnospira, and Roseburia were more inhibited in the A group than in W group. Moreover, the CAGs enriched in the A group had a stronger negative correlation with the luteinizing hormone (LH)/follicle-stimulating hormone (FSH) ratio, testosterone, homeostasis model assessment-insulin resistance (HOMA-IR), α-1-acid glycoprotein (α-AGP), and leptin, and positive correlation with adiponectin and spexin, while the CAGs inhibited showed an opposite trend.

CONCLUSIONS

High-fiber diet could alleviate the chronic metabolic inflammation, reproductive function, and brain-gut peptides secretion of patients with PCOS, and high-fiber diet combined with acarbose could better improve the PCOS clinical phenotypes. The remodeling of gut microbiota by our intervention may play an important role in these improvements.

CLINICAL TRIAL REGISTRATION

http://www.chictr.org.cn/showproj.aspx?proj=4500, ChiCTR-TRC-14005075.

Extraction of Phenolics and Flavonoids from Four Hosta Species Using Reflux and Ultrasound-Assisted Methods with Antioxidant and α-Glucosidase Inhibitory Activities

The total phenolic and flavonoid contents (TPC and TFC) from the genus Hosta with antioxidant and α-glucosidase inhibitory activities were reported for the first time. Sixteen extracts from the aboveground and underground parts of the four Hosta species, including H. plantaginea, H. ventricosa, H. ensata, and H. albofarinosa, using reflux extraction (RE) and ultrasound-assisted extraction (UAE) techniques have high TPC and TFC with good antioxidant and α-glucosidase inhibitory activities. Furthermore, no significant differences on extraction yields, TPC, and TFC were found between RE and UAE techniques. Additionally, extracts from the aboveground parts of the four Hosta species had higher TPC, TFC, antioxidant, and α-glucosidase inhibitory activities compared to the underground parts by means of RE or UAE techniques. Lastly, the extracts of H. albo-marginata displayed a very remarkable α-glucosidase inhibitory activity compared to the positive control acarbose. The relationships of sixteen extracts of the four Hosta species were analyzed by RE and UAE techniques between extraction yields, TPC, TFC, antioxidant activity, and α-glucosidase inhibitory activity. The present study demonstrated that H. plantaginea, H. ventricosa, H. ensata, and H. albofarinosa could be new sources of natural antioxidants and antidiabetes for pharmaceutical and industrial purposes.

Identification of QTLs Controlling α-Glucosidase Inhibitory Activity in Pepper (Capsicum annuum L.) Leaf and Fruit Using Genotyping-by-Sequencing Analysis

Diabetes mellitus, a group of metabolic disorders characterized by hyperglycemia, is one of the most serious and common diseases around the world and is associated with major complications such as diabetic neuropathy, retinopathy, and cardiovascular diseases. A widely used treatment for non-insulin-dependent diabetes is α-glucosidase inhibitors (AGIs) such as acarbose, which hinders hydrolytic cleavage of disaccharides and retard glucose absorption. The ability to inhibit α-glucosidase activity has been reported in leaf and fruit of pepper (Capsicum annuum L.). In this study, we aimed to identify quantitative trait loci (QTLs) controlling α-glucosidase inhibitory activity (AGI activity) in pepper leaf and fruit using enzyme assay and genotyping-by-sequencing (GBS) analysis. The AGI activity at three stages of leaf and one stage of fruit development was analyzed by 96 F2 individuals. GBS analysis identified 17,427 SNPs that were subjected to pepper genetic linkage map construction. The map, consisting of 763 SNPs, contained 12 linkage groups with a total genetic distance of 2379 cM. QTL analysis revealed seven QTLs (qAGI1.1, qAGI11.1, qAGI5.1, qAGI9.1, qAGI12.1, qAGI5.2, and qAGI12.2) controlling AGI activity in pepper leaf and fruit. The QTLs for AGI activity varied by plant age and organ. This QTL information is expected to provide a significant contribution to developing pepper varieties with high AGI activity.

