Yaobitong capsule is a compound preparation of traditional Chinese medicine that has been widely applied in disease treatment. To insight into the therapeutic effects of the yaobitong capsule on rheumatoid arthritis and its mechanisms, a liquid chromatography‐mass spectrometry untargeted urine metabolomics method was established and validated, combined with the quantitative analysis of seven potential amino acid biomarkers in rat urine. The results showed that 35 potential biomarkers were found in untargeted metabonomics, which was related to amino acid metabolism, lipid metabolism, energy metabolism, and purine metabolism. Moreover, seven amino acid biomarkers, including proline, methionine, glutamic acid, histidine, lysine, cysteine, and glutamine, were further separated and quantified in multiple‐reaction monitoring with a positive ionization mode. Then the linearity, standard curves, accuracy, precision, limit of quantitation, recovery, stability, carryover, and matrix effect of the quantitative method were examined. Finally, the validated method was successfully applied to investigate the urine samples of the control group, adjuvant‐induced rheumatoid arthritis model group, yaobitong capsule‐treatment group, and positive control group in rats. The contents of seven amino acids in different groups showed significant differences. Consequently, our findings revealed that the yaobitong capsule exerted therapeutic effects on rheumatoid arthritis rats by maintaining amino acid homeostasis.

Kidney‐yang‐deficiency‐syndrome is a neuroendocrine disease caused by the dysfunction of the adrenal‐pituitary‐target gland axis. Gushudan is a traditional Chinese medicine prescription with the functions of tonifying the kidney and strengthening bone, and its bone‐strengthening effect has been confirmed by previous anti‐osteoporosis research. However, its kidney‐tonifying mechanism has not been clear so far. In this study, renal metabolomics and lipidomics based on gas chromatography‐mass spectrometry and ultra‐high‐performance liquid chromatography‐high resolution mass spectrometry were integrated to find the metabolic disorders in kidney‐yang‐deficiency‐syndrome rats. Protein precipitation and liquid‐liquid extraction were used to extract metabolome and lipidome from the kidney. Gushudan regulated abnormal levels of amino acids, lipids, purines, and carbohydrates, such as L‐arginine, hypoxanine, stearic acid, and phosphatidylethanolamine (P‐18:1/20:4), which had effects on many metabolic pathways, such as glycerophospholipid metabolism, sphingolipid metabolism, glycine, serine and threonine metabolism and purine metabolism, and so forth. By integrating metabolomics and lipidomics, this study comprehensively revealed the abnormal metabolic activities of amino acids, lipids, and nucleotides in kidney‐yang‐deficiency‐syndrome, and the metabolic regulation mechanism of Gushudan in preventing kidney‐yang‐deficiency‐syndrome, as well as the improvement of Gushudan in maintaining renal cell structure, mitochondrial function, and energy supply, which also provided some new evidence and connotation for “kidney‐bone” axis.

Gushudan (GSD) has the effect of strengthening bones and nourishing kidneys. However, its specific intervention mechanism still remains unclear. In this study, to investigate the pathogenesis of glucocorticoid‐induced osteoporosis (GIOP) and the preventive mechanism of GSD on GIOP, fecal metabolomics based on 1H‐NMR and ultra‐high‐performance liquid chromatography‐quadrupole time‐of‐flight‐mass spectrometry method was established. The changes in endogenous metabolites and the relevant metabolic pathways in the control group, model group, and GSD treatment group were investigated via multivariate statistical analysis. As a result, a total of 39 differential metabolites were identified. Of these, 22 metabolites, such as L‐methionine, guanine, and sphingosine, were newly discovered as differential metabolites of GIOP. Amino acid metabolism, energy metabolism, intestinal flora metabolism, and lipid metabolism were significantly changed in the fecal profiles of GIOP rats, and GSD could play an anti‐osteoporosis role by regulating these metabolic pathways. Finally, compared with our previous study of the GSD to prevent kidney yang deficiency syndrome, this study suggested that there were some identical differential metabolites and metabolic pathways. It showed that there was some correlation among the metabolic profiles of the intestine, kidney, and bone in GIOP rats. Therefore, this study offered new insights into the in‐depth understanding of the pathogenesis of GIOP and the intervention mechanism of GSD.