Arabinoxylan activates lipid catabolism and alleviates liver damage in rats induced by high-fat diet

Lipid metabolism regulation by dietary polysaccharides with different structural properties

Lipid metabolism plays an important role in energy homeostasis maintenance in response to stress. Nowadays, hyperlipidemia-related chronic diseases such as obesity, diabetes, atherosclerosis, and fatty liver pose significant health challenges. Dietary polysaccharides (DPs) have gained attention for their effective lipid-lowering properties. This review examines the multifaceted mechanisms that DPs employ to lower lipid levels in subjects with hyperlipidemia. DPs could directly inhibit lipid intake and absorption, promote lipid excretion, and regulate key enzymes involved in lipid metabolism pathways, including triglyceride and cholesterol anabolism and catabolism, fatty acid oxidation, and bile acid synthesis. Additionally, DPs indirectly improve lipid homeostasis by modulating gut microbiota composition and alleviating oxidative stress. Moreover, the lipid-lowering mechanisms of particular structural DPs (including β-glucan, pectin, glucomannan, inulin, arabinoxylan, and fucoidan) are summarized. The relationship between the structure and lipid-lowering activity of DPs is also discussed based on current researches. Finally, potential breakthroughs and future directions in the development of DPs in lipid-lowering activity are discussed. The paper could provide a reference for further exploring the mechanism of DPs for lipid regulations and utilizing DPs as lipid-lowering dietary ingredients.

Wheat bran arabinoxylans: Chemical structure, extraction, properties, health benefits, and uses in foods

Wheat bran (WB) is a well-known and valuable source of dietary fiber. Arabinoxylan (AX) is the primary hemicellulose in WB and can be isolated and used as a functional component in various food products. Typically, AX is extracted from the whole WB using different processes after mechanical treatments. However, WB is composed of different layers, namely, the aleurone layer, pericarp, testa, and hyaline layer. The distribution, structure, and extractability of AX vary within these layers. Modern fractionation technologies, such as debranning and electrostatic separation, can separate the different layers of WB, making it possible to extract AX from each layer separately. Therefore, AX in WB shows potential for broader applications if it can be extracted from the different layers separately. In this review, the distribution and chemical structures of AX in WB layers are first discussed followed by extraction, physicochemical properties, and health benefits of isolated AX from WB. Additionally, the utilization of AX isolated from WB in foods, including cereal foods, packaging film, and the delivery of food ingredients, is reviewed. Future perspectives on challenges and opportunities in the research field of AX isolated from WB are highlighted.

Structural characteristics and biological activities of polysaccharides from barley: a review

Barley (Hordeum vulgare L.) is rich in starch and non-starch polysaccharides (NSPs), especially β-glucan and arabinoxylan. Genotypes and isolation methods may affect their structural characteristics, properties and biological activities. The structure-activity relationships of NSPs in barley have not been paid much attention. This review summarizes the extraction methods, structural characteristics and physicochemical properties of barley polysaccharides. Moreover, the roles of barley β-glucan and arabinoxylan in the immune system, glucose metabolism, regulation of lipid metabolism and absorption of mineral elements are summarized. This review may help in the development of functional products in barley.

Excessive dietary soluble arabinoxylan impairs the intestinal physical and immunological barriers via activating MAPK/NF-κB signaling pathway in rainbow trout (Oncorhynchus mykiss)

Arabinoxylan (AX) has been deemed as an antinutritional factor, but limited information has addressed the effects of dietary AX on intestinal health of fish. The present study investigated the effects of dietary AX on intestinal mucosal physical and immunological barriers of rainbow trout (Oncorhynchus mykiss). Five isoproteic and isolipidic experimental diets (AXE, AX0, AX2.5, AX5 and AX10) were formulated to contain 0.03% arabinoxylanase as well as 0%, 2.5%, 5% and 10% AX, respectively. Each diet was randomly distributed to triplicate groups of 35 juvenile (average weight 3.14 ± 0.02 g) per tank in a rearing system maintained at 17 ± 1 °C for 9 weeks. Dietary AX supplementation regardless of inclusion levels significantly (P < 0.05) depressed the growth performance and feed utilization. The plasma endothelin-1 and d-lactic acid contents as well as diamino oxidase activity were significantly higher in fish fed diet AX10 compared to fish fed diet AX0. Dietary inclusion of 5-10% AX resulted in decreased intestinal villus height, goblet cell number and desmosome density, increased crypt depth, short and irregular microvilli, widened intercellular space; down-regulated the mRNA levels of occludin in hindgut, claudin3 and ZO-1 in foregut and midgut, but up-regulated the mRNA levels of claudin12 and claudin15 in midgut as well as claudin23 in foregut, midgut and hindgut. Furthermore, dietary 5-10% AX supplementation decreased the midgut and hindgut complement 3, complement 4 and sIgT contents as well as the midgut IgM and hindgut IL-10 contents. Conversely, the hindgut TNF-α and IL-6 contents increased with the rising dietary AX level. RT-qPCR demonstrated that the pro-inflammatory cytokines (IL-1β, IL-6, IL-8, IL-12β, IFN-γ, and TNF-α) and pIgR mRNA levels in midgut and hindgut were up-regulated by dietary AX inclusion of 5-10% AX. Meanwhile, the mRNA levels of p38 MAPK, IκBα, and NF-κB p65 in midgut and hindgut raised gradually with the increasing dietary AX content. The Western blot results showed that the protein expression levels of p38 MAPK and NF-κB generally increased with the rising dietary AX content. Dietary treatment with 0.03% arabinoxylanase did not affect the growth performance and intestinal health of rainbow trout (P > 0.05). In conclusion, excessive dietary AX inclusion (5-10%) increased the intestinal permeability and induced the intestinal inflammatory response via activating MAPK/NF-κB signaling pathway, and ultimately damaged the intestinal barrier function of rainbow trout.

