Carbohydrate Research Articles

Discovery of two novel Flavobacterium species with potential for complex polysaccharide degradation

Polysaccharides are recognized for their extensive biological functions, holding significant promise for applications in both medicine and food industries. However, their utilization is frequently constrained by challenges such as high molecular weights and indistinct sugar chain structures. Recently, two novel bacterial strains, N6T and J3T, were isolated from the Nakdong River in Korea. These strains, which belong to the phylum Bacteroidota, are Gram-stain-negative, non-motile, aerobic, rod-shaped bacteria and have shown polysaccharide-degrading capabilities. Through comprehensive analyses, including 16S rRNA gene sequencing, whole-genome sequencing, and detailed morphological, physiological, and chemotaxonomic characterizations, these strains have been identified as new species within the genus Flavobacterium. KEGG pathway analysis further confirmed their robust capabilities for carbohydrate utilization. Additional investigations using the dbCAN and dbCAN-PUL databases identified the presence of carbohydrate-hydrolyzing enzymes (CAZymes) and polysaccharide utilization loci (PULs) within these strains, suggesting their potential to degrade various polysaccharides. Subsequent in vitro growth experiments demonstrated that strains N6T and J3T can degrade chitin, β-glucan, κ-carrageenan, and cellulose. Given their diverse polysaccharide degradation abilities, these strains are formally proposed to be named Flavobacterium polysaccharolyticum sp. nov. and Flavobacterium aureirubrum sp. nov. The type strains are designated as N6T (= KCTC 102173T = GDMCC 1.4609T) and J3T (= KCTC 102172T = GDMCC 1.4608T), respectively.

Identification of retinol dehydrogenase 10 as a shared biomarker for metabolic dysfunction-associated steatotic liver disease and type 2 diabetes mellitus

BackgroundMetabolic dysfunction-associated steatotic liver disease (MASLD) is an independent risk factor for type 2 diabetes mellitus (T2DM), and its early identification and intervention offer opportunities for reversing diabetes mellitus.MethodsIn this study, we identified biomarkers for the MASLD dataset (GSE33814, GSE48452) and the T2DM dataset (GSE76895 and GSE89120) by bioinformatics analysis. Next, we constructed weighted gene co-expression network (WGCNA) for disease module analysis to screen out shared genes strongly associated with diseases. We also analyzed the enriched pathways of shared genes using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Next, hub gene validation was performed using the least absolute shrinkage and selection operator (LASSO) and receiver operating characteristic (ROC) curves. Finally, we used RT-qPCR, immunofluorescence, Western blotting and Elisa to validate hub gene expression in MASLD and T2DM mouse models.ResultsThis analysis identified 20 genes shared by MASLD and T2DM that were enriched in the bile secretion, phototransduction, cancer, carbohydrate digestion and absorption, cholesterol/glycerol metabolism, and retinol metabolism. The LASSO algorithm and ROC curve identified Retinol Dehydrogenase 10 (RDH10) as the best diagnostic gene for MASLD and T2DM. Immunofluorescence and Western blot showed that RDH10 expression was reduced in the liver and pancreatic islets of MASLD and T2DM model mice. Similarly, serum levels of RDH10 were significantly lower in MASLD and T2DM model mice and humans than in controls.ConclusionOur study suggests that RDH10 is a common diagnostic marker for MASLD and T2DM and provides new research directions for the prevention and treatment of MASLD and T2DM.

Effects of rumen-degradable starch on lactation performance, gastrointestinal fermentation, and plasma metabolomic in dairy cows.

