Preparation of a novel Grifola frondosa polysaccharide-chromium (III) complex and its hypoglycemic and hypolipidemic activities in high fat diet and streptozotocin-induced diabetic mice

Preparation of a hydrolyzed yeast β-glucan chromium(III) complex and evaluation of its hypoglycemic activity and sub-acute toxicity

Yeast β-glucan (BYG) possesses extremely low solubility that has limited its applications. In this study, we hydrolyzed BYG using snail enzyme to obtain hydrolyzed yeast β-glucan (HBYG) with desirable water solubility and hypoglycemic activity. On the basis of HBYG, HBYG‑chromium(III) complex (HBYG-Cr) was synthesized. The molecular weight of the complex was 4.41 × 104 Da, and the content of trivalent chromium was 8.95 %. The hydroxyl groups of HBYG participated in the coordination and formed the chromium complex. The space conformations of HBYG exhibited remarkable changes after complex formation. HBYG-Cr existed mainly in an amorphous state and presented good dispersibility, and the surface was uneven. The hypoglycemic activity of HBYG-Cr was studied in db/db and C57 mice. The results showed that HBYG-Cr had good hypoglycemic activity. Histopathological studies demonstrated that the liver, kidney, pancreas, and skeletal muscle in the treatment group were significantly improved compared with those in the diabetic model group. The sub-acute toxicity of HBYG-Cr was studied in KM mice and the results indicated that the complex did not cause adverse reactions or toxic side effects. This study broadened the application of yeast β-glucan and provided an important reference for the development of hypoglycemic functional foods and drugs.

Preparation of a Novel Oat β-Glucan-Chromium(III) Complex and Its Hypoglycemic Effect and Mechanism

This study synthesized a novel oat β-glucan (OBG)-Cr(III) complex (OBG-Cr(III)) and explored its structure, inhibitory effects on α-amylase and α-glucosidase, and hypoglycemic activities and mechanism in vitro using an insulin-resistant HepG2 (IR-HepG2) cell model. The Cr(III) content in the complex was found to be 10.87%. The molecular weight of OBG-Cr(III) was determined to be 7.736 × 104 Da with chromium ions binding to the hydroxyl groups of OBG. This binding resulted in the increased asymmetry and altered spatial conformation of the complex along with significant changes in morphology and crystallinity. Our findings demonstrated that OBG-Cr(III) exhibited inhibitory effects on α-amylase and α-glucosidase. Furthermore, OBG-Cr(III) enhanced the insulin sensitivity of IR-HepG2 cells, promoting glucose uptake and metabolism more efficiently than OBG alone. The underlying mechanism of its hypoglycemic effect involved the modulation of the c-Cbl/PI3K/AKT/GLUT4 signaling pathway, as revealed by Western blot analysis. This research not only broadened the applications of OBG but also positioned OBG-Cr(III) as a promising Cr(III) supplement with enhanced hypoglycemic benefits.

Grifola frondosa polysaccharides: A review on structure/activity, biosynthesis and engineering strategies

Polysaccharides are the main polymers in edible fungi Grifola frondosa, playing a crucial role in the physiology and representing the healthy benefits for humans. Recent efforts have well elucidated the fine structures and biological functions of G. frondosa polysaccharides. The recently-rapid developments and increasing availability in fungal genomes also accelerated the better understanding of key genes and pathways involved in biosynthesis of G. frondosa polysaccharides. Herein, we provide a brief overview of G. frondosa polysaccharides and their activities, and comprehensively outline the complex process, genes and proteins corresponding to G. frondosa polysaccharide biosynthesis. The regulation strategies including strain improvement, process optimization and genetic engineering were also summarized for maximum production of G. frondosa polysaccharides. Some remaining unanswered questions in describing the fine synthesis machinery were also pointed out to open up new avenues for answering the structure-activity relationship and improving polysaccharide biosynthesis in G. frondosa. The review hopefully presents a reasonable full picture of activities, biosynthesis, and production regulation of polysaccharide in G. frondosa.