Is there any hepatic impact associated with rice bran arabinoxylan compound supplementation? A systematic review and dose-response meta-analysis of randomized controlled trials

BACKGROUND & AIMS

Rice Bran Arabinoxylan Compound (RBAC) results from an enzymatic modification of rice bran, which is reported to have immunomodulatory, anti-oxidant, and anti-inflammatory effects by regulating the production of pro-inflammatory cytokines. The current systematic review and meta-analysis aimed to determine the hepatic adverse effects of RBAC by assessing the effect through liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST).

METHODS

In the present study, the Medline (PubMed), Web of Sciences, and Scopus databases were searched for relevant publications from the beginning to October 2022. The meta-analysis was based on the Mixed effect model to generate the mean effect sizes in weighted mean differences (WMD) and the 95% confidence intervals (95%CI). The heterogeneity was assessed using the Cochrane Chi-squared test, and the analysis of Galbraith plots was applied.

RESULTS

Subgroup meta-analysis on five eligible randomized controlled trials (n = 239) showed a significant decrease in serum AST regarding RBAC supplementation in powder form (WMD (95%CI) = -3.52 (-5.62, -1.42) U/L; P-value = 0.001, I2 (%) = 46.9; P heterogeneity = 0.170), three months and more supplementation duration (WMD (95%CI) = -3.71 (-5.95, -1.48) U/L; P-value = 0.001, I2 (%) = 29.9; P heterogeneity = 0.240) and studies with a good quality (WMD (95%CI) = -3.52 (-5.62, -1.42) U/L; P-value = 0.001, I2 (%) = 46.9; P heterogeneity = 0.170).

CONCLUSIONS

In conclusion, RBAC supplementation seems to not have any hepatic adverse effects and its supplementation as powder or for three months and more may decrease serum AST levels. However, we need further studies to confirm the results.

REGISTRY NUMBER FOR SYSTEMATIC REVIEWS OR META-ANALYZES

CRD42022361002, registration time: 29/09/2022.

Effect of Arabinoxylan from Wastewater Generated during Vital Wheat Gluten Production on Liver Metabolism in Type 2 Diabetic Mice

Arabinoxylan (AX) is a dietary fiber that has been proven to have a significant antidiabetic effect. Liver metabolic disorders frequently coincide with the development of type 2 diabetes, but research on the hepatoprotective effects of AX in type 2 diabetic mice is lacking. As AX is abundant in the wastewater produced during vital wheat gluten protein production, this study used it as a raw material to evaluate its protective effect on liver function. The study employed an AX intervention in type 2 diabetic mice induced by a high-fat diet combined with streptozotocin and collected serum and liver tissue samples after 4 weeks. Serum and liver function indicators were measured using an automatic biochemistry analysis apparatus, and liver fat accumulation was observed using oil red O staining. Nontargeted metabolomics analysis of liver tissues was conducted using UHPLC-MS/MS. The results showed that AX significantly improved liver function indicators and histopathological damage, and regulated liver metabolic disorders by improving the differential metabolites of pantothenate and CoA biosynthesis, as well as purine metabolism. This study demonstrated that AX may exert a significant hepatoprotective effect by regulating metabolic disorders.

