Acarbose. A preliminary review of its pharmacodynamic and pharmacokinetic properties, and therapeutic potential

Diabetes and Glucose Management in People on Hemodialysis

Diabetes is a major cause of end-stage kidney disease (ESKD). Glycemic management is challenging in this population, and A1C, commonly used for monitoring glycemic control, is unreliable. Continuous glucose monitoring indices can be used for glycemic monitoring in people with ESKD. Dipeptidyl peptidase 4 inhibitors, incretin mimetic agents (glucagon-like peptide 1 and glucose-dependent insulinotropic peptide receptor agonists), and insulin using an automated insulin delivery system are preferred to manage diabetes in people with ESKD on hemodialysis.

Exploring Thiazolidinedione-Naphthalene Analogues as Potential Antidiabetic Agents: Design, Synthesis, Molecular Docking and In-vitro Evaluation

Thiazolidinedione-naphthalene analogues were synthesized and evaluated for antidiabetic activity as Pancreatic α-Amylase (PAA) and intestinal α-glucosidase (IAG) inhibitors. The activity of the compounds (14a-g,17a-k) is compared with acarbose as the standard drug and all the compounds shows good to moderate antidiabetic activity. In-vitro PAA and IAG inhibition assay is performed for the all compounds, the compounds 17e shows superior PAA and IAG inhibitory activity with respective to standard (IC50 = 12.455 ± 0.04 μM and 9.145 ± 0. 01 μM). The molecular interaction with PAA and IAG protein was also studied with the help of molecular docking studies using AutoDock software. while SwissADME and Osiris property explorer tools computed in-silico drug likeliness and toxicity properties. The in-silico results confirmed the 17e molecule as a superior drug with high binding affinity and good drug likeness against PAA and IAG, confirming in-vitro results. We also studied antioxidant activity (AOA) of all synthesized compounds and results confined that the compound 14g and 17e has good antioxidant potential IC50 = 8.04 ± 0.02 μM and 6.36 ± 0.03 μM respectively among all compounds. In conclusion, in-vitro, in-silico antidiabetic and antioxidant studies revealed 17e compound was found to be potential compound.

A new bicyclo [3.3.1]nonadienemethanol-type lignan from the leaves of Taxus wallichiana Zucc

Following an α-glucosidase inhibitory activity-guided phytochemical study, a rare new bicyclo[3.3.1]nonadienemethanol-type lignan named 9,9'-oxidolanceolatanin B (1) and four known lignans, lanceolatanin B (2), pinoresinol (3), syringaresinol (4), and medioresinol (5), were isolated from a CHCl3-soluble fraction of Taxus wallichiana Zucc. leaves. The absolute configuration of 9,9'-oxidolanceolatanin B was elucidated based on NMR spectroscopic interpretation and ECD data. All isolated compounds 1-5 showed stronger α-glucosidase inhibitory potency than the positive control, acarbose. This data could support the conceit that Taxus wallichiana leaves could be a promising source for plant-based anti-diabetic drug discovery.

A systematic review, meta-analysis, dose-response, and meta-regression of the effects of acarbose intake on glycemic markers in adults

Purpose

Prior research has yielded mixed results regarding the impact of acarbose intake on glycemic markers. To provide a more comprehensive analysis, a systematic review and meta-analysis was performed to compile data from various randomized controlled trials (RCTs) examining the effects of acarbose intake on fasting blood sugar (FBS), insulin, hemoglobin A1C (HbA1c), and homeostasis model assessment of insulin resistance (HOMA-IR) in adults.

Methods

To identify relevant literature up to April 2023, a comprehensive search was conducted on various scholarly databases, including PubMed, Web of Science, and Scopus databases. The effect size of the studies was evaluated using a random-effects model to calculate the weighted mean differences (WMD) and 95% confidence intervals (CI). Heterogeneity between studies was assessed using Cochran's Q test and I2.

Results

This systematic review and meta-analysis included a total of 101 RCTs with a total of 107 effect sizes. The effect sizes for FBS in milligrams per deciliter (mg/dl), insulin in picomoles per liter (pmol/l), hemoglobin A1C (HbA1c) in percentage (%), and homeostasis model assessment of insulin resistance (HOMA-IR) were 92, 46, 80, and 22, respectively. The pooled analysis indicated that acarbose intake resulted in significant decreases in FBS (p = 0.018), insulin (p < 0.001), HbA1c (p < 0.001), and HOMA-IR (p < 0.001).

Conclusion

The findings of this systematic review and meta-analysis suggest that acarbose intake can potentially lead to significant improvements in glycemic parameters by decreasing the levels of FBS, HbA1c, and insulin. However, larger and more rigorously designed studies are still needed to further evaluate and strengthen this association.

Probing benzenesulfonamide-thiazolidinone hybrids as multitarget directed ligands for efficient control of type 2 diabetes mellitus through targeting the enzymes: α-glucosidase and carbonic anhydrase II

Diabetes mellitus is a chronic metabolic disorder characterized by improper expression/function of a number of key enzymes that can be regarded as targets for anti-diabetic drug design. Herein, we report the design, synthesis, and biological assessment of two series of thiazolidinone-based sulfonamides 4a-l and 5a-c as multitarget directed ligands (MTDLs) with potential anti-diabetic activity through targeting the enzymes: α-glucosidase and human carbonic anhydrase (hCA) II. The synthesized sulfonamides were evaluated for their inhibitory activity against α-glucosidase where most of the compounds showed good to potent activities. Compounds 4d and 4e showed potent inhibitory activities (IC50 = 0.440 and 0.3456 μM), comparable with that of the positive control (acarbose; IC50 = 0.420 μM). All the synthesized derivatives were also tested for their inhibitory activities against hCA I, II, IX, and XII. They exhibited different levels of inhibition against these isoforms. Compound 4d outstood as the most potent one against hCA II with Ki equals to 7.0 nM, more potent than the reference standard (acetazolamide; Ki = 12.0 nM). In silico studies for the most active compounds within the active sites of α-glucosidase and hCA II revealed good binding modes that can explain their biological activities. MM-GBSA refinements and molecular dynamic simulations were performed on the top-ranking docking pose of the most potent compound 4d to confirm the formation of stable complex with both targets. Compound 4d was screened for its in vivo antihyperglycemic efficacy by using the oral glucose tolerance test. Compound 4d decreased blood glucose level to 217 mg/dl, better than the standard acarbose (234 mg/dl). Hence, this revealed its synergistic mode of action on post prandial hyperglycemia and hepatic gluconeogenesis. Thus, these benzenesulfonamide thiazolidinone hybrids could be considered as promising multi-target candidates for the treatment of type II diabetes mellitus.

