The objective of this study was to investigate the oxidative metabolism pathways of 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin (17-DMAG), a geldanamycin (GA) derivative and 90-kDa heat shock protein inhibitor. In vitro metabolic profiles of 17-DMAG were examined by using pooled human liver microsomes (HLMs) and recombinant CYP450 isozymes in the presence or absence of reduced GSH. In addition to 17-DMAG hydroquinone and 19-glutathionyl 17-DMAG, several oxidative metabolites of 17-DMAG were detected and characterized by liquid chromatography-tandem mass spectrometry. Different from previously reported primary biotransformations of GA and GA derivatives, 17-DMAG was not metabolized primarily through the reduction of benzoquinone and GSH conjugation in HLMs. In contrast, the primary biotransformations of 17-DMAG in HLMs were hydroxylation and demethylation on its side chains. The most abundant metabolite was produced by demethylation from the methoxyl at position 12. The reaction phenotyping study showed that CYP3A4 and 3A5 were the major cytochrome P450 isozymes involved in the oxidative metabolism of 17-DMAG, whereas CYP2C8, 2D6, 2A6, 2C19, and 1A2 made minor contributions to the formation of metabolites. On the basis of the identified metabolite profiles, the biotransformation pathways for 17-DMAG in HLMs were proposed.
This work was supported in part by the National Institutes of Health National Cancer Institute [Grants R01-CA120023, R21-CA143474]; and the University of Michigan Cancer Center Research [Grant Munn].
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
- 90-kDa heat shock protein
- 19-glutathionyl 17-(allylamino)-17-demethoxygeldanamycin
- 17-(allylamino)-17-demethoxygeldanamycin hydroquinone
- 17-(dimethylaminoethylamino)-17-demethoxy geldanamycin
- 19-glutathionyl 17-(dimethylaminoethylamino)-17-demethoxy geldanamycin
- 17-(dimethylaminoethylamino)-17-demethoxygeldanamycin hydroquinone
- enhanced product ion
- geldanamycin hydroquinone
- human liver microsome
- high-performance liquid chromatography
- liquid chromatography-tandem mass spectrometry
- protonated molecular ion
- multiple reaction monitoring
- mass spectrometry
- cytochrome P450.
- Received September 23, 2010.
- Accepted December 22, 2010.
- Copyright © 2011 by The American Society for Pharmacology and Experimental Therapeutics