Effects of hazelnut soluble dietary fiber on lipid-lowering and gut microbiota in high-fat-diet-fed rats

Hazelnut is one of the most popular nuts in the world, rich in nutrients and various active substances. In this study, soluble dietary fiber (SDF) was extracted from hazelnut kernels, and its physicochemical properties and absorbability were explored. Hazelnut-SDF exhibited ideal water-holding, oil-holding and swelling capacity, and glucose, cholesterol and cholate absorbing ability. Scanning electron microscopy and fourier transform infrared spectroscopy showed that hazelnut-SDF had typical polysaccharide structure of functional groups. The main monosaccharides were identified as arabinose, rhamnose, xylose, ribose, glucuronic acid, mannose and glucose by gas chromatography-mass spectrometry. In high-fat diet rats, hazelnut-SDF could improve serum lipid parameters, inhibit lipid accumulation in liver and adipocytes, and regulate the expression level of liver lipid synthesis-related genes. It also could adjust intestinal short chain fatty acids, promote the composition and structure of intestinal microbiota, and significantly balance the abundance of Alloprevotella, Fusicatenibacter, Lactobacillus, Roseburia, Ruminococcaceae_UCG-005, Ruminococcaceae_UCG-014 and Clostridiales. The results concluded that oral administration of hazelnut-SDF could alleviate hyperlipidemia and obesity, and might serve as a potential functional food ingredient.

2-Pyridinecarboxaldehyde-Modified Chitosan-Silver Complexes: Optimized Preparation, Characterization, and Antibacterial Activity

The widespread prevalence of infectious bacteria is one of the greatest threats to public health, and consequently, there is an urgent need for efficient and broad-spectrum antibacterial materials that are antibiotic-free. In this study, 2-pyridinecarboxaldehyde (PCA) was grafted onto chitosan (CS) and the modified CS coordinated with silver ions to prepare PCA-CS-Ag complexes with antibacterial activity. To obtain complexes with a high silver content, the preparation process was optimized using single-factor experiments and response surface methodology. Under the optimal preparation conditions (an additional amount of silver nitrate (58 mg), a solution pH of 3.9, and a reaction temperature of 69 °C), the silver content of the PCA-CS-Ag complex reached 13.27 mg/g. The structure of the PCA-CS-Ag complex was subsequently verified using ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, proton nuclear magnetic resonance spectroscopy, and thermogravimetric analysis. Furthermore, three possible complexation modes of the PCA-CS-Ag complex were proposed using molecular mechanics calculations. The results of the antibacterial assay in vitro showed that the PCA-CS-Ag complex exhibited strong antibacterial activity against both Gram-positive and Gram-negative bacteria, exerting the synergistic antibacterial effect of modified chitosan and silver ions. Therefore, the PCA-CS-Ag complex is expected to be developed as an effective antibacterial material with promising applications in food films, packaging, medical dressings, and other fields.

Structural Characterization of Zinc-Sucrose Complex and Its Ability to Promote Zinc Absorption in Caco-2 Monolayer Cells and Mice

Sucrose emerges as a metal-ion chelating agent with excellent stability that may increase metal-ion absorption. This study aimed to characterize the structure of zinc-sucrose complex and investigate its ability to promote zinc absorption in Caco-2 monolayer cells and mice. Based on the results of the inductively coupled plasma emission spectrometer (ICP-ES), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), and Fourier transform infrared spectroscopy (FT-IR), it can be inferred that zinc and sucrose were chelated at a 1:1 ratio, with the hydroxyl groups playing a significant role. The Caco-2 monolayer cell model revealed that zinc-sucrose complex increased the amount of zinc uptake, retention, and transport in a dose- and time-dependent manner. Through the upregulation of genes and proteins for ZIP4, MT1, and DMT1, treatment with zinc-sucrose complex improved the proportion of absorbed zinc utilized for transport compared to ZnCl2 (26.21 ± 4.96 versus 8.50 ± 1.51%). Pharmacokinetic analysis of mice confirmed the zinc absorption-promoting effect of zinc-sucrose complex, as indicated by the considerably higher serum zinc level (4.16 ± 0.53 versus 2.56 ± 0.45 mg/L) and intestinal ZIP4, MT1, and DMT1 gene expression than ZnCl2. Further treatment of different zinc channel inhibitors and CETSA demonstrated the direct interaction of zinc-sucrose complex with ZIP4 protein and ZIP4-mediated cellular transport of zinc-sucrose complex. These findings provide a novel insight into the zinc absorption-promoting mechanism of zinc-sucrose complex, which could be used as an ingredient in functional foods to treat zinc deficiency.