This study investigated the effects of rumen-degradable starch (RDS) on lactation performance, gastrointestinal fermentation, and plasma metabolomics in dairy cows. Six mid-lactation cows, fitted with rumen, duodenum, and ileum cannulas, were used in a duplicated 3 × 3 Latin square design with 28-day periods. The cows were fed a low RDS (LRDS; 62.18 %), medium-RDS (MRDS; 71.25 %), or high-RDS (HRDS; 80.32 %) diet. The results showed that cows fed HRDS had diet a lower milk fat content by 14.77 % (LRDS) and 11.73 % (MRDS), while increased somatic cell count compared to the LRDS and MRDS groups (34.42 and 29.38 %, respectively). Additionally, rumen fluid pH was decreased in the HRDS group than in the MRDS and LRDS groups (7.81 and 7.08 %, respectively), while microbial protein (MCP) concentration was higher in the MRDS group. The HRDS group had lower concentrations of total volatile fatty acids (TVFA) and acetate in the ileal digesta than the LRDS group. The HRDS diet decreased neutral detergent fibre (NDF) digestibility compared with LRDS and MRDS groups (7.68 and 8.50 %, respectively), and reduced plasma concentrations of superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX), while increasing plasma lipopolysaccharide (LPS) and serum amyloid-A (SAA) levels. Pathway analysis revealed that starch and sucrose metabolism, galactose metabolism, and carbohydrate digestion and absorption were upregulated in the MRDS and HRDS groups. The HRDS diet had a tendency to negatively affect linoleic acid metabolism, glycerophospholipid metabolism, and alpha-linolenic acid metabolism. These findings provide insights into optimising feed efficiency and milk quality by regulating RDS levels in dairy cow diets.

Characterization of a 4'-O-rhamnosyltransferase and de novo biosynthesis of bioactive steroidal triglycosides from Paris polyphylla.

Steroidal saponins in Paris polyphylla featuring complicated sugar chains exhibit notable biological activities, but the sugar chain biosynthesis is still not fully understood. Here, we identified a 4'-O-rhamnosyltransferase (UGT73DY2) from P. polyphylla, which catalyzes the 4'-O-rhamnosylation of polyphyllins V and VI, producing dioscin and pennogenin 3-O-β-chacotrioside, respectively. UGT73DY2 exhibits strict substrate specificity towards steroidal diglycosides and UDP-Rha, and a new steroidal triglycoside was synthesized through enzyme catalysis. A mutation library was generated based on semi-rational design, identifying three mutants, I358T, A342V, and A132T, which displayed approximately two-fold enhanced enzyme activity. Molecular dynamics simulations revealed that shortened distances between the 4'-OH group of sugar acceptor and either the crucial residue H20 or the donor UDP-Rha contributed to the enhanced enzyme activity. Moreover, subcellular localization analysis of UGT73DY2 and other biosynthetic enzymes indicated that dioscin biosynthesis predominantly occurred in the endoplasmic reticulum of plant cells. By co-expressing 14 biosynthetic genes in Nicotiana benthamiana, optimizing HMGR subcellular localization and CYP450 gene sets, and engineering UGT73DY2, we successfully established a dioscin biosynthesis system with a yield of 3.12 ± 0.11 μg/g dry weight. This study not only uncovers the 4'-O-rhamnosylation process in steroidal saponin biosynthesis, but also presents an alternative approach for the production of steroidal saponins in P. polyphylla through synthetic biology and metabolic engineering.

Dietary inclusion of high Amylose cornstarch increased Lactobacillus and Terrisporobacter and decreased Streptococcus in the cecal digesta of weanling pigs.