β-1,4-Galactan suppresses lipid synthesis in sebaceous gland cells via TLR4

Sebum is a lipid mixture secreted from sebaceous glands of the skin. The excessive secretion of sebum causes acne vulgaris and seborrheic dermatitis, while its deficiency causes xerosis. Therefore, the appropriate control of sebum secretion is crucially important to keep the skin healthy. In the present study, we evaluated the effects of naturally occurring polysaccharides on lipid biosynthesis in hamster sebaceous gland cells. Among the tested polysaccharides, β-1,4-galactan, the main chain of type I arabinogalactan, most potently suppressed lipid synthesis in the sebaceous gland cells as analysed by oil red O staining. Toll-like receptor (TLR)4 inhibitors counteracted this suppressive effect and lipopolysaccharide, a TLR4 ligand, mimicked this effect, suggesting the involvement of the TLR4 signalling pathway. In the cells β-1,4-galactan significantly decreased mRNA levels of lipogenesis-related transcription factors (peroxisomeGraphical Abstract$\includegraphics{\bwartpath }$ proliferator-activated receptor γ and sterol regulatory element-binding protein 1) and enzymes (acetyl-CoA carboxylase and fatty acid synthase) as well as the glucose transporter GLUT4. Furthermore, β-1,4-galactan increased the production of lactic acid serving as a natural moisturizing factor and enhanced the proliferation of sebaceous gland cells. These results suggest potential of β-1,4-galactan as a material with therapeutic and cosmetic values for the skin.

Advances in extraction, purification, structural characteristics and biological activities of hemicelluloses: A review

Hemicelluloses, a major component of plant cell walls, are a non-cellulosic heteropolysaccharide composed of several distinct sugars that is second in abundance to cellulose, which are one of the most abundant and cheapest renewable resources on earth. Hemicelluloses structure is complex and its chemical structure varies greatly among the different plant species. In addition to its wide use in production of feed and other chemical materials, hemicelluloses are known for its remarkable biological activities that remain largely underutilised to date. Therefore, comprehensive investigations of hemicelluloses structural and biological properties would be helpful for achieving rational utilisation and high-value conversion of this underutilised substance into agents with enhanced health benefits for incorporation in drugs and health foods. In this review, details of diverse research initiatives that have enhanced our understanding of hemicelluloses properties are summarised, including hemicelluloses sources, extraction and purification methods, structural characteristics and biological activities. Furthermore, hemicelluloses structure-activity relationships and new directions for future hemicelluloses research studies are discussed.

Effect of Lactobacillus fermentum HFY06 Combined with Arabinoxylan on Reducing Lipid Accumulation in Mice Fed with High-Fat Diet

In this experiment, a high-fat diet was used to induce hyperlipidemia in mice to determine the synergistic effect of AX and L. fermentum HFY06 on the prevention of hyperlipidemia and its potential regulatory mechanism. The results of this study showed that after the AX and L. fermentum HFY06 synergistic intervention, the body weight, epididymal fat index, blood lipid level, and liver function indexes of mice were improved. In addition, the synbiotics comprising AX and L. fermentum HFY06 increased the CAT activity in the serum of mice on a high-fat diet, reduced NO and MDA levels, and improved the body's oxidative stress. From the perspective of molecular biology, on the one hand, AX and L. fermentum HFY06 synergistic intervention activated the AMPK pathway to regulate body lipid metabolism; up-regulated the mRNA expressions of CPT-1, PPAR-α, CYP7A1, and HSL; and down-regulated the mRNA expressions of ACC, C/EBPα, and LPL. On the other hand, the synergistic effect of AX and HFY06 enhanced the mRNA expressions of ZO-1, occludin, and claudin-1 in the small intestine of mice, increased the strength of the intestinal barrier, and optimized the composition of the intestinal microbiota. From the above results, it can be concluded that AX and L. fermentum HFY06 have a synergistic effect in improving hyperlipidemia. However, this study was only performed using animal models, and the lipid synthesis and metabolism mechanism are complicated; hence, further clinical studies are needed.

Isolation, Structural, Functional, and Bioactive Properties of Cereal Arabinoxylan─A Critical Review

Arabinoxylans (AXs) are widely distributed in various cereal grains, such as wheat, corn, rye, barley, rice, and oat. The AX molecule contains a linear (1,4)-β-D-xylp backbone substituted by α-L-araf units and occasionally t-xylp and t-glcpA through α-(1,2) and/or α-(1,3) glycosidic linkages. Arabinoxylan shows diversified functional and bioactive properties, influenced by their molecular mass, branching degree, ferulic acid (FA) content, and the substitution position and chain length of the side chains. This Review summarizes the extraction methods for various cereal sources, compares their structural features and functional/bioactive properties, and highlights the established structure-function/bioactivity relationships, intending to explore the potential functions of AXs and their industrial applications.