Preparation and structural characterization of acid-extracted polysaccharide from Grifola frondosa and antitumor activity on S180 tumor-bearing mice

In this study, an acid-extracted polysaccharide (GFP-A) was extracted from the fruiting bodies of G. frondosa with 1 % hydrochloric acid solution. Our study aimed to imitate the processes of digestion, absorption and antitumor activities of polysaccharides from G. frondosa under the acid environment of stomach in the body. The preliminary structural analysis resulted that GFP-A (about 1.10 × 10⁶ Da) was a neutral polysaccharide composed of xylose, mannose, glucose (molar ratio: 0.12:1.00:6.98) with α-type glycosidic linkages. Additionally, antitumor activities on S180 tumor-bearing mice showed that GFP-A could effectively inhibit the growth of S180 tumor cells by protecting immune organs (thymus and spleen), activating immune cells (NK cells, lymphocytes and macrophages), upregulating the secretion of serum cytokines (TNF-α, IL-2 and IFN-γ) in vivo. H & E staining and cell cycle determination further demonstrated that GFP-A could induce S180 tumor cells apoptosis via arresting them in G₁ phase. These results demonstrated that GFP-A could provide a theoretical basis for treatment of cancer.

Mushroom polysaccharides with potential in anti-diabetes: Biological mechanisms, extraction, and future perspectives: A review

Diabetes mellitus (DM) is a global health threat. Searching for anti-diabetic components from natural resources is of intense interest to scientists. Mushroom polysaccharides have received growing attention in anti-diabetes fields due to their advantages in broad resources, structure diversity, and multiple bioactivities, which are considered an unlimited source of healthy active components potentially applied in functional foods and nutraceuticals. In this review, the current knowledge about the roles of oxidative stress in the pathogenesis of DM, the extraction method of mushroom polysaccharides, and their potential biological mechanisms associated with anti-diabetes, including antioxidant, hypolipidemic, anti-inflammatory, and gut microbiota modulatory actions, were summarized based on a variety of in vitro and in vivo studies, with aiming at better understanding the roles of mushroom polysaccharides in the prevention and management of DM and its complications. Finally, future perspectives including bridging the gap between the intervention of mushroom polysaccharides and the modulation of insulin signaling pathway, revealing structure-bioactivity of mushroom polysaccharides, developing synergistic foods, conducting well-controlled clinical trials that may be very helpful in discovering valuable mushroom polysaccharides and better applications of mushroom polysaccharides in diabetic control were proposed.

Therapeutic potential of non-starch polysaccharides on type 2 diabetes: from hypoglycemic mechanism to clinical trials

Non-starch polysaccharides (NSPs) have been reported to exert therapeutic potential on managing type 2 diabetes mellitus (T2DM). Various mechanisms have been proposed; however, several studies have not considered the correlations between the anti-T2DM activity of NSPs and their molecular structure. Moreover, the current understanding of the role of NSPs in T2DM treatment is mainly based on in vitro and in vivo data, and more human clinical trials are required to verify the actual efficacy in treating T2DM. The related anti-T2DM mechanisms of NSPs, including regulating insulin action, promoting glucose metabolism and regulating postprandial blood glucose level, anti-inflammatory and regulating gut microbiota (GM), are reviewed. The structure-function relationships are summarized, and the relationships between NSPs structure and anti-T2DM activity from clinical trials are highlighted. The development of anti-T2DM medication or dietary supplements of NSPs could be promoted with an in-depth understanding of the multiple regulatory effects in the treatment/intervention of T2DM.

