Antidiabetic effect of chitosan oligosaccharide (GO2KA1) is mediated via inhibition of intestinal alpha-glucosidase and glucose transporters and PPARγ expression

Characterisation of High Alkaline-Tolerant Novel Ulvan Lyase from Pseudoalteromonas agarivorans: Potential Applications of Enzyme Derived Oligo-Ulvan as Anti-Diabetic Agent

Green algae, particularly Ulva species, are rich in complex polysaccharides, such as ulvan, which have significant potential for biotechnological applications. However, the biochemical properties of ulvan depolymerised products remain underexplored. The enzymatic depolymerisation of ulvan has garnered attention owing to its cost advantages over alternative methods. Nevertheless, the biochemical characterisation of ulvan lyases, specifically those belonging to the polysaccharide lyase family 25 (PL25), is limited. In this study, we identified and biochemically characterised a novel PL25 ulvan lyase, PaUL25, which functions optimally at pH 10. Additionally, we explored the alpha (α)-glucosidase inhibitory properties of ulvan depolymerised products. PaUL25 exhibited optimum activity at 35 °C in Tris-HCl buffer (pH 10). Moreover, enzyme activity was enhanced by more than 150% in the presence of Mn2+ metal ions at and below concentrations of 10 mM. The endolytic action of PaUL25 produced ulvan oligosaccharides with degrees of polymerisation of 2 and 4 as its end products. Partially and completely hydrolysed ulvan oligosaccharides exhibited α-glucosidase inhibitory activity, with half inhibitory concentration IC50 values of 3.21 ± 0.13 and 2.51 ± 0.19 mg/mL, respectively. These findings expand our understanding of PL25 and highlight the pharmaceutical potential of ulvan oligosaccharides, particularly as antidiabetic agents.

Suppression of the postprandial hyperglycemia in patients with type 2 diabetes by a raw medicinal herb powder is weakened when consumed in ordinary hard gelatin capsules: A randomized crossover clinical trial

INTRODUCTION

Contradictory claims about the efficacy of several medicinal plants to promote glycemic control in patients with type 2 diabetes mellitus (T2DM) have been explained by divergences in the administration form and by extrapolation of data obtained from healthy individuals. It is not known whether the antidiabetic effects of traditional herbal medicines are influenced by gelatin capsules. This randomized crossover trial aimed to evaluate the acute effect of a single dose of raw cinnamon consumed orally either dissolved in water as a beverage or as ordinary hard gelatin capsules on postprandial hyperglycemia (>140 mg/dL; >7.8 mmol/L) in T2DM patients elicited by a nutritionally-balanced meal providing 50 g of complex carbohydrates.

METHODS

Fasting T2DM patients (n = 19) randomly ingested a standardized meal in five experimental sessions, one alone (Control) and the other after prior intake of 3 or 6 g of crude cinnamon in the form of hard gelatin capsules or powder dissolved in water. Blood glucose was measured at fasting and at 0.25, 0.5, 0.75, 1, 1.5 and 2 hours postprandially. After each breakfast, its palatability scores for visual appeal, smell and pleasantness of taste were assessed, as well as the taste intensity sweetness, saltiness, bitterness, sourness and creaminess.

RESULTS

The intake of raw cinnamon dissolved in water, independently of the dose, decreased the meal-induced large glucose spike (peak-rise of +87 mg/dL and Δ1-hour glycemia of +79 mg/dL) and the hyperglycemic blood glucose peak. When cinnamon was taken as capsules, these anti-hyperglycemic effects were lost or significantly diminished. Raw cinnamon intake did not change time-to-peak or the 2-h post-meal glycaemia, but flattened the glycemic curve (lower iAUC) without changing the shape that is typical of T2DM patients.

CONCLUSIONS

This cinnamon's antihyperglycemic action confirms its acarbose-like property to inhibit the activities of the carbohydrate-digesting enzymes α-amylases/α-glucosidases, which is in accordance with its exceptionally high content of raw insoluble fiber. The efficacy of using raw cinnamon as a diabetes treatment strategy seems to require its intake at a specific time before/concomitantly the main hyperglycemic daily meals. Trial registration: Registro Brasileiro de Ensaios Clínicos (ReBEC), number RBR-98tx28b.

Shiitake polysaccharides acted as a non-competitive inhibitor to α-glucosidase and inhibited glucose transport of digested starch from Caco-2 cells monolayer

The inhibition mechanism of shitake mushroom polysaccharides (Lentinula edodes polysaccharides, LEP) against α-glucosidase was studied by enzyme kinetic assay, fluorescence quenching and molecular docking. The effect of LEP on glucose transport of digested starch was investigated via an in vitro digestion/Caco-2 transwell model. LEP exhibited a stronger inhibiting effect (IC50 = 0.66 mg/mL) than acarbose and presented a non-competitive inhibition mechanism. The interaction between LEP and α-glucosidase primarily involved electrostatic interaction and hydrogen bonding. Molecular docking modelling showed that the four structures of LEP were bound to the allosteric tunnel or adjacent pocket of α-glucosidase via electrostatic force and hydrogen bonds. The (1 → 6)-linkages in LEP structures favoured its binding affinity to the α-glucosidase. The α-glucosidase inhibiting activity of LEP was also found to emanate from the reduction in glucose transport of digested starch as deducted from the in vitro digestion/Caco-2 transwell data. The release of glucose from digested starch cooked with LEP was significantly reduced (33.7%) compared to the digested starch without LEP. The findings from the current study suggest that LEP could be a promising ingredient to inhibit α-glucosidase activity as well as control the level of postprandial blood glucose when incorporated into starchy foods.

