Modulation of hyperglycemia by sodium alginate is associated with changes of serum metabolite and gut microbiota in mice

Algae-derived compounds: Bioactivity, allergenicity and technologies enhancing their values

As a rapidly growing source of human nutrients, algae biosynthesize diverse metabolites which have promising bioactivities. However, the potential allergenicity of algal components hinder their widespread adoption. This review provides a comprehensive review of various macro and micronutrients derived from algal biomass, with particular focus on bioactive compounds, including peptides, polyphenols, carotenoids, omega-3 fatty acids and phycocyanins. The approaches used to produce algal bioactive compounds and their health benefits (antioxidant, antidiabetic, cardioprotective, anti-inflammatory and immunomodulatory) are summarised. This review particularly focuses on the state-of-the-art of precision fermentation, encapsulation, cold plasma, high-pressure processing, pulsed electric field, and subcritical water to reduce the allergenicity of algal compounds while increasing their bioactivity and bioavailability. By providing insights into current challenges of algae-derived compounds and opportunities for advancement, this review contributes to the ongoing discourse on maximizing their application potential in the food nutraceuticals, and pharmaceuticals industries.

Dietary kelp meal improves serum antioxidants, intestinal immunity, and lipid metabolism in hybrid snakehead (Channa maculata ♀ × Channa argus ♂)

BACKGROUND

Dietary kelp possesses a variety of useful biological qualities but does not have a toxic effect on the host. In this study, we examine how kelp dietary supplementation enhances the serum biochemistry, intestinal immunity, and metabolism of hybrid snakehead. A total of 810 juvenile hybrid snakeheads (Channa maculata ♀ × Channa argus ♂), with an initial average weight of 11.4 ± 0.15 g, were allocated randomly to three treatment groups (three replicates per group). The fish were fed for 60 days with isonitrogenous and isolipidic diets. The groups were the control group (C) (20% high-gluten flour), the medium replacement group (MR) (10% high-gluten flour and 10% kelp meal), and the full replacement group (FR) (0% high-gluten flour and 15% kelp meal).

RESULTS

The results showed that dietary kelp increased the activity of serum antioxidant enzymes significantly and decreased the content of serum malondialdehyde (MDA) in hybrid snakeheads, with significant changes in the FR group (P < 0.05). The intestinal morphology results showed that dietary kelp helped to increase the specific surface area of intestinal villi, which was beneficial for intestinal digestion and absorption. According to transcriptome and quantitative real-time polymerase chain reaction (qRT-PCR) analysis, dietary kelp can improve the expression of intestinal immunity and metabolism-related pathways. Among them, immune-related genes MHC1 and HSPA1 were significantly up-regulated, and IGH, MHC2, and IL-8 were significantly down-regulated (P < 0.05). Lipid metabolism-related genes DGAT2, FABP2, RXRα, and PLPP1 were all significantly up-regulated (P < 0.05).

CONCLUSION

Dietary kelp can effectively improve the antioxidant function of hybrid snakeheads, improve intestinal morphology, reduce intestinal inflammation, and promote intestinal lipid synthesis and transportation, thereby improving intestinal immunity and metabolic functions. © 2024 Society of Chemical Industry.

Enhancing effect on postharvest quality of potatoes through combined treatment of edible coating with UV-C irradiation

Various edible polymers [sodium alginate, carboxyl methylcellulose, sodium oleate, liquid paraffin, pectin, pullulan, polyvinyl acetate, and shellac (SHE)] as potato-coating materials and their effect on extending the shelf life of potatoes when combined with an edible coating and UV-C irradiation treatments were evaluated. As a result of the characterization of the edible polymers, SHE was selected as the optimal coating material because it had the best moisture and light barrier properties. SHE coating successfully prevented the greening, respiration, and sprouting of potatoes caused by exposure to light and oxygen. Additionally, it reduced weight loss by inhibiting transpiration on the potato surface. While the SHE coating did not exhibit antimicrobial effects, a significant effect was observed when combined with UV-C irradiation. This study suggests the potential of combined treatment of SHE coating and UV-C irradiation in extending the postharvest quality of potatoes.

