α-Glucosidase inhibitors boost gut immunity by inducing IgA responses in Peyer's patches.

Peyer's patches (PPs) are specialized gut-associated lymphoid tissues that initiate follicular helper T (Tfh)-mediated immunoglobulin A (IgA) response to luminal antigens derived from commensal symbionts, pathobionts, and dietary sources. IgA-producing B cells migrate from PPs to the small intestinal lamina propria and secrete IgA across the epithelium, modulating the ecological balance of the commensal microbiota and neutralizing pathogenic microorganisms. α-glucosidase inhibitors (α-GIs) are antidiabetic drugs that inhibit carbohydrate digestion in the small intestinal epithelium, leading to alterations in the commensal microbiota composition and metabolic activity. The commensal microbiota and IgA responses exhibit bidirectional interactions that modulate intestinal homeostasis and immunity. However, the effect of α-GIs on the intestinal IgA response remains unclear. We investigated whether α-GIs affect IgA responses by administering voglibose and acarbose to mice via drinking water. We analyzed Tfh cells, germinal center (GC) B cells, and IgA-producing B cells in PPs by flow cytometry. We also assessed pathogen-specific IgA responses. We discovered that voglibose and acarbose induced Tfh cells, GCB cells, and IgA-producing B cells in the PPs of the proximal small intestine in mice. This effect was attributed to the modification of the microbiota rather than a shortage of monosaccharides. Furthermore, voglibose enhanced secretory IgA (S-IgA) production against attenuated Salmonella Typhimurium. Our findings reveal a novel mechanism by which α-GIs augment antigen-specific IgA responses by stimulating Tfh-GCB responses in PPs, and suggest a potential therapeutic application as an adjuvant for augmenting mucosal vaccines.

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.

Inhibition mechanism of α-glucosidase inhibitors screened from Tartary buckwheat and synergistic effect with acarbose.

Tartary buckwheat has been shown to provide a good antihyperglycemic effect. However, it is unclear which active compounds play a key role in attenuating postprandial hyperglycemia. Presently, acetone extract from the hull of Tartary buckwheat had the best effect for α-glucosidase inhibition (IC50 = 0.02 mg/mL). Twelve potential α-glucosidase inhibitors from Tartary buckwheat were screened and identified by the combination of ultrafiltration and high-performance liquid chromatography coupled with mass spectrometry. Myricetin and quercetin exhibited the highest anti-α-glucosidase activity with IC50 values of 0.02 and 0.06 mg/mL, respectively. These inhibitors manifested different types of inhibition manners against α-glucosidase via direct interaction with the amino acid residues. The results of structure-activity relationships indicated that an increase in the number of -OH on the B-ring greatly strengthened α-glucosidase inhibitory activity, but glucoside and rutinoside replacement on the C-ring obviously weakened this influence. Furthermore, a synergistic effect was observed between inhibitors with different inhibition manners.

Acarbose, an α-Glucosidase Inhibitor, Maintains Altered Redox Homeostasis During Aging by Targeting Glucose Metabolism in Rat Erythrocytes.

Increasing age is the single largest risk factor for a variety of chronic illnesses. As a result, improving the capability to target the aging process leads to an increased health span. A lack of appropriate glucoregulatory control is a recurring issue associated with aging and chronic illness, even though many longevity therapies result in the preservation of glucoregulatory control. In this study, we suggest that targeting glucose metabolism to improve regulatory control can help slow the aging process. Male Wistar rats, both young (age 4 months) and old (age 24 months), were given acarbose (ACA) (30 mg/kg b.w.) for 6 weeks. An array of oxidative stress indicators was assessed after the treatment period, including plasma antioxidant capacity as determined by the ferric reducing ability of plasma (FRAP), reactive oxygen species (ROS), lipid peroxidation (malondialdehyde [MDA]), reduced glutathione (GSH), total plasma thiol (sulfhydryl [SH]), plasma membrane redox system (PMRS), protein carbonyl (PCO), advanced oxidation protein products (AOPPs), advanced glycation end products (AGEs), and sialic acid (SA) in control and treated groups. When compared with controls, ACA administration increased FRAP, GSH, SH, and PMRS activities in both age groups. The treated groups, on the contrary, showed substantial decreases in ROS, MDA, PCO, AOPP, AGE, and SA levels. The effect of ACA on almost all parameters was more evident in old-age rats. ACA significantly increased PMRS activity in young rats; here the effect was less prominent in old rats. Our data support the restoration of antioxidant levels in older rats after short-term ACA treatment. The findings corroborate the potential role of ACA as a putative calorie restriction mimetic.