The study investigated the effect of dietary inclusion of high amylose cornstarch (HA-starch) on cecal microbiota composition and volatile fatty acid (VFA) concentrations in weanling pigs fed high levels of cold-pressed canola cake (CPCC). Weaned pigs (240 mixed sex; 7.1 ± 1.2kg) were housed in 40 pens (6 pigs/pen) and fed a common commercial diet for 7 days, followed by the experimental diets for 28-d, which contained either 0% or 40% CPCC with either 0% or 40% HA-starch. At the end of the study, one pig from each pen (n=8) was selected and euthanized to collect cecal digesta for microbial and VFA composition analyses. The HA-starch increased (p < 0.001) acetate, propionate, and butyrate concentrations, thereby increasing total VFA concentration (p < 0.001). There was a tendency for cecal butyrate and total VFA concentrations to decrease when pigs were fed the 40% CPCC diet without HA-starch but increase when fed the 40% CPCC diet containing 40% HA-starch (CPCC × HA-starch effect; p = 0.09), indicating HA-starch can increase cecal butyrate and total VFA concentrations in pigs fed a diet with high CPCC level. The proportions of Lactobacillus and Terrisporobacter were high, whereas low proportions of Streptococcus genus were observed in the cecal microbiota of pigs fed diets containing 40% HA-starch. Also, pathways consistent with carbohydrate digestion, absorption, and phosphate metabolism were enriched in pigs when the diet included 40% HA-starch. In summary, incorporating high amounts of HA-starch in a weanling pig diet containing high levels of CPCC may benefit intestinal health and digestive performance by enhancing the abundance of probiotic commensal bacteria, contributing to increased enzymatic activity and carbohydrate metabolism.

Structural characterization and anti-weightless bone loss activity of an anionic polysaccharide from Dictyophora indusiata.

This study explores the extraction and purification of polysaccharides from Dictyophora indusiata (D. indusiata) with its antioxidant and anti-weightlessness bone loss properties. An anionic polysaccharide (SADIP) with a molecular weight of 13.42 kDa was isolated and purified from D. indusiata. SADIP consists of a glucose-based sugar chain backbone. Its backbone consists of glycosidic linkages of →4)-α-D-Glcp-(1 → and →4)-β-D-Glcp-(1→, with sulfate groups attached at the O-6 position of →4)-β-D-Glcp-(1 → residues. Side chains were α-D-Glcp-(1 → 6)-α-D-Glcp-(1 → linked at C-6 position of →4,6)-α-D-Glcp-(1 → through O-6 bonds. In vitro, SADIP scavenged up to 99.32 ± 0.24 % of 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS) radicals and 76.72 ± 0.34 % of hydroxyl radicals. In vivo, SADIP reduced malondialdehyde (MDA) levels induced by weightlessness and increased low levels of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) caused by weightlessness. Additionally, three-point mechanical bending tests and Micro-CT analysis demonstrated that SADIP has ability to alleviate bone loss induced by weightlessness. This study provides a theoretical foundation for the rational developmation of D. indusiata resources.

Phytochemical investigation and evaluation of antioxidant and antidiabetic activities in aqueous extracts of Cedrus atlantica

Abstract Diabetes mellitus is a global health problem requiring innovative approaches for effective management. Natural compounds derived from medicinal plants offer promising avenues due to their diverse biological activities. The aim of this study was to assess the inhibitory effects of Cedrus atlantica extracts on the enzymes α-amylase and α-glucosidase, which play a crucial role in the regulation of postprandial glucose levels, as well as to investigate their phytochemical composition and antioxidant capabilities. Aqueous extract of bark (EA), aqueous extract of cones (CA), and aqueous extract of leaves (FA) of C. atlántica were prepared and evaluated for enzyme inhibition using acarbose as a standard. The CA extract showed potent α-amylase inhibition (IC50 307 ± 0.02 μg/mL) and remarkable α-glucosidase inhibition (IC50 70 ± 0.04 μg/mL), outperforming the FA and EA extracts. Quantitative analysis revealed that EA and CA extracts had higher total phenolic content, flavonoid content, and tannin content than FA extract. Antioxidant assessments highlighted the outstanding performance of CA extract, with a low IC50 ABTS (30.65 ± 0.1 μg/mL) and an impressive EC50 FRAP (59.43 ± 1.19 μg/mL), outperforming FA extract. The results demonstrate the remarkable antidiabetic potential of C. atlantica extracts, particularly the CA extract, by inhibiting key enzymes involved in carbohydrate digestion. These extracts possess various phytochemical compounds with significant antioxidant capacities, suggesting that they are suitable for pharmaceutical, nutraceutical, and cosmetic applications. Further research to isolate and identify the bioactive compounds in CA extract could lead to new therapeutic strategies for managing diabetes and oxidative stress-related conditions.

