## 3. Results and Discussion
### Sodium Tuarocholate Binding Capacity In Vitro  
Cholesterol is an important cause of hyperlipidemia. Research has demonstrated that natural polysaccharides have the ability to bind cholesterol. Figure 9A demonstrates the cholesterol binding capacity of the four FPs. The cholesterol binding capacities of FPF, FPFI, FPV, FPH and CMC were 60.08, 57.86, 42.72, 50.14 and 74.13 mg/g at a concentration of 10 mg/mL, respectively. FPF has the highest cholesterol binding capacity. The cholesterol binding capacity of FPF was 40.64% higher than that of FPV, equivalent to 81.05% of CMC.  
In the liver, cholesterol is oxidatively degraded to produce bile acids in the form of bile salts. Polsaccharides reduce the reabsorption of bile acid salts by binding with bile acid salts, preventing the accumulation of bile acid salts in the intestinal and hepatic circulation, and also promote the conversion of cholesterol to bile acid salts, exerting the efficacy of lowering blood lipids [41]. Sodium taurocholate is the most difficult bile acid salt to bind, and is commonly used to assess lipid-lowering levels. The sodium taurocholate binding capacity of the four FPs is shown in Figure 9B. They all exhibited sodium taurocholate binding capacity which was lower than that of the positive control. The binding capacity of all four FPs to sodium tautrocholate increased with increasing concentration. In the range of 2.0-10.0 mg/mL, the maximum binding of FPF, FPH, FPV and FPFI was 57.02%, 44.19%, 48.17% and 51.50%, respectively. It can be seen that FPF has the strongest bile salt binding capacity, followed by FPFI, and FPH has the weakest bile salt binding capacity.  
The difference in binding ability of polysaccharides with cholesterol and bile acids may be due to their different uronic acid, molecular weight, monosaccharide composition and apparent viscosity [46]. Pearson correlation coefficient analysis of cholesterol, bile acid binding ability and polysaccharide structure was shown in Figure 5. Cholesterol adsorption capacity and bile acid binding capacity were significantly positively correlated with uronic acid content (***), GalA (**) and Rha (*), and significantly negatively correlated with molecular weight (**), apparent viscosity (**), Gal (**) and Ara (*). The content of glucuronic acid of FPF was 12.05%, 11.22% and 5.72% higher than that of FPH, FPV and FPFI, respectively, and the molar ratio of GalA was higher than that of the other three polysaccharides, which made it easier for FPF to capture cholesterol and sodium taurine cholate. Due to their high molecular weight and apparent viscosity, FPH and FPV have poor fluidity and limit the absorption of cholesterol and bile acids. [PERSON] et al. [47] reported that polysaccharides from fruiting bodies of _Lentinuula edodes_ had the best cholesterol and bile acid binding capacity, possibly due to their highest polysaccharide content, lower viscosity, and average viscosity molecular weight. In addition, the surface structure of FPF is smooth and stable, which can provide more binding sites to bind cholesterol and cholate. In summary, FPF has the highest hypolipidemic activity compared with FPH, FPV and FPFI.