Biochemical Characterization of GacI, a Bifunctional Glycosyltransferase-Phosphatase Enzyme Involved in Acarbose Biosynthesis in Streptomyces glaucescens GLA.O.

Acarbose, a pseudotetrasaccharide produced by several strains of Actinoplanes and Streptomyces, is an α-glucosidase inhibitor clinically used to control type II diabetes. Bioinformatic analysis of the biosynthetic gene clusters of acarbose in Actinoplanes sp. SE50/110 (the acb cluster) and Streptomyces glaucescens GLA.O (the gac cluster) revealed their distinct genetic organizations and presumably biosynthetic pathways. However, to date, only the acarbose pathway in the SE50/110 strain has been extensively studied. Here, we report that GacI, one of the proteins that appear to be different between the two pathways, is a bifunctional glycosyltransferase family 5 (GT5)-phosphatase (PP) enzyme that functions at two different steps in acarbose biosynthesis in S. glaucescens GLA.O. In the acb pathway, the GT and the PP reactions are performed by two different enzymes. Truncated GacI proteins having only the GT or the PP domain showed comparable catalytic activity with the full-length GacI, indicating that domain separation does not significantly affect their respective catalytic activity. GacI, which is widely distributed in many Streptomyces, represents the first example of naturally occurring GT5-PP bifunctional enzymes biochemically characterized.

Complete biosynthetic pathway to the antidiabetic drug acarbose.

Acarbose is a bacterial-derived α-glucosidase inhibitor clinically used to treat patients with type 2 diabetes. As type 2 diabetes is on the rise worldwide, the market demand for acarbose has also increased. Despite its significant therapeutic importance, how it is made in nature is not completely understood. Here, we report the complete biosynthetic pathway to acarbose and its structural components, GDP-valienol and O-4-amino-(4,6-dideoxy-α-D-glucopyranosyl)-(1→4)-O-α-D-glucopyranosyl-(1→4)-D-glucopyranose. GDP-valienol is derived from valienol 7-phosphate, catalyzed by three cyclitol modifying enzymes, whereas O-4-amino-(4,6-dideoxy-α-D-glucopyranosyl)-(1→4)-O-α-D-glucopyranosyl-(1→4)-D-glucopyranose is produced from dTDP-4-amino-4,6-dideoxy-D-glucose and maltose by the glycosyltransferase AcbI. The final assembly process is catalyzed by a pseudoglycosyltransferase enzyme, AcbS, which is a homologue of AcbI but catalyzes the formation of a non-glycosidic C-N bond. This study clarifies all previously unknown steps in acarbose biosynthesis and establishes a complete pathway to this high value pharmaceutical.

[Biosynthesis and regulatory mechanism of acarbose and its structural analogs: a review].

Acarbose is widely used as α-glucosidase inhibitor in the treatment of type Ⅱ diabetes. Actinoplanes sp. is used for industrial production of acarbose. As a secondary metabolite, the biosynthesis of acarbose is quite complex. In addition to acarbose, a few acarbose structural analogs are also accumulated in the culture broth of Actinoplanes sp., which are hard to remove. Due to lack of systemic understanding of the biosynthesis and regulation mechanisms of acarbose and its structural analogs, it is difficult to eliminate or reduce the biosynthesis of the structural analogs. Recently, the advances in omics technologies and molecular biology have facilitated the investigations of biosynthesis and regulatory mechanisms of acarbose and its structural analogs in Actinoplanes sp.. The genes involved in the biosynthesis of acarbose and its structural analogs and their regulatory mechanism have been extensively explored by using bioinformatics analysis, genetic manipulation and enzymatic characterization, which is summarized in this review.

The human microbiome encodes resistance to the antidiabetic drug acarbose.

