Xu Si

Enhanced anti-obesity effects of complex of resistant starch and chitosan in high fat diet fed rats

This study investigated the interventional effect of resistant starch (RS), chitosan (CS) and chitosan-starch complexes (CL) on blood glucose, lipid composition and oxidative stress in high-fat diet fed rats. Compared with RS or CS alone, CL administration performed more efficiently in controlling body weight and adipose tissue mass, together with an increase in HDL-C concentration, oxidative stress suppression by increasing body antioxidant capacity. Gene expression analysis demonstrated the fatty acid and triglyceride synthesis and metabolism gene SREBP-1, adipocyte differentiation gene PPARγ, cholesterol synthesis gene HMGCR, gluconeogenesis gene GAPDH, were significantly down-regulated, whilst lipid oxidation gene Acox1 and liver functional genes Gstm2, Gclc were up-regulated following CL consumption compared with single RS or CS treatment. Hypolipidemic effects were observed by CL administration and oxidative stress suppression by CL appeared to be associated with elevated antioxidant enzyme activity, increased lipid oxidation, as well as improved fatty acid and cholesterol homeostasis.

Gamma-aminobutyric Acid Enriched Rice Bran Diet Attenuates Insulin Resistance and Balances Energy Expenditure via Modification of Gut Microbiota and Short-Chain Fatty Acids

In this study, gamma-aminobutyric acid (GABA) enriched rice bran (ERB) was supplemented to obese rats to investigate the attenuation of metabolic syndromes induced by high-fat diet. ERB-containing diet stimulated butyrate and propionate production by promoting Anaerostipes, Anaerostipes sp., and associated synthesizing enzymes. This altered short-chain fatty acid (SCFA) distribution further enhanced circulatory levels of leptin and glucagon-like peptide-1, controlling food intake by downregulating orexigenic factors. Together with the enhanced fatty acid β-oxidation highlighted by Prkaa2, Ppara, and Scd1 expression via AMPK signaling pathway and nonalcoholic fatty liver disease pathway, energy expenditure was positively modulated. Serum lipid compositions showed ERB supplement exhibited a more efficient effect on lowering serum sphingolipids, which was closely associated with the status of insulin resistance. Consistently, genes of Ppp2r3b and Prkcg, involved in the function of ceramides in blocking insulin action, were also downregulated following ERB intervention. Enriched GABA and phenolic acids were supposed to be responsible for the health-beneficial effects.

Carboxymethylation of corn bran polysaccharide and its bioactive property

Corn bran polysaccharides were extracted using an ultrasonic-assisted method with a yield of 33.50% and then carboxymethylated. The occurrence of modification was confirmed using Fourier transform infrared spectral analysis. The surface of polysaccharide particles became loosened following the carboxymethylation. The effect of sodium hydroxide concentration, reaction temperature, and the reaction time on the degree of substitution was investigated, and the relationship among the substitution degree, total phenolic content and antioxidant activity were studied. With sodium hydroxide concentration of 6.0 mol L , keeping the reaction temperature of 60 °C and reaction time of 5.0 h, the modified polysaccharides possessed the highest degree of substitution and antioxidant activity. Cell culture model indicated that the carboxymethylated polysaccharide significantly inhibited the proliferation of A549 and HepG-2 cells, and these antitumour characteristics may be associated with the elevated expression of CASP3, CASP8, CASP9, and p53, as well as the significantly decreased expression of Bcl-2 and iNOS genes. The excellent antioxidant capacity and strong antitumour activity of these polysaccharides might provide a potential application as a naturally functional ingredient.

Effect of interactions between starch and chitosan on waxy maize starch physicochemical and digestion properties

ABSTRACT Physicochemical and digestion properties of chitosan modified starch prepared by dry heat treatment were investigated. Starch granule aggregation occurred following the addition of chitosan and this trend was enhanced with increasing chitosan concentration. The size of chitosan modified starch particles was about six times of that of the native starch granules. Interactions between the hydroxyl groups of starch and the amino groups of chitosan was confirmed by Fourier transform infrared spectroscopy analysis. The disappearance of the trough in the Rapid Visco Analyzer profile indicated that the cross-links increased the starch shear resistance. The cross-links between starch and chitosan also reduced starch digestion rate compared to the control (p < 0.001), and this reduction was further enhanced with an increasing chitosan concentration. Additionally, the addition of chitosan altered starch digestion kinetics from one phase to two phases, implying that chitosan modification changed both starch structure and its digestion behaviors.

Gut Microbiome-Induced Shift of Acetate to Butyrate Positively Manages Dysbiosis in High Fat Diet

SCOPE A recent study revealed that the accumulation of gut microbiota-produced acetate (GMPA) led to insulin over-secretion and obesity symptom. To further develop this scientific point, the effect of resistant starch (RS) or exogenous acetate carried by RS (RSA) in the gut on metabolic syndrome is investigated using diet-induced obese rats. METHODS AND RESULTS The metabonomics analysis shows that the gut of rats in the RSA group generate more butyrate in both serum and feces rather than acetate compared to the rats in RS group, indicating the conversion among metabolites, in particular from acetate to butyrate via gut microbiota. Consistently, the gut microbiome uses acetate as a substrate to produce butyrate, such as Coprococcus, Faecalibacterium, Roseburia, and Eubacterium and was highly promoted in RSA group, which further supports the metabolic conversion. This is the first report to reveal the accumulation of gut microbiota-produced butyrate (GMPB) but not GMPA significantly enriched AMPK signaling pathway with reduced expression of lipogenesis-associated genes for suppressing sphingosines and ceramides biosynthesis to trigger insulin sensitivity. CONCLUSION Gut microbiome profile and lipogenesis pathway are regulated by GMPB, which substantially influences energy harvesting in the gut from patterns opposed to GMPA.

