# Metabolic Profiling and Detoxification of Eupalinolide A and B in Human Liver Microsomal Systems

## TL;DR

This study examines how two isomeric compounds from a plant are metabolized in human liver systems and finds they are likely to be safe with low toxicity.

## Contribution

The study identifies specific metabolic pathways and detoxification mechanisms for Eupalinolide A and B in human liver microsomes.

## Key findings

- Sixteen metabolites of Eupalinolide A and 19 of Eupalinolide B were identified in human liver microsomes.
- Hydrolysis was the main metabolic pathway for both compounds, leading to lower hepatocyte toxicity compared to oxidative metabolites.
- Both compounds showed low hepatotoxicity, suggesting a relatively safe profile in vivo.

## Abstract

Eupalinolide A (EA, Z-configuration) and Eupalinolide B (EB, E-configuration) are cis-trans isomeric sesquiterpenoid monomers isolated from Eupatorium lindleyanum DC. (Asteraceae). Although these compounds display anti-inflammatory and anti-tumor activities, their metabolite profiles and possible hepatotoxicity remain largely unknown. This study aimed to investigate the metabolic profiles of EA and EB in liver microsomes and clarify whether they undergo metabolic activation or detoxification. EA and EB were metabolically profiled in human liver microsomes (HLMs) via UPLC-Q-TOF-MS. A HepG2-HLM co-culture system was used to compare the hepatocyte toxicity of parent compounds and their hydrolysis, oxidation, and hydrolysis–oxidation metabolites, thus evaluating their metabolic detoxification pathways. Sixteen metabolites of EA and 19 of EB were identified, with hydrolysis being the predominant metabolic pathway for both isomers. Both compounds showed low hepatocyte toxicity and underwent metabolic detoxification mainly via hydrolytic and oxidative pathways. Notably, hydrolysis metabolites had significantly lower toxicity than oxidative products in HepG2 cells. These results suggest that EA and EB could present a relatively low risk of in vivo hepatotoxicity, which provides useful information for understanding the metabolic behavior and safety profile of these bioactive sesquiterpenoids.