Extraction kinetics, thermodynamics, rheological properties and anti-BVDV activity of Glycyrrhiza polysaccharide by hot water assisted extraction

The extraction kinetics and thermodynamic parameters of Glycyrrhiza polysaccharide (GP) were studied, and the rheological properties and antiviral activity of GP were evaluated. The results showed that the extraction process was fitted with Fick's second law of diffusion. The optimum concentration (97.62 mg/mL) was obtained at solid-liquid ratio (1:15, g/mL), extraction time (120 min) and extraction temperature (80 °C). The whole extraction process was spontaneous and endothermic. GP was a acid glycoprotein with the complex structure by high performance liquid chromatography (HPLC), Circular dichroism (CD) and Fourier Transform Infrared Spectroscopy (FT-IR). The results of rheological properties showed the typical non-Newtonian pseudoplastic fluids characteristic, which could be significantly affected by temperature, pH and others ions. The branched and soft fiber structures with irregular molecular aggregation were observed by scanning electron microscopy (SEM) and atomic force microscope (AFM). Moreover, GP showed a good inhibitory activity against BVDV by regulation the relative expression of IRF-1 and IRF-3 genes in MDBK cells. This activity depended on the physicochemical and structure properties of GP. Those description above implied that GP can be considered as a natural source of active material for prevention viral disease.