Recent progressions in biomedical and pharmaceutical applications of chitosan nanoparticles: A comprehensive review

Nowadays, the most common approaches in the prognosis, diagnosis, and treatment of diseases are along with undeniable limitations. Thus, the ever-increasing need for using biocompatible natural materials and novel practical modalities is required. Applying biomaterials, such as chitosan nanoparticles (CS NPs: FDA-approved long-chain polymer of N-acetyl-glucosamine and D-glucosamine for some pharmaceutical applications), can serve as an appropriate alternative to overcome these limitations. Recently, the biomedical applications of CS NPs have extensively been investigated. These NPs and their derivatives can not only prepare through different physical and chemical approaches but also modify with various molecules and bioactive materials. The potential properties of CS NPs, such as biocompatibility, biodegradability, serum stability, solubility, non-immunogenicity, anti-inflammatory properties, appropriate pharmacokinetics and pharmacodynamics, and so forth, have made them excellent candidates for biomedical applications. Therefore, CS NPs have efficiently applied for various biomedical applications, like regenerative medicine and tissue engineering, biosensors for the detection of microorganisms, and drug delivery systems (DDS) for the suppression of diseases. These NPs possess a high level of biosafety. In summary, CS NPs have the potential ability for biomedical and clinical applications, and it would be remarkably beneficial to develop new generations of CS-based material for the future of medicine.

Novel Cytocompatible Chitosan Schiff Base Derivative as a Potent Antibacterial, Antidiabetic, and Anticancer Agent

This study intends to develop a novel bioactive chitosan Schiff base (CTS-SB) derivative via coupling of chitosan (CTS) with 4-((5, 5-dimethyl-3-oxocyclohex-1-en-1-yl) amino) benzene-sulfonamide. The alteration in the chemical structure of CTS-SB was verified using 1H NMR and FT-IR analysis, while the thermal and morphological properties were inspected by TGA and SEM characterization tools, respectively. Ion exchange capacity of the developed CTS-SB derivative recorded a maximal value of 12.1 meq/g compared to 10.1 meq/g for pristine CTS. In addition, antibacterial activity of CTS-SB derivative was greatly boosted against Escherichia coli (E coli) and Staphylococcus aureus (S. aureus) bacteria. Minimum inhibition concentration of CTS-SB derivative was perceived at 50 µg/mL, while the highest concentration (250 µg/mL) could inhibit the growth of S. aureus up to 91%. What’s more, enhanced antidiabetic activity by CTS-SB derivative, which displayed higher inhibitory values of α-amylase (57.9%) and α-glucosidase (63.9%), compared to those of pure CTS (49.8 and 53.4%), respectively Furthermore, cytotoxicity investigation on HepG-2 cell line revealed potential anticancer activity along with good safety margin against primary human skin fibroblasts (HSF cells) and decent cytocompatibility. Collectively, the gained results hypothesized that CTS-SB derivative could be effectively applied as a promising antibacterial, anticancer and antidiabetic agent for advanced biomedical applications.

Antidiabetic Properties of Chitosan and Its Derivatives

Diabetes mellitus is a chronic metabolic disorder. In addition to taking medication, adjusting the composition of the diet is also considered one of the effective methods to control the levels of blood glucose. Chitosan and its derivatives are natural and versatile biomaterials with health benefits. Chitosan has the potential to alleviate diabetic hyperglycemia by reducing hepatic gluconeogenesis and increasing skeletal muscle glucose uptake and utility. Scientists also focus on the glucose-lowering effect of chitosan oligosaccharide (COS). COS supplementation has the potential to alleviate abnormal glucose metabolism in diabetic rats by inhibiting gluconeogenesis and lipid peroxidation in the liver. Both high and low molecular weight chitosan feeding reduced insulin resistance by inhibiting lipid accumulation in the liver and adipose tissue and ameliorating chronic inflammation in diabetic rats. COS can reduce insulin resistance but has less ability to reduce hepatic lipids in diabetic rats. A clinical trial showed that a 3-month administration of chitosan increased insulin sensitivity and decreased body weight and triglycerides in obese patients. Chitosan and COS are considered Generally Recognized as Safe; however, they are still considered to be of safety concerns. This review highlights recent advances of chitosan and its derivatives in the glucose-lowering/antidiabetic effects and the safety.