Multiomics analysis revealed the mechanism of the anti-diabetic effect of Salecan

Salecan, a natural β-glucan compromising nine residues connected by β-(1 → 3)/α-(1 → 3) glycosidic bonds, is one of the newly approved food ingredients. Salecan has multiple health-improving effects, yet its mechanism against Type 2 diabetes mellitus (T2DM) remains poorly understood. In this study, the hypoglycemic effect and underlying mechanism of Salecan intervention on STZ-induced diabetic model mice were investigated. After 8 weeks of gavage, Salecan attenuated insulin resistance and repaired pancreatic β cells in a dose-dependent manner. In addition, Salecan supplement remodel the structure of the gut microbiota and altered the level of intestinal metabolites. Serum metabolites, especially unsaturated fatty acids, were also affected significantly. In addition, tight junction proteins in the colon and autophagy-related proteins in the pancreas were upregulated. Multiomics analysis indicated that Lactobacillus johnsonii, Muribaculaceae, and Lachnoclostridium were highly associated with fatty acid esters of hydroxy fatty acids (FAHFA) levels in the colon, accordingly enhancing arachidonic acid and linoleic acid in serum, and promoting GLP-1 release in the intestine and insulin secretion in the pancreas, thus relieving insulin resistance and exhibiting hypoglycemic effects. These findings provide a novel understanding of the anti-diabetic effect of Salecan in mice from a molecular perspective, paving the way for the wide use of Salecan.

Unraveling the bioactive interplay: seaweed polysaccharide, polyphenol and their gut modulation effect

Seaweed is rich in many unique bioactive compounds such as polyphenols and sulfated polysaccharides that are not found in terrestrial plant. The discovery of numerous biological activities from seaweed has made seaweed an attractive functional food source with the potential to be exploited for human health benefits. During food processing and digestion, cell wall polysaccharide and polyphenols commonly interact, and this may influence the nutritional properties of food. Interactions between cell wall polysaccharide and polyphenols in plant-based system has been extensively studied. However, similar interactions in seaweed have received little attention despite the vast disparity between the structural and chemical composition of plant and seaweed cell wall. This poses a challenge in extracting seaweed bioactive compounds with intact biological properties. This review aims to summarize the cell wall polysaccharide and polyphenols present in brown, red and green seaweed, and current knowledge on their potential interactions. Moreover, this review gives an overview of the gut modulation effect of seaweed polysaccharide and polyphenol.

Microbiome-Metabolomic Analysis Reveals Beneficial Effects of Dietary Kelp Resistant Starch on Intestinal Functions of Hybrid Snakeheads (Channa maculata ♀ × Channa argus ♂)

The benefits of resistant starch on hypoglycemia, obesity prevention, antioxidant status and the alleviation of metabolic syndrome have received considerable attention. In this study, we explored how dietary kelp resistant starch (KRS) enhances intestinal morphology and function through a microbiome-metabolomic analysis. Hybrid snakeheads (initial weight: 11.4 ± 0.15 g) were fed experimental diets for 60 days. Fish were fed a basic wheat starch diet and the KRS diet. Dietary KRS improved intestinal morphology and enhanced intestinal antioxidant and digestive capabilities, as evidenced by decreased intestinal damage and upregulated intestinal biochemical markers. The microbiome analysis showed that KRS administration elevated the proportion of butyrate-producing bacteria and the abundance of beneficial bacteria that increases insulin sensitivity. Furthermore, significant alterations in metabolic profiles were observed to mainly associate with the amino acid metabolism (particularly arginine production), the metabolism of cofactors and vitamins, fat metabolism, glutathione metabolism, and the biosynthesis of other secondary metabolites. Additionally, alterations in intestinal microbiota composition were significantly associated with metabolites. Collectively, changes in intestinal microbiota and metabolite profiles produced by the replacement of common starch with dietary KRS appears to play an important role in the development of intestinal metabolism, thus leading to improved intestinal function and homeostasis.