Traditional Chinese Medicine Formula Jian Pi Tiao Gan Yin Reduces Obesity in Mice by Modulating the Gut Microbiota and Fecal Metabolism

The current study employed the high-fat diet (HFD) induced murine model to assess the relationship between the effect of Jian Pi Tiao Gan Yin (JPTGY) and the alterations of gut microbiota and fecal metabolism. C57BL/6 mice were used to establish an animal model of obesity via HFD induce. Serum biochemical indicators of lipid metabolism were used to evaluate the pharmacodynamics of JPTGY in obese mice. Bacterial communities and metabolites in the feces specimens from the controls, the Group HFD, and the JPTGY-exposed corpulency group were studied by 16s rDNA genetic sequence in combination with liquid chromatography-mass spectrometry (LC-MS) based untargeted fecal metabolomics techniques. Results revealed that JPTGY significantly decreased the levels of total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and elevated high-density lipoprotein cholesterol (HDL-C). Moreover, JPTGY could up-regulate the abundance and diversity of fecal microbiota, which was characterized by the higher phylum of proteobacteria. Consistently, at the genus levels, JPTGY supplementation induced enrichments in Lachnospiraceae NK4A136 group, Oscillibacter, Turicibacter, Clostridium sensu stricto 1, and Intestinimonas, which were intimately related to 14 pivotal fecal metabolins in respond to JPTGY therapy were determined. What is more, metabolomics further analyses show that the therapeutic effect of JPTGY for obesity involves linoleic acid (LA) metabolism paths, alpha-linolenic acid (ALA) metabolism paths, glycerophospholipid metabolism paths, arachidonic acid (AA) metabolism paths, and pyrimidine metabolism paths, which implied the potential mechanism of JPTGY in treating obesity. It was concluded that the linking of corpulency phenotypes with intestinal flora and fecal metabolins unveils the latent causal link of JPTGY in the treatment of hyperlipidemia and obesity.

Structural Characterization and Hypoglycemic Activity of a Novel Pumpkin Peel Polysaccharide-Chromium(III) Complex

The aim of our study was to synthesize a pumpkin peel polysaccharide (PPP)-Cr(III) complex and investigate its hypoglycemic activity. Firstly, a novel PPP-Cr(III) complex with a Cr content of 23.77 mg/g was synthesized and characterized. Physicochemical characterization indicated that PPP-Cr(III) had some changes in chemical composition, monosaccharide composition, and morphological structure compared with PPP. The molecular weights of PPP-Cr(III) and PPP were 1.398 × 106 g/mol and 3.386 × 106 g/mol, respectively, showing a lower molecular weight after the introduction of Cr(III). Fourier transform infrared spectroscopy showed that a new characteristic absorption peak of Cr-O appeared at 534 cm-1 in PPP-Cr(III), indicating that Cr(III) was successfully complexed with PPP. Secondly, the hypoglycemic activity of PPP-Cr(III) based on α-glucosidase inhibitory and insulin resistance (IR)-HepG2 cells was evaluated. Compared with PPP, PPP-Cr(III) exhibited a more significantly α-glucosidase inhibitory activity. The IR-HepG2 cells confirmed an obvious increase in glucose consumption. Western blot analysis demonstrated that the treated IR-HepG2 cells were able to increase the protein levels of p-AMPK and p-GSK-3β, indicating that IR-HepG2 cells exerted hypoglycemic activity via the AMPK/GSK-3β signaling pathway. These results suggested that PPP-Cr(III) had good hypoglycemic activity, which could provide theoretical support for the development of novel hypoglycemic products.

Synthesis, Characterization, and Bioactivities of Polysaccharide Metal Complexes: A Review

Natural polysaccharides are critical to a wide range of fields (e.g., medicine, food production, and cosmetics) for their various remarkable physical properties and biological activities. However, the bioactivities of naturally acquired polysaccharides may be unsatisfactory and limit their further applications. It is generally known that the chemical structure exhibited by polysaccharides lays the material basis for their biological activities. Accordingly, possible structural modifications should be conducted on polysaccharides for their enhancement. Recently, polysaccharides complexed with metal ions (e.g., Fe, Zn, Mg, Cr, and Pt) have been reported to be possibly used to improve their bioactivities. Moreover, since the properties exhibited by metal ions are normally conserved, polysaccharides may be endowed with new applications. In this review, the synthesis methods, characterization methods, and bioactivities of polysaccharide metal complexes are summarized specifically. Then, the application prospects and limitations of these complexes are analyzed and discussed.

