Systematic Screening and Characterization of Cardamonin Metabolites using UHPLC-Q-Exactive Orbitrap MS after Oral Administration to Rats

Abstract Cardamonin is a chalcone that presents at high content in the seeds of Alpinia katsumadai Hayata. In recent decades, researchers have found that it is not only an edible spice, but also a remarkable herb with a wide range of pharmacological properties. However, its specific metabolic routes in vivo remain unclear while these metabolites may accumulate to exert pharmacological effects. Our study aimed to clarify the metabolic pathways of cardamonin after oral administration to rats. Here, an advanced UHPLC-Q-Exactive Orbitrap MS analytical technique was applied for efficient detection of metabolites in vivo, which especially showed benefits in obtainment of the fragment ions with relatively lower contents. We also established a novel strategy to identify metabolites based on typical fragmentation routes. The results indicated that a total of 40 metabolites could be categorized into 3 types with consideration of the particular structures and characteristic fragment ions. Then, diagnostic product ions (DPIs) of each type were summarized for further screening and identification of metabolites derived from cardamonin. Finally, methylation, demethylation, hydrogenation, hydroxylation, dehydroxylation, glucuronidation and sulfation were confirmed to be the major metabolic pathways in vivo. Our observation extended the metabolic mechanism of cardamonin and could be of great benefits to interpreting the action mechanism of cardamonin in vivo.