Ultrasound-assisted extraction of Codonopsis pilosula (Franch.) Nannf. polysaccharide: Kinetic and thermodynamic analysis, antioxidant and immunological activities

Based on an optimized kinetic model derived from Fick's second law of diffusion, a process flow for extracting crude polysaccharides from Codonopsis pilosula (Franch.) Nannf. polysaccharide (CPNP) using an ultrasonic-assisted method was established, and its thermodynamic effects were analyzed. The monosaccharide composition and polysaccharide structure were analyzed using HPLC, molecular weight analysis, thermogravimetric analysis (TGA), Fourier infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. The results show that according to Fick's second diffusion law, the extraction kinetics curve of CPNP has a good linear relationship with the linear correlation coefficient (R 2 )≥ 0.9. Under the conditions of a material-to-liquid ratio of 1:16, ultrasonic power of 540 W, and temperature of 353.15 K, the maximum extraction rate of 15.56% was obtained after 80 min of treatment. Glucose (Glc) and Galactose (Gal) are the main components of this polysaccharide. Furthermore, CPNP exhibits antioxidant activities, including free radical scavenging, reducing ability, ferrous ion chelating ability, and ability to inhibit lipid peroxidation. It also directly inactivated bovine viral diarrhea virus (BVDV) particles and interfered with viral adsorption processes, and modulated the expression of co-stimulatory factors (CD28, CD40, 4–1BB, and 4–1BBL), immune factors (TRAF-1, Bcl-xL, Bim, TNF-α, and IL-1β), as well as IFN-γ, IL-2, IgG-2α, and TNFRSF13B proteins or mRNA expression. In summary, our findings demonstrate that CPNP exhibits both antiviral activity against BVDV and immunomodulatory properties, suggesting its potential as a therapeutic candidate for the prevention and treatment of BVDV infection.