Deep eutectic solvents extraction of polysaccharides from Chuanminshen violaceum: process optimization, structure characterization and in vitro fecal fermentation

This study focuses on the extraction of Chuanminshen violaceum polysaccharides (CVPs) using selected deep eutectic solvents (DES). The optimal extraction process for CVPs was determined using a Box-Behnken design, with an extraction temperature of 70 o C, an extraction time of 120 min, and a liquid-solid ratio of 20:1 (mL/g), resulting in a yield of 44.17 %. Furthermore, CVPs were isolated using chromatography techniques to obtain purified CVPs-1, CVPs-2, CVPs-1-1, and CVPs-2-1. These were characterized by their monosaccharide composition, infrared spectroscopy, nuclear magnetic resonance (NMR), thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. After in vitro fecal fermentation, the abundance of Bacteroides , Lactococcus , Bifidobacterium , and Lachnoclostridium significantly increased in the CVPs group. In contrast, the abundance of Enterobacteriaceae , Escherichia-Shigella , and Fusobacterium decreased dramatically, particularly in the CVPs-2-1 group. Dynamic changes during in vitro fermentation indicated that the pH value decreased, while gas production and short-chain fatty acids (SCFAs) significantly increased in the CVPs groups. Overall, these results suggest that the composition of the human gut microbiota can be modulated by CVPs, indicating that CVPs may have the potential to maintain gut homeostasis and enhance human intestinal health. • This study investigated the extraction of Chuanminshen violaceum polysaccharides (CVPs) using deep eutectic solvents (DES) with optimized parameters. • CVPs stimulated the growth of Bacteroides , Lactococcus , and Bifidobacterium while enhancing short-chain fatty acids (SCFAs) production in vitro. • CVPs fermentation preferentially increased the levels of acetic and propionic acids while decreasing the isomers of valeric acid.