Identification of the In Vitro and In Vivo Metabolites of Chrysotoxine Using Liquid Chromatography Combined With Benchtop Orbitrap High-Resolution Mass Spectrometry

Rationale

Chrysotoxine, a bibenzyl derivative from the stems of Dendrobium medicinal herbs, has recently emerged as a promising therapeutic candidate for cervical cancer. This study aimed to characterize chrysotoxine metabolites across multiple hepatocyte species and in rat urine.

Methods

Metabolites were identified and characterized using liquid chromatography coupled with benchtop Orbitrap high-resolution mass spectrometry (LC–Orbitrap–MS/MS) combined with Compound Discoverer software. Structural elucidation relied on accurate mass measurements (mass error < 5 ppm) and comprehensive MS² fragmentation pattern interpretation.

Results

Twelve distinct metabolites were structurally identified. Among these, M4, M6, M7, M8, M10, M11, and M12 are newly reported. Metabolic transformations occurred via five principal pathways: hydroxylation, demethylation, glucuronidation, sulfation, and glutathione (GSH) conjugation. Cross-species analysis of hepatocytes revealed direct glucuronidation as the predominant metabolic reaction. Urinary excretion profiles in rats identified hydroxylated (M9) and glucuronidated (M11) metabolites as the major elimination products. During the metabolism, chrysotoxine can be metabolized into quinone methide and ortho quinone intermediates that can be conjugated with GSH, forming the adducts M1, M2, M3, and M5.

Conclusions

This study delineates chrysotoxine metabolites in vitro and in vivo, providing critical insights for further pharmacokinetic and toxicity assessments.