Combination Therapy of Acarbose and Cyclosporine a Ameliorates Imiquimod-Induced Psoriasis-Like Dermatitis in Mice

Moderate to severe psoriasis, an immune-mediated inflammatory disease, adversely affects patients' lives. Cyclosporin A (CsA), an effective immunomodulator, is used to treat psoriasis. CsA is ineffective at low doses and toxic at high doses. Acarbose (Acar), a common antidiabetic drug with anti-inflammatory and immunomodulatory effects, reduces imiquimod (IMQ)-induced psoriasis severity. Combinations of systemic drugs are generally more efficacious and safer than higher doses of single drugs. We observed that mice treated with a combination of Acar (250 mg/kg) and low-dose CsA (10 or 20 mg/kg) exhibited significantly milder IMQ-induced psoriasis-like dermatitis and smoother back skin than those treated with Acar (250 mg/kg), low-dose CsA (10 or 20 mg/kg), or IMQ alone. The combination therapy significantly reduced serum and skin levels of Th17-related cytokines (interleukin (IL)-17A, IL-22, and IL-23) and the Th1-related cytokine tumor necrosis factor-α (TNF-α) compared with Acar, low-dose CsA, and IMQ alone. Additionally, the combination therapy significantly reduced the percentages of IL-17- and IL-22-producing CD4⁺ T-cells (Th17 and Th22 cells, respectively) and increased that of Treg cells. Our data suggested that Acar and low-dose CsA in combination alleviates psoriatic skin lesions by inhibiting inflammation. The findings provide new insights into the effects of immunomodulatory drugs in psoriasis treatment.

Acarbose improved survival for Apc+/Min mice

Acarbose blocks the digestion of complex carbohydrates, and the NIA Intervention Testing Program (ITP) found that it improved survival when fed to mice. Yet, we do not know if lifespan extension was caused by its effect on metabolism with regard to the soma or cancer suppression. Cancer caused death for ~80% of ITP mice. The ITP found rapamycin, an inhibitor to the pro-growth mTORC1 (mechanistic target of rapamycin complex 1) pathway, improved survival and it suppressed tumors in Apc+/Min mice providing a plausible rationale to ask if acarbose had a similar effect. Apc+/Min is a mouse model prone to intestinal polyposis and a mimic of familial adenomatous polyposis in people. Polyp-associated anemia contributed to their death. To address this knowledge gap, we fed two doses of acarbose to Apc+/Min mice. Acarbose improved median survival at both doses. A cross-sectional analysis was performed next. At both doses, ACA fed mice exhibited reduced intestinal crypt depth, weight loss despite increased food consumption and reduced postprandial blood glucose and plasma insulin, indicative of improved insulin sensitivity. Dose-independent and dose-dependent compensatory liver responses were observed for AMPK and mTORC1 activities, respectively. Only mice fed the high dose diet exhibited reductions in tumor number with higher hematocrits. Because low-dose acarbose improved lifespan but failed to reduced tumors, its effects seem to be independent of cancer. These data implicate the importance of improved carbohydrate metabolism on survival.

Potential Antidiabetic Activity of Extracts and Isolated Compound from Adenosma bracteosum (Bonati)

Adenosma bracteosum Bonati. (A. bracteosum) has been used in traditional and modern medicine in Vietnam for curing hepatitis. In this study, ethanol and aqueous extracts of A. bracteosum were evaluated for their α-glucosidase inhibitory activities and anti-hyperglycemic effects on glucose loaded hyperglycemic and streptozotocin (STZ) induced diabetic mice. The α-glucosidase inhibition of the extracts was evaluated by colorimetric assays, and the anti-diabetic activity was tested on a STZ-induced diabetic mice model. The ethanol and aqueous extracts showed a significant α-glucosidase inhibitory activity, which was more effective than acarbose at the same concentration. In the STZ-induced diabetic mice, both extracts showed a strong anti-hyperglycemic activity, with the group receiving 50 mg/kg of ethanol extract and the group receiving 50 mg/kg of aqueous extract presenting 64.42% and 57.69% reductions, respectively, in the blood glucose levels when compared with the diabetic control group, on day 21 (p > 0.05). Isoscutellarein-8-O-β-D-glucopyranoside (IG) was identified from the ethanol extract, which showed a strong inhibitory activity against α-glucosidase, with a ten times higher potency compared with the positive control acarbose. The anti-hyperglycemic effect of IG was effectively similar to the standard drug, glibenclamide, at the same dose of 10 mg/kg (p > 0.05). These results indicated that A. bracteosum has a great antidiabetic potential.

Protective effects of acarbose against vascular endothelial dysfunction through inhibiting Nox4/NLRP3 inflammasome pathway in diabetic rats