The human microbiome encodes a large repertoire of biochemical enzymes and pathways, most of which remain uncharacterized. Here, using a metagenomics-based search strategy, we discovered that bacterial members of the human gut and oral microbiome encode enzymes that selectively phosphorylate a clinically used antidiabetic drug, acarbose1,2, resulting in its inactivation. Acarbose is an inhibitor of both human and bacterial α-glucosidases3, limiting the ability of the target organism to metabolize complex carbohydrates. Using biochemical assays, X-ray crystallography and metagenomic analyses, we show that microbiome-derived acarbose kinases are specific for acarbose, provide their harbouring organism with a protective advantage against the activity of acarbose, and are widespread in the microbiomes of western and non-western human populations. These results provide an example of widespread microbiome resistance to a non-antibiotic drug, and suggest that acarbose resistance has disseminated in the human microbiome as a defensive strategy against a potential endogenous producer of a closely related molecule.

Comparative study of inhibition mechanisms of structurally different flavonoid compounds on α-glucosidase and synergistic effect with acarbose.

Flavonoid compounds have anti-diabetic activity, which can control blood glucose levels by inhibiting α-glucosidase activity. In this paper, the inhibition mechanisms between four flavonoid compounds and α-glucosidase were studied by multispectroscopic methods and molecular docking. The results showed that the inhibitory activities of flavonoid compounds were higher than that of acarbose, and the sequence of inhibition effect was scutellarein > nepetin > apigenin > hispidulin > acarbose. Also, the synergistic effects of flavonoid compounds combined with acarbose on inhibiting α-glucosidase activity were observed. The fluorescence results showed that flavonoid compounds combined with α-glucosidase to form a stable complex. And the spectral analysis indicated that the microenvironmental and secondary structure of α-glucosidase were changed. The present study demonstrated that the molecular structure of flavonoid compounds played an important role in the inhibition process, namely, scutellarein with more hydroxyl groups on the A-ring might serve as the most effective α-glucosidase inhibitor.

Maltoheptaoside hydrolysis with chromatographic detection and starch hydrolysis with reducing sugar analysis: Comparison of assays allows assessment of the roles of direct α-amylase inhibition and starch complexation.

The aim was to determine inhibition of human α-amylase activity by (poly)phenols using maltoheptaoside as substrate with direct chromatographic product quantification, compared to hydrolysis of amylose and amylopectin estimated using 3,5-dinitrosalicylic acid. Acarbose exhibited similar IC50 values (50% inhibition) with maltoheptaoside, amylopectin or amylose as substrates (2.37 ± 0.11, 3.71 ± 0.12 and 2.08 ± 0.01 µM respectively). Epigallocatechin gallate, quercetagetin and punicalagin were weaker inhibitors of hydrolysis of maltoheptaoside (<50% inhibition) than amylose (IC50: epigallocatechin gallate = 20.41 ± 0.25 µM, quercetagetin = 30.15 ± 2.05 µM) or amylopectin. Interference using 3,5-dinitrosalicylic acid was in the order punicalagin > epigallocatechin gallate > quercetagetin, with minimal interference using maltoheptaoside as substrate. The main inhibition mechanism of epigallocatechin gallate and punicalagin was through complexation with starch, especially amylose, whereas only quercetagetin additionally binds to the α-amylase active site. Interference is minimised using maltoheptaoside as substrate with product detection by chromatography, potentially allowing assessment of direct enzyme inhibition by almost any compound.

Absence of the highly expressed small carbohydrate-binding protein Cgt improves the acarbose formation in Actinoplanes sp. SE50/110.

Actinoplanes sp. SE50/110 (ATCC 31044) is the wild type of industrial producer strains of acarbose. Acarbose has been used since the early 1990s as an inhibitor of intestinal human α-glucosidases in the medical treatment of type II diabetes mellitus. The small secreted protein Cgt, which consists of a single carbohydrate-binding module (CBM) 20-domain, was found to be highly expressed in Actinoplanes sp. SE50/110 in previous studies, but neither its function nor a possible role in the acarbose formation was explored, yet. Here, we demonstrated the starch-binding function of the Cgt protein in a binding assay. Transcription analysis showed that the cgt gene was strongly repressed in the presence of glucose or lactose. Due to this and its high abundance in the extracellular proteome of Actinoplanes, a functional role within the sugar metabolism or in the environmental stress protection was assumed. However, the gene deletion mutant ∆cgt, constructed by CRISPR/Cas9 technology, displayed no apparent phenotype in screening experiments testing for pH and osmolality stress, limited carbon source starch, and the excess of seven different sugars in liquid culture and further 97 carbon sources in the Omnilog Phenotypic Microarray System of Biolog. Therefore, a protective function as a surface protein or a function within the retainment and the utilization of carbon sources could not be experimentally validated. Remarkably, enhanced production of acarbose was determined yielding into 8-16% higher product titers when grown in maltose-containing medium.

