Metabolomic profiling of rat urine after oral administration of the prescription antipyretic Hao Jia Xu Re Qing Granules by UPLC/Q‐TOF‐MS

Hao Jia Xu Re Qing Granules (HJ), is an effective clinically used antipyretic based on traditional Chinese medicine. Although its antipyretic therapeutic effectiveness is obvious, its therapeutic mechanism has not been comprehensively explored yet. In this research, we first identified potential biomarkers which may be relevant for the antipyretic effect of HJ based on urine metabolomics using ultra‐performance liquid chromatography–quadrupole time‐of‐flight mass spectrometry (UPLC‐Q‐TOF‐MS). A rat model of fever was established using the yeast‐induced febrile response. Total‐ion‐current metabolic profiles of different groups were acquired and the data were processed by multivariate statistical analysis–partial least‐squares discriminant analysis. As envisioned, the results revealed changes of urine metabolites related to the antipyretic effect. Fourteen potential biomarkers were selected from the urine samples based on the results of Student's t‐test, “shrinkage t”, variable importance in projection and partial least‐squares discriminant analysis. N‐Acetylleucine, kynurenic acid, indole‐3‐ethanol, nicotinuric acid, pantothenic acid and tryptophan were the most significant biomarkers found in the urine samples, and may be crucially related to the antipyretic effect of HJ. Consequently, we propose the hypothesis that the significant antipyretic effect the HJ may be related to the inhibition of tryptophan metabolism. This research thus provides strong theoretical support and further direction to explain the antipyretic mechanism of HJ, laying the foundation for future studies.