Influence of Degree of Polymerization of Low-Molecular-Weight Chitosan Oligosaccharides on the α-Glucosidase Inhibition

Chitosan oligosaccharide (COS) is a bioactive compound derived from marine by-products. COS consumption has been demonstrated to lower the risk of diabetes. However, there are limited data on the inhibitory effect of low-molecular-weight COSs with different degrees of polymerization (DP) on α-glucosidase. This study investigates the α-glucosidase inhibitory activity of two low-molecular-weight COSs, i.e., S-TU-COS with DP2−4 and L-TU-COS with DP2−5, both of which have different molecular weight distributions. The inhibition constants of the inhibitors binding to free enzymes (Ki) and an enzyme−substrate complex (Kii) were investigated to elucidate the inhibitory mechanism of COSs with different chain lengths. The kinetic inhibition model of S-TU-COS showed non-completive inhibition results which are close to the uncompetitive inhibition results with Ki and Kii values of 3.34 mM and 2.94 mM, respectively. In contrast, L-TU-COS showed uncompetitive inhibition with a Kii value of 5.84 mM. With this behavior, the IC50 values of S-TU-COS and L-TU-COS decreased from 12.54 to 11.84 mM and 20.42 to 17.75 mM, respectively, with an increasing substrate concentration from 0.075 to 0.3 mM. This suggests that S-TU-COS is a more potent inhibitor, and the different DP of COS may cause significantly different inhibition (p < 0.05) on the α-glucosidase activity. This research may provide new insights into the production of a COS with a suitable profile for antidiabetic activity.

Effect of chitooligosaccharides with a specific degree of polymerization on multiple targets in T2DM mice

Chitooligosaccharides (COS) are found naturally in the ocean and present a variety of physiological activities, of which hypoglycemic action has attracted considerable research attention. This study aimed to assess the therapeutic effect of COS on mice suffering from type 2 diabetes mellitus (T2DM). COS effectively reduced blood glucose and blood lipid levels and improved glucose tolerance. Furthermore, COS revealed strong inhibitory activity against α-glucosidase, reducing postprandial blood glucose levels. Molecular docking data showed that COS might interact with surrounding amino acids to form a complex and decrease α-glucosidase activity. Additionally, COS enhanced insulin signal transduction and glycogen synthesis while restricting gluconeogenesis in the liver and muscles, reducing insulin resistance (IR) as a result. Moreover, COS effectively protected and restored islet cell function to increase insulin secretion. These results indicated that COS exhibited a significant hypoglycemic effect with multi-target participation. Therefore, COS may serve as a new preventive or therapeutic drug for diabetes to alleviate metabolic syndrome.

Ameliorative Effect of Ocimum forskolei Benth on Diabetic, Apoptotic, and Adipogenic Biomarkers of Diabetic Rats and 3T3-L1 Fibroblasts Assisted by In Silico Approach

Diabetes mellitus (DM) is a complicated condition that is accompanied by a plethora of metabolic symptoms, including disturbed serum glucose and lipid profiles. Several herbs are reputed as traditional medicine to improve DM. The current study was designed to explore the chemical composition and possible ameliorative effects of Ocimum forskolei on blood glucose and lipid profile in high-fat diet/streptozotocin-induced diabetic rats and in 3T3-L1 cell lines as a first report of its bioactivity. Histopathological study of pancreatic and adipose tissues was performed in control and treatment groups, along with quantification of glucose and lipid profiles and the assessment of NF-κB, cleaved caspase-3, BAX, and BCL2 markers in rat pancreatic tissue. Glucose uptake, adipogenic markers, DGAT1, CEBP/α, and PPARγ levels were evaluated in the 3T3-L1 cell line. Hesperidin was isolated from total methanol extract (TME). TME and hesperidin significantly controlled the glucose and lipid profile in DM rats. Glibenclamide was used as a positive control. Histopathological assessment showed that TME and hesperidin averted necrosis and infiltration in pancreatic tissues, and led to a substantial improvement in the cellular structure of adipose tissue. TME and hesperidin distinctly diminished the mRNA and protein expression of NF-κB, cleaved caspase-3, and BAX, and increased BCL2 expression (reflecting its protective and antiapoptotic actions). Interestingly, TME and hesperidin reduced glucose uptake and oxidative lipid accumulation in the 3T3-L1 cell line. TME and hesperidin reduced DGAT1, CEBP/α, and PPARγ mRNA and protein expression in 3T3-L1 cells. Moreover, docking studies supported the results via deep interaction of hesperidin with the tested biomarkers. Taken together, the current study demonstrates Ocimum forskolei and hesperidin as possible candidates for treating diabetes mellitus.

Chitosan Oligosaccharides Alleviate Colitis by Regulating Intestinal Microbiota and PPARγ/SIRT1-Mediated NF-κB Pathway

Chitosan oligosaccharides (COS) have been shown to have potential protective effects against colitis, but the mechanism underlying this effect has not been fully elucidated. In this study, COS were found to significantly attenuate dextran sodium sulfate-induced colitis in mice by decreasing disease activity index scores, downregulating pro-inflammatory cytokines, and upregulating Mucin-2 levels. COS also significantly inhibited the levels of nitric oxide (NO) and IL-6 in lipopolysaccharide-stimulated RAW 264.7 cells. Importantly, COS inhibited the activation of the NF-κB signaling pathway via activating PPARγ and SIRT1, thus reducing the production of NO and IL-6. The antagonist of PPARγ could abolish the anti-inflammatory effects of COS in LPS-treated cells. COS also activated SIRT1 to reduce the acetylation of p65 protein at lysine 310, which was reversed by silencing SIRT1 by siRNA. Moreover, COS treatment increased the diversity of intestinal microbiota and partly restored the Firmicutes/Bacteroidetes ratio. COS administration could optimize intestinal microbiota composition by increasing the abundance of norank_f_Muribaculaceae, Lactobacillus and Alistipes, while decreasing the abundance of Turicibacte. Furthermore, COS could also increase the levels of propionate and butyrate. Overall, COS can improve colitis by regulating intestinal microbiota and the PPARγ/SIRT1-mediated NF-κB pathway.

