The unique living environment of marine microorganisms endows them with the potential to produce novel chemical compounds with various biological activities. Among them, the exopolysaccharides produced by marine microbes are an important factor for them to survive in these extreme environments. Up to now, exopolysaccharides from marine microbes, especially from extremophiles, have attracted more and more attention due to their structural complexity, biodegradability, biological activities, and biocompatibility. With the development of culture and separation methods, an increasing number of novel exopolysaccharides are being found and investigated. Here, the source, structure and biological activities of exopolysaccharides, as well as their potential applications in environmental restoration fields of the last decade are summarized, indicating the commercial potential of these versatile EPS in different areas, such as food, cosmetic, and biomedical industries, and also in environmental remediation.

Outbreaks of starfish (Asterias amurensis) pose a major threat to aquaculture and marine ecosystems in Qingdao, China, and no effective methods have been found to control them. A comprehensive study of collagen in starfish could be an alternative to high efficient utilization. Based on this, collagen was firstly extracted from Qingdao A. amurensis. Then, its protein pattern, amino acid composition, secondary structure, microstructure and thermal stability were investigated. The results showed that the A. amurensis collagen (AAC) is a type I collagen composed of α₁, α₂, and β chains. Glycine, hydroxyproline, and alanine were the major amino acids. The melting temperature was 57.7 °C. From FTIR, UV spectra and CD chromatography, the AAC had an intact triple helix and secondary structure, and microstructural analysis showed that the AAC had a loose, fibrous porous structure. Next, the osteogenic differentiation effect of AAC on Mouse bone marrow stem cells (BMSCs) was investigated, and the results showed that AAC induced osteogenic differentiation of cells by promoting the proliferation of BMSCs, enhancing alkaline phosphatase (ALP) activity, promoting cell mineralization nodules and upregulating the expression of mRNA of relevant osteogenic genes. These results suggest that AAC might have the potential application to bone health-related functional foods.

Tumor immunotherapy, a revolutionary cancer treatment, is hindered by inadequate immune cell activation, immunosuppressive tumor microenvironment (TME), and off-target toxicities of immunotherapeutics. These bottlenecks necessitate innovative strategies to enhance efficacy and reduce side effects. Marine polysaccharides have garnered significant attention due to their potential to enhance immune cell activity and regulate the tumor microenvironment, among other benefits. Due to their excellent biocompatibility, modifiability, and relatively low cost, polysaccharides are increasingly being explored as materials for drug delivery systems. The development of marine polysaccharide-based drug delivery systems represents an opportunity for advancing tumor immunotherapy. This review focuses on the application of marine polysaccharide drug delivery systems in tumor immunotherapy, exploring the mechanisms underlying the bioactivity of marine polysaccharides, the design of drug delivery systems, and the interactions between these systems and tumor immunotherapy, aiming to provide a framework for advancing marine polysaccharide-based therapeutics, accelerating the clinical translation of effective, safe, and targeted tumor immunotherapy strategies.

Aims: Panax quinquefolius Radix (American ginseng) is a medicinal herb used for its neuroprotective and tonic effects. However, the antidepressant potential of its polysaccharide components is not well studied. This research aimed to investigate the antidepressant effects of XYS1, a polysaccharide from American ginseng, focusing on mechanisms related to the complement system and the gut‐brain axis. Methods: A chronic unpredictable mild stress (CUMS) mouse model was used to induce depressive behaviors. Mice were treated with XYS1 via oral gavage, followed by assessments of behavior, molecular changes, and gut microbiota. Results: XYS1 treatment significantly alleviated depression‐like behaviors in CUMS mice, as demonstrated by reduced immobility time in the TST and FST, and increased sucrose preference and body weight. Mechanistically, XYS1 attenuated complement system activation by downregulating C1Q expression in microglia and C3 expression in astrocytes, not only in the hippocampal CA1 region but also in the mPFC and PVN, as well as in the colon. Furthermore, XYS1 inhibited microglial activation and associated synaptic phagocytosis, preserved glutamatergic neuron density, restored excitatory synapse density, and reversed CUMS‐induced gut microbiota dysbiosis by enriching Bacillota and reducing Bacteroidota abundance. Additionally, XYS1 effectively mitigated both colonic and systemic inflammation, reducing pro‐inflammatory cytokines TNF‐α and IL‐1β and complement components C1Q and C3, while restoring anti‐inflammatory IL‐10 levels, thereby modulating the gut‐brain axis. Conclusions: XYS1 exerts antidepressant effects by modulating the C1Q/C3 complement pathway, inhibiting microglial‐mediated synaptic pruning, and restoring gut microbiota homeostasis.