This paper introduces research background of polysaccharide-based composite hydrogel materials, discusses definition, classification and preparation of hydrogels, and summarizes research progress of chitosan-based hydrogels, hyaluronic acid-based hydrogels, alginate-based hydrogels, starch-based hydrogels and cellulose-based hydrogels according to different types of polysaccharides. In addition, we summarize the applications of polysaccharide-based complex hydrogels in wound healing, tissue engineering, and drug delivery. Finally, the development opportunities and challenges faced by polysaccharide-based complex hydrogels are summarized, and the future research directions are prospected, hoping to broaden their potential application fields.

Auricularia auricula polysaccharide (AAP) was extracted with ethanol of different concentrations (50%, 60%, 70%, 80%, 90%). Taking the yield, total sugar content, and uronic acid content as the indexes, the optimal alcohol precipitation concentration of AAP was 50%, and the polysaccharide content was 58.89%. In vitro digestion experiment showed that the content of reducing sugar in AAP was almost unchanged in the saliva and gastric juice digestion phase. However, the reducing sugar content of AAP increased from 0.062 mg/mL at 0.5 h to 1.162 mg/mL at 3 h during the intestinal juice digestion phase. In addition, in vitro antioxidant results showed that AAP still maintained high 2,2’-azido bis (3-ethyl benzothiazole line-6-sulfonic acid) (ABTS) free radical scavenging activity after digestion.

Vaginal microorganisms, dominated by Lactobacillus spp., are an important defense against infections including pathogenic sexually transmitted infections. Extracellular vesicles (EVs) are recognized and endocytosed by tissue cells through specific interactions between membrane surface proteins, and thereafter deliver their molecular cargo. Bacteria can use their EVs to interact with neighboring bacteria and play an important role in the physiology and pathogenesis of cells. Herein, we investigated whether the bacteriostatic effect of Lactobacillus was mediated by extracellular vesicles released by these bacteria. L. gasseri-derived EVs were isolated by ultracentrifugation and loaded with metronidazole to observe their antibacterial activity. Our results showed that L. gasseri-derived EVs could effectively encapsulate drug, enhanced drug retardation, and had good biosafety. EVs and EVs-metronidazole have inhibitory effects on E. coli, S. aureus, and L. monocytogenes, with the best inhibitory effect on L. monocytogenes. Together, our work provides a new potential strategy for vaginitis treatment.

Alzheimer's disease (AD) is the most common form of dementia, affecting nearly 10% of individuals over the age of 65 and nearly 50% of those over the age of 85. It is responsible for incapacitation of the individual by degrading cognitive functions, and its evolution leads the individual to death after a few years. It is characterized by brain degeneration triggered by several factors. One of the triggering factors is in the acetylcholine system. There is a decrease in the count of this neurotransmitter in individuals with this disease. The involvement of endogenous metal ions such as iron, copper, and zinc has also been involved in neurodegeneration mechanisms, in which there is the formation of radical species that cause oxidative stress, with important contribution of the neutrophil-derived enzyme myeloperoxidase, forming lesions in the neuronal cytoplasm and functional deficiency of neurons. In the present work, we report the evaluation of seventeen Camphor hydrazone derivatives 3a—3q, prepared in accordance with our previous work, as probable inhibitors of myeloperoxidase (MPO), acetylcholinesterase (AChE), and free radical-scavenging, to be used as potential agents against AD. Nine compounds showed significant activity against MPO. Among them, 3j and 3k had 78.4 and 53.9 μM (IC ₅₀), respectively. Three compounds showed stronger activity, 3d, 3k, and 3l with EC ₅₀ of 15.2, 21.3, and 14.4 µM, respectively, for free radical-scavenging activity, being similar to the standard quercetin (12.8 µM). All the final compounds were analyzed for drug-likeness. With exception for 3e and 3p, all were suitable on all filters evaluated. These results show that the compounds of hydrazone class are promising in the search for potential candidates for new agents against AD.