Structural characterization of a heteropolysaccharide from the fruit of Crataegus pinnatifida and its bioactivity on the gut microbiota of immunocompromised mice

Crataegus pinnatifida is a common food in China, Europe and North America. In order to confirm polysaccharide was the material basis for C. pinnatifida to exert immune regulation. A polysaccharide (CPP) with a molecular weight of 13.58 kDa was isolated from C. pinnatifida. The structure of CPP was determined to be a backbone composed of → 3,5)-α-l-Araf-(1→, with two branches consisting of → 4)-α-d-Galp-(1 → and → 5)-α-l-Araf-(1→, with α-l-Araf and α-d-Manp as the terminal unit. CPP (10 ∼ 500 μg/mL) could promote the secretion of nitric oxide, interleukin-2, interleukin-6 and tumor necrosis factor-α in vitro. CPP could significantly restore the body weight of immunosuppressive mice and improve the immune organ index and interleukin-2, interleukin-6, and tumor necrosis factor-α secretion. In addition, CPP increased the abundance of Bacteroidetes and Verrucomicrobia and decreased the abundance of Proteobacteria at the phylum level. So CPP can regulate the gut microbiota and play an important role in immune regulation.