The cardiovascular efficacy of glucose-lowering drugs is needed due to the cardiovascular complication in type 2 diabetes mellitus (T2DM). Acarbose is an α-glucosidase inhibitor that suppresses postprandial hyperglycemia, however, the cardiovascular protection of acarbose has still remained controversial. NLRP3 inflammasome activation mediated tight junction disruption, a hallmark event of endothelial barrier dysfunction leading to endothelial hyperpermeability in diabetes. Given the anti-inflammatory property of acarbose, it was investigated that acarbose protected against vascular endothelial barrier dysfunction through inhibiting NLRP3 inflammasome in vascular endothelial cells in T2DM rats. The rat aortic endothelial cells (RAECs) were incubated with high glucose (HG, 30 mM) for 24 h in vitro. It was found that HG significantly induced the formation and activation of NLRP3 inflammasome, which was markedly blocked by acarbose treatment. Furthermore, acarbose blocked the Nox4-dependent superoxide (O₂^.-) generation, which regulated NLRP3 inflammasome in RAECs. Importantly, we found that acarbose remarkably enhanced the junction protein expression of ZO-1 and VE-Cadherin and consequently abolished vascular hyperpermeability, which was associated with inhibiting NLRP3 inflammasome in RAECs. In vivo, acarbose intervention relieved vascular leakage in the heart of diabetic rats injected with Evans blue dye and the vasodilatory response to acetylcholine, which was accompanied with the restoration of ZO-1, VE-Cadherin, Nox4 and NLRP3 inflammasome in the aortal endothelium of diabetic rats. Taken together, our data indicated that acarbose ameliorated endothelial barrier dysfunction by directly inhibiting NLRP3 inflammasome which was dependent on inhibiting Nox4 oxidase-dependent O₂^.- production. These properties might carry a potential significance for acarbose in cardiovascular protection in diabetic patients.

Alpha-glucosidase inhibition and molecular docking studies of 1,2-benzothiazine 1,1-dioxide based carbohydrazides

Diabetes Mellitus is a chronic disease in which the infected cells do not have the ability to produce sufficient amount of insulin that resulted in the abnormality of carbohydrates metabolism and an increase in blood glucose level. Long time exposure to Diabetes Mellitus resulted in failure or dysfunction of different organs like kidneys, nerves, heart, eyes, etc. A common practice to cure diabetes is the use of α-glucosidase inhibitors which help in lowering the blood glucose level. We presented 1,2-benzothiazine 1,1-dioxide derivatives as novel and more potent α-glucosidase inhibitors via their in vitro and in silico screenings. Excellent enzyme inhibitions were observed for compounds 2, 8, 10 and 12 having IC₅₀ values of 6.91, 14.0, 4.2, 5.9 and 29.2μ respectively which were found better than the reference acarbose (IC₅₀=38.31μM). Molecular docking studies suggested high binding energies and good binding interactions of these compounds with the active site residues of the receptor protein. A good agreement was found between the results of both modes of evaluation. Moreover, the envisioned candidates have a good potential to treat diabetes.

Bifunctional Hybrid Enzyme-Catalytic Metal Organic Framework Reactors for α-Glucosidase Inhibitor Screening

The screening strategy based on α-glucosidase inhibition has been widely employed for the discovery of antidiabetic drugs, but it still faces some challenges in practical applications, such as poor stability of enzyme, high consumption of test compounds, low sensitivity of screening methods and so on. In this work, a bifunctional hybrid enzyme-catalytic metal organic framework reactor (GAA@GOx@Cu-MOF) with a flower-shaped globular structure was innovatively prepared via self-assembling of α-glucosidase (GAA), glucose oxidase (GOx), Cu²⁺, and 4,4'-bipyridine. It was found that GAA@GOx@Cu-MOF not only enjoyed merits of high stability, selectivity, and sensitivity but also possessed the character of assembly line work, with about 4.58 times enhanced enzyme activity compared with the free enzyme system. Based on the above characteristics, a highly sensitive screening of GAA inhibitors could be achieved with the detection limit of 7.05 nM for acarbose. Furthermore, the proposed method was successfully applied to the screening of oleanolic acid derivatives as potential antidiabetic drugs. Therefore, it was expected that this work could provide new insights and inspirations for the screening of clinical antidiabetic drugs and for further exploration of functional MOF composites.

Changes in the gut microbiome and fermentation products concurrent with enhanced longevity in acarbose-treated mice

BACKGROUND

Treatment with the α-glucosidase inhibitor acarbose increases median lifespan by approximately 20% in male mice and 5% in females. This longevity extension differs from dietary restriction based on a number of features, including the relatively small effects on weight and the sex-specificity of the lifespan effect. By inhibiting host digestion, acarbose increases the flux of starch to the lower digestive system, resulting in changes to the gut microbiota and their fermentation products. Given the documented health benefits of short-chain fatty acids (SCFAs), the dominant products of starch fermentation by gut bacteria, this secondary effect of acarbose could contribute to increased longevity in mice. To explore this hypothesis, we compared the fecal microbiome of mice treated with acarbose to control mice at three independent study sites.