Ecological and Functional Changes in the Hindgut Microbiome of Holstein Cows at High Altitudes.

The extreme environmental conditions of the Qinhai-Tibetan Plateau (QTP) challenge livestock survival and productivity, yet little is known about how high-altitude environments impact the gut microbiota of dairy cows. To fill this gap, we systematically investigated the differences in the hindgut microbiome between 87 plateau Holstein cows and 72 plain Holstein cows using 16S rRNA gene sequencing. Our analysis revealed that the hindgut microbiota of the plateau group exhibited lower species richness but higher evenness than that in the plain group. Additionally, significant separation in hindgut microbiota composition between the two groups was observed based on altitude, while parity, days in milk, and age did not show a comparable impact. Moreover, altitude had a lasting impact on bacterial communities and their co-occurrence networks, resulting in reduced microbial interactions and lower modularity in the plateau group. Furthermore, we identified four key microbial taxa, the Bacteroidaceae and Rikenellaceae families, as well as the Prevotella and Treponema genera, which were associated with the regulation of carbohydrate digestion and energy metabolism and might help the Holstein cows adapt to the plateau environment. Our findings provide insights into strategies for enhancing the adaptability of dairy cows to high-altitude environments through microbiota modulation, which could ultimately contribute to improving livestock management and sustainability in these extreme environments.

Kifunensine-sensitive ADP-ribosylation factor A1EG69R mutant revealed coordination of protein glycosylation and vesicle transport pathways.

Complex N-glycans are asparagine (N)-linked branched sugar chains attached to secretory proteins in eukaryotes. They are produced by modification of N-linked oligosaccharide structures in the endoplasmic reticulum (ER) and Golgi apparatus. Complex N-glycans formed in the Golgi apparatus are often assigned specific roles unique to the host organism, with their roles in plants remaining largely unknown. Using inhibitor (kifunensine, KIF)-hypersensitivity as read-out, we identified Arabidopsis mutants that require complex N-glycan modification. Among over 100 KIF-sensitive mutants, one showing abnormal secretory organelles and a salt-sensitive phenotype contained a point mutation leading to amino-acid replacement (G69R) in ARFA1E, a small Arf1-GTPase family protein presumably involved in vesicular transport. In-vitro assays showed that the G69R exchange interferes with protein activation. In vivo, ARFA1EG69R caused dominant-negative effects, altering the morphology of the ER, Golgi apparatus, and trans-Golgi network (TGN). Post-Golgi transports (endocytosis/endocytic recycling) of essential glycoprotein KORRIGAN1, one of KIF-sensitivity targets, is slowed down constitutively as well as under salt stress in ARFA1EG69R mutant. Because regulated cycling of plasma membrane proteins is required for stress tolerance of the host plants, ARFA1EG69R mutant established a link between KIF-targeted luminal glycoprotein functions/dynamics and cytosolic regulators of vesicle transport in endosome-/cell wall-associated tolerance mechanisms.

Substituted piperazine conjugated to quinoline-thiosemicarbazide as potent α-glucosidase inhibitors to target hyperglycemia

Diabetes mellitus, particularly type 2 diabetes, is a growing global health challenge characterized by chronic hyperglycemia due to insulin resistance. One therapeutic approach to managing this condition is the inhibition of α-glucosidase, an enzyme involved in carbohydrate digestion, to reduce postprandial blood glucose levels. In this study, a series of thiosemicarbazide-linked quinoline-piperazine derivatives were synthesized and evaluated for their α-glucosidase inhibitory activity, to identify new agents for type 2 diabetes management. Structure-activity relationship (SAR) analysis revealed that the nature and position of substituents on the aryl ring significantly impacted the inhibitory potency. Among the synthesized derivatives, the 2,5-dimethoxy phenyl substitution (7j) exhibited the most potent activity with an IC50 value of 50.0 µM, demonstrating a 15-fold improvement compared to the standard drug acarbose. Kinetic studies identified compound 7j as a competitive inhibitor, with a Ki value of 32 µM. Molecular docking simulations demonstrated key interactions between compound 7j and the active site of α-glucosidase, while molecular dynamics simulations confirmed the stability of the enzyme-ligand complex, reflected in low RMSD and RMSF values.

