[Mechanism of Cyathulae Radix in treatment of knee osteoarthritis based on metabolomics]

Metabolomics based on ultra-high performance liquid chromatography-tandem quadrupole time-of-flight mass spectrometry(UHPLC-Q-TOF-MS) was employed to analyze the effect of Cyathulae Radix on serum and urine in rats with knee osteoarthritis, and to decipher the mechanism of Cyathulae Radix in the treatment of knee osteoarthritis. SD rats were randomized into a normal group, a model group, a positive drug group, and a Cyathulae Radix group. The knee osteoarthritis model was established by injecting 2% pa-pain and 0.03 mol·L~(-1) cysteine, and the serum levels of tumor necrosis factor-α(TNF-α) and matrix metalloproteinase-3(MMP-3) in the model group was measured to preliminarily evaluate the therapeutic effect of Cyathulae Radix on knee osteoarthritis. UHPLC-Q-TOF-MS was employed to establish the metabolic profile of endogenous small molecule metabolites in the four groups. Potential biomarkers were screened out by multivariate analysis methods such as partial least squares discriminant analysis(PLS-DA) and orthogonal partial least squares discriminant analysis(OPLS-DA) in combination with t-test, variable importance for projection(VIP), and fold-change. The related metabolic pathways were enriched with the help of MetaboAnalyst 5.0. The results showed that Cyathulae Radix alleviated the general signs of rats with knee osteoarthritis, and reduced the levels of TNF-α and MMP-3 in the rat serum. Twenty-eight differential metabolites that might be associated with the therapeutic effect of Cyathulae Radix were screened out from serum and urine. They were mainly involved in arginine biosynthesis, nicotinate and nicotinamide metabolism, tricarboxylic acid cycle, alanine, aspartate and glutamate metabolism, riboflavin metabolism, glyoxylate and dicarboxylate metabolism, and pyrimidine metabolism. Through metabonomics analysis, this study predicted the possible mechanism of Cyathulae Radix in the treatment of knee osteoarthritis, which laid a foundation for further research.