The antihyperglycemic potential of pyrazolobenzothiazine 1, 1-dioxide novel derivative in mice using integrated molecular pharmacological approach

Diabetes Mellitus is a metabolic disease characterized by elevated blood sugar levels caused by inadequate insulin production, which subsequently leads to hyperglycemia. This study was aimed to investigate the antidiabetic potential of pyrazolobenzothiazine derivatives in silico, in vitro, and in vivo. Molecular docking of pyrazolobenzothiazine derivatives was performed against α-glucosidase and α-amylase and compounds were selected based on docking score, bonding interactions and low root mean square deviation (RMSD). Enzyme inhibition assay against α-glucosidase and α-amylase was performed in vitro using p-nitrophenyl-α-D-glucopyranoside (PNPG) and starch substrate. Synthetic compound pyrazolobenzothiazine (S1) exhibited minimal conformational changes during the 100 ns MD simulation run. S1 also revealed effective IC50 values for α-glucosidase (3.91 µM) and α-amylase (8.89 µM) and an enzyme kinetic study showed low ki (- 0.186 µM, - 1.267 µM) and ki' (- 0.691 µM, - 1.78 µM) values with the competitive type of inhibition for both enzymes α-glucosidase and α-amylase, respectively. Moreover, studies were conducted to check the effect of the synthetic compound in a mouse model. A low necrosis rate was observed in the liver, kidney, and pancreas through histology analysis performed on mice. Compound S1 also exhibited a good biochemical profile with lower sugar level (110-115 mg/dL), increased insulin level (25-30 μM/L), and low level of cholesterol (85 mg/dL) and creatinine (0.6 mg/dL) in blood. The treated mice group also exhibited a low % of glycated haemoglobin (3%). This study concludes that S1 is a new antidiabetic-agent that helps lower blood glucose levels and minimizes the complications associated with type-II diabetes.

Pharmacological overview of hederagenin and its derivatives

Hederagenin is a pentacyclic triterpenoid isolated from plants and widely distributed in a variety of medicinal plants. By integrating and analyzing external related literature reports, the latest research progress on the pharmacological effects and structural modification of hederagenin was reviewed. Hederagenin has a wide range of pharmacological activities, including antitumor, anti-inflammatory, antidepressant, anti-neurodegenerative, antihyperlipidemic, antidiabetic, anti-leishmaniasis, and antiviral activities. Among them, it shows high potential in the field of anti-tumor treatment. This paper also reviews the structural modifications of hederagenin, including carboxyl group modifications and two hydroxyl group modifications. Future research on hederagenin will focus on prolonging its half-life, improving its bioavailability and structural modification to enhance its pharmacological activity, accelerating the preclinical research stage of hederagenin for it to enter the clinical research stage as soon as possible.

Theoretical Studies for the Discovery of Potential Sucrase-Isomaltase Inhibitors from Maize Silk Phytochemicals: An Approach to Treatment of Type 2 Diabetes

A theoretical analysis of the potential inhibition of human sucrase-isomaltase (SI) by flavonoids was carried out with the aim of identifying potential candidates for an alternative treatment of type 2 diabetes. Two compounds from maize silks, maysin and luteolin, were selected to be studied with the structure-based density functional theory (DFT), molecular docking (MDock), and molecular dynamics (MD) approaches. The docking score and MD simulations suggested that the compounds maysin and luteolin presented higher binding affinities in N-terminal sucrase-isomaltase (NtSI) than in C-terminal sucrase-isomaltase (CtSI). The reactivity parameters, such as chemical hardness (η) and chemical potential (µ), of the ligands, as well as of the active site amino acids of the NtSI, were calculated by the meta-GGA M06 functional in combination with the 6-31G(d) basis set. The lower value of chemical hardness calculated for the maysin molecule indicated that this might interact more easily with the active site of NtSI, in comparison with the values of the acarbose and luteolin structures. Additionally, a possible oxidative process was proposed through the quantum chemical calculations of the electronic charge transfer values (∆N) between the active site amino acids of the NtSI and the ligands. In addition, maysin displayed a higher ability to generate more oxidative damage in the NtSI active site. Our results suggest that maysin and luteolin can be used to develop novel α-glucosidase inhibitors via NtSI inhibition.

Inactivation of the antidiabetic drug acarbose by human intestinal microbial-mediated degradation

Drugs can be modified or degraded by the gut microbiota, which needs to be considered in personalized therapy. The clinical efficacy of the antidiabetic drug acarbose, an inhibitor of α-glucosidase, varies greatly among individuals for reasons that are largely unknown. Here we identify in the human gut acarbose-degrading bacteria, termed Klebsiella grimontii TD1, whose presence is associated with acarbose resistance in patients. Metagenomic analyses reveal that the abundance of K. grimontii TD1 is higher in patients with a weak response to acarbose and increases over time with acarbose treatment. In male diabetic mice, co-administration of K. grimontii TD1 reduces the hypoglycaemic effect of acarbose. Using induced transcriptome and protein profiling, we further identify an acarbose preferred glucosidase, Apg, in K. grimontii TD1, which can degrade acarbose into small molecules with loss of inhibitor function and is widely distributed in human intestinal microorganisms, especially in Klebsiella. Our results suggest that a comparatively large group of individuals could be at risk of acarbose resistance due to its degradation by intestinal bacteria, which may represent a clinically relevant example of non-antibiotic drug resistance.

Design, synthesis of new phenyl acetylene and isoxazole analogues of arjunolic acid as potent tyrosinase and alpha glucosidase inhibitors

A series of new phenyl acetylene and isoxazole analogues of arjunolic acid were designed, synthesized and evaluated (3-8) for their tyrosinase and alpha glucosidase inhibitory potential. All the tested analogues exhibited stronger inhibitory activity than the standard drug or parent compound. Of these, compound (7) displayed the most potent tyrosinase inhibitory action with IC₅₀ (14.3 ± 7.6) of about three folds more than the standard drug, kojic acid (41.5 ± 1.0). Further, compound (8) (14.5 ± 0.15) possessed the potent alpha glucosidase inhibitory action with IC₅₀ value comparable to that of standard, acarbose (10.4 ± 0.06). Henceforth, compounds (7) and (8) are promising candidates for further studies.

Novel studies on Drosophila melanogaster model reveal the roles of JNK-Jak/STAT axis and intestinal microbiota in insulin resistance

The JNK pathway play a critical role in insulin resistance induced by a long-term high-sugar diet. However, the roles of up- and downstream molecules of the JNK pathway in insulin resistance are less known in vertebrates and invertebrates. As a classical organism in biological research, Drosophila melanogaster (D. melanogaster) has been widely applied to the studies of mechanism of insulin resistance. Based on previous studies, we found a novel predictive mechanism of the formation of insulin resistance in D. melanogaster. We found that JNK activated by high-sugar diet and dysregulated intestinal microbiota could mediate inflammation, and then the activated JNK released Upd3, which in turn stimulated Jak/STAT pathway to release ImpL2. ImpL2 can compete with Drosophila insulin-like peptides (Dilps) for binding with the insulin receptor and inhibit the activation of insulin pathway. In this study, we reviewed novel studies on the insulin signalling pathway based on the D. melanogaster model. The findings support our hypothesis. We, therefore, described how a long-term high-sugar diet disrupts intestinal microbiota to induce inflammation and the disruption of JNK-Jak/STAT axis. This description may offer some new clues to the formation of insulin resistance.