Disaccharidase Enzyme Deficiency in Adult Patients with Gas and Bloating.

Disaccharidases produced by the small intestinal brush border facilitate digestion of dietary carbohydrates. If deficient, they can cause carbohydrate malabsorption resulting in several abdominal symptoms. Our aim was to examine the prevalence of disaccharidase deficiency and correlate this with abdominal symptoms in adult patients with chronic abdominal symptoms. In a retrospective study, patients with gas and bloating and normal endoscopy and commuted tomography (CT) scan were assessed for lactase, sucrase, maltase, palatinase and glucoamylase activity. Nine common symptoms such as pain, cramping, constipation, belching, bloating, fullness, indigestion, nausea, diarrhea, vomiting, and gas were assessed for their frequency, intensity and duration using a validated scale and a total symptom index was calculated and compared. K-means cluster analysis was performed on lactase deficient and pandeficient patients with deficiency in 3 or more enzymes. 496 patients (78.4% female) were enrolled of whom, 143 (28.8%) had single enzyme deficiency, 9 (1.8%) had double enzyme deficiency and 48 (9.7%) were pandeficient. Mean symptom prevalence and its severity were not significantly different between those with or without disaccharidase deficiency. Patients with pandeficiency did not have worse symptoms than those with single or double enzyme deficiency. No single symptom was more prevalent in patients with confirmed enzyme deficiency than those without. Three groups were identified in cluster analysis of pandeficient patients with one group demonstrating significantly lower average symptoms of cramping, indigestion, and nausea. Disaccharidase deficiency is common in adults presenting with gas, bloating, distention and pain. Because these deficiencies are treatable with enzyme supplements or diet an evaluation for disaccharidase deficiency should be routinely considered.

Design, synthesis, in-vitro and in-silico studies of novel N-heterocycle based hydrazones as α-glucosidase inhibitors.

Diabetes mellitus has dominated the globe as a chronic health condition and has become a major global health concern. The inhibition of the key metabolic enzymes of carbohydrates digestion including α-amylase and α-glucosidase are the promising targets for the treatment of diabetes via delaying glucose absorption. Therefore, nitrogen containing saturated heterocycle (pyrrolidinyl, piperidinyl and N-methylpiperazinyl) based hydrazones derivatives 5-23 were synthesized through two step reactions and evaluated for their anti-diabetic potential. All compounds exhibited potent α-glucosidase inhibitory capability ranging (IC50=10.26-47.35µM), as compared to acarbose (IC50 = 871.40±1.24µM). Interestingly these derivatives also exhibited significant inhibitory capability against α-amylase with IC50 values in the range 25.81-76.05µM. Mechanistic study on the most potent compound indicated a competitive type of inhibition with a Ki value of 8.30±0.0076µM. Molecular docking was performed to predict binding interactions between receptor proteins and moiety. In QSAR analysis, through use of QSARINS different 1D and 2D descriptors were used to generate different models that enabled further identification of structural requirements that contributed to activity. pIC50 values were also predicted by QSAR model. Furthermore, in-silico ADMET and BOILED-egg model analysis showed that all analogues exhibited passive GI absorption, and all showed BBB penetration.

The role of light in regulating plant growth, development and sugar metabolism: a review.

