LC-MS based urinary metabolomics study of the intervention effect of aloe-emodin on hyperlipidemia rats

Hyperlipidemia has been highlighted to be one of the most prominent and global chronic condition nowadays. Daming capsule (DMC), a traditional Chinese medicine (TCM) preparation, has treated hyperlipidemia on clinic in China for decades. Our recent study showed that aloe-emodin (AE) is one of the main bioactive components in DMC. Therefore, the present study aims to further investigate the lipid-lowering effect by serum biochemistry and histopathological examination, and reveal the underlying mechanisms by urinary metabolomics approach. After oral administration of AE for 6 weeks, the total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-c) levels in 50 and 100 mg/kg AE groups were both decreased significantly (P < 0.05 and P < 0.001). An ultra-performance liquid chromatography/electrospray ionization quadruple time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS) followed by principal components analysis (PCA), partial least squares- discriminant analysis (PLS-DA), orthogonal partial least squares-discriminant analysis (OPLS-DA), correlation analysis, heat map, and KEGG pathways was employed to identify 26 potential biomarkers. Twenty three among them were restored by AE including L-citrulline, 6-methylaminopurine, imidazoleacetic acid riboside, N-acetylhistamine, 3-methyladenine, 1-methyladenosine, dopamine, N1-methyl-4-pyridone-3-carboxamide, formylanthranilic acid, 4-pyridoxate, cAMP, salsolinol, isethionate, d-ribonic acid, 3-sulfolactic acid, vitamin C, mesaconic acid, sulfosalicylic acid, salicyluric acid, N-acetylanthranilic acid, 4,6- Dihydroxyquinoline, sebacic acid and hyocholic Acid. The related metabolic pathways include TCA cycle, the metabolism of amino acids, taurine, B vitamins, purines and pyrimidines. The results indicate that AE has a favorable therapeutic effect on HFD-induced hyperlipidemia by adjusting the metabolic disorders. Notably, urinary metabolomics combined with pattern recognition analysis provides a powerful and reliable approach into the research and development of TCM and phytochemicals.