Metabolites extracted from microorganisms as potential inhibitors of glycosidases (α-glucosidase and α-amylase): A review

α-Glucosidase and α-amylase are the two main glycosidases that participate in the metabolism of carbohydrates. Inhibitors of these two enzymes are considered an important medical treatment for carbohydrate uptake disorders, such as diabetes and obesity. Microbes are an important source of constituents that have the potential to inhibit glycosidases and can be used as sources of new drugs and dietary supplements. For example, the α-glucosidase inhibitor acarbose, isolated from Actinoplanes sp., has played an important role in adequately controlling type 2 diabetes, but this class of marketed drugs has many drawbacks, such as poor compliance with treatment and expense. This demonstrates the need for new microorganism-derived resources, as well as novel classes of drugs with better compliance, socioeconomic benefits, and safety. This review introduces the literature on microbial sources of α-glucosidase and α-amylase inhibitors, with a focus on endophytes and marine microorganisms, over the most recent 5 years. This paper also reviews the application of glycosidase inhibitors as drugs and dietary supplements. These studies will contribute to the future development of new microorganism-derived glycosidase inhibitors.

Metagenomic analysis reveals crosstalk between gut microbiota and glucose-lowering drugs targeting the gastrointestinal tract in Chinese patients with type 2 diabetes: a 6 month, two-arm randomised trial

AIMS/HYPOTHESIS

The use of oral glucose-lowering drugs, particularly those designed to target the gut ecosystem, is often observed in association with altered gut microbial composition or functional capacity in individuals with type 2 diabetes. The gut microbiota, in turn, plays crucial roles in the modulation of drug efficacy. We aimed to assess the impacts of acarbose and vildagliptin on human gut microbiota and the relationships between pre-treatment gut microbiota and therapeutic responses.

METHODS

This was a randomised, open-labelled, two-arm trial in treatment-naive type 2 diabetes patients conducted in Beijing between December 2016 and December 2017. One hundred participants with overweight/obesity and newly diagnosed type 2 diabetes were recruited from the Pinggu Hospital and randomly assigned to the acarbose (n=50) or vildagliptin (n=50) group using sealed envelopes. The treatment period was 6 months. Blood, faecal samples and visceral fat data from computed tomography images were collected before and after treatments to measure therapeutic outcomes and gut microbiota. Metagenomic datasets from a previous type 2 diabetes cohort receiving acarbose or glipizide for 3 months were downloaded and processed. Statistical analyses were applied to identify the treatment-related changes in clinical variables, gut microbiota and associations.

RESULTS

Ninety-two participants were analysed. After 6 months of acarbose (n=44) or vildagliptin (n=48) monotherapy, both groups achieved significant reductions in HbA_1c (from 60 to 46 mmol/mol [from 7.65% to 6.40%] in the acarbose group and from 59 to 44 mmol/mol [from 7.55% to 6.20%] in the vildagliptin group) and visceral fat areas (all adjusted p values for pre-post comparisons <0.05). Both arms showed drug-specific and shared changes in relative abundances of multiple gut microbial species and pathways, especially the common reductions in Bacteroidetes species. Three months and 6 months of acarbose-induced changes in microbial composition were highly similar in type 2 diabetes patients from the two independent studies. Vildagliptin treatment significantly enhanced fasting active glucagon-like peptide-1 (GLP-1) levels. Baseline gut microbiota, rather than baseline GLP-1 levels, were strongly associated with GLP-1 response to vildagliptin, and to a lesser extent with GLP-1 response to acarbose.

CONCLUSIONS/INTERPRETATION

This study reveals common microbial responses in type 2 diabetes patients treated with two glucose-lowering drugs targeting the gut differently and acceptable performance of baseline gut microbiota in classifying individuals with different GLP-1 responses to vildagliptin. Our findings highlight bidirectional interactions between gut microbiota and glucose-lowering drugs.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02999841 FUNDING: National Key Research and Development Project: 2016YFC1304901.

Design, synthesis and bioevaluation of new vanillin hybrid as multitarget inhibitor of α-glucosidase, α-amylase, PTP-1B and DPP4 for the treatment of type-II diabetes

Diabetes mellitus (DM) is a real challenge to the recent era and is one of the major diseases for initiating life-threatening disorders. In current research, a compound was designed by combining vanillin, thiazolidinedione and morpholine. The goal of our designed work is to demonstrate the ability of our design compound (9) to modulate more than one target responsible for hyperglycemia at the same time. The synthesized compound was able to show good to moderate inhibition potential against α-glucosidase, α-amylase and protein tyrosine phosphatase 1B. However, it exhibited excellent in-vitro inhibition of Dipeptidyl peptidase-4 (DPP-4) with IC₅₀ value of 0.09 µM. Antioxidant activity by using DPPH assay also showed its good antioxidant potential. In in-vivo experiments, the compound 9 was proved to be safe in experimental mice. The activity profile of the compound was observed for 21 days which showed that the compound was also effective in experimental mice. Binding orientations and Interactions with key amino acid residues of the selected targets were also studied by using docking studies. Overall, we were successful in synthesizing multitarget preclinical therapeutic by combining three pharmacophoric moieties into a single chemical entity that can modulate more than one target at the same time.

Inhibitory Effect of Ascorbic Acid on in vitro Enzymatic Digestion of Raw and Cooked Starches

Ascorbic acid, also known as vitamin C, was previously reported to inhibit the activity of pancreatic α-amylase, the primary digestive enzyme for starch. A major implication of such inhibition is a slowed rate of starch digestion into glucose, which thereby reduces postprandial hyperglycemia. The aim of this study was to explore the inhibitory effects of ascorbic acid at various concentrations on the in vitro digestion of high amylose maize starch (HAMS) and potato starch (PS) in both raw and cooked conditions. Resistant starch (RS) content, defined as the starch that remained after 4 h of simulated in vitro enzymatic digestion, was measured for the starch samples. Upon the addition of ascorbic acid, the RS contents increased in both raw and cooked starches. Cooking significantly reduced the RS contents as compared to raw starches, and less increase in RS was observed with the addition of ascorbic acid. The inhibitory effect of ascorbic acid on the digestion of raw starches showed a dose-dependent trend until it reached the maximum extent of inhibition. At the concentrations of 12.5 and 18.75 mg/mL, ascorbic acid exhibited the most potent inhibitory effect on the in vitro starch digestion in raw and cooked conditions, respectively. Overall, our results strongly indicate that ascorbic acid may function as a glycemic modulatory agent beyond other important functions, and its effects persist upon cooking with certain concentrations applied.