Hypolipidemic effect of chromium-modified enzymatic product of sulfated rhamnose polysaccharide from Enteromorpha prolifera in type 2 diabetic mice

Sulfated rhamnose polysaccharide (SRP) derived from Enteromorpha prolifera is a metal-ion chelating agent that could potentially be used to treat diabetes. The aim of our study was to determine the effect of a variant of SRP on DIABETES. First, we synthesized and characterized SRPE-3 chromium(III) [SRPE-3-Cr(III)] complex using an enzymatic method. The maximum chelation rate was 18.2% under optimal chelating conditions of pH 6.0, time 4 h, and temperature 60 °C. Fourier transform infrared spectroscopy results showed important sites for Cr(III)-binding were O-H and C=O groups. We then studied the hypolipidemic effects of SRPE-3-Cr(III) on type 2 diabetes mellitus (T2DM) induced by a high-fat, high-sucrose diet (HFSD). Decreased blood glucose content, body fat ratio, serum TG, TC, LDL-C, and increased serum HDL-C were observed after treatment with SRPE-3-Cr(III). In addition, SRPE-3-Cr(III) significantly reduced leptin, resistin, and TNF-α levels, and increased adiponectin contents relative to T2DM. Histopathology results also showed that SRPE-3-Cr(III) could alleviate the HFSD-lesioned tissues. SRPE-3-Cr(III) also improved lipid metabolism via a reduction in aspartate aminotransferase, alanine aminotransferase, fatty acid synthase, and acetyl-CoA carboxylase activities in the liver. SRPE-3-Cr(III) at low doses exhibited better lipid-lowering activities, hence, could be considered to be a novel compound to treat hyperlipidemia and also act as an anti-diabetic agent.

A comprehensive review on polysaccharides with hypolipidemic activity: Occurrence, chemistry and molecular mechanism

Currently, research on natural products is facing challenging future in various aspects. A large group of natural polysaccharides such as β-glucan, cellulose, hemicellulose, chitin, pectin, agaropectin, heteroglycans, lignins, hydrocolloids, homopolysaccharides, heteropolysaccharides were studied extensively for their various therapeutical potential. Several research works have already demonstrated those polysaccharides has tremendous health benefits, and found to exhibit anticancer, antiviral, immunomodulatory, antimicrobial, anticoagulant, anti-inflammatory, antidiabetic, antioxidant and antitumor activities. Different mushroom, plant, fungus, algae, vegetables, microalgae etc. are some important source of several polysaccharide macromolecules such as glucans, ulvan A, ulvan B, fucoidan, rhamnan sulfate, laminarin sulfate, agar, alginate, heteroglycans. Earlier research work demonstrated that natural polysaccharides have the highest ability to carry biological properties along with some biopolymers like as proteins and nucleic acids due to their structural variability. The preventive effect of these biomacromolecules was extensively studied, especially their beneficial effect on chronic metabolic conditions like dyslipidemia and related disorders. Dyslipidemia is a serious metabolic disorder associated with coronary heart disease, coronary artery diseases, hypercholesterolemia, atherosclerosis, etc. Dietary natural polysaccharides could play an important role in the management and prevention of dyslipidemia. Polysaccharides from natural sources mainly sulfated polysaccharides exhibited predominant lipid-lowering and cholesterol-lowering activities through different mechanisms. Polysaccharides isolated from different edible plants, vegetables, plant, algae, mushroom with higher biological activities, particularly hypolipidemic activity were highlighted in this paper, in a way for their futuristic therapeutic application. This review aims to comprehensively discuss overall advances in hypolipidemic activity of polysaccharides, including their sources, structural characteristic and chemistry, biological activity and their probable mode of action.

Antidiabetic potential of polysaccharides from Brasenia schreberi regulating insulin signaling pathway and gut microbiota in type 2 diabetic mice

This study aimed to investigate the hypoglycemic activities and gut microbial regulation effects of polysaccharides from Brasenia schreberi (BS) in diabetic mice induced by high-fat diet and streptozotocin. Our data indicated that BS polysaccharides not only improved the symptoms of hyperglycemia and relieved metabolic endotoxemia-related inflammation but also optimized the gut microbiota composition of diabetic mice with significantly decreased Firmicutes/Bacteroidetes ratios. More importantly, altered gut microbiota components may affect liver glycogen and muscle glycogen by increasing the mRNA expression of phosphatidylinositol-3-kinase (PI3K) and protein kinase B (Akt) in the liver of mice through modulated the abundance of beneficial bacteria (Lactobacillus). Altogether, our findings, for the first time, demonstrate that BS polysaccharides may be used as a beneficial probiotic agent that reverses gut microbiota dysbiosis and the hypoglycemic mechanisms of BS polysaccharides may be related to enhancing the abundance of Lactobacillus to activate PI3K/Akt-mediated signaling pathways in T2DM mice.

