Construction, characterization, and in vitro hypolipidemic activity of Auricularia auricula-judae soluble dietary fiber-phenol complexes

To investigate the interaction between polyphenols and soluble dietary fiber, we prepared complexes of Auricularia auricula-judae soluble dietary fiber (ASDF) with catechin (CC) and chlorogenic acid (CGA) using the isothermal adsorption method. The resulting complexes were ASDF-CC complex (ASDF-CC) and ASDF-CGA complex (ASDF-CGA). Spectral analysis confirmed the successful construction of ASDF-polyphenol complexes. The results of the sugar composition analysis indicate that the monosaccharide composition of ASDF is not altered by the non-covalent binding of CC and CGA. The molecular weights of ASDF-CC and ASDF-CGA were 102.26 × 103 Da and 99.87 × 103 Da, respectively, which were significantly larger than the molecular weight of ASDF. Thermal analyses showed that ASDF-CC and ASDF-CGA are more thermally stable than ASDF. Morphological analysis revealed that the particle size of ASDF-polyphenol complexes decreased, while the specific surface area increased, and the surface became sparser and more uniformly arranged compared to ASDF. The results of the cholesterol and bile acid salt adsorption capacity assays showed that both complexes exhibited increased in vitro hypolipidemic activity compared to ASDF. Notably, the ASDF complex with CC and CGA effectively enhanced the bio-accessibility of CC and CGA. In conclusion, the interaction between soluble dietary fibers and phenolic compounds through non-covalent bonds is a feasible approach to enhance their bioactivity.