Essential moieties of myricetins, quercetins and catechins for binding and inhibitory activity against α-Glucosidase

α-Glucosidase inhibition of 11 flavonoids, including myricetins, quercetins and catechins were studied through initial reaction velocity, IC₅₀ value, inhibition kinetics, fluorescence quenching and molecular docking. It was found that C4 = O, C2 = C3, 3-OH and 5'-OH were essential moieties for α-glucosidase inhibition of myricetin that was shown with the highest inhibitory activity. The trans-conformational catechins was shown with stronger inhibition effects than the cis-conformational ones. Further, gallocatechin was an uncompetitive inhibitor, while myricetin, myricetrin, quercetin and catechin were competitive ones. 3-OH and 5'-OH promoted myricetin to bind with the enzyme active site through hydrogen bondings. The presence of C4 = O and C2 = C3 increased electron delocalization in ring A-C for myricetin and quercetin, and this enhanced stability of π-conjugations with aromatic residues of amino acids. However, 5'-OH decreased the quenching effects because it limited π-conjugations of ring B with key fluorescent residues. Notably, for same flavonoid sort, the constants that indicate binding affinity of flavonoids to α-glucosidase, including reciprocal of competitive inhibition constant, fluorescence quenching constant and binding energy followed same order as the inhibitory activity, indicating that α-glucosidase inhibition of the flavonoids resulted from binding interactions between them, and that the methods above can be combined reasonably to characterize flavonoid-enzyme binding interactions.

Diabetes medications as potential calorie restriction mimetics-a focus on the alpha-glucosidase inhibitor acarbose

The field of aging research has grown rapidly over the last half-century, with advancement of scientific technologies to interrogate mechanisms underlying the benefit of life-extending interventions like calorie restriction (CR). Coincident with this increase in knowledge has been the rise of obesity and type 2 diabetes (T2D), both associated with increased morbidity and mortality. Given the difficulty in practicing long-term CR, a search for compounds (CR mimetics) which could recapitulate the health and longevity benefits without requiring food intake reductions was proposed. Alpha-glucosidase inhibitors (AGIs) are compounds that function predominantly within the gastrointestinal tract to inhibit α-glucosidase and α-amylase enzymatic digestion of complex carbohydrates, delaying and decreasing monosaccharide uptake from the gut in the treatment of T2D. Acarbose, an AGI, has been shown in pre-clinical models to increase lifespan (greater longevity benefits in males), with decreased body weight gain independent of calorie intake reduction. The CR mimetic benefits of acarbose are further supported by clinical findings beyond T2D including the risk for other age-related diseases (e.g., cancer, cardiovascular). Open questions remain regarding the exclusivity of acarbose relative to other AGIs, potential off-target effects, and combination with other therapies for healthy aging and longevity extension. Given the promising results in pre-clinical models (even in the absence of T2D), a unique mechanism of action and multiple age-related reduced disease risks that have been reported with acarbose, support for clinical trials with acarbose focusing on aging-related outcomes and incorporating biological sex, age at treatment initiation, and T2D-dependence within the design is warranted.

Acarbose has sex-dependent and -independent effects on age-related physical function, cardiac health, and lipid biology

With an expanding aging population burdened with comorbidities, there is considerable interest in treatments that optimize health in later life. Acarbose (ACA), a drug used clinically to treat type 2 diabetes mellitus (T2DM), can extend mouse life span with greater effect in males than in females. Using a genetically heterogeneous mouse model, we tested the ability of ACA to ameliorate functional, pathological, and biochemical changes that occur during aging, and we determined which of the effects of age and drug were sex dependent. In both sexes, ACA prevented age-dependent loss of body mass, in addition to improving balance/coordination on an accelerating rotarod, rotarod endurance, and grip strength test. Age-related cardiac hypertrophy was seen only in male mice, and this male-specific aging effect was attenuated by ACA. ACA-sensitive cardiac changes were associated with reduced activation of cardiac growth-promoting pathways and increased abundance of peroxisomal proteins involved in lipid metabolism. ACA further ameliorated age-associated changes in cardiac lipid species, particularly lysophospholipids - changes that have previously been associated with aging, cardiac dysfunction, and cardiovascular disease in humans. In the liver, ACA had pronounced effects on lipid handling in both sexes, reducing hepatic lipidosis during aging and shifting the liver lipidome in adulthood, particularly favoring reduced triglyceride (TAG) accumulation. Our results demonstrate that ACA, already in clinical use for T2DM, has broad-ranging antiaging effects in multiple tissues, and it may have the potential to increase physical function and alter lipid biology to preserve or improve health at older ages.

Glycoside hydrolase stabilization of transition state charge: new directions for inhibitor design

Carbasugars are structural mimics of naturally occurring carbohydrates that can interact with and inhibit enzymes involved in carbohydrate processing. In particular, carbasugars have attracted attention as inhibitors of glycoside hydrolases (GHs) and as therapeutic leads in several disease areas. However, it is unclear how the carbasugars are recognized and processed by GHs. Here, we report the synthesis of three carbasugar isotopologues and provide a detailed transition state (TS) analysis for the formation of the initial GH-carbasugar covalent intermediate, as well as for hydrolysis of this intermediate, using a combination of experimentally measured kinetic isotope effects and hybrid QM/MM calculations. We find that the α-galactosidase from Thermotoga maritima effectively stabilizes TS charge development on a remote C5-allylic center acting in concert with the reacting carbasugar, and catalysis proceeds via an exploded, or loose, S_N2 transition state with no discrete enzyme-bound cationic intermediate. We conclude that, in complement to what we know about the TS structures of enzyme-natural substrate complexes, knowledge of the TS structures of enzymes reacting with non-natural carbasugar substrates shows that GHs can stabilize a wider range of positively charged TS structures than previously thought. Furthermore, this enhanced understanding will enable the design of new carbasugar GH transition state analogues to be used as, for example, chemical biology tools and pharmaceutical lead compounds.

Positive charge stabilized on remote C5-allylic center with catalysis occurring via a loose S_N2 transition state.

Isolation and characterization of an iridoid, Arbortristoside-C from Nyctanthes arbor-tristis Linn., a potential drug candidate for diabetes targeting α-glucosidase

Many parts of the plant Nyctanthes arbor-tristis Linn. are widely investigated for their biological properties. Purified Arbortristosides from seeds are reported as anticancer, anti-leishmania, anti-inflammatory, anti-allergic, immunomodulatory and antiviral. The present study elaborates on the isolation, structural and functional characterization of Arbortristoside-C and its inhibition properties against alpha-glucosidase, an important target for diabetes mellitus. Arbortristoside-C is purified from seeds of N. arbor-tristis by extraction using polar fractionation and chromatographic techniques. Arbortristoside-C has been characterized using Ultra Violet (UV), Mass (MS), Infra-Red (IR) and Nuclear Magnetic Resonance (NMR). Inhibition kinetics and Isothermal Titration Calorimetry (ITC) were used for activity and binding characteristics of acarbose and Arbortristoside-C using in-house purified α-glucosidase from Bos taurus. Modeling, docking and structural comparison with acarbose bound structure revealing the similar binding characteristics of Arbortristoside-C which include interaction with catalytic acid/base Aspartic acid residue. Cytotoxicity assay revealed that 100 µg/ml is the maximum toxic-free concentration of Arbortristoside-C. The purified Arbortristoside-C showed inhibition against mammalian α-glucosidase, suggesting its potential to treat Diabetes mellitus.