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Brasenia schreberi polysaccharides ameliorated hyperglycemia and dyslipidemia in mice.

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The polysaccharides regulated glucose metabolism through activating PI3K-Akt pathway.

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The polysaccharides modulated gut microbiota profile of diabetic mice.

Metal-ion-binding properties of ulvan extracted from Ulva clathrata and structural characterization of its complexes

The acidic polysaccharide ulvan extracted from the cell wall of the green algae Ulva is a good ligand for metal ions. Therefore, the adsorption properties of the U. clathrata derived ulvan toward Ca(II), Zn(II), Co(II), Cu(II), and Cr(III) were investigated in this study. The results demonstrate that ulvan exhibited good metal ion adsorption capacity at pH 7 and 50 °C. These adsorption processes can largely be explained by the Freundlich isotherm model and the pseudo-second-order kinetic model. The order of the adsorption capacity and affinity is as follows: Cr(III) > Cu(II) > Zn(II) ≈ Co(II) > Ca(II) and Cr(III) > Zn(II) > Co(II) ≈ Cu(II) > Ca(II). Furthermore, structural characterization revealed that the hydroxyl and carboxyl groups were the main functional groups involved in metal ion binding. Unlike the divalent metal ions, Cr(III) can trigger crosslinking of the ulvan chains, and its adsorption capacity was approximately 4.0 mmol/g.

Spirulina platensis polysaccharides attenuate lipid and carbohydrate metabolism disorder in high-sucrose and high-fat diet-fed rats in association with intestinal microbiota

This study aimed to evaluate the possibility that Spirulina platensis crude polysaccharides may ameliorate the lipid and carbohydrate metabolism disorder, including obesity, hyperlipidemia, hyperglycemia, hepatic steatosis, and gut dysbiosis. The results showed Spirulina platensis crude polysaccharides could improve body weight, serum/liver lipid and carbohydrate indexes, and liver antioxidant parameters in high-sucrose and high-fat diet (HFD)-fed rats, which were accompanied by regulated liver mRNA expressions involved in lipid and carbohydrate metabolism disorder. In addition, SPLP intervention significantly decreased cecal level of propionic acid in HFD-fed rats. Notably, the SPLP could alter the relative abundance of Firmicutes, Bacteroides, Proteobacteria, and Actinobacteria at phylum levels. Based on Spearman's rank correlation coefficient, serum/liver lipid and carbohydrate profiles were found significantly positively correlated with genera Romboutsia, Allobaculum, Blautia, Phascolarctobacterium, Bifidobacterium, Coprococcus, Turicibacter, Erysipelotrichaceae_unclassified, Olsenella, Escherichia/Shigella, Coprobacillus, Lachnospiracea incertae, and Lactobacillus, but strongly negatively correlated with genera Atopostipes, Flavonifractor, Porphyromonadaceae_unclassified, Barnesiella, Oscillibacter, Paraprevotella, Jeotgalicoccus, Corynebacterium, Alloprevotella and Bacteroides. It was concluded that oral administration of SPLP could remarkably ameliorate the lipid and carbohydrate metabolism disorder and significantly modulate the intestinal microbiota in HFD-fed rats.

The role of Rho1 gene in the cell wall integrity and polysaccharides biosynthesis of the edible mushroom Grifola frondosa

Grifola frondosa polysaccharides, especially β-glucans, showed the significant antitumor, hypoglycemic, and immune-stimulating activities. In the present study, a predominant regulatory subunit gfRho1p of β-1,3-glucan synthase in G. frondosa was identified with a molecular weight of 20.79 kDa and coded by a putative 648-bp small GTPase gene gfRho1. By constructing mutants of RNA interference and over-expression gfRho1, the roles of gfRho1 in the growth, cell wall integrity and polysaccharide biosynthesis were well investigated. The results revealed that defects of gfRho1 slowed mycelial growth rate by 22% to 33%, reduced mycelial polysaccharide and exo-polysaccharide yields by 4% to 7%, increased sensitivity to cell wall stress, and down-regulated gene transcriptions related to PKC-MAPK signaling pathway in cell wall integrity. Over-expression of gfRho1 improved mycelial growth rate and polysaccharide production of G. frondosa. Our study supports that gfRho1 is an essential regulator for polysaccharide biosynthesis, cell growth, cell wall integrity and stress response in G. frondosa.