Hierarchical build-up of vertically oriented lignin-based aerogel for photothermally assisted uranium uptake and recovery from acidic wastewater

Developing the lignin-based functional materials for uranium uptake is extremely attractive, but challenging due to the complex structure, poor solubility and reactivity of lignin. Herein, a novel phosphorylated lignin (LP)/sodium alginate/ carboxylated carbon nanotube (CCNT) composite aerogel (LP@AC) with vertically oriented lamellar configuration was created for efficient uranium uptake from acidic wastewater. The successful phosphorylation of lignin by a facile solvent-free mechanochemical method achieved more than six-times enhancement in U(VI) uptake capacity of lignin. While, the incorporation of CCNT not only increased the specific surface area of LP@AC, but also improved its mechanical strength as a reinforcing phase. More importantly, the synergies between LP and CCNT components endowed LP@AC with an excellent photothermal performance, resulting in a local heat environment on LP@AC and further boosting the U(VI) uptake. Consequently, the light irradiated LP@AC exhibited an ultrahigh U(VI) uptake capacity (1308.87 mg g^-1), 61.26% higher than that under dark condition, excellent adsorptive selectivity and reusability. After exposure to 10 L of simulated wastewater, above 98.21% of U(VI) ions could be rapidly captured by LP@AC under light irradiation, revealing the tremendous feasibility in industrial application. The electrostatic attraction and coordination interaction were considered as the main mechanism for U(VI) uptake.

Sodium Alginate Prevents Non-Alcoholic Fatty Liver Disease by Modulating the Gut-Liver Axis in High-Fat Diet-Fed Rats

Previous studies have suggested that the sodium alginate (SA) is beneficial for the treatment of non-alcoholic fatty liver disease (NAFLD), while the potential mechanisms are largely unknown. The present study aimed to clarify the effects and potential mechanisms of SA in preventing NAFLD via the gut−liver axis. Thirty-two male Sprague−Dawley rats were randomly divided into four groups: normal control group (NC); high-fat diet group (HFD); HFD with 50 mg/kg/d sodium alginate group (LSA); HFD with 150 mg/kg/d sodium alginate group (HSA). After 16 weeks, the rats were scarified to collect blood and tissues. The results indicated that SA significantly reduced their body weight, hepatic steatosis, serum triglyceride (TG), alanine transaminase (ALT) and tumor necrosis factor α (TNF-α) levels and increased serum high-density lipoprotein-cholesterol (HDL-C) levels in comparison with HFD group (p < 0.05). The elevated mRNA and protein expression of genes related to the toll-like receptor 4 (TLR-4)/nuclear factor-kappa B (NF-κB)/nod-like receptor protein 3 (NLRP3) inflammatory signaling pathway in the liver of HFD-fed rats was notably suppressed by SA. In terms of the gut microbiota, the LSA group showed a significantly higher fecal abundance of Oscillospiraceae_UCG_005, Butyricicoccaceae_UCG_009 and Colidextribacter compared with the HFD group (p < 0.05). The rats in the HSA group had a higher abundance of unclassified_Lachnospiraceae, Colidextribacter and Oscillibacter compared with the HFD-associated gut community (p < 0.05). In addition, rats treated with SA showed a significant increase in fecal short chain fatty acids (SCFAs) levels and a decline in serum lipopolysaccharide (LPS) levels compared with the HFD group (p < 0.05). Moreover, the modulated bacteria and microbial metabolites were notably correlated with the amelioration of NAFLD-related indices and activation of the hepatic TLR4/NF-κB/NLRP3 pathway. In conclusion, SA prevented NAFLD and the potential mechanism was related to the modulation of the gut−liver axis.

A Comprehensive Review of the Cardioprotective Effect of Marine Algae Polysaccharide on the Gut Microbiota

Cardiovascular disease (CVD) is the number one cause of death worldwide. Recent evidence has demonstrated an association between the gut microbiota and CVD, including heart failure, cerebrovascular illness, hypertension, and stroke. Marine algal polysaccharides (MAPs) are valuable natural sources of diverse bioactive compounds. MAPs have many pharmaceutical activities, including antioxidant, anti-inflammatory, immunomodulatory, and antidiabetic effects. Most MAPs are not utilized in the upper gastrointestinal tract; however, they are fermented by intestinal flora. The relationship between MAPs and the intestinal microbiota has drawn attention in CVD research. Hence, this review highlights the main action by which MAPs are known to affect CVD by maintaining homeostasis in the gut microbiome and producing gut microbiota-generated functional metabolites and short chain fatty acids. In addition, the effects of trimethylamine N-oxide on the gut microbiota composition, bile acid signaling properties, and CVD prevention are also discussed. This review supports the idea that focusing on the interactions between the host and gut microbiota may be promising for the prevention or treatment of CVD. MAPs are a potential sustainable source for the production of functional foods or nutraceutical products for preventing or treating CVD.