Digestion properties of Alismatis Rhizoma crude polysaccharide derived from aqueous two-phase extraction and their influence on gut microbiota with obesity.

While Alismatis Rhizoma polysaccharides demonstrated promising anti-obesity potential, several research gaps remain, including extraction methods, chemical composition, and gut microbiota interactions. Herein, a new method termed the salt concentration saturation Oil Red O staining method (SCS-ORO) was developed to screen 7 salts capable of forming biphasic systems with ethanol from a pool of 28 salts, of which the K2HPO4/ethanol system was suitable for extracting A. Rhizoma crude polysaccharides (ARP). Meanwhile, ARP obtained from the K2HPO4/ethanol system alleviated lipid accumulation in Caenorhabditis elegans, and was primarily composed of glucan and arabinogalactan, among which arabinogalactan has anti-digestive potential. In vitro fermentation of gut microbiota from obese patients revealed that ARP enriched the abundance of Bifidobacterium and Lactobacillus, resulting in the upregulation of indole derivatives, including tryptamine, 3-indoleacetic acid, and 3-indoleacrylic acid. These findings provide a theoretical foundation for ARP to combat obesity by mediating gut microbiota.