Light provides the necessary energy for plant photosynthesis, which allows plants to produce organic matter and energy conversion, during plant growth and development. Light provides material energy to plants as the basis for cell division and differentiation, chlorophyll synthesis, tissue growth and stomatal movement, and light intensity, photoperiod, and light quality play important roles in these processes. There are several regulatory mechanisms involved in sugar metabolism in plants, and light, as one of the regulatory factors, affects cell wall composition, starch granules, sucrose synthesis, and vascular bundle formation. Similarly, sugar species and genes are affected in the context of light-regulated sugar metabolism. We searched the available databases and found that there are fewer relevant reviews. Therefore, this paper provides a summary of the effects of light on plant growth and development and sugar metabolism, further elaborates on the mechanisms of light effects on plants, and provides some new insights for a better understanding of how plant growth is regulated under different light conditions.

Thermal Responses and Cell Adhesive Properties of Glycosylated Jigsaw‐Shaped Self‐Assembling Peptides

ABSTRACTAs represented by the posttranslational modifications of proteins, the chemical modifications of side chains of peptide residues enable to regulate their physicochemical properties, conformation, and biological activities. Glycosylation is a main post‐translational modification, which allows for recognition by partner proteins to exert diverse function including increase in the conformational stability. Here, we studied the effects of glucose modification, which is a representative glycosylation sugar chains, to different positions of an amphiphilic peptide having a jigsaw‐shaped hydrophobic part (JigSAP). JigSAP forms a β‐sheet structure to self‐assemble into fibrous objects providing a hydrogel that can be used as a matrix for regenerative medicine. JigSAPs modified with glucose at the N‐terminus and middle portion were synthesized, and both of them self‐assemble in water to form hydrogels. The hydrogel composed of JigSAP containing the glucose group attached to the N‐terminus undergoes a gel‐to‐sol macroscopic phase transition upon heating, accompanied by a conformational change of JigSAP from the β‐sheet to an α‐helix structure. On the other hand, JigSAP with the glucose group in the middle, retained its β‐sheet structure even at high temperatures maintaining the gel state. Both glucose‐modified JigSAP fibers showed cell adhesion activity similar to that of non‐glycosylated JigSAP. This suggests that the glycosylation is effective in regulating the thermal stability of JigSAP fibers while maintaining their extracellular matrix properties depending on the modification site.

Cadmium promotes hyaluronan synthesis by inducing hyaluronan synthase 3 expression in cultured vascular endothelial cells via the c-Jun N-terminal kinase-c-Jun pathway.

Cadmium is a heavy metal risk factor for various cardiovascular diseases, such as atherosclerosis. In atherosclerotic lesions, hyaluronan, a glycosaminoglycan consisting of β4-glucuronic acid-β3-N-acetylglucosamine disaccharides repeats, is highly accumulated, regulating signal transduction, cell migration, and angiogenesis. Hyaluronan is synthesized by hyaluronan synthase (HAS)1-3 in the plasma membrane and secreted into the extracellular space. Hyaluronan derived from HAS3 promotes inflammatory responses. Recently, we found that cadmium elongates chondroitin/dermatan sulfate chains in vascular endothelial cells and that glycosaminoglycan sugar chains are potential targets for the vascular toxicity of cadmium. Therefore, hyaluronan, a glycosaminoglycan sugar chain, may also affected by cadmium; however, this has not yet been clarified. In this study, we aimed to analyze the effect of cadmium on hyaluronan synthesis using cultured aortic endothelial cells. Cadmium at a concentration of 2µM upregulated hyaluronan synthesis in the medium and specifically induced HAS3 mRNA and protein expression. However, cadmium-mediated HAS3 induction was abolished by the inhibition of the c-Jun N-terminal kinase (JNK)-c-Jun pathway. Moreover, JNK inhibition prevented the increase in hyaluronan levels in the medium. These results revealed that the JNK-c-Jun pathway was involved in HAS3-mediated hyaluronan synthesis by cadmium in vascular endothelial cells, suggesting that endothelial HAS3 induction contributes to atherosclerotic lesion formation by promoting inflammatory responses.

