Metabolite profiling and identification of triptolide in rats

•Metabolite profile of triptolide using radio-labeled compound was reported for the first time.•Major metabolites of triptolide in plasma were reported for the first time.•Major metabolites of triptolide was identified using authentic standards for the first time.

The purpose of the current study was to investigate the metabolite profile of [3H]triptolide in rats. The separation and characterisation techniques used to identify the major metabolites were high-performance liquid chromatography-online radiodetector, ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry, and nuclear magnetic resonance. In all, 33 major metabolites were detected. The major components found in the rat plasma included the parent drug and its monohydroxy- and dihydroxy-metabolites. Reference standards for the monohydroxy-metabolites were obtained either by the incubation of the parent drug with rat liver microsomes or by microbial transformation with Cunninghamella blakesleana. The metabolites’ structures were identified as 17-hydroxytriptolide, 16-hydroxytriptolide, tripdiolide, and 15-hydroxytriptolide. The major metabolites found in male rat urine included the monohydroxy-, dihydroxy-, and trihydroxy-metabolites. The major metabolites in female rat urine were the monohydroxy- and dihydroxy-metabolites, as well as sulphates of the monohydroxy-metabolites. A glutathione adduct, multiple hydroxy-metabolites, and a number of unidentified metabolites were detected in the bile and faeces of male rats. Sulphates of monohydroxy-metabolites were detected in the bile and faeces of female rats.