Heterocyclic compounds as a magic bullet for diabetes mellitus: a review

Diabetes mellitus (DM) is a major metabolic disorder due to hyperglycemia, which is increasing all over the world. From the last two decades, the use of synthetic agents has risen due to their major involvement in curing of chronic diseases including DM. The core skeleton of drugs has been studied such as thiazolidinone, azole, chalcone, pyrrole and pyrimidine along with their derivatives. Diabetics assays have been performed in consideration of different enzymes such as α-glycosidase, α-amylase, and α-galactosidase against acarbose standard drug. The studied moieties were depicted in both models: in vivo as well as in vitro. Molecular docking of the studied compounds as antidiabetic molecules was performed with the help of Auto Dock and molecular operating environment (MOE) software. Amino acid residues Asp349, Arg312, Arg439, Asn241, Val303, Glu304, Phe158, His103, Lys422 and Thr207 that are present on the active sites of diabetic related enzymes showed interactions with ligand molecules. In this review data were organized for the synthesis of heterocyclic compounds through various routes along with their antidiabetic potential, and further studies such as pharmacokinetic and toxicology studies should be executed before going for clinical trials.

Diabetes mellitus (DM) is a major metabolic disorder due to hyperglycemia, which is increasing all over the world.

Chitosan for biomedical applications, promising antidiabetic drug delivery system, and new diabetes mellitus treatment based on stem cell

Since chitosan's excellent pharmacokinetic and chemical properties, it is an attractive and promising carbohydrate biopolymer in biomedical applications. Chitosan's beneficial function in the defense and propagation of pancreatic β cells, reducing hyperglycemia, and avoiding diabetes mellitus associated with impaired lipid metabolism has been demonstrated in several studies. Additionally, chitosan has also been used in various nanocarriers to deliver various antidiabetic drugs to reduce glucose levels. Herein, the first to provide the currently available potential benefits of chitosan in diabetes mellitus treatment focuses on chitosan-based nanocarriers for oral administration of various antidiabetic drugs nasal and subcutaneous passages. Moreover, chitosan is used to activate and deliver stem cells and differentiate them into cells similar to pancreatic beta cells as a new type of treatment for type one diabetes mellitus. The results of this review will be helpful in the development of promising treatments and better control of diabetes mellitus.

Dietary natural products as a potential inhibitor towards advanced glycation end products and hyperglycemic complications: A phytotherapy approaches

Natural products exist in various natural foods such as plants, herbs, fruits, and vegetables. Furthermore, marine life offers potential natural products with significant biological activity. The biochemical reaction is known as advanced glycation end products (AGEs) occurs in the human body. On the other hand, foods are capable of a wide range of processing conditions resulting in the generation of exogenous AGEs adducts. Protein glycation and the formation of advanced glycation end products both contribute to the pathogenesis of hyperglycemic complications. AGEs also play a pivotal role in microvascular and macrovascular complications progression by receptors for advanced glycation end products (RAGE). RAGE activate by AGEs leads to up-regulation of transcriptional factor NF-kB and inflammatory genes. Around the globe, researchers are working in various approaches for therapeutical implications on controlling AGEs mediated disease complications. In this regard, one of the potential promising agents observed with a wide range of AGEs inhibition by food-derived natural products. Current biotechnological tools have been turned to natural products or phytochemicals to manufacture the molecules without compromising their functionality. Metabolic engineering and bioinformatics perspectives have recently enabled the generation of a few potent metabolites with anti-diabetic activity. As the primary focus, this review article will also discuss multidisciplinary approaches that emphasize current advances in anti-diabetic therapeutic action and future perspectives of natural products.

The Role of Chitosan Oligosaccharide in Metabolic Syndrome: A Review of Possible Mechanisms

Metabolic syndrome, a cluster of metabolic disorders including central obesity, insulin resistance, hyperglycemia, dyslipidemia, and hypertension, has become a major public health problem worldwide. It is of great significance to develop natural products to prevent and treat metabolic syndrome. Chitosan oligosaccharide (COS) is an oligomer of chitosan prepared by the deacetylation of chitin, which is the second most abundant polymer in nature. In recent years, COS has received widespread attention due to its various biological activities. The present review will summarize the evidence from both in vitro and in vivo studies of the beneficial effects of COS on obesity, dyslipidemia, diabetes mellitus, hyperglycemia, and hypertension, and focus attention on possible mechanisms of the prevention and treatment of metabolic syndrome by COS.