Isolation, identification, and inhibitory enzyme activity of phenolic substances present in Spirulina

Spirulina species are edible with high nutritional as well as potential therapeutic values. In this work, we show that phenolic extracts from Spirulina (p-Coumaric acid) possessed inhibitory potential on α-glucosidase (IC₅₀  = 1.67 ± 0.02 mM) and tyrosinase (IC₅₀  = 52.71 ± 3.01 mM). Moreover, p-Coumaric acid inhibited α-glucosidase and tyrosinase in a reversible mixed-type manner. Interestingly, molecular docking demonstrated that p-Coumaric acid penetrated in depth of the active-site of tyrosinase and α-glucosidase by the noncovalent force or interaction. Among them, making polar interactions with Cu²⁺ ions and the amino acid residue capable of forming cation-π significantly contribute to the strong binding of p-Coumaric acid on tyrosinase. p-Coumaric acid was isolated and identified from Spirulina for the first time, which can be used as a lead compound for the design of functional food additives and skin-lightening active ingredient in cosmetics, and pharmaceuticals against type 2 diabetes. PRACTICAL APPLICATIONS: A natural, food-derived compound possessing the potential for the development of an anti-hyperglycaemic and skin-lightening supplement is very promising in cosmetics, functional food, and pharmaceuticals against type 2 diabetes. Herein, the present study is the first to present high levels of p-Coumaric acid from Spirulina, which simultaneously possessed inhibition potential on α-glucosidase and tyrosinase. Importantly, we gained initial information about the polypeptide-inhibitor interactions and underlying mechanisms for Spirulina's therapeutic effects, which will provide the bases for developing new drugs for preventing or treating type 2 diabetes and enzyme inhibitors. Moreover, this work also demonstrates the potential of the extraction of high-value chemicals from Spirulina waste.

Rapid Determination of Acarbose in Tablets by 1H NMR Spectroscopy

Introduction:

Acarbose, an anti-diabetic drug, is commonly used to treat diabetes mellitus type 2. Determinationof acarbose is crucial for routine quality control of acarbose tablets.

Materials and Methods:

In this report, a rapid, stable and precise method was developed and validated for the quantification of acarbose in tablets by 1H NMR. Two characteristic signals at 5.80 and 2.31 ppm were used to determine acarbose. The assay was linear over a concentration range of 0.25-10.0 mg/mL. The precision was 0.26% and 1.02% for signals at 5.80 and 2.31 ppm, respectively. The average recoveries of acarbose were 99.7% and 99.2%, with RSD values 0.51% and 0.61% at two signals, respectively.

Results and Discussion:

The content of tested tablets was 100.4% and 100.8% of the label claim with RSD values 0.96% and 1.47% at two signals, which met the requirement of Chinese Pharmacopoeia criteria for content uniformity of tablets. The assay has been successfully applied to determine the content of acarbose in tablets for quality evaluation.

Conclusion:

This method has been successfully applied to determine the content of acarbose in tablets for quality evaluation.

Ethnobotany, ethnopharmacology, phytochemistry, biological activities and toxicity of Pistacia chinensis subsp. integerrima: A comprehensive review

Pistacia chinensis subsp. integerrima (J. L. Stewart ex Brandis) Rech. F. is a valuable medicinal plant used in south Asian communities for the treatment of asthma, diarrhea, diabetes, liver diseases, fever, pain and inflammation. This review critically evaluates the available information on P. integerrima's ethnobotany, ethnopharmacology, phytochemistry, pharmacology and toxicology. Electronic databases such as Google Scholar, PubMed, Springer Link, and so forth, books and theses were used to find relevant information about P. integerrima using keywords such as "Pistacia integerrima," "P. integerrima," "Ethnopharmacology," "Phytochemistry," "Traditional uses". A number of in vitro and in vivo pharmacological activities have been reported; however, the most promising and attractive activity observed was its role in Alzheimer, diabetes, convulsions, cancer, asthma, diabetes, diarrhea and as an immunomodulatory, analgesic and antiinflammatory. In addition, Pistagremic acid exerted anti-Alzheimer's activity based on a hitherto unknown mechanism through interference with the amyloidogenic pathway. Most of the pharmacological activities were linked with traditional uses. A range of compounds have been reported from P. integerrima extracts including triterpenes, volatile oils, flavonoids, fatty acids, phenolic, phytosterols, tannins and oligosaccharides as well as unknown triterpenes and flavonoids. Pistagremic acid, a novel triterpene, was attributed to most of the activities. in vivo toxicological studies in animal suggested a toxic dose of 1,500 mg kg^-1 , for its methanolic extract. All reported pharmacological activities were carried out in vitro and a gap in research, that is, preclinical and clinical investigation exists. Its outstanding activity as an antiglycating agent is the most promising and a so far unique activity and needs further evaluation. In-depth research and clinical trials on human subjects in order to investigate P. integerrima pharmacological activity, clinical efficacy and safety are crucial next steps.

The Sweet Taste of Acarbose and Maltotriose: Relative Detection and Underlying Mechanism

Although sweet-tasting saccharides possess similar molecular structures, their relative sweetness often varies to a considerable degree. Current understanding of saccharide structure/sweetness interrelationships is limited. Understanding how certain structural features of saccharides and/or saccharide analogs correlate to their relative sweetness can provide insight on the mechanisms underlying sweetness potency. Maltotriose is a short-chain glucose-based oligosaccharide, which we recently reported to elicit sweet taste. Acarbose, an α-glucosidase inhibitor, is a pseudo-saccharide that has an overall resemblance to a glucose-based oligosaccharide and thus may be viewed as a structural analog. During other studies, we recognized that acarbose can also elicit sweet taste. Here, we formally investigated the underlying taste detection mechanism of acarbose, while confirming our previous findings for maltotriose. We found that subjects could detect the sweet taste of acarbose and maltotriose in aqueous solutions but were not able to detect them in the presence of a sweet taste inhibitor lactisole. These findings support that both are ligands of the human sweet taste receptor, hT1R2/hT1R3. In a separate experiment, we measured the relative sweetness detection of acarbose, maltotriose, and other sweet-tasting mono- and disaccharides (glucose, fructose, maltose, and sucrose). Whereas maltotriose was found to have a similar discriminability profile to glucose and maltose, the discriminability of acarbose matched that of fructose at the concentrations tested (18, 32, and 56 mM). These findings are discussed in terms of how specific molecular features (e.g., degree of polymerization and monomer composition) may contribute to the relative sweetness of saccharides.

Synthesis of sandwich-structured magnetic graphene-Zn-MOFs composites for quantitative determination of acarbose in rat plasma

In this study, sandwich-structured magnetic graphene composites with Zn metal-organic framework layer coated on both two sides (denoted as magG@Zn-MOFs) were synthesized. The composites have large specific surface of 114 m² g⁻¹, uniform porous structure and rapid magnetic separation within 10 s. The magG@Zn-MOFs composites were used for extraction of acarbose in plasma prior to its quantitative analysis by LC-MS/MS. The established method has good linearity (10-1000 ng mL^-1), satisfactory recovery (94.3-107.5%), low detection limit (as low as 2.5 ng mL^-1), good intra-day precision (RSD 3.5-5.3%) and inter-day precision (RSD 6.3-8.1%). Finally, the method was successfully applied to pharmacokinetic study of acarbose in rats.

