Antioxidant Activity of Radix Cyathula officinalis Kuan Polysaccharides and Their Modulatory Effects on the Gut Microbiota of Caenorhabditis elegans.

Polysaccharides isolated from Radix Cyathula officinalis Kuan (RCP) are key bioactive components with immunomodulatory, antioxidant, and anti-inflammatory effects. Their efficacy varies according to their geographic origin and processing methods. However, the systemic anti-aging mechanisms and antioxidant efficacy of RCP have not yet been comprehensively characterized. This study investigated the antioxidant and anti-aging effects of RCP in vitro and in vivo using a Caenorhabditis elegans heat stress model, comparing rRCP (RCP from raw samples) and wRCP (RCP from wine-processed samples) from key production areas. Among these, the RCP collected from the Zhonggang region exhibited the strongest antioxidant activity. Both rRCP and wRCP enhanced worms' oxidative stress resistance, reduced their ROS levels, increased their antioxidant enzyme activities, prolonged their lifespan, and improved their reproductive capacity under thermal stress. Notably, the wRCP exhibited more pronounced benefits. Additionally, 16S rRNA sequencing revealed that RCP altered the gut microbiota's composition by increasing its microbial diversity, enriching beneficial bacteria like Bacillus, and decreasing potential pathogens such as Escherichia and Citricoccus. The treatment also led to an increased abundance of Firmicutes and a slight reduction in Bacteroidetes. Collectively, these findings suggest that RCP, particularly wRCP, holds promise as a therapeutic agent for combating oxidative stress and promoting longevity, in part by modulating the gut microbiome.