Bifunctional Inhibitor Lentinan Inhibits Fibrillogenesis of Amyloid-ß Protein and α-Synuclein and Alleviates Their Cytotoxicity: In Vitro and In Vivo Studies.

Alzheimer's disease (AD) and Parkinson's disease (PD) are the two most common neurodegenerative diseases in the world. Misfolding of ß-amyloid (Aß) and α-synuclein (α-syn) and subsequent fibril formation are closely associated with the pathogenesis of AD and PD, respectively. Lentinan is a natural product commonly used in medicine and dietary supplements. It has potential antitumor, anti-inflammatory, and antiviral effects, but the underlying mechanism of its action on AD and PD remains unclear. In this study, lentinan inhibited the formation of Aß and α-syn fibers in a dose-dependent manner and disrupted their mature fibers. Lentinan inhibited the conversion of Aß and α-syn conformations to ß-sheet-rich conformations. Additionally, lentinan protected Caenorhabditis elegans against damage caused by the accumulation of Aß and α-syn aggregation and prolonged their lifespan. Notably, the beneficial effects of lentinan in AD and PD mice were also demonstrated, including ameliorating the cognitive and memory impairments in AD mice and behavioral deficits in PD mice. Finally, molecular interactions between lentinan and Aß/α-syn pentamers were also explored using molecular docking.

Ultrasound-Assisted Multi-Enzyme Extraction for Highly Efficient Extraction of Polysaccharides from Ulva lactuca.

Ulva polysaccharides present several physiological activities including antiviral, antitumor and anti-plasmodial effects. However, current processing usually results in low yields and high prices, thus lacking commercialization potential. The aim of this study was to develop an efficient method for the extraction of Ulva polysaccharides with high biological activity. The effect of cell wall-degrading enzymes including cellulase, hemicellulase, pectinase and protease on Ulva polysaccharide extraction was studied by statistical mixing design. Using the most effective enzyme preparations as the basic components, the optimal proportions of the enzyme mixture were determined as follows: cellulase 35.3%, pectinase 34.5%, alkaline protease 30.2%, which increased the polysaccharide yield from 6.43% in the absence of enzymes to 26.68%. Subsequently, through response surface analysis, the optimal conditions were determined: enzyme concentration of 1.5%, enzymatic time of 1.1 h, ultrasonic time of 90 min and enzymatic temperature of 60 °C. Under the optimal extraction conditions, the extraction yield of Ulva polysaccharides could be increased to 30.14%. Moreover, extracted polysaccharides exhibit strong antioxidant properties in DPPH, ABTS, hydroxyl radical, superoxide radical and H2O2-induced cellular damage models. This study laid a solid foundation for the use and development of Ulva polysaccharides.