RESULTS

Microbial communities and the concentrations of SCFAs in the feces of mice treated with acarbose were notably different from those of control mice. At all three study sites, the bloom of a single bacterial taxon was the most obvious response to acarbose treatment. The blooming populations were classified to the largely uncultured Bacteroidales family Muribaculaceae and were the same taxonomic unit at two of the three sites. Propionate concentrations in feces were consistently elevated in treated mice, while the concentrations of acetate and butyrate reflected a dependence on study site. Across all samples, Muribaculaceae abundance was strongly correlated with propionate and community composition was an important predictor of SCFA concentrations. Cox proportional hazards regression showed that the fecal concentrations of acetate, butyrate, and propionate were, together, predictive of mouse longevity even while controlling for sex, site, and acarbose.

CONCLUSION

We observed a correlation between fecal SCFAs and lifespan in mice, suggesting a role of the gut microbiota in the longevity-enhancing properties of acarbose. Treatment modulated the taxonomic composition and fermentation products of the gut microbiome, while the site-dependence of the responses illustrate the challenges facing reproducibility and interpretation in microbiome studies. These results motivate future studies exploring manipulation of the gut microbial community and its fermentation products for increased longevity, testing causal roles of SCFAs in the observed effects of acarbose.

The effects of acarbose on chemokine and cytokine production in human monocytic THP-1 cells

BACKGROUND AND OBJECTIVES

Chronic inflammation induced by proinflammatory cytokines and chemokines is postulated to be involved in insulin resistance and β-cell dysfunction in type 2 diabetes mellitus (T2DM). Acarbose, the α-glucosidase inhibitor, is an oral antidiabetic drug for T2DM. Acarbose suppresses inflammatory cytokine production in patients with T2DM, though the underlying mechanisms are unclear. In the present study, we aimed to investigate the anti-inflammatory effects and the exact mechanisms of acarbose in human monocytic THP-1 cells.

METHODS

THP-1 cells were pretreated with acarbose and then stimulated with lipopolysaccharide (LPS). The levels of Th1-related chemokines, including interferon-γ-inducible protein-10 (IP-10), monocyte chemoattractant protein-1 (MCP-1), Th2-related chemokine macrophage-derived chemokine (MDC), and proinflammatory cytokine tumor necrosis factor-α (TNF-α), were determined by enzyme-linked immunosorbent assay. Intracellular signaling pathways were explored by Western blot analysis and using a chromatin immunoprecipitation assay.

RESULTS

Acarbose suppressed the levels of IP-10, MCP-1, MDC, and TNF-α and downregulated phosphorylation of p38, c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK), and nuclear factor-kappa B-p65 (NF-κB-p65) in LPS-stimulated THP-1 cells. Acarbose suppressed LPS-induced acetylation of histones H3 (H3) and H4 in the IP-10 and MCP-1 promoter regions. These findings revealed the suppressive effects of acarbose on IP-10, MCP-1, MDC, and TNF-α production in THP-1 cells via, at least partially, the p38, JNK, ERK, and NF-κB-p65 pathways, as well as through epigenetic regulation via histone H3 and H4 acetylation.

CONCLUSION

Our study points to the therapeutic anti-inflammatory potential of acarbose.

Suppressive effect of ascophyllan HS on postprandial blood sugar level through the inhibition of α-glucosidase and stimulation of glucagon-like peptide-1 (GLP-1) secretion

A sulfated polysaccharide ascophyllan inhibited α-glucosidase in a concentration dependent manner, and >90% activity was inhibited at 1.0 mg/mL. The inhibitory activity was much higher than that of acarbose. No significant inhibitory effect of ascophyllan on α-amylase was observed up to 10.0 mg/mL. Ascophyllan HS, a commercially available ascophyllan preparation showed even higher inhibitory effect on α-glucosidase than ascophyllan. Interestingly, ascophyllan and ascophyllan HS induced the secretion of glucagon-like peptide-1 (GLP-1) from human intestinal NCI-H716 cell line in a concentration dependent manner (10-100 ng/mL). The oral glucose tolerance tests revealed that after continuous 8-week ingestion of ascophyllan HS at 100 mg/day, the glucose area under the curve values of the ascophyllan HS ingested group were significantly lower than placebo ingested group. Serum glycosylated hemoglobin (HbA1c) level in ascophyllan HS ingested group tended to decrease after 8-week ingestion, whereas no significant change was observed in placebo ingested group. This is the first report indicating that ascophyllan can induce the secretion of GLP-1 from human intestinal cell line (NCI-H716), besides the potent inhibitory effect on α-glucosidase. Furthermore, clinical trial suggested that ascophyllan HS may be a practically applicable blood glucose controlling agent in humans.