The Interactive Effect of High Doses of Chromium(III) and Different Iron(III) Levels on the Carbohydrate Status, Lipid Profile, and Selected Biochemical Parameters in Female Wistar Rats

The aim of the study was to evaluate the main and interactive effects of chromium(III) propionate complex (Cr3) supplementation and different iron supply on the carbohydrate metabolism, lipid profile and other selected biochemical parameters of rats. The experiment was carried out in a two-factor design, in which rats were fed a diet with different proportions of Fe(III) and Cr(III) for six weeks. Fifty-four healthy female Wistar rats were divided into nine experimental groups with different Fe(III) levels, i.e. adequate-control group (45 mg/kg)-100% recommended daily dietary dose of Fe for rodents, deficient (5 mg/kg) and oversupply (180 mg/kg-400%). At the same time they were supplemented with Cr(III) of doses 1 (adequate), 50 and 500 mg/kg of diet. The activity and concentrations of most biochemical parameters were measured with standard enzymatic, kinetic, and colorimetric methods. HOMA-IR and QUICKI indexes were calculated according to appropriate formulas. It was found that there was an interactive effect of high Cr(III) doses and different Fe(III) levels in the diet on the carbohydrate metabolism and insulin resistance indexes. The presented results suggested that iron deficient diet fed animals led to insulin resistance; however, an effect is attenuated by Cr(III) supplementation at high doses. There were no significant changes in the rats' lipid profile (except for the high density lipoprotein cholesterol (HDL-C) level) and most of the other biochemical parameters, such as the leptin, aspartate aminotransferase (AST), alanine transaminase (ALT), total protein (TP), creatinine (Crea) and the urea (BUN) concentrations. The study proved that the Cr(III) supplementation, independently and in combination with diversified Fe(III) content in the diet, affected the carbohydrate metabolism and insulin resistance indexes but did not affect lipid profile and most of the other biochemical parameters in healthy rats. The findings proved the role of Fe and Cr(III) and their interactions on disturbances carbohydrates metabolism.

UDP-glucose pyrophosphorylase gene affects mycelia growth and polysaccharide synthesis of Grifola frondosa

To elucidate potential roles of UDP-glucose pyrophosphorylase (UGP) in mycelial growth and polysaccharide synthesis of Grifola frondosa, a putative 2036-bp UDP-glucose pyrophosphorylase gene gfugp encoding a 53.17-kDa protein was cloned and re-annotated. Two dual promoter RNA silencing vectors of pAN7-iUGP-P-dual and pAN7-iUGP-C-dual were constructed to down-regulate gfugp expression by targeting its promoter or conserved functional sequences, respectively. Results showed that silence of gfugp promoter sequence had a higher down-regulating efficiency with slower mycelial growth and polysaccharide production than those of conserved sequence. The monosaccharide compositions/percentages of mycelial and exo-polysaccharides significantly changed with the increase of galactose and arabinose contents possibly due to block of UDP-glucose supply by gfugp silence and alteration of sugar metabolism via up-regulation of UDP-glucose-4-epimerase (gfuge) and UDP-xylose-4-epimerase (gfuxe) transcription. Our findings would provide a reference to know the biosynthesis pathway of mushroom polysaccharides and improve their production by metabolic regulation.