Gene Cascade Shift and Pathway Enrichment in Rat Kidney Induced by Acarbose Through Comparative Analysis

Acarbose is an effective anti-diabetic drug to treat type 2 diabetes mellitus (T2DM), a chronic degenerative metabolic disease caused by insulin resistance. The beneficial effects of acarbose on blood sugar control in T2DM patients have been confirmed by many studies. However, the effect of acarbose on patient kidney has yet to be fully elucidated. In this study, we report in detail the gene expression cascade shift, pathway and module enrichment, and interrelation network in acarbose-treated Rattus norvegicus kidneys based on the in-depth analysis of the GSE59913 microarray dataset. The significantly differentially expressed genes (DEGs) in the kidneys of acarbose-treated rats were initially screened out by comparative analysis. The enriched pathways for Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were further identified. The protein-protein interaction (PPI) analysis for DEGs was achieved through the STRING database mining. Pathway interrelation and hub genes for enriched pathways were further examined to uncover key biological effects of acarbose. Results revealed 44 significantly up-regulated genes and 86 significantly down-regulated genes (130 significant differential genes in total) in acarbose-treated rat kidneys. Lipid metabolism pathways were considerably improved by acarbose, and the physical conditions in chronic kidney disease (CKD) patients were improved possibly through the increase of the level of high-density lipoprotein (HDL) by lecithin-cholesterol acyl-transferase (LCAT). These findings suggested that acarbose may serve as an ideal drug for CKD patients, since it not only protects the kidney, but also may relieve the complications caused by CKD.

In vitro fermentation of flaxseed polysaccharide by fecal bacteria inhibits energy intake and adipogenesis at physiological concentration

Obesity and its related metabolic disorders have been a global pandemic. Recently, we found an anti-obesity effect of flaxseed polysaccharide (FP) that could be achieved by regulating intestinal microbiota. The anti-obesity effect of FP is mainly attributed to the metabolites produced by the interaction with FP, which remains to be elucidated. In this research, the in vitro effects of metabolites of FP fermented by fecal bacteria on energy metabolism and adipogenesis were investigated. The effect of energy metabolism was analyzed by mRNA and protein expression of the intestinal glucose transporters, including sodium dependent glucose transporter (SGLT1) and glucose transporter 2 (GLUT2), and glucose uptake in intestinal Caco-2 cells. The lipogenic effect were evaluated by Oil red O staining of intracellular lipid droplets and the mRNA and protein expression of peroxisome proliferator-activated receptor (PPAR) γ, CCAAT-enhancer-binding proteins (C/EBP) α and β in 3T3-L1 cells. The results showed the metabolites significantly inhibited glucose intake through downregulating the mRNA and protein expression of GLUT2 and SGLT1 in Caco-2 cells. Besides, they also led to the decrease of lipid accumulation through downregulating the mRNA and protein expression of PPARγ, C/EBPα, and C/EBPβ in differentiating adipocytes. The inhibitory effects on energy intake and adipogenesis were concentration dependent, and metabolites at physiological concentration showed the most significant effect. Metabolites of fecal bacteria fermenting FP inhibited energy intake and adipogenesis at physiological concentration, which might be one of the weight-loss mechanisms of FP-diet.

Anti-Obesity and Anti-Adipogenic Effects of Chitosan Oligosaccharide (GO2KA1) in SD Rats and in 3T3-L1 Preadipocytes Models

Excess body weight is a major risk factor for type 2 diabetes (T2D) and associated metabolic complications, and weight loss has been shown to improve glycemic control and decrease morbidity and mortality in T2D patients. Weight-loss strategies using dietary interventions produce a significant decrease in diabetes-related metabolic disturbance. We have previously reported that the supplementation of low molecular chitosan oligosaccharide (GO2KA1) significantly inhibited blood glucose levels in both animals and humans. However, the effect of GO2KA1 on obesity still remains unclear. The aim of the study was to evaluate the anti-obesity effect of GO2KA1 on lipid accumulation and adipogenic gene expression using 3T3-L1 adipocytes in vitro and plasma lipid profiles using a Sprague-Dawley (SD) rat model. Murine 3T3-L1 preadipocytes were stimulated to differentiate under the adipogenic stimulation in the presence and absence of varying concentrations of GO2KA1. Adipocyte differentiation was confirmed by Oil Red O staining of lipids and the expression of adipogenic gene expression. Compared to control group, the cells treated with GO2KA1 significantly decreased in intracellular lipid accumulation with concomitant decreases in the expression of key transcription factors, peroxisome proliferator-activated receptor gamma (PPARγ) and CCAAT/enhancer-binding protein alpha (CEBP/α). Consistently, the mRNA expression of downstream adipogenic target genes such as fatty acid binding protein 4 (FABP4), fatty acid synthase (FAS), were significantly lower in the GO2KA1-treated group than in the control group. In vivo, male SD rats were fed a high fat diet (HFD) for 6 weeks to induced obesity, followed by oral administration of GO2KA1 at 0.1 g/kg/body weight or vehicle control in HFD. We assessed body weight, food intake, plasma lipids, levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) for liver function, and serum level of adiponectin, a marker for obesity-mediated metabolic syndrome. Compared to control group GO2KA1 significantly suppressed body weight gain (185.8 ± 8.8 g vs. 211.6 ± 20.1 g, p < 0.05) with no significant difference in food intake. The serum total cholesterol, triglyceride, and low-density lipoprotein (LDL) levels were significantly lower in the GO2KA1-treated group than in the control group, whereas the high-density lipoprotein (HDL) level was higher in the GO2KA1 group. The GO2KA1-treated group also showed a significant reduction in ALT and AST levels compared to the control. Moreover, serum adiponectin levels were significantly 1.5-folder higher than the control group. These in vivo and in vitro findings suggest that dietary supplementation of GO2KA1 may prevent diet-induced weight gain and the anti-obesity effect is mediated in part by inhibiting adipogenesis and increasing adiponectin level.

