Maillard Reaction Products of Stir Fried Hordei Fructus Germinatus Are Important for Its Efficacy in Treating Functional Dyspepsia

Hordei Fructus Germinatus (HFG) has been used as a traditional medicine to treat functional dyspepsia (FD) in China. Stir fried HFG (F-HFG) containing Maillard reaction products (MRPs) is used more widely than the raw HFG (R-HFG). However, the exact mechanisms in its functionality remain unclear. This article investigated the effect of R-HFG, F-HFG, and MRPs on brain-gut peptides, gut microbiota, and digestive enzymes using an FD animal mode. After administration of R-HFG, F-HFG, and MRPs, higher mRNA expression level of gastrin (GAS) and lower mRNA expression level of vasoactive intestinal peptide (VIP) were exhibited in F-HFG and MRPs rats than R-HFG rats (P < .05). Furthermore, compared with the R-HFG group, the contents of motilin (MTL) and GAS showed an upward tendency, whereas the contents of VIP and chokcystokinin (CCK) showed a downward tendency in the F-HFG group. In addition, bacterial communities in the control, F-HFG, and MRPs groups clustered closely to one another, and bacterial communities in the model and recovery groups clustered together, whereas the bacterial communities in the R-HFG group were clustered into a category. Moreover, there were no apparent differences in brain-gut peptides and gut microbiota between the F-HFG and MRPs groups. However, after the oral administration of R-HFG, F-HFG, and MRPs, the level of digestive enzyme did not show a significant change as compared with the recovery group. These results indicated that the stronger effect of F-HFG could be attributed to the MRPs produced during stir frying, and MRPs possessed the effect of regulating brain-gut peptides and gut microbiota.