Wheat bran with enriched gamma-aminobutyric acid attenuates glucose intolerance and hyperinsulinemia induced by a high-fat diet

In this study, the level of gamma-aminobutyric acid (GABA) in wheat bran was increased to be six times higher through the action of endogenous glutamate decarboxylase compared with untreated bran. The process of GABA formation in wheat bran also led to an increased level of phenolic compounds with enhanced antioxidant capacity 2 times higher than the untreated status. The interventional effect of a diet containing GABA-enriched bran on hyperinsulinemia induced by a high-fat diet (HFD) was investigated in a rat model. The results showed that, when compared with animals fed with HFD-containing untreated bran (NB group), the consumption of HFD-containing GABA-enriched bran (GB group) demonstrated a greater improvement of insulin resistance/sensitivity as revealed by the changes in the homeostatic model assessment for insulin resistance index (HOMA-IR) and the quantitative insulin sensitivity check index (QUICKI). The expression of hepatic genes, cytochrome P450 family 7 subfamily A member 1 (Cyp7a1) and ubiquitin C (Ubc), which are involved in the adipogenesis-associated PPAR signalling pathway, was found to be significantly down-regulated in the GB group compared with the HFD group (P = 0.0055). Meanwhile, changes in the expression of a number of genes associated with lipid metabolism and gluconeogenesis were also noted in the GB group versus the HFD group, but not in the NB group, indicating different regulatory patterns between the two brans in a high-fat diet. More importantly, the analysis of key genes related to glucose metabolism further revealed that the expression of insulin-induced gene 1/2 (Insig-1/2) was increased following GB intervention with a corresponding reduction in phosphoenolpyruvate carboxykinase 1 (Pepck) and glucose-6-phosphatase, catalytic subunit (G6pc) expression, suggesting that glucose homeostasis is greatly improved through the intervention of GABA-enriched bran in the context of a high-fat diet.

Resistant starch attenuates impaired lipid biosynthesis induced by dietary oxidized oil via activation of insulin signaling pathways

The current study found that deep-frying process led to an increased content of oxidized triacylglycerols in canola oil, 3.5 times higher than that of fresh canola oil (not used for frying). A rat model was then used to study the effect of the consumption of oxidized oil on blood lipid compositions and investigate the mechanism involved in lipids metabolism in the liver of rats with resistant starch (RS) intervention. Studies involving animals revealed that the consumption of deep-fried oil (DO group) significantly reduced the level of both triglycerides and high-density lipoprotein cholesterols (P < 0.05) in the serum, indicating that lipid biosynthesis was impaired. However, the supplementation of RS in the DO-containing diet (DO–RS group) attenuated the abovementioned status. The further study found that Insig expression was down-regulated with an increased mRNA expression of PPARα, together with reduced expressions of SREBP1 and downstream lipogenesis-associated genes in the rats of the DO group. In contrast, RS supplementation up-regulated Prkag2 (an AMPK related gene) and Insig-1/2 expressions in the DO–RS group compared to that in the DO group. The activation of the Insig pathway might be one of the key regulators for attenuating the impaired lipid biosynthesis induced by the oxidized fat following RS intervention.

Efecto de las interacciones entre el almidón y el chitosán en las propiedades fisicoquímicas y digestivas del almidón de maíz ceroso

ABSTRACT Physicochemical and digestion properties of chitosan modified starch prepared by dry heat treatment were investigated. Starch granule aggregation occurred following the addition of chitosan and this trend was enhanced with increasing chitosan concentration. The size of chitosan modified starch particles was about six times of that of the native starch granules. Interactions between the hydroxyl groups of starch and the amino groups of chitosan was confirmed by Fourier transform infrared spectroscopy analysis. The disappearance of the trough in the Rapid Visco Analyzer profile indicated that the cross-links increased the starch shear resistance. The cross-links between starch and chitosan also reduced starch digestion rate compared to the control (p < 0.001), and this reduction was further enhanced with an increasing chitosan concentration. Additionally, the addition of chitosan altered starch digestion kinetics from one phase to two phases, implying that chitosan modification changed both starch structure and its digestion behaviors.

Effect of sulfation on the antioxidant properties and in vitro cell proliferation characteristics of polysaccharides isolated from corn bran

ABSTRACT Polysaccharides were extracted from corn bran (CBPs) and then modified by a sulfating reaction to obtain sulfated corn bran polysaccharides (SCBPs). Synthesized sulfated polysaccharides were located in the equatorial bonds of monosaccharide residues. A more orderly and smooth surface of SCBPs was observed. Single factor experiment results showed 2.0 g of aminosulfonic acid, 60 mL of N-dimethylformamide and 2.5 h of reaction time were the optimum conditions for SCBPs preparation. Phenolic content of SCBPs significantly decreased with increasing concentration of aminosulfonic acid, while it increased with increasing DMF concentration and reaction time. SCBPs had higher DPPH, ABTS and iron chelating capacity under the optimum conditions. SCBPs significantly inhibited the proliferation of A549 and HepG2 cell lines, which was associated with the up-regulation at the mRNA expression level of pro-apoptotic genes CASP3, CASP8, CASP9 and reduced expression of p53, gene Bcl-2 and gene iNOS.