Chitin and Chitosan Derivatives as Biomaterial Resources for Biological and Biomedical Applications

Chitin is a long-chain polymer of N-acetyl-glucosamine, which is regularly found in the exoskeleton of arthropods including insects, shellfish and the cell wall of fungi. It has been known that chitin can be used for biological and biomedical applications, especially as a biomaterial for tissue repairing, encapsulating drug for drug delivery. However, chitin has been postulated as an inducer of proinflammatory cytokines and certain diseases including asthma. Likewise, chitosan, a long-chain polymer of N-acetyl-glucosamine and d-glucosamine derived from chitin deacetylation, and chitosan oligosaccharide, a short chain polymer, have been known for their potential therapeutic effects, including anti-inflammatory, antioxidant, antidiarrheal, and anti-Alzheimer effects. This review summarizes potential utilization and limitation of chitin, chitosan and chitosan oligosaccharide in a variety of diseases. Furthermore, future direction of research and development of chitin, chitosan, and chitosan oligosaccharide for biomedical applications is discussed.

Chitosan modifies glycemic levels in people with metabolic syndrome and related disorders: meta-analysis with trial sequential analysis

BACKGROUND

Chitosan supplementation has been shown to modulate glycemic levels; however, studies have reported conflicting results. The present meta-analysis with trial sequential analysis was conducted to verify the overall influence of chitosan on glycemic levels in patients with metabolic syndrome.

METHODS

The PubMed, Cochrane library, and EMBASE databases were systematically searched for randomized controlled studies of chitosan intake and glycemic levels.

RESULTS

A total of ten clinical trials including 1473 subjects were included in this meta-analysis. Pooled effect sizes were determined by random-effects meta-analysis. Subgroup analysis was performed to analyze the sources of heterogeneity and their influence on the overall results. The results revealed a significant reduction in fasting glucose levels (SMD: - 0.39 mmol/L, 95% CI: - 0.62 to - 0.16) and hemoglobin A1c (HbA1c) levels (SMD: -1.10; 95% CI: - 2.15 to - 0.06) following chitosan supplementation but no effect on insulin levels (SMD: - 0.20 pmol/L, 95% CI: - 0.64 to 0.24). Subgroup analyses further demonstrated significant reductions in fasting glucose levels in subjects administered 1.6-3 g of chitosan per day and in studies longer than 13 weeks. Trial sequential analysis of the pooled results of the hypoglycemic effect demonstrated that the cumulative Z-curve crossed both the conventional boundary and trial sequential monitoring boundary for glucose and HbA1c.

CONCLUSIONS

The glucose level of patients who are diabetic and obese/overweight can be improved by supplementation with chitosan for at least 13 weeks at 1.6-3 g per day. Additional clinical research data are needed to confirm the role of chitosan, particularly in regulating glycosylated hemoglobin and insulin.

Advances in the Study of Marine Products with Lipid-Lowering Properties

With twice the number of cancer's deaths, cardiovascular diseases have become the leading cause of death worldwide. Atherosclerosis, in particular, is a progressive, chronic inflammatory cardiovascular disease caused by persistent damage to blood vessels due to elevated cholesterol levels and hyperlipidemia. This condition is characterized by an increase in serum cholesterol, triglycerides, and low-density lipoprotein, and a decrease in high-density lipoprotein. Although existing therapies with hypolipidemic effects can improve the living standards of patients with cardiovascular diseases, the drugs currently used in clinical practice have certain side effects, which insists on the need for the development of new types of drugs with lipid-lowering effects. Some marine-derived substances have proven hypolipidemic activities with fewer side effects and stand as a good alternative for drug development. Recently, there have been thousands of studies on substances with lipid-lowering properties of marine origin, and some are already implemented in clinical practice. Here, we summarize the active components of marine-derived products having a hypolipidemic effect. These active constituents according to their source are divided into algal, animal, plant and microbial and contribute to the development and utilization of marine medicinal products with hypolipidemic effects.

Assessment of Oligo-Chitosan Biocompatibility toward Human Spermatozoa

The many interesting properties of chitosan polysaccharides have prompted their extensive use as biomaterial building blocks, for instance as antimicrobial coatings, tissue engineering scaffolds, and drug delivery vehicles. The translation of these chitosan-based systems to the clinic still requires a deeper understanding of their safety profiles. For instance, the widespread claim that chitosans are spermicidal is supported by little to no data. Herein, we thoroughly investigate whether chitosan oligomer (CO) molecules can impact the functional and structural features of human spermatozoa. By using a large number of primary sperm cell samples and by isolating the effect of chitosan from the effect of sperm dissolution buffer, we provide the first realistic and complete picture of the effect of chitosans on sperms. We found that CO binds to cell surfaces or/and is internalized by cells and affected the average path velocity of the spermatozoa, in a dose-dependent manner. However, CO did not affect the progressive motility, motility, or sperm morphology, nor did it cause loss of plasma membrane integrity, reactive oxygen species production, or DNA damage. A decrease in spermatozoa adenosine triphosphate levels, which was especially significant at higher CO concentrations, points to possible interference of CO with mitochondrial functions or the glycolysis processes. With this first complete and in-depth look at the spermicidal activities of chitosans, we complement the complex picture of the safety profile of chitosans and inform on further use of chitosans in biomedical applications.

