UPLC-Q-TOF/MS-based metabolic profiling comparison of four major bioactive components in normal and CKD rat plasma, urine and feces following oral administration of Cornus officinalis Sieb and Rehmannia glutinosa Libosch herb couple extract

Cornus officinalis-Rehmannia glutinosa herb couple is widely used herb medicine in clinical practice to treat chronic kidney disease (CKD). However, the in vivo integrated metabolism of its main bioactive components in CKD rats remains unknown. In this study, UPLC-Q-TOF/MS technique combined with Metabolynx™ software, was developed and successfully applied for analysis of metabolic profiles of the bioactive components of the herb couple in normal and CKD rat biological samples. Main parent components of the herb couple extract such as loganin, morroniside and catalpol were absorbed into the blood circulation of the normal and CKD rats. Another parent component acteoside was almost completely degraded. Seventeen metabolites involved in the in vivo metabolism processes were tentatively identified. These metabolites indicated that loganin was mainly metabolized to the demethylated product, and morroniside was firstly deglycosylated to the aglycone and the latter was subsequently demethylated and acetylated. Additionally, hydrogenation and deglycosylation were the principal metabolic reactions of catalpol; while O-glucuronide and O-sulphate conjugates were observed as major metabolites for methylated caffeic acid and hydroxytyrosol released from acteoside. Compared with the normal group, the CKD rat showed lower conversion capability. Few kinds and minor amounts of the metabolites appeared in the CKD rat samples. While considerable amounts of the parent compounds were detected in the CKD plasma. This will help maintain a high blood drug concentration which might be beneficial for the treatment of CKD. The proposed method could develop an integrated template approach to analyze screening and identification of the bioactive components in plasma, urine and feces after oral administration of herb medicines. Additionally, this investigation might provide helpful chemical information for further pharmacology and active mechanism research on herb medicines.