Different inhibition properties of catechins on the individual subunits of mucosal α-glucosidases as measured by partially-purified rat intestinal extract

Mucosal α-glucosidases from rat intestinal powder were employed, with a step to remove α-amylase, to measure the possibility of different inhibition of catechins, particularly those found in tea, on the four α-glucosidase enzymes.

Sargassum sagamianum Extract Alleviates Postprandial Hyperglycemia in Diabetic Mice

In this study, we investigated the postprandial hypoglycemic effect of Sargassum sagamianum extract (SSE) in streptozotocin-induced diabetic mice. Freeze-dried S. sagamianum was extracted with 80% ethanol and concentrated. The inhibition of postprandial hyperglycemia was determined by the inhibitory activity against α-glucosidase and α-amylase as well as the measurement of postprandial blood glucose levels. SSE demonstrated a high inhibitory activity against α-glucosidase and α-amylase. The IC50 value of SSE against α-glucosidase and α-amylase was 0.095 mg/mL and 0.199 mg/mL, respectively, and thus it was significantly more efficacious than the pharmaceutical acarbose (0.115 mg/mL and 0.229 mg/mL, respectively). The postprandial blood glucose levels in the SSE-administered group were significantly lower than those in the control group. Furthermore, the area under the curve significantly decreased following the administration of SSE. These results indicate that SSE can be used as an α-glucosidase and α-amylase inhibitor and can delay the absorption of dietary carbohydrates.

Sex-dependent Differences in Liver and Gut Metabolomic Profiles With Acarbose and Calorie Restriction in C57BL/6 Mice

Acarbose, an alpha-glucosidase inhibitor used in treating type 2 diabetes, impairs complex carbohydrate digestion and absorption and extends life span in mice (without a requisite reduction in food intake). To assess sex-differential effects coincident with calorie restriction versus a nonrestricted longevity enhancing intervention, we evaluated the metabolite profiles (by liquid chromatography-mass spectroscopy) from livers and cecal contents of C57BL/6J mice (n = 4/sex/group), which were maintained for 10 months under one of the three diet treatments: ad libitum control diet (CON), ad libitum control diet containing 0.1% acarbose (ACA), or 40% calorie restriction using the control diet (CR). Principal component analysis revealed sex-differential profiles with ACA in livers. Of the identified metabolites (n = 621) in liver, CR significantly altered ~44% (males:187↑/131↓, females:74↑/148↓) compared with CON, in contrast with ACA (M:165↑/61↓, F:52↑/60↓). Dissimilarity in ACA-F liver metabolites was observed for ~50% of common metabolites from ACA-M and CR-M/F. CR resulted in fewer significant cecal metabolite differences (n = 615 metabolites; M:86↑/66↓, F:51↑/48↓ vs CON), relative to ACA treatment (M:32↑/189↓, F:36↑/137↓). Metabolomic profiling identifies sex-differential and tissue-specific effects with amino acid metabolism sub-pathways including those involving tryptophan, branch-chain and sulfur amino acids, and the urea cycle, as well as bile acid, porphyrin, and cofactor metabolism pathways.

A phlorotannin constituent of Ecklonia cava alleviates postprandial hyperglycemia in diabetic mice

CONTEXT

2,7″-Phloroglucinol-6,6'-bieckol is a type of phlorotannin isolated from brown algae, Ecklonia cava Kjellman (Phaeophyceae; Laminareaceae). 2,7″-Phloroglucinol-6,6'-bieckol mediates antioxidant activities. However, there has been no research on improving postprandial hyperglycaemia using 2,7″-phloroglucinol-6,6'-bieckol.

OBJECTIVE

This study investigated the inhibitory effects of 2,7″-phloroglucinol-6,6'-bieckol on activities of α-glucosidase and α-amylase as well as its alleviating effect on postprandial hyperglycaemia in streptozotocin-induced diabetic mice.

MATERIALS AND METHODS

α-Glucosidase and α-amylase inhibitory assays were carried out. The effect of 2,7″-phloroglucinol-6,6'-bieckol on hyperglycaemia after a meal was measured by postprandial blood glucose in streptozotocin-induced diabetic and normal mice. The mice were treated orally with soluble starch (2 g/kg BW) alone (control) or with 2,7″-phloroglucinol-6,6'-bieckol (10 mg/kg bw) or acarbose (10 mg/kg BW) dissolved in 0.2 mL water. Blood samples were taken from tail veins at 0, 30, 60, and 120 min and blood glucose was measured by a glucometer.

RESULTS

2,7″-Phloroglucinol-6,6'-bieckol showed higher inhibitory activities than acarbose, a positive control against α-glucosidase and α-amylase. The IC50 values of 2,7″-phloroglucinol-6,6'-bieckol against α-glucosidase and α-amylase were 23.35 and 6.94 μM, respectively, which was found more effective than observed with acarbose (α-glucosidase IC50 of 130.04 μM; α-amylase IC50 of 165.12 μM). In normal mice, 2,7″-phloroglucinol-6,6'-bieckol significantly suppressed the postprandial hyperglycaemia caused by starch. The 2,7″-phloroglucinol-6,6'-bieckol administration group (2349.3 mmol·min/L) had a lower area under the curve (AUC) glucose response than the control group (2690.83 mmol·min/L) in diabetic mice.

DISCUSSION AND CONCLUSION

2,7″-Phloroglucinol-6,6'-bieckol might be used as an inhibitor of α-glucosidase and α-amylase as well as to delay absorption of dietary carbohydrates.

The α-glucosidase inhibitor voglibose stimulates delayed gastric emptying in healthy subjects: a crossover study with a 13C breath test

The gastrointestinal effects of α-glucosidase inhibitors have not been sufficiently investigated. The aim of this study was to determine whether a single dose of pre-prandial voglibose might affect the rate of gastric emptying, determined using the ¹³C breath test. Ten healthy male volunteers participated in this randomized, two-way crossover study. The subjects fasted overnight and received 0.2 mg voglibose or a placebo 2 h before a test meal. They were then served a liquid test meal consisting of 200 kcal per 200 ml that contained 100 mg ¹³C-acetate. Breath samples were collected under both conditions until 150 min after the meal. A comparison of the control and voglibose conditions revealed that for gastric emptying rates (with values expressed as median: range), T_1/2 [(87.9: 78.0–104.9 min) vs (88.4: 74.3–106.3 min), p = 1], T_lag [(47.1: 39.6–60.1 min) vs (45.4: 31.2–63.3 min), p = 0.432], β [(1.89: 1.68–2.18) vs (1.90: 1.35–2.15), p = 0.846] and κ [(0.81: 0.71–0.98) vs (0.81: 0.50–0.94), p = 0.922] did not significantly differ between conditions. A significant difference between the control and voglibose conditions was found for the GEC [(4.28: 4.09–4.44) vs (4.06: 3.69–4.50), p = 0.0138]. In conclusion, this study demonstrated that the ingestion of oral voglibose led to delayed gastric emptying of a liquid meal.

