Photoelectrocatalytic degradation of hyaluronic acid and regulation effects of its degradation products on gut microbiota in vitro.

Hyaluronic acid (HA) has multiple biological activities which are closely related to its molecular weight. In the present study, the photoelectrocatalytic method was established for HA degradation and the influences of bias potentials, H₂O₂ additions and reaction times on the degradation results were investigated to optimize the reaction condition. Moreover, a series of analysis methods, such as FT-IR and NMR were used to analyze chemical compositions of the degradation products, revealing that photoelectrocatalytic degradation did not damage the structural blocks of HA obviously. Then 11 oligosaccharides with polymerization degrees from 2 to 8 in the degradation products were identified by mass spectroscopy and their reducing ends were all GlcA or AraA. In addition, in the photoelectrocatalytic degradation of HA, ·OH were identified as the most influential among the produced free radicals, and it could be proposed that ·OH specifically targeted the anomeric carbon of GlcA, resulting in the disaggregation of polysaccharides chain. Furthermore, the results of in vitro fermentation with fecal microbiota demonstrated that HA and its degradation products regulated microbiota structure discriminately, indicating their possible different outcomes as nutritional supplements and agents.