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Dehydroalanine Analog of Glutathione: An Electrophilic Busulfan Metabolite That Binds to Human Glutathione S-Transferase A1-1

NCJ Number
Journal of Pharmacology and Experimental Therapeutics Volume: 327 Issue: 3 Dated: December 2008 Pages: 770-776
Date Published
December 2008
7 pages

The authors discuss their research, including methodology and outcomes, regarding the production of EdAG, an α,β-unsaturated dehydroalanyl analog of GSH.


Elimination of hydrogen sulfide from glutathione (GSH) converts a well-known cellular nucleophile to an electrophilic species, γ-glutamyldehydroalanylglycine (EdAG). The authors have found that a sulfonium metabolite formed from GSH and busulfan undergoes a facile β-elimination reaction to give EdAG, which is an α,β-unsaturated dehydroalanyl analog of GSH. EdAG was identified as a metabolite of busulfan in a human liver cytosol fraction. EdAG condenses with GSH in a Michael addition reaction to produce a lanthionine thioether [(2-amino-5-[[3-[2-[[4-amino-5-hydroxy-5-oxopentanoyl]amino]-3-(carboxymethylamino)-3-oxopropyl]sulfanyl-1-(carboxymethylamino)-1-oxopropan-2-yl]amino]-5-oxopentanoic acid); GSG], which is a nonreducible analog of glutathione disulfide. EdAG was less cytotoxic than busulfan to C6 rat glioma cells. GSH and EdAG were equally effective in displacing a glutathione