Diverse domains of raspberry pectin: critical determinants for protecting against IBDs.

Inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis (UC), are chronic conditions characterized by periods of intestinal inflammation and have become global diseases. Dietary pectins have shown protective effects on IBD models. However, the development of pectin-based diet intervention for IBD individuals requires knowledge of both the bioactive structural patterns and the mechanisms underlying diet-microbiota-host interactions. Here, dextran sulfate sodium (DSS) induced colitis mice were fed with different pectins with various domain compositions, including AG, P37, P55 and P85, in order to understand why different structural patterns function differently on colitis mouse models. The structural diversity of pectin manifests in the different percentages of the homogalacturonan (HG) backbone, Ara sidechains, and Gal sidechains. AG comprises only neutral sugar chains consisting of 14% Ara and 86% Gal, and P85 is a commercial HG pectin mainly composed of 85% HG. P37 and P55 were isolated from raspberry pulps with different domain ratios (P37 = 37% HG + 22% Ara + 32% Gal; P55 = 55% HG + 16% Ara + 18% Gal). Compared to the monotonous structure of AG and P85, the domain-diverse pectins P37 and P55 show superior protective effects against colitis through inhibiting the proliferation of the mucin-consuming bacteria and the pro-inflammatory microorganisms, potentiating the MUC2 expression and the mucus layer and regulating the gut-spleen axis. The HG structure promoted the proliferation of the mucin-degrading microbiota and potentiated mucus erosion. AG enhanced the mucus thickness but increased the growth of the pro-inflammatory microbiota. Our study revealed that the specific domain composition of pectic fibers was a key factor on which the diet-induced alterations in the gut microbiota and the intestinal barrier function highly depended.

Comparison of three different in vitro digestion methods for carbohydrates.

Spectrophotometer method, ELISA, and High-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) method have been widely used to quantify and characterize the glucose released from rice after in vitro digestion. Despite this, the results of the three methods may not be comparable. This work investigated the limitation of detection (LOD) and quantification (LOQ) of the glucose released after in vitro rice digestion. Intra-day and inter-day precision were evaluated through analyzing the contents of rapidly digestible starch (RDS), DS (RDS + slowly digestible starch (SDS)), and total starch (TS). Tests of accuracies were also conducted. The results demonstrated that all three methods showed good linear correlations, i.e., y = 0.3417x + 0.0799 (r2 = 0.994), y = 0.1719x + 0.0900 (r2 = 0.993), and y = 58078x + 6039.4 (r2 = 0.999), respectively. Concerning the LOD and LOQ, HPAEC-PAD showed the lowest 0.07 and 0.24mg/L, followed by the Spectrophotometer of 2.72 and 9.07mg/L. ELISA showed the highest 9.95 and 33.16mg/L. The recoveries of these methods ranged from 98.62% to 100.56%, 99.05% to 102.72%, and 96.71% to 103.27%, respectively. HPAEC-PAD method had lower contents of RDS, DS, and TS, indicating it may be poor. Combining above factors, Spectrophotometer was chosen and used in digestion of biscuits and steamed buns. RS of biscuits was the highest, possibly due to the formation of lipid-starch complex. Additionally, steamed buns had the highest RDS. These observations suggested that Spectrophotometer method was suitable for accurately and reproducibly analyzing carbohydrate digestion in different food systems.

Integrated computer aided methods to designing potent α-Glucosidase inhibitors based on quinoline scaffold derivative

