Study of the cholesterol adsorption and characterization of montmorillonite and bentonite clay

In recent years, dietary and pharmacological agents inhibiting cholesterol intestinal absorption have attracted considerable interest. These compounds inhibit cholesterol absorption through several mechanisms affecting cholesterol solubilization in the intestinal lumen, interfering with luminal cholesterol diffusion to the intestinal epithelium, and/or inhibiting the molecular mechanisms responsible for cholesterol absorption by enterocytes. Some authors have reported that clays can lower cholesterol levels through in- vivo studies with rats and in-vitro models. Nevertheless, no cholesterol adsorption studies have been previously reported. In this study, characterization of 5 different types of clays with different specific surface area and/or modified with different chemical agents was carried out by means of several instrumental techniques. Furthermore, cholesterol adsorption isotherms were described by the Langmuir and Freundlich models to elucidate the Montmorillonite (MMT) action as an inhibitor of cholesterol at intestinal level. Characterization of different clays was performed assessing particle size, polidispersity index (PDI), zeta potential, FT-IR, XRD, SEM, BET surface area, and adsorption capacity of the clays. MMT Nanoclay® possesses the highest cation exchange capacity (75.77 meq/100 g) and lowest Z potential (−38.20 mV) which correlates to the highest values for Methylene Blue (MB) adsorption. On the other hand, MMT K10® and K30® show the highest cholesterol adsorption due to their high surface area (241.37 and 242.75 m2/g, respectively). The isothermal studies suggest that MMT allows the multilayer adsorption of cholesterol through hydrophobic sites.