Recent Updates in Pharmacological Properties of Chitooligosaccharides

Chemical structures derived from marine foods are highly diverse and pharmacologically promising. In particular, chitooligosaccharides (COS) present a safe pharmacokinetic profile and a great source of new bioactive polymers. This review describes the antioxidant, anti-inflammatory, and antidiabetic properties of COS from recent publications. Thus, COS constitute an effective agent against oxidative stress, cellular damage, and inflammatory pathogenesis. The mechanisms of action and targeted therapeutic pathways of COS are summarized and discussed. COS may act as antioxidants via their radical scavenging activity and by decreasing oxidative stress markers. The mechanism of COS antidiabetic effect is characterized by an acceleration of pancreatic islets proliferation, an increase in insulin secretion and sensitivity, a reduction of postprandial glucose, and an improvement of glucose uptake. COS upregulate the GLUT2 and inhibit digestive enzyme and glucose transporters. Furthermore, they resulted in reduction of gluconeogenesis and promotion of glucose conversion. On the other hand, the COS decrease inflammatory mediators, suppress the activation of NF-κB, increase the phosphorylation of kinase, and stimulate the proliferation of lymphocytes. Overall, this review brings evidence from experimental data about protective effect of COS.

Cloning and Characterization of a Cold-adapted Chitosanase from Marine Bacterium Bacillus sp. BY01

Chitosanase plays an important role in the production of chitooligosaccharides (CHOS), which possess various biological activities. Herein, a glycoside hydrolase (GH) family 46 chitosanase-encoding gene, csnB, was cloned from marine bacterium Bacillus sp. BY01 and heterologously expressed in Escherichia coli. The recombinant chitosanase, CsnB, was optimally active at 35 °C and pH 5.0. It was also revealed to be a cold-adapted enzyme, maintaining 39.5% and 40.4% of its maximum activity at 0 and 10 °C, respectively. Meanwhile, CsnB showed wide pH-stability within the range of pH 3.0 to 7.0. Then, an improved reaction condition was built to enhance its thermostability with a final glycerol volume concentration of 20%. Moreover, CsnB was determined to be an endo-type chitosanase, yielding chitosan disaccharides and trisaccharides as the main products. Overall, CsnB provides a new choice for enzymatic CHOS production.

Can functional oligosaccharides reduce the risk of diabetes mellitus?

Diabetes significantly affects the life quality and length of patients with diabetes, and almost half of the 4 million people who die from diabetes are under the age of 60. Because of the increasing number of patients with diabetes and the side effects of antidiabetic drugs, the search for new dietary supplementation from natural resources, especially functional oligosaccharides, has attracted much attention among scientific researchers. Functional oligosaccharides are potential antidiabetic treatments because of their nondigestible, low-calorie, and probiotic features. The antidiabetic activity of multiple functional oligosaccharides such as fructo-oligosaccharides, galacto-oligosaccharides, and xylo-oligosaccharides has been reviewed in this paper. Molecular mechanisms involved in the antidiabetic activity of oligosaccharides have been systematically discussed from multiple perspectives, including the improvement of pancreas function, α-glucosidase inhibition, the relief of insulin and leptin resistance, anti-inflammatory effects, regulation of gut microbiota and hormones, and the intervention of diabetic risk factors. In addition, the antidiabetic effects of functional oligosaccharides through the complex gut-brain-liver axis are summarized. The concepts addressed in this review have important clinical implications, although more works are needed to confirm the antidiabetic mechanisms of functional oligosaccharides, standardize safe dose levels, and clarify their metabolism in the human body.-Zhu, D., Yan, Q., Liu, J., Wu, X., Jiang, Z. Can functional oligosaccharides reduce the risk of diabetes mellitus?

c-MYB- and PGC1a-dependent metabolic switch induced by MYBBP1A loss in renal cancer

The tumor microenvironment may alter the original tumorigenic potential of tumor cells. Under harsh environmental conditions, genetic alterations conferring selective advantages may initiate the growth of tumor subclones, providing new opportunities for these tumors to grow. We performed a genetic loss-of-function screen to identify genetic alterations able to promote tumor cell growth in the absence of glucose. We identified that downregulation of MYBBP1A increases tumorigenic properties under nonpermissive conditions. MYBBP1A downregulation simultaneously activates PGC1α, directly by alleviating direct repression and indirectly by increasing PGC1α mRNA levels through c-MYB, leading to a metabolic switch from glycolysis to OXPHOS and increased tumorigenesis in low-glucose microenvironments. We have also identified reduced MYBBP1A expression in human renal tumor samples, which show high expression levels of genes involved in oxidative metabolism. In summary, our data support the role of MYBBP1A as a tumor suppressor by regulating c-MYB and PGC1α. Therefore, loss of MYBBP1A increases adaptability spanning of tumors through metabolic switch.

Therapy to Obese Type 2 Diabetes Mellitus: How Far Will We Go Down the Wrong Road?

