This project systematically reviewed the published scientific evidence of the interactions between β-glucans (βGs) and bile acids/bile salts (BA/BS). In vitro bile-binding studies suggest that lower molecular weight βGs exhibit higher bile-binding capacity due to greater solubility and mobility. However, other studies indicate that higher molecular weight βGs may bind bile more effectively by forming a viscous gel that restricts BA/BS diffusion. These conflicting findings highlight the complexity of βG-BA interactions, emphasizing the importance of molecular weight and viscosity. NMR studies confirmed that βGs interact with BA/BS primarily through weak, dynamic interactions that may stabilize bile salt micelles. While NMR provides molecular-level insights, these interactions remain transient (≤0.18 ppm) rather than strong or permanent. Factors such as pH, molecular weight, viscosity, and βG concentration influence the extent of these interactions. Chemical modifications, including oxidation, acetylation, and carboxymethylation, have been explored to enhance bile-binding capacity by improving solubility and introducing functional groups. However, these modifications also reduce molecular weight and viscosity, potentially diminishing the physiological benefits associated with βGs' gel-forming properties. Dialysis studies demonstrated that as viscosity increases, the permeability rate constant (K) decreases, indicating greater bile retention due to reduced diffusion.
Higher viscosity slows diffusion, with glycine-conjugated BS sodium glycocholate (NaGC) exhibiting the highest diffusion rates and sodium glycochenodeoxycholate (NaGCDC) the lowest, particularly at higher OβG concentrations. Sodium cholate (NaC) remains relatively unaffected by OβG concentration. Notably, OβG significantly (p < 0.05) reduces the diffusion rate of NaGCDC () and sodium chenodeoxycholate (NaCDC), whereas NaC shows minimal changes. These findings highlight OβG concentration as a key factor in modulating BS diffusion, with varying effects on different bile salts.
In summary, this study underscores the critical role of molecular weight, viscosity, and concentration in βG-BA interactions. While βGs can modulate bile salt diffusion, their effectiveness depends on specific physicochemical properties and external conditions. Chemical modifications can enhance bile-binding capacity but may compromise viscosity-related physiological benefits. The findings provide valuable insights into the mechanisms governing βG-BA interactions, contributing to the understanding of βGs' potential applications in cholesterol management and gut health.
