In-vivo metabolic profiling of the Natural products Emodin and Emodin-8-O-β-D-glucoside in rats using liquid chromatography quadrupole Orbitrap mass spectrometry

Abstract

Emodin (EM) and emodin-8-O-β-D-glucoside (EG) were found in various medicinal plants such as Rheum palmatum, Aloe vera, Polygonum multiflorum, and Polygonum cuspidatum. They have different pharmacological properties and are considered potentially toxic substances. It is necessary to identify the metabolites and their distribution in the body. In this study, a comprehensive analytical strategy was developed to characterize the metabolites of EM and EG in vivo using UHPLC-Q-Exactive Orbitrap MS. 190 metabolites were identified in the bio-samples, in addition to the commonly reported glycoside hydrolysis, hydrogenation, hydroxylation, glucuronide conjugation, and sulfation conjugation. We also discovered new pathways such as formylation, acetylation, glycol acylation, lactation, glycerolization, malonylation, glycerol acid acylation, hydroxyvalerylation, erythrosylation, glutaric acidfication, hydroxybenzoylation, glutamylation, hydroxyglutamylation, ascorbylation, aspartylglycylation, dihydroxyphenylglycylation, trihydroxyphenylglycylation, dihydroxymethoxyphenylglycylation, and ring-opening of EM. Cluster analysis revealed that each tissue in the EM and EG groups exhibited a high degree of similarity in their metabolic pathway preferences and bodily distributions, as they clustered together. Interestingly, the presence of glycol acylation, glycerolization, and glycerol acid acylation in the liver may be related to the lipid-lowering effects of EM and EG. These findings offer valuable insights for a more comprehensive understanding of the safety and efficacy of EM and EG, as well as valuable methods for metabolic characterization.