A severe leakage of intermediates to shunt products in acarbose biosynthesis.

The α-glucosidase inhibitor acarbose, produced by Actinoplanes sp. SE50/110, is a well-known drug for the treatment of type 2 diabetes mellitus. However, the largely unexplored biosynthetic mechanism of this compound has impeded further titer improvement. Herein, we uncover that 1-epi-valienol and valienol, accumulated in the fermentation broth at a strikingly high molar ratio to acarbose, are shunt products that are not directly involved in acarbose biosynthesis. Additionally, we find that inefficient biosynthesis of the amino-deoxyhexose moiety plays a role in the formation of these shunt products. Therefore, strategies to minimize the flux to the shunt products and to maximize the supply of the amino-deoxyhexose moiety are implemented, which increase the acarbose titer by 1.2-fold to 7.4 g L-1. This work provides insights into the biosynthesis of the C7-cyclitol moiety and highlights the importance of assessing shunt product accumulation when seeking to improve the titer of microbial pharmaceutical products.

Evaluation of vector systems and promoters for overexpression of the acarbose biosynthesis gene acbC in Actinoplanes sp. SE50/110.

BACKGROUND: Actinoplanes sp. SE50/110 is a natural producer of acarbose. It has been extensively studied in the last decades, which has led to the comprehensive analysis of the whole genome, transcriptome and proteome. First genetic and microbial techniques have been successfully established allowing targeted genome editing by CRISPR/Cas9 and conjugal transfer. Still, a suitable system for the overexpression of singular genes does not exist for Actinoplanes sp. SE50/110. Here, we discuss, test and analyze different strategies by the example of the acarbose biosynthesis gene acbC. RESULTS: The integrative φC31-based vector pSET152 was chosen for the development of an expression system, as for the replicative pSG5-based vector pKC1139 unwanted vector integration by homologous recombination was observed. Since simple gene duplication by pSET152 integration under control of native promoters appeared to be insufficient for overexpression, a promoter screening experiment was carried out. We analyzed promoter strengths of five native and seven heterologous promoters using transcriptional fusion with the gusA gene and glucuronidase assays as well as reverse transcription quantitative PCR (RT-qPCR). Additionally, we mapped transcription starts and identified the promoter sequence motifs by 5'-RNAseq experiments. Promoters with medium to strong expression were included into the pSET152-system, leading to an overexpression of the acbC gene. AcbC catalyzes the first step of acarbose biosynthesis and connects primary to secondary metabolism. By overexpression, the acarbose formation was not enhanced, but slightly reduced in case of strongest overexpression. We assume either disturbance of substrate channeling or a negative feed-back inhibition by one of the intermediates, which accumulates in the acbC-overexpression mutant. According to LC-MS-analysis, we conclude, that this intermediate is valienol-7P. This points to a bottleneck in later steps of acarbose biosynthesis. CONCLUSION: Development of an overexpression system for Actinoplanes sp. SE50/110 is an important step for future metabolic engineering. This system will help altering transcript amounts of singular genes, that can be used to unclench metabolic bottlenecks and to redirect metabolic resources. Furthermore, an essential tool is provided, that can be transferred to other subspecies of Actinoplanes and industrially relevant derivatives.

Use of a deoxynojirimycin-fluorophore conjugate as a cell-specific imaging probe targeting α-glucosidase on cell membranes.

