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Extraction of Polysaccharides From Bletilla Striata Using a Modified Low-temperature Method and Evaluation of Their Efficacy Against Alzheimer’s Disease


 Background: Amyloid-β (Aβ) peptides play a key role in Alzheimer’s disease (AD), the most common type of dementia. AD is characterized by progressive cognitive and memory loss accompanied by personality changes. Bletilla striata, a traditional Chinese medicine, has been widely used in Eastern Asian countries for alimentary canal damage, ulcer, bleeding, bruises, and burns. in this study, we investigated whether BSP could prevent the ROS from Aβ and the possibility to recover from the disease by memory improvement.Methods: In this study, a polysaccharide from Bletilla striata (BSP) with strong antioxidant and anti-inflammatory properties was extracted following a low-temperature method and tested for its efficacy against AD in vitro using N2a and BV-2 cells and in vivo using AD rats.Results: The characterization of the extracted BSP for its molecular structure and the functional group demonstrated the efficiency of the modified method to retain its bioactivity. In vitro, BSP reduced ROS levels in N2a cells and the expression levels of inflammatory-related genes in BV-2 cells treated with Aβ fibrils. In vivo, BSP recovered the learning memory, ameliorated the morphological damages in the hippocampus and cortex, and reduced the expression of the β-secretase protein in AlCl3-induced AD rats.Conclusions: To the best of our knowledge, this is the first study of BSP applicating in AD. Collectively, these findings demonstrated the efficacy of BSP to prevent and alleviate the effects of AD.