DOI: 10.4231/a0az-0k81
title: Gut bacterial O-demethylation is prevalent and governs systemic exposure to orally administered etoposide

description: &lt;p style="text-align:start; margin-bottom:11px"&gt;&lt;br /&gt;
&lt;span style="font-size:medium"&gt;&lt;span style="line-height:18.4px"&gt;&lt;span style="font-family:Aptos, sans-serif"&gt;&lt;span style="color:#000000"&gt;&lt;span style="font-style:normal"&gt;&lt;span style="font-weight:400"&gt;&lt;span style="white-space:normal"&gt;&lt;span style="text-decoration:none"&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;Gut microbial &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylation has been reported for plant-derived dietary compounds containing &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-methylated aromatic(s). However, the significance of gut microbial &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylation in drug metabolism and disposition remains unexplored. This study examined 64 clinically used oral drugs containing one or more methoxylated aromatics for gut microbial &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylation using high-resolution mass spectrometry (HRMS). For 35 of the tested drugs, including the anticancer agent etoposide, we detected metabolites corresponding to &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylation (i.e., a mass difference of -14 and its multiples) when individual drugs were incubated with mouse cecal contents. We confirmed that the &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylated metabolite (M1) of the model drug etoposide is etoposide catechol using HRMS and proton nuclear magnetic resonance spectroscopy. By testing an in-house collection of 56 gut bacteria individually, we identified seven previously unknown gut bacterial species that exhibit etoposide &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylating activity. Etoposide anticancer therapy has been associated with an increased risk of acute myeloid leukemia. We demonstrated that M1 is more genotoxic to myeloid cells when orally administered to mice, whereas M1 is less cytotoxic against MCF-7 and HeLa cancer cells than the parent etoposide, suggesting that gut microbiota may contribute to the secondary genotoxicity of etoposide via &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylation. Comparative pharmacokinetic analysis of orally administered etoposide in control and antibiotic-treated mice showed that systemic exposure to etoposide increased 1.9-fold, while M1 exposure decreased 3.7-fold in antibiotic-treated mice, suggesting that gut microbial &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylation is a significant determinant of etoposide metabolism and disposition. Collectively, our study reveals the prevalence of gut bacteria with &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylation activity, illustrates the contribution of gut microbial &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylation to altering drug efficacy and toxicity with the model drug etoposide, and provides a knowledge basis for in-depth characterization of other drugs identified as being susceptible to gut microbial &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;i&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;O&lt;/span&gt;&lt;/span&gt;&lt;/i&gt;&lt;span style="font-size:13.5pt"&gt;&lt;span style="line-height:20.700001px"&gt;&lt;span style="font-family:Helvetica"&gt;&lt;span style="color:black"&gt;&lt;span style="float:none"&gt;-demethylation.&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;
description: We examined gut microbial O-demethylation of clinically used oral drugs and characterized its impact on drug disposition using etoposide, an anticancer drug, as an example.