Hypolipidemic and Hypoglycaemic Effect of Wholemeal Bread with Amaranth (Amaranthus dubius Mart. ex Thell.) on Sprague Dawley Rats

The effect of consuming breads made with wheat flour and Amaranth (Amaranthus dubius Mart. ex Thell.) wholemeal flour on Sprague Dawley rats with hyperlipidaemia and hyperglycaemia induced through feeding was studied. Four diets were provided: control (CD: Ratarina^®), commercial bread (CBD), bread with 100 g·kg⁻¹ (ABD10) and 200 g·kg⁻¹ (ABD20) amaranth flour. Zoometric and blood chemistry parameters were measured before and after consuming the diets. A completely random factorial design of 2 × 4 × 2 was used. The factors were blood lipids and glucose level (normal, N and elevated, E), diet (CD, CBD, ABD10 and ABD20) and sex (female, F and male, M). The rats consuming ABD10 and ABD20 diets presented the lowest glucose values, although with no differences (p > 0.05) between the groups of elevated blood lipids and glucose rats (E). Triglyceride concentrations decreased in ABD10 and ABD20 treatments in comparison with CD, elevated blood lipids and glucose (E) rats, while ABD10 rats showed lower total cholesterol level than normal (N) rats. The high-density lipoprotein cholesterol values increased in the ABD10 and ABD20 groups (p < 0.05), while it did lower for very low-density lipoprotein cholesterol and cardiac risk index (p < 0.05). In ABD10 and ABD20 treatments, the abdominal circumference decreased in both sexes (p < 0.05) between weeks 23 and 31. In conclusion, consumption of bread with amaranth improved lipid profiles of rats and could help to prevent metabolic and cardiovascular diseases.

Relationship between heat treatment on structural properties and antitumor activity of the cold-water soluble polysaccharides from Grifola frondosa

Grifola frondosa is a basidiomycete fungus with potential biomedical applications owing to the presence of bioactive polysaccharides. The activities of polysaccharides are influenced by many factors, particularly temperature; however, the optimal temperature and conditions for preparation of polysaccharides from this organism have not yet been determined. Therefore, in this study, cold-water soluble polysaccharides from Grifola frondosa were extracted at 4 °C (GFP-4) and purified. GFP-4-30, GFP-4-60 and GFP-4-90 were obtained from GFP-4 after treatment at 30 °C, 60 °C, or 90 °C, respectively, for 6 h. MTT results showed that GFP-4 had the highest inhibitory effects on the proliferation of SPC-A-1 cells in vitro. High-performance gel permeation chromatography results demonstrated that the molecular weight of GFP-4 was 1.05 × 10⁶ Da and that GFP-4-30, GFP-4-60, and GFP-4-90 showed different levels of degradation and generated small molecule sugars. Fourier transform infrared spectroscopy, gas chromatography, and nuclear magnetic resonance results indicated that GFPs mainly consisted of α-D-Galp, α-D-Manp and α-D-Glcp. Periodate oxidation, Smith degradation, and methylation results showed that the backbones of the molecules consisted of 1,3-linked-Galp. After heat treatment, percentages of (1 → 3,4) α-D-Galp in heat-treated polysaccharides were obviously decreased, indicating their lower branching degree, and resulting in weaker antitumor effects. Overall, our findings demonstrated changes in the structure-activity relationships of GFP-4 after heat treatment and provided a theoretical basis for the application of GFP-4 in the food and drug industries.

Effects of chromium supplementation on body composition, human and animal health, and insulin and glucose metabolism

PURPOSE OF REVIEW

Chromium(III) has been proposed to have a nutritional or pharmacological role in changing body composition and improving symptoms of insulin resistance, type 2 diabetes, and related conditions although the mode of action of Cr(III) at a molecular level has failed to be elucidated. This review details the current status of studies into Cr(III) supplementation.

RECENT FINDINGS

Clinical trials, meta-analyses and systematic reviews have failed to demonstrate clinically significant effects from Cr(III) supplementation on body composition or symptoms of insulin resistance and related conditions in humans and farm animals. Although new Cr(III) supplements continue to appear in the scientific literature, studies have failed to elucidate the mechanism of chromium action at a molecular level. Conflicting results on a role of transferrin in Cr(III) transport and detoxification have appeared.

SUMMARY

Cr(III) supplementation cannot currently be recommended in humans or farm animals. Further studies are required to probe the mechanism of Cr(III) action in increasing insulin sensitivity and glucose uptake in rodent models of insulin resistance and diabetes, with particular attention being turned to a potential role of transferrin in Cr(III) transport and detoxification.