Molecules designed for cell-specific imaging were studied, taking advantage of an enzyme-inhibitor interaction. 1-Deoxynojirimycin (DNJ) can be actively captured by cells which express the surface membrane protein α-glucosidase. New probes composed of DNJ for recognition linked to a fluorophore signal portion were prepared (DNJ-CF31, DNJ-Dans 2 and DNJ-DEAC 3). Docking simulations revealed that the inhibitors acarbose and miglitol and the inhibitor portion of the probes bind at the same position in the pocket of α-glucosidase (human-derived PDB: 3TON). The ability of probes 1-3 to detect the difference between HeLa cells (from human cervical cancer tissue), Neuro-2a cells (from a mouse neuroblastoma C1300 tumor), N1E-115 cells (from a mouse brain neuroblastoma C1300 tumor), A1 cells (from the astrocyte of a newborn mouse brain), and Caco-2 cells (from a human colon carcinoma) was evaluated, and cell-specific fluorescence imaging was possible for conjugate probes 1 and 2. Caco-2 cells treated with probes 1 and 2 showed blue and green fluorescence, respectively, from the cell membrane, and did not stain the Caco-2 cells inside. These results show that DNJ-CF31 and DNJ-Dans 2 recognize an α-glucosidase protein on the surface of Caco-2 cells. Probes 1 and 2 did not stain any part of the other cells. This cell-specific imaging strategy is applicable for a variety of therapeutic agents for many diseases.

Peptidyl-prolyl isomerase-B is involved in Mycobacterium tuberculosis biofilm formation and a generic target for drug repurposing-based intervention.

Tuberculosis (TB), a disease caused by Mycobacterium tuberculosis (M.tb), takes one human life every 15 s globally. Disease relapse occurs due to incomplete clearance of the pathogen and reactivation of the antibiotic tolerant bacilli. M.tb, like other bacterial pathogens, creates an ecosystem of biofilm formed by several proteins including the cyclophilins. We show that the M.tb cyclophilin peptidyl-prolyl isomerase (PpiB), an essential gene, is involved in biofilm formation and tolerance to anti-mycobacterial drugs. We predicted interaction between PpiB and US FDA approved drugs (cyclosporine-A and acarbose) by in-silico docking studies and this was confirmed by surface plasmon resonance (SPR) spectroscopy. While all these drugs inhibited growth of Mycobacterium smegmatis (M.smegmatis) when cultured in vitro, acarbose and cyclosporine-A showed bacteriostatic effect while gallium nanoparticle (GaNP) exhibited bactericidal effect. Cyclosporine-A and GaNP additionally disrupted M.tb H37Rv biofilm formation. Co-culturing M.tb in their presence resulted in significant (2-4 fold) decrease in dosage of anti-tubercular drugs- isoniazid and ethambutol. Comparison of the cyclosporine-A and acarbose binding sites in PpiB homologues of other biofilm forming infectious pathogens revealed that these have largely remained unaltered across bacterial species. Targeting bacterial biofilms could be a generic strategy for intervention against bacterial pathogens.

A New Series of Salicylic Acid Derivatives as Non-saccharide α-Glucosidase Inhibitors and Antioxidants.

In this study, a series of salicylic acid derivatives were designed and synthesized as novel non-saccharide α-glucosidase inhibitors. Biological evaluation indicated that when compared to acarbose, compounds T9, T10, and T32 exhibited a higher potency of α-glucosidase inhibitory activity with IC50 values of 0.15 ± 0.01, 0.086 ± 0.01 and 0.32 ± 0.02 mM, respectively. Evaluation of the inhibition kinetics indicated that T9, T10, T32, and acarbose interacted with α-glucosidase in a mixed non-competitive inhibitory manner. Moreover, T9, T10, and T32 statically quenched the fluorescence of α-glucosidase by formation of an inhibitor-α-glucosidase complex. The docking results showed that hydrogen bonds were generated between the test compounds and α-glucosidase. The antioxidant study revealed that compound T10 exhibited a higher antioxidant activity via scavenging 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH), thereby inhibiting lipid peroxidation and the total reduction capacity. In brief, the salicylic acid derivatives identified in this study were promising candidates for development as novel non-saccharide α-glucosidase inhibitors.

Inhibitory effect of epigallocatechin-3-O-gallate on α-glucosidase and its hypoglycemic effect via targeting PI3K/AKT signaling pathway in L6 skeletal muscle cells.

