Conjugation reaction with ferulic acid boosts the antioxidant property of arabinogalactan-protein and enhances its ability to form complex with β-lactoglobulin

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.

Attenuation of carbon tetrachloride-induced nephrotoxicity by gum Arabic extract via modulating cellular redox state, NF-κB pathway, and KIM-1

The current study investigated the ameliorating impact of GA water extract (GAE) on CCl4-induced nephrotoxicity in renal cells and tissue by comparing its effectiveness with the Ketosteril (Ks) drug in restoring oxidative stress and necroinflammation. The cell morphology, necrosis, and redox state were evaluated in Vero cells. The influence of GAE on CCl4-induced oxidative stress, inflammation, and necrosis was examined in rats. The predicted inhibitory mechanism of GAE phenolic constituents against COX-2 and iNOS was also studied. The results revealed that GAE contains crucial types of phenolic acids, which are associated with its antiradical activities. GAE improved CCl4-induced Vero cell damage and restored renal architecture damage, total antioxidant capacity, ROS, TBARS, NO, GSH, GPX, SOD, and MPO in rats. GAE downregulated the gene expression of renal NF-κB, TNF-α, iNOS, and COX-2, as well as kidney injury molecule-1 (KIM-1) in rats. The GAE improved blood urea, creatinine, cholesterol, and reducing power. The computational analysis revealed the competitive inhibitory mechanism of selected phenolic composites of GAE on COX-2 and iNOS activities. The GAE exhibited higher potency than Ks in most of the studied parameters, as observed by the heatmap plots. Thus, GAE is a promising extract for the treatment of kidney toxicity.

Fluorescence probe technique for determining the hydrophobic interactions and critical aggregation concentrations of Gleditsia microphylla gum, circular Gleditsia sinensis gum, and tara gum

Circular Gleditsia sinensis gum, Gleditsia microphylla gum, and tara gum are galactomannans (GMs) with similar mannose/galactose (M/G) molar ratios, which complicates the characterization of physicochemical properties using conventional methods. Herein, the hydrophobic interactions and critical aggregation concentrations (CACs) of the GMs were compared using a fluorescence probe technique, in which the I1/I3 ratio of pyrene indicated polarity changes. With increasing GM concentration, the I1/I3 ratio decreased slightly in dilute solutions below the CAC but decreased sharply in semidilute solutions above the CAC, indicating that the GMs formed hydrophobic domains. However, increases in temperature destroyed the hydrophobic microdomains and increased the CACs. Higher concentrations of salts (SO42-, Cl-, SCN-, and Al3+) promoted hydrophobic microdomain formation, and the CACs in Na2SO4 and NaSCN solutions were lower than those in pure water. Hydrophobic microdomain formation also occurred upon Cu2+ complexation. Although urea addition promoted hydrophobic microdomain formation in dilute solutions, the microdomains were destroyed in semidilute solutions and the CACs increased. The formation or destruction of hydrophobic microdomains depended on the molecular weight, M/G ratio and galactose distribution of GMs. Therefore, the fluorescent probe technique enables the characterization of hydrophobic interactions in GM solutions, which can provide valuable insight into molecular chain conformations.

Comparative Transcriptome Profiling Reveals Two WRKY Transcription Factors Positively Regulating Polysaccharide Biosynthesis in Polygonatum cyrtonema

Polygonatum cyrtonema (P. cyrtonema) is a valuable rhizome-propagating traditional Chinese medical herb. Polysaccharides (PCPs) are the major bioactive constituents in P. cyrtonema. However, the molecular basis of PCP biosynthesis in P. cyrtonema remains unknown. In this study, we measured the PCP contents of 11 wild P. cyrtonema germplasms. The results showed that PCP content was the highest in Lishui Qingyuan (LSQY, 11.84%) and the lowest in Hangzhou Lin'an (HZLA, 7.18%). We next analyzed the transcriptome profiles of LSQY and HZLA. Through a qRT-PCR analysis of five differential expression genes from the PCP biosynthesis pathway, phosphomannomutase, UDP-glucose 4-epimerase (galE), and GDP-mannose 4,6-dehydratase were determined as the key enzymes. A protein of a key gene, galE1, was localized in the chloroplast. The PCP content in the transiently overexpressed galE1 tobacco leaves was higher than in the wild type. Moreover, luciferase and Y1H assays indicated that PcWRKY31 and PcWRKY34 could activate galE1 by binding to its promoter. Our research uncovers the novel regulatory mechanism of PCP biosynthesis in P. cyrtonema and is critical to molecular-assisted breeding.

Plant type II arabinogalactan: Structural features and modification to increase functionality

Type II arabinogalactans (AGs) are a highly diverse class of plant polysaccharides generally encountered as the carbohydrate moieties of certain extracellular proteoglycans, the so-called arabinogalactan-proteins (AGPs), which are found on plasma membranes and in cell walls. The basic structure of type II AG is a 1,3-β-D-galactan main chain with 1,6-β-D-galactan side chains. The side chains are further decorated with other sugars such as α-l-arabinose and β-d-glucuronic acid. In addition, AGs with 1,6-β-D-galactan as the main chain, which are designated as 'type II related AG' in this review, can also be found in several plants. Due to their diverse and heterogenous features, the determination of carbohydrate structures of type II and type II related AGs is not easy. On the other hand, these complex AGs are scientifically and commercially attractive materials whose structures can be modified by chemical and biochemical approaches for specific purposes. In the current review, what is known about the chemical structures of type II and type II related AGs from different plant sources is outlined. After that, structural analysis techniques are considered and compared. Finally, structural modifications that enhance or alter functionality are highlighted.

Structural Characterization of an Alcohol-Soluble Polysaccharide from Bletilla striata and Antitumor Activities in Vivo and in Vitro

In general, Bletilla striata polysaccharides were mostly water-soluble. However, the structural property, immunomodulatory effects and antitumor activities of alcohol-soluble Bletilla striata polysaccharide were rarely reported. In this study, an alcohol-soluble Bletilla striata polysaccharide was firstly extracted, investigated the structural property and evaluated the antitumor activity in vivo and in vitro. Results showed that BSAP was a low molecular weight polysaccharide (2.29×10⁴  Da) and consisted of glucose, xylose and mannose (molar ratio: 2.39 : 1.00 : 0.21). Animal experiments results suggested that BSAP could effectively inhibit the expansion of H22 solid tumors, protect thymus and spleen, improve macrophages, lymphocytes and NK cells activities and enhance lymphocyte subsets proportion, presenting a better immunological enhancement effect in vivo. Additionally, the results of cell experiments showed that BSAP had obvious antitumor effect in vitro, including inhibiting the proliferation of H22 cells and inducing the apoptosis of tumor cells. These results would provide theoretical basis and new ideas for the further development and utilization of BSAP in the biomedical field.