Traditional glucose-lowering chemical agents, including various types of insulin and insulin secretagogues, insulin sensitizers, gliptins, etc., are based on diabetic pathogenesis of insulin resistance (IR) and islet insufficiency. Numerous evidence-based medical studies have shown that these traditional hypoglycemic chemical agents do not provide cardiovascular benefit to patients with type 2 diabetes mellitus (T2DM) and may even increase the risk of all-cause mortality. Based on research evidence published to date, these studies show that overload of energy could increase the incidence and prevalence of T2DM, and reduction in the heat load can significantly reduce the incidence of T2DM. Therefore, the essence of T2DM is heat overload, meaning heat overload is the etiology of obese T2DM. At the same time, results of numerous studies show that heat overloading is the cause of IR. IR and islet dysfunction are protective factors in intervening with heat overload. These drugs, which are based on the mechanisms of IR and islet insufficiency, increase caloric reserve and cause or worsen obesity, which is equivalent to exacerbating the basic etiology and the cardiovascular risk factor of T2DM. Thus, a reasonable strategy for prevention and treatment of obese T2DM appears to promote the negative balance of calories and the elimination of caloric reserves. Chinese herbal medicines can promote negative balance of heat in many aspects, which can bring new hope for prevention and treatment of T2DM.

Chitosan oligosaccharide improves the therapeutic efficacy of sitagliptin for the therapy of Chinese elderly patients with type 2 diabetes mellitus

Sitagliptin improves glycemic control in type 2 diabetes mellitus (T2DM) patients but its side effects are undesirable. Chitosan oligosaccharide (COS) is expected to improve the therapeutic result as a natural product. A total of 200 elderly T2DM patients were evenly assigned into four groups: sitagliptin group (SG), receiving sitagliptin 100 mg/day; COS group (CG), receiving COS 100 mg/day; combination therapy of sitagliptin and COS group (SCG), receiving both sitagliptin and COS 100 mg/day; and placebo group (PG), receiving placebo 100 mg/day. After 42-week therapy, biochemical indices and clinical parameters for the alterations from start points were analyzed. The related molecular mechanism was tested by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot at cell level. Lower risk of hypoglycemia was found in the SCG group when compared with SG and other groups (P<0.05). More patients from the SCG group than other groups attained hemoglobin A1c (HbA1c) reduction >2.5% (P<0.05). Weight reduction of 1.2±0.9, 2.6±0.8, 4.7±1.3, and 0.9±0.6 kg was observed in the patients from SG, CG, SCG, and PG groups, respectively (P<0.05). The combined treatment of COS and sitagliptin presented better therapeutic results by improving insulin sensitivity, lipid profile, adiponectin levels, and glucagon-like peptide 1 and reducing side effects, insulin resistance, HbA1c, body mass index, resistin, tumor necrosis factor (TNF)-α, and C-reactive protein (CRP) (P<0.05). qRT-PCR and Western blot analysis also showed that COS treatment reduced the levels of resistin, TNF-α, and CRP, and increased the level of adiponectin. The combination of COS and sitagliptin provided better glycemic control with fewer side effects and with more weight reduction in the elderly participants with T2DM.

壳寡糖改善TNBS/乙醇法诱导的小鼠溃疡性结肠炎

目的

观察壳寡糖(chitosan oligosaccharide, COS)对2,4,6一三硝基苯磺酸(2,4,6-trinitrobenzene sulfonic acid, TNBS)/乙醇法诱导的小鼠溃疡性结肠炎(ulcerative colitis, UC)的改善作用, 探讨其治疗UC的作用机制.

方法

采用TNBS/乙醇法制备UC小鼠模型, 小鼠随机分3组: 正常组、模型组、COS组. 造模成功后给予干预治疗, 分别在12、24 h处死全部小鼠, 进行一般状态、形态及组织学观察(肉眼观察、显微镜观察); 应用Western blot检测COS组小鼠于COS处理0、12、24 h后对核因子-κB(nuclear factor-κB, NF-κB)表达的影响.

结果

COS组小鼠一般状态较模型组好转. 模型组小鼠结肠黏膜组织损伤肉眼观积分较正常组明显增高(12 h组: 4.5±0.5 vs 0; 24 h组: 4.67±0.47 vs 0), 差异有统计学意义(P<0.05). COS组肉眼积分较模型组明显下降(12 h组: 2.67±0.47 vs 4.5±0.5; 24 h组: 1.83±0.69 vs 4.67±0.47), 差异有统计学意义(P<0.05). COS 12 h组肉眼积分较24 h组差异不显著(2.67±0.47 vs 1.83±0.69), 无统计学意义(P>0.05). 模型组小鼠结肠黏膜组织病理积分较正常组明显升高(12 h组: 8.00±0.63 vs 0; 24 h组: 8.17±0.75 vs 0), 差异有统计学意义(P<0.05). COS组小鼠结肠组织病理积分较模型组明显下降(12 h组: 3.67±0.52 vs 8.00±0.63; 24 h组: 3.83±0.41 vs 8.17±0.75), 差异有统计学意义(P<0.05). COS 12 h组小鼠结肠组织病理积分与COS 24 h组比较差异不显著(3.67±0.52 vs 3.83±0.41), 无统计学意义(P>0.05). COS组小鼠于COS处理12、24 h后NF-κB表达下调, 表明COS抑制NF-κB表达.

结论

COS通过抑制NF-κB的表达对TNBS/乙醇法诱导的UC小鼠有改善作用.