Epigallocatechin-3-O-gallate (EGCG), a tea polyphenol is renowned for its anti-diabetic properties, however limited studies elucidate its hypoglycemic mechanism from multi-perspectives. In the present study, the interaction between EGCG and α-glucosidase was investigated through kinetics analysis, fluorescence spectra, Fourier transform infrared (FT-IR) spectra and molecular docking studies. Additionally, the effect of EGCG on glucose uptake and its related signaling pathway in L6 muscle cells were also investigated. The results showed that the α-glucosidase inhibitory activity of EGCG (IC50 = 19.5 ±â€¯0.3 µM) was higher than that acarbose (IC50 = 278.7 ±â€¯1.1 µM). EGCG inhibited α-glucosidase in a reversible and non-competitive manner. EGCG quenched the fluorescence of α-glucosidase due to the complex formation between EGCG and α-glucosidase, where the hydrogen bonds played a critical role. Microenvironment and the secondary structure of α-glucosidase were highly influenced by EGCG. Molecular docking results indicated that the binding sites on α-glucosidase for EGCG were close to the active site pocket of the enzyme. EGCG was also found to enhance the glucose uptake and promote GLUT4 translocation to plasma membrane via PI3K/AKT signaling pathway in L6 skeletal muscle cells. Overall, these results revealed the possible hypoglycemic mechanism of EGCG.

Taste of glucose elicits cephalic-phase insulin release in mice.

We reported previously that when C57BL/6 (B6) mice ingest glucose, plasma insulin levels rise above baseline before blood glucose levels do so. This observation led us to speculate that the taste of glucose elicits cephalic-phase insulin release (CPIR) in mice. Here, we examined the specific contributions of taste and glucose to CPIR. In Experiment 1, we bypassed the mouth and delivered glucose directly to the stomach. We found that plasma insulin levels did not rise above baseline until after blood glucose levels did so. This revealed that taste stimulation is necessary for rapid insulin release (i.e., CPIR) in mice. In Experiment 2, we examined the observation that sucrose, maltose and Polycose (a maltodextrin) all elicit CPIR. We proposed in a prior study that these carbohydrates did not directly elicit CPIR; instead, they were digested by oral amylases and alpha-glucosidases, and that it was the enzymatically liberated glucose that elicited CPIR. In support of this possibility, we reported that acarbose (an alpha-glucosidase inhibitor) prevented sucrose, maltose and Polycose from eliciting CPIR. Here, we sought to confirm that glucose alone could elicit CPIR in the presence of acarbose. Indeed, we found that glucose alone and glucose+acarbose each elicited equally robust CPIR. Taken together, these results provide further support for the hypothesis that mice possess a glucose-specific taste transduction pathway that triggers rapid insulin release.

Functional expression and enzymatic characterization of Lactobacillus plantarum cyclomaltodextrinase catalyzing novel acarbose hydrolysis.

Cyclomaltodextrinases (CDases) belong to Glycoside Hydrolases (GH) family 13, which show versatile hydrolyzing and/or transglycosylation activity against cyclodextrin (CD), starch, and pullulan. Especially, some CDases have been reported to hydrolyze acarbose, a potent α-glucosidase inhibitor, and transfer the resulting acarviosine-glucose to various acceptors. In this study, a novel CDase (LPCD) gene was cloned from Lactobacillus plantarum WCFS1, which encodes 574 amino acids (64.6 kDa) and shares less than 44% of identities with the known CDase-family enzymes. Recombinant LPCD with C-terminal six-histidines was produced and purified from Escherichia coli. It showed the highest activity on ß-CD at 45°C and pH 5.0, respectively. Gel permeation chromatography analysis revealed that LPCD exists as a dodecameric form (~826 kDa). Its hydrolyzing activity on ß- CD is almost same as that on starch, whereas it can hardly attack pullulan. Most interestingly, LPCD catalyzed the unique modes of action in acarbose hydrolysis to produce maltose and acarviosine, as well as to glucose and acarviosineglucose.

Dietary Carbohydrates Impair Healthspan and Promote Mortality.

The prospective cohort study, named PURE, found that in >135,000 participants from 18 countries, nutritive carbohydrates increase human mortality, whereas dietary fat reduces it, requesting a fundamental change of current nutritional guidelines. Experimental evidence from animal models provides synergizing mechanistic concepts as well as pharmacological options to mimic low-carb or ketogenic diets.