Effects of Xylooligosaccharides on Lipid Metabolism, Inflammation, and Gut Microbiota in C57BL/6J Mice Fed a High-Fat Diet

Xylooligosaccharide (XOS) is a source of prebiotics with multiple biological activities. The present study aimed to investigate the effects of XOS on mice fed a high-fat diet. Mice were fed either a normal diet or a high-fat diet supplemented without or with XOS (250 and 500 mg/kg), respectively, for 12 weeks. The results showed that the XOS inhibited mouse weight gain, decreased the epididymal adipose index, and improved the blood lipid levels, including triglyceride (TG), total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels. Moreover, XOS reduced the activity of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and alleviated the damage to the liver caused by the high-fat diet. XOS also reduced hyperlipidemia-associated inflammatory responses. Additionally, quantitative real-time polymerase chain reaction results showed that XOS intervention activated the AMP-activated protein kinase (AMPK) pathway to regulate the fat synthesis, decomposition, and β oxidation; upregulated the mRNA expression levels of carnitine palmitoyl transferase 1 (CPT-1), peroxisome proliferator-activated receptors α (PPAR-α), and cholesterol 7-alpha hydroxylase (CYP7A1); and downregulated the mRNA expression levels of acetyl-CoA carboxylase (ACC), CCAAT/enhancer-binding protein alpha (C/EBPα), and lipoprotein lipase (LPL). On the other hand, XOS enhanced the mRNA expression levels of zonula occludens-1 (ZO-1), occludin, and claudin-1 in the small intestine; increased the strength of the intestinal barrier; and optimized the composition of the intestinal microbiota. Therefore, it was concluded that XOS regulated the intestinal barrier, changed the intestinal microecology, and played an important role in preventing hyperlipidemia through the unique anatomical advantages of the gut-liver axis.

Isosteviol Sodium Attenuates High Fat/High Cholesterol-Induced Kidney Dysfunction by Inhibiting Inflammation, Oxidative Stress and Apoptosis

The sodium salt of isosteviol (STVNa) is a beyerane diterpene synthesized through acid hydrolysis of stevioside. STVNa improves multiple types of tissue injuries. However, it is not known how isosteviol sodium affects high-fat and high cholesterol diet (HFD)-induced kidney. Therefore, in this study we examined the potential molecular mechanism underlying STVNa mediated protective effect against high fat/high cholesterol-induced kidney dysfunction in HFD-induced kidney injury. Sprague-Dawley (SD) rats were allocated into six groups: the normal group, HFD group and HFD treated with three doses of STVNa, fenofibrate treatment group. The results indicated that HFD induced kidney injury evident by a 60% increase in serum creatinine (CRE) leves. In addition, there was a significant accumulation of triglycerides (approx. 60%), fatty acids (approx. 50%) and total cholesterol (approx. 2.5 fold) in the kidneys. STVNa inhibited HFD-induced kidney injury evident by reducing the increased levels of serum CRE. Specifically, STVNa attenuated HFD-induced kidney injury by inhibiting inflammation, oxidative stress, and apoptosis. These findings indicate that STVNa has a therapeutic potential for HFD-induced kidney dysfunction. The mechanisms of this pharmacological effect are through the inhibition of inflammation, oxidative stress and apoptosis.

Interactive effects of molecular weight and degree of substitution on biological activities of arabinoxylan and its hydrolysates from triticale bran

Arabinoxylan (AX) has many beneficial health effects that are closely related to its structural characteristics. The current study aimed to investigate the effects of molecular weight (Mw) and degree of substitution (DS) on the antioxidant and hypoglycemic activities of triticale bran AX and its hydrolysates in vitro. At low and similar Mw, the antioxidant activity of AX was inversely proportional to its DS. When DS was close, the antioxidant activity of AX was inversely proportional to its Mw at high DS, but the opposite result was found at low DS. As for the hypoglycemic performance, when DS was similar, the hypoglycemic activity of AX was proportional to its Mw. At low and similar Mw, the α-glucosidase inhibitory ability and glucose adsorption ability of AX was positively correlated with DS, whereas the α-amylase inhibitory ability and glucose delayed absorption ability showed the opposite results. Mw and DS had significant effects on the antioxidant and hypoglycemic activities of AX, and these two factors often need to be combined to explain the varied effects under different conditions.

Ferulated Arabinoxylans and Their Gels: Functional Properties and Potential Application as Antioxidant and Anticancer Agent

In the last years, biomedical research has focused its efforts in the development of new oral delivery systems for the treatment of different diseases. Ferulated arabinoxylans are polysaccharides from cereals that have been gaining attention in the pharmaceutical field due to their prebiotic, antioxidant, and anticancer properties. The antioxidant and anticancer properties of these polysaccharides make them attractive compounds for the treatment of cancer, particularly colon cancer. In addition, ferulated arabinoxylans can form covalent gels through the cross-linking of their ferulic acids. Due to their particular characteristics, ferulated arabinoxylan gels represent an excellent alternative as colon-targeted drug delivery systems. The aim of the present work is to review the physicochemical and functional properties of ferulated arabinoxylans and their gels and to present the future perspectives for potential application as antioxidant and anticancer agents.