Bridging Type 2 Diabetes and Alzheimer's Disease: Assembling the Puzzle Pieces in the Quest for the Molecules With Therapeutic and Preventive Potential

Type 2 diabetes (T2D) and Alzheimer's disease (AD) are two age-related amyloid diseases that affect millions of people worldwide. Broadly supported by epidemiological data, the higher incidence of AD among type 2 diabetic patients led to the recognition of T2D as a tangible risk factor for the development of AD. Indeed, there is now growing evidence on brain structural and functional abnormalities arising from brain insulin resistance and deficiency, ultimately highlighting the need for new approaches capable of preventing the development of AD in type 2 diabetic patients. This review provides an update on overlapping pathophysiological mechanisms and pathways in T2D and AD, such as amyloidogenic events, oxidative stress, endothelial dysfunction, aberrant enzymatic activity, and even shared genetic background. These events will be presented as puzzle pieces put together, thus establishing potential therapeutic targets for drug discovery and development against T2D and diabetes-induced cognitive decline-a heavyweight contributor to the increasing incidence of dementia in developed countries. Hoping to pave the way in this direction, we will present some of the most promising and well-studied drug leads with potential against both pathologies, including their respective bioactivity reports, mechanisms of action, and structure-activity relationships.

Reappraisal and perspectives of clinical drug-drug interaction potential of α-glucosidase inhibitors such as acarbose, voglibose and miglitol in the treatment of type 2 diabetes mellitus

1. Amidst the new strategies being developed for the management of type 2 diabetes mellitus (T2DM) with both established and newer therapies, alpha glucosidase inhibitors (AGIs) have found a place in several treatment protocols. 2. The objectives of the review were: (a) to compile and evaluate the various clinical pharmacokinetic drug interaction data for AGIs such as acarbose, miglitol and voglibose; (b) provide perspectives on the drug interaction data since it encompasses coadministered drugs in several key areas of comorbidity with T2DM. 3. Critical evaluation of the interaction data suggested that the absorption and bioavailability of many coadministered drugs were not meaningfully affected from a clinical perspective. Therefore, on the basis of the current appraisal, none of the AGIs showed an alarming and/or overwhelming trend of interaction potential with several coadministered drugs. Hence, dosage adjustment is not warranted in the use of AGIs in T2DM patients in situations of comorbidity. 4. The newly evolving fixed dose combination strategies with AGIs need to be carefully evaluated to ensure that the absorption and bioavailability of the added drug are not impaired due to concomitant food ingestion.

Targeting glucose metabolism for healthy aging

Advancing age is the greatest single risk factor for numerous chronic diseases. Thus, the ability to target the aging process can facilitate improved healthspan and potentially lifespan. Lack of adequate glucoregulatory control remains a recurrent theme accompanying aging and chronic disease, while numerous longevity interventions result in maintenance of glucoregulatory control. In this review, we propose targeting glucose metabolism to enhance regulatory control as a means to ameliorate the aging process. We highlight that calorie restriction improves glucoregulatory control and extends both lifespan and healthspan in model organisms, but we also indicate more practical interventions (i.e., calorie restriction mimetics) are desirable for clinical application in humans. Of the calorie restriction mimetics being investigated, we focus on the type 2 diabetes drug acarbose, an α-glucosidase inhibitor that when taken with a meal, results in reduced enzymatic degradation and absorption of glucose from complex carbohydrates. We discuss alternatives to acarbose that yield similar physiologic effects and describe dietary sources (e.g., sweet potatoes, legumes, and berries) of bioactive compounds with α-glucosidase inhibitory activity. We indicate future research should include exploration of how non-caloric compounds like α-glucosidase inhibitors modify macronutrient metabolism prior to disease onset, which may guide nutritional/lifestyle interventions to support health and reduce age-related disease risk.

Humans Can Taste Glucose Oligomers Independent of the hT1R2/hT1R3 Sweet Taste Receptor

It is widely accepted that humans can taste mono- and disaccharides as sweet substances, but they cannot taste longer chain oligo- and polysaccharides. From the evolutionary standpoint, the ability to taste starch or its oligomeric hydrolysis products would be highly adaptive, given their nutritional value. Here, we report that humans can taste glucose oligomer preparations (average degree of polymerization 7 and 14) without any other sensorial cues. The same human subjects could not taste the corresponding glucose polymer preparation (average degree of polymerization 44). When the sweet taste receptor was blocked by lactisole, a known sweet inhibitor, subjects could not detect sweet substances (glucose, maltose, and sucralose), but they could still detect the glucose oligomers. This suggests that glucose oligomer detection is independent of the hT1R2/hT1R3 sweet taste receptor. Human subjects described the taste of glucose oligomers as "starchy," while they describe sugars as "sweet." The dose-response function of glucose oligomer was also found to be indistinguishable from that of glucose on a molar basis.

Glycogen phosphorylase inhibitors: a patent review (2013 - 2015)

INTRODUCTION

Control of glycemia is crucial in the treatment of type 2 diabetes complications. Glycogen phosphorylase (GP) releases glucose from the liver into the blood stream. Design of potent GP inhibitors is a therapeutic strategy in the context of type 2 diabetes.

AREAS COVERED

Glucose-based inhibitors have found potential applications since they now reach low nanomolar Ki values. Another set of patents disclose cholic acid/7-aza-indole conjugates for targeted drug delivery to the liver. A series of benzazepinones have also been reported as potent GP inhibitors. In vitro data are reported for GP inhibition but the in vivo biological data at the cellular or animal levels are often missing, even though the literature reported for these molecules is also discussed.

EXPERT OPINION

A structural analogy between glucose-based GP inhibitors and C-glucosides targeting sodium glucose co-transporter 2 (SGLT2) is intriguing. Cholic acid/7-aza-indole conjugates are promising in vivo drug delivery systems to the liver. Benzazepinones were very recently described and no associated literature is available, making it very difficult to comment at present. While industry has slowed down on GP inhibitors design, academic groups are pursuing investigations and have provided potential drug candidates which will resuscitate the interest for GP, including its potential for targeting cancer.

Acarbose: safe and effective for lowering postprandial hyperglycaemia and improving cardiovascular outcomes

α-Glucosidase inhibitors (AGIs) are a class of oral glucose-lowering drugs used exclusively for treatment or prevention of type 2 diabetes mellitus. AGIs act by altering the intestinal absorption of carbohydrates through inhibition of their conversion into simple sugars (monosaccharides) and thus decrease the bioavailability of carbohydrates in the body, significantly lowering blood glucose levels. The three AGIs used in clinical practice are acarbose, voglibose and miglitol. This review will focus on the cardiovascular properties of acarbose. The current available data suggest that AGIs (particularly acarbose) may be safe and effective for the treatment of prediabetes and diabetes.

