A metabolomic study of the urine of rats with Alzheimer's disease and the efficacy of Ding-Zhi-Xiao-Wan on the afflicted rats

As a well-known traditional Chinese medicine formula, Ding-Zhi-Xiao-Wan has long been used for the routine treatment of Alzheimer's disease. However, the mechanism of Ding-Zhi-Xiao-Wan in treating Alzheimer's disease is unclear. Therefore, a nontargeted metabolomics method based on ultrahigh performance liquid chromatography with quadrupole time-of-flight mass spectrometry has been established to explore the metabolic variations in the urine of Alzheimer's disease rats and investigate the therapeutic mechanism of Ding-Zhi-Xiao-Wan on Alzheimer's disease. To develop a better rat model of Alzheimer's disease, amyloid beta 25-35 was injected into the bilateral hippocampus of Sprague-Dawley rats. Multivariate analysis approaches were applied to differentiate the urine components between the four groups. Thereafter, a targeted metabolomics method was used to verify the identified endogenous metabolites and determine the mechanism of action of Ding-Zhi-Xiao-Wan. Altogether, 26 potential biomarkers were found, of which 15 biomarkers (10 of which are potential biomarkers found in nontargeted metabolomics) were identified. The results show that Ding-Zhi-Xiao-Wan mainly affects the pathways of taurine and hypotaurine metabolism, tryptophan metabolism, and phenylalanine metabolism. Ding-Zhi-Xiao-Wan might play a role in the treatment of Alzheimer's disease by mediating antioxidative stress, regulation of energy metabolism, improvement of intestinal microbes, and protection of nerve cells.