Diabetes mellitus is a serious health disease that affects people all over the world. The number of persons identified with diabetes mellitus rises each year. α -Glucosidase is a digestive enzyme used to control diabetes mellitus. The searching for new potent α-glucosidase inhibitors capable of delaying carbohydrate digestion in the human body is an important strategy towards control of diabetes mellitus. In this work, a series of quinoline-based Schiff base derivatives already identified as α-glucosidase inhibitory activity was studied by using 2D/3D-QSAR approach. The best HQSAR/A-B-C-H-Ch-DA and CoMSIA/SEDA models were constructed using thirteen molecules in the training set, resulting in favorable values of Q2 (0.834 and 0.607), and high values of R2 (0.985 and 0.912), respectively. The generated HQSAR/A-B-C-H-Ch-DA and CoMSIA/SEDA contour plots were precious for designing and enhancing the α-glucosidase inhibitory activity of quinoline-based Schiff base molecules. Considering these results, two novel α-glucosidase compounds were designed to possess significant activity. The newly suggested molecules showed good outcomes in the preliminary in silico ADME/Tox evaluations. Molecular docking results revealed that the new designed inhibitors have a good stability in the active pocket of the studied receptor compared to voglibose, clinically used as an α-glucosidase inhibitor. MD simulation and MM-GBSA results confirmed the molecular docking outcomes. Finally, DFT analysis was useful in determining the most electrophilic and nucleophilic centers of the two designed α-glucosidase inhibitors.

Identification of bioactive compounds in Brassica oleracea var. capitata L. with enzyme-inhibitory activity against postprandial hyperglycemia.

Postprandial hyperglycemia is a hallmark of diabetes, and inhibition of key carbohydrate digestion enzymes such as α-amylase (α-AMY) and α-glucosidase (α-GLU) is an effective therapeutic target. A potential unexplored source of inhibitory compounds of these enzymes is Brassica oleracea var. capitata L (BOCE). This study explored the in vitro inhibition mechanism of BOCE and studied in silico the interaction of its compounds identified and quantified by UPLC-QTOF-MS on α-AMY and α-GLU. BOCE demonstrated IC50 values of 3.08 mg/mL for α-AMY and 22.63 mg/mL for α-GLU, indicating competitive and mixed-type inhibitions, respectively. Untargeted metabolomics identified 21 compounds, primarily phenolic acids such as t-cinnamic, sinapic, and caffeoylquinic acid. In the targeted analysis, 11 compounds were quantified, mainly phenolic acids. The most impactful biosynthetic pathways identified were phenylpropanoids and brassinosteroids. In silico analysis revealed that for α-AMY and α-GLU, castasterone and 26-hydroxybrassinolide displayed the lowest binding free energies with specific hydrogen bond patterns to catalytic residues in the binding site, respectively. B. oleracea is a promising source of compounds with the ability to modulate key enzymes related to hyperglycemia. Specifically, compounds such as castasterone and 26-hydroxybrassinolide show potential against α-AMY and α-GLU inhibition, offering a novel approach to diabetes.

Purple and red rice (Oryza sativa L.) bran polyphenols show antiobesity and antidiabetic activities

AbstractBackground and ObjectivesRice bran is a source of bioactive polyphenols. This study aimed to characterize the antidiabetic potential of different rice brans (one brown, two red, and two purple) by examining their ability to inhibit α‐amylase, α‐glucosidase, and pancreatic lipase, and to stimulate glucose uptake in adipocytes.FindingsAll pigmented bran extracts significantly inhibited α‐glucosidase. Both red rice brans inhibited α‐amylase close to 50% at the highest dose tested. All four pigmented rice brans inhibited lipase in vitro (IC50 values 4.38–10.09 mg/mL). The pigmented rice brans studied contained higher levels of total polyphenolic content (TPC), total flavonoid content (TFC), and antioxidant capacity when compared to brown rice bran. Purple bran contained anthocyanins and red brans contained proanthocyanidins. The pigmented brans consisted of higher levels of total benzoic acids, while the brown rice bran had higher levels of total cinnamic acids. Tricin was identified in all pigmented brans.ConclusionsOur study indicates that pigmented rice brans have the ability to manage obesity and diabetes due to their inhibitory effects on lipid and carbohydrate digestion. Several bioactive polyphenols were identified.Significance and NoveltyThe potential of pigmented rice bran to inhibit α‐amylase, α‐glucosidase, and lipase was confirmed.