Effect of acarbose on postprandial blood glucose concentrations in healthy cats fed low and high carbohydrate diets

OBJECTIVES

Feeding a low carbohydrate diet is recommended for diabetic cats; however, some cats may require diets containing moderate-to-high carbohydrate and may benefit from the use of therapeutic agents to improve glycemic control. The aim of the study was to determine the effect of the α-glucosidase inhibitor acarbose on postprandial plasma glucose concentration when combined with commercially available feline diets high and low in carbohydrate.

METHODS

Twelve healthy, adult, non-obese, neutered cats were enrolled. Plasma glucose concentrations were assessed over 24 h after feeding high and low carbohydrate diets, with and without acarbose, during single and multiple meal tests, in a crossover study. Commercially available feline diets were used, which were high and low in carbohydrate (providing 51% and 7% of metabolizable energy, respectively).

RESULTS

In cats fed the high carbohydrate diet as a single meal, mean 24 h glucose concentrations were lower when acarbose was administered. Mean glucose concentrations were lower in the first 12 h when acarbose was given once daily, whereas no significant difference was observed in mean results from 12-24 h. Acarbose had little effect in cats eating multiple meals. Compared with consumption of the high carbohydrate diet with acarbose, lower mean 24 h and peak glucose concentrations were achieved by feeding the low carbohydrate diet alone.

CONCLUSIONS AND RELEVANCE

In healthy cats meal-fed diets of similar composition to the diets used in this study, acarbose has minimal effect when a low carbohydrate diet is fed but reduces postprandial glucose concentrations over 24 h when a high carbohydrate diet is fed. However, mean glucose concentrations over 24 h are still higher when a high carbohydrate diet with acarbose is fed relative to the low carbohydrate diet without acarbose. Future studies in diabetic cats are warranted to confirm these findings.

Acarbose Monotherapy and Type 2 Diabetes Prevention in Eastern and Western Prediabetes: An Ethnicity-specific Meta-analysis

PURPOSE

Acarbose is effective in delaying or preventing the progression of prediabetes to type 2 diabetes mellitus (T2DM). The aim of this study was to assess differences in the preventive effects of acarbose in Eastern and Western populations with prediabetes.

METHODS

We performed a systematic search of databases and reference lists of clinical trials conducted through August 2013. Randomized controlled trials of acarbose alone, with a minimum intervention duration of 3 years and which provided data on T2DM incidence, were included for analysis. Analyses were conducted by using Review Manager version 5.1 software.

FINDINGS

Eight randomized controlled trials with 2628 participants were included. Acarbose decreased the occurrence of T2DM (number needed to treat [NNT], 6.7). Compared with the control (placebo and/or lifestyle intervention), the incidence of T2DM was significantly lower in the Eastern group (NNT, 5.9) than in the Western group (NNT, 11.1) (P < 0.0001, I(2) = 94.7%). At the end of follow-up, reversal of prediabetes to normal glucose tolerance was more likely in the Eastern group (NNT, 4.3) than in the Western group (NNT, 25) (P = 0.004, I(2) = 92%). Among those remaining prediabetic, there was no significant difference between the subtotal estimates for the subgroups (P = 0.17, I(2) = 46.5%). There was no positive correlation between preventive effect and dose, and no difference in studies with varying follow-up durations within and across either ethnic group.

IMPLICATIONS

The preventive effect of acarbose on the development of diabetes seems superior in Eastern populations with prediabetes compared with Western populations.

Food protein-derived bioactive peptides in management of type 2 diabetes

BACKGROUND

Type 2 diabetes (T2D), one of the major common human health problems, is growing at an alarming rate around the globe. Alpha-glucosidase and dipeptidyl peptidase IV (DPP-IV) enzymes play a significant role in development of T2D. Hence, reduction or inhibition of their activity can be one of the important strategies in management of T2D. Studies in the field of bioactive peptides have shown that dietary proteins could be natural source of alpha-glucosidase and DPP-IV inhibitory peptides.

PURPOSE

The purpose of this review is to provide an overview of food protein-derived peptides as potential inhibitors of alpha-glucosidase and DPP-IV with major focus on milk proteins.

METHODS

Efforts have been made to review the available information in literature on the relationship between food protein-derived peptides and T2D. This review summarizes the current data on alpha-glucosidase and dipeptidyl peptidase IV inhibitory bioactive peptides derived from proteins and examines the potential value of these peptides in the treatment and prevention of T2D. In addition, the proposed modes of inhibition of peptide inhibitors are also discussed.

RESULTS

Studies revealed that milk and other food proteins-derived bioactive peptides play a vital role in controlling T2D through several mechanisms, such as the satiety response, regulation of incretin hormones, insulinemia levels, and reducing the activity of carbohydrate degrading digestive enzymes.

CONCLUSIONS

The bioactive peptides could be used in prevention and management of T2D through functional foods or nutraceutical supplements. Further clinical trials are necessary to validate the findings of in vitro studies and to confirm the efficiency of these peptides for applications.

Management of glycemia in diabetic patients with stage IV and V chronic kidney disease

Diabetic kidney disease is a leading cause of end-stage kidney disease worldwide. Data suggest that prevention of progression to end-stage may lie in excellent blood glucose control; however, as kidney disease progresses, the risk of hypoglycemia increases, due to unpredictable insulin kinetics and altered pharmacokinetics of hypoglycemic agents. In addition, whole classes of hypoglycemic agents become contraindicated and regimens must be adjusted for declining kidney function. There is no consensus regarding the best therapy for the patient with advanced chronic kidney disease. In the best of circumstances, the care of these patients will involve intensive monitoring, with the input of a team of health care providers creating a coordinated care plan, including dietary advice and a drug regimen tailored to the specific issues faced by the individual patient. An open dialogue is necessary at all times, as patients may become frustrated and attempt self-treatment using over the counter alternatives.

Phlorofucofuroeckol A isolated from Ecklonia cava alleviates postprandial hyperglycemia in diabetic mice

This study was designed to investigate whether phlorofucofuroeckol A inhibited α-glucosidase and α-amylase activities and alleviated postprandial hyperglycemia in diabetic mice. Phlorofucofuroeckol A that was isolated from Ecklonia cava (brown algae) demonstrated prominent inhibitory effects against α-glucosidase and α-amylase activities. The IC50 values of phlorofucofuroeckol A against α-glucosidase and α-amylase were 19.52 and 6.34μM, respectively. These inhibitory activities of phlorofucofuroeckol A were higher than those of acarbose, which was used as a positive control. Increases in postprandial blood glucose levels were significantly more suppressed in the group administered phlorofucofuroeckol A compared to the control group in both diabetic and normal mice. Moreover, the area under the curve was significantly lower after phlorofucofuroeckol A administration (2296 versus 2690mmolmin/l) in the diabetic mice. These results suggested that phlorofucofuroeckol A is a potent α-glucosidase inhibitor and can alleviate the postprandial hyperglycemia that is caused by starch.