Arsenic, a known environmental carcinogen, disrupts intestinal homeostasis, posing a significant threat to human health. Mitigating its toxic effects is crucial, and this study explores the potential of swim bladder sulfated glycosaminoglycan (SBSG) in achieving this. Our previous in vitro studies have shown that SBSG to ameliorate arsenic-induced damage in intestinal epithelial cells, but its in vivo effects remain elusive. The current investigation demonstrates that SBSG exhibits a beneficial prebiotic action in vivo, regulating gut microbiota, metabolites, and intestinal barrier function to counter arsenic's adverse effects. Specifically, SBSG regulates microbiota composition, suppressing pathogenic species like Alistipes and Candidatus_Saccharimonas while promoting beneficial ones such as Ruminococcus and Akkermansia. In the colon, SBSG fermentation enhances the production of short-chain fatty acids (SCFAs), leading to the upregulation of GPR43, GPR109A, and Olfr78 receptors. Additionally, SBSG strengthens the intestinal barrier by increasing the expression of Claudin-1, Occludin, and ZO-1, and enhances mucin gene expression (MUC-1 and MUC-2) to address chemical barrier disruptions. Immunologically, SBSG modulates the RORγt/Foxp3 pathway and the TLR4/MyD88/NF-κB signaling cascade, regulating the immune barrier. These findings suggest that SBSG could be a promising prebiotic candidate for maintaining intestinal health and may serve as a dietary supplement or adjunct in heavy metal detoxification therapies.

As a seaweed supplement, the powdered, entire herb of Asparagopsis taxiformis can effectively promote immune response in animals. However, the active factors responsible for this effect are currently unknown. A novel polysaccharide, ATP-1, was isolated and purified from the red alga A. taxiformis, and its structural and immunomodulatory properties were determined. ATP-1 is a neutral polysaccharide with a molecular weight of 307.978 kDa and is primarily composed of galactose (94.07%), glucose (1.27%), and xylose (4.66%). Scanning electron microscopy and atomic force microscopy revealed that ATP‑1 had an amorphous structure and was composed of molecular chain entanglement and intramolecular hydrogen bonding interactions. The microstructure of ATP-1 exhibited asymmetric sheet–like cracks and pores. Results from immunomodulatory activity showed that ATP-1 promoted inducible nitric oxide (NO) synthase and cyclooxygenase (COX)-2 protein expression in RAW264.7 macrophages, improved macrophage phagocytic ability, and stimulated cytokine production (NO, tumor necrosis factor [TNF]-α, and interleukin [IL]-6). Quantitative proteome analysis identified 178 differentially expressed proteins (70 upregulated and 108 downregulated) that were involved in various molecular pathways, among which, TNF was one of the 20 most common and significant signaling pathways in inflammation and immunoregulation. Western blotting indicated that ATP-1 significantly upregulated the expression of IKKα, IKKβ, COX-2, and TNF-α proteins in the TNF pathway. In contrast, ATP‑1 downregulated the expression of IκBα, Fas, and AIPI. Results from molecular docking suggested that hydrogen bonding predominantly contributed to the affinity between TNF-α and galactose, glucose, and xylose. These findings indicated that ATP-1 may play an immunomodulatory role by activating the TNF signaling pathway. ATP-1 enhanced macrophage phagocytic capacity and stimulated the production of cytokines NO, TNF-α, and IL-6, thereby exerting immunoregulatory effects. Our findings highlight the potential of ATP-1 as a natural immune modulator with applications as a functional food.

Freezing is the primary preservation method for surimi gel. However, repeated freezing and thawing during storage, processing, or consumption can cause ice crystal growth and recrystallization, leading to mechanical damage to muscle cells and tissue. Additionally, it can induce protein denaturation and oxidation, ultimately resulting in a decline in the quality of surimi gel. This includes moisture loss, nutrient depletion, as well as deterioration in taste and texture. Therefore, it is crucial to incorporate cryoprotectants or utilize innovative freezing/thawing technologies to enhance the quality of freeze-thawed surimi gel. This review aims to elucidate the mechanisms underlying the quality deterioration of surimi gel during freeze-thawing cycles, summarize changes in myofibrillar protein and alterations in surimi gel quality after freeze-thawing cycle treatment, and finally strategies for enhancing the quality of surimi gel throughout the freeze-thawing cycles are discussed. This review will offer valuable references for improving the stability of freeze-thawed surimi gel and provide insights into the development of novel cryoprotectants and freezing/thawing technologies.