LC-HRMS-based metabolomics of Sida rhombifolia and evaluation of its biological activity using different extracting solvent concentrations

Sida rhombifolia is a medicinal plant known to have antigout properties and is widely used in traditional medicine. The potential of S. rhombifolia as an antigout arises from the presence of bioactive metabolites contained therein. The composition and concentration of these metabolites in S. rhombifolia can vary due to the use of different extracting solvents, so it is important to evaluate an effective extractive solvent with a high level of biological activity. In this study, we evaluated differences in the metabolite profiles using liquid chromatography high resolution mass spectrometry (LCHRMS)-based metabolomics, antioxidant activity, and xanthine oxidase inhibition of S. rhombifolia using ethanol solvents with different concentrations. S. rhombifolia was extracted using ethanol p.a., 70% ethanol, 50% ethanol, 30% ethanol, and water. Each extract was analyzed using LCHRMS and determined its DPPH free radical scavenging activity and xanthine oxidase inhibition. A total of 34 metabolites were putatively identified using LCHRMS. Principal component analysis (PCA) can clearly distinguish each sample based on the extraction solvent. Hierarchical cluster analysis (HCA) heatmap illustrates the variation of metabolite composition in each sample. The DPPH free radical scavenging activity of S. rhombifolia extract ranged from 31.08 to 40.28%, while the xanthine oxidase inhibition activity ranged from 15.15 to 42.67%. Based on the data obtained, it can be concluded that the extracting solvent concentration significantly affects the metabolite profile, DPPH free radical scavenging activity, and inhibition of xanthine oxidase of S. rhombifolia.