Wenting Shang

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.

Characterization of endogenous antioxidant attributes and its influence on thermal stability of canola oil

Difference in thermal stability of two commercially available canola oils prepared by either expeller-extraction (EE) or solvent-extraction (SE) method was investigated. After 5 days consecutive deep-fry, content of oxidized-triacylglycerols (oxTAGs) in SE oil increased by 250.0% compared to its original status. However, 62.5% increase of oxTAGs in EE oil occurred, indicating that EE oil exhibits superior thermal stability to SE oil. Antioxidant capacity of EE oil was highly retained and loss rate of tocopherols in EE oil was much slower than in SE oil during deep-fry. Lipidomics showed that although there was no significant difference in molecular profile of either triacylglycerols or diacylglycerols between two oils, EE oil was characterized with 19 times higher phosphatidylcholine contents than SE oil. Considering no difference in antioxidant capacity between the two oils in their original status, it is proposed that synergetic mechanism is simultaneously initiated by antioxidant compounds and phosphatidylcholines, which plays key roles for maintaining better thermo-stability of vegetable oil during deep-fry.

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.

Functional enrichment of mannanase-treated spent brewer yeast

ABSTRACT In this study, the effect of Bacillus amyloliquefaciens-produced β-mannanase on the nutrient diffusion (release) and antioxidant activity of spent brewer yeast (SBY) was investigated. Three pretreatments were performed: (1) autolysis at 50°C for 24 h; (2) autolysis at 50°C for 24 h, with the addition of β-mannanase during the autolysis; (3) autolysis at 50°C for 24 h, and the β-mannanase was added for another 12 h treatment. The pretreatments with the addition of β-mannanase caused significant cell wall degradation, markedly increased the yield of SBY extracts. More importantly, this study found that polysaccharides were degraded to be oligosaccharides with a considerable reduction in molecular weights. Meanwhile, pretreatment with the enzyme also exhibited a higher antioxidant activity in SBY extract compared to autolysis itself. The current study indicated that pretreatment (3) had a better effect than pretreatment (2) in terms of improving in antioxidant activity in SBY extract. These improved characteristics of SBY extracts isolated through enzymatic treatment appear to show promising features for their prospective use as natural functional agents.

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.

Functional peptides derived from rice bran proteins

ABSTRACT Rice bran has been predominantly used in the feed industry, and only recently it has attracted greater attention in terms of human nutrition with increasing knowledge of its bioactivity. A growing interest is the analysis of physiologically active peptides derived from rice bran proteins. In this paper, the bioactivities of rice bran proteins hydrolysates and peptides are reviewed based on recent studies. These enzymatic hydrolysates and peptides exert various biological activities including antioxidant, antidiabetic, anticancer and inhibitory activity for angiotensin converting enzyme (ACE), which may ultimately prevent certain chronic diseases. Nevertheless, these functionalities can be highly associated with their corresponding structural characteristics, in particular specific sequences and molecular weight distribution. This article may facilitate the expansion of the prospective applications of the bioactive peptides in a number of fields and provide some clues of the relationship between peptides structure and functionality for future research.