Abstract:[Objective] To explore the structural characteristics and biological functions of polysaccharides extracted from Patinopecten yessoensis skirt by twice enzymatic hydrolysis and alcohol precipitation. [Method] High performance liquid chromatography, ultraviolet spectroscopy, and Fourier transform infrared spectroscopy were employed to characterize the structure of polysaccharides extracted from Patinopecten yessoensis skirt, and the antioxidant activity and immunomodulatory activity of the extracted polysaccharides were determined. Furthermore, animal experiments were carried out to examine the effects of the extracted polysaccharides on gut microbiota and colonic immunoglobins in mice. [Result] The polysaccharides extracted from Patinopecten yessoensis skirt were composed of five monosaccharides, with an average molecular weight of 2.538×105. The polysaccharides had a D type pyran ring structure with α?-glycosidic bond and no uronic acid. The extracted polysaccharides showed weak antioxidant activity, with the 1,1-diphenyl-2-picrylhydrazyl （DPPH） and hydroxyl free radical scavenging rates only 19.7% and 20.1% those of vitamin C (positive control), respectively. The extracted polysaccharides promoted macrophages to secrete cytokines and nitric oxide (NO). At the mass concentration of 200 μg/mL, the extracted polysaccharides increased the mass concentrations of tumor necrosis factor-α （TNF-α）, and interleukin-1β （IL-1β）, and the concentration of NO by 75.7%, 22.8%, and 46.6%, respectively. In addition, the polysaccharides improved the gut microbiota structure in mice by significantly increasing the relative abundance of probiotic genera (Bifidobacterium and Bacteroides). The mass concentrations of immunoglobin A, immunoglobin G, and immunoglobin M in the colon tissue of mice fed with a high dose of the extracted polysaccharides increased by 13.6%, 68.7%, and 23.9%, respectively. [Conclusion] The polysaccharides from Patinopecten yessoensis skirt promoted the proliferation of probiotics and regulated the immunity. The findings provide a theoretical basis for the further development and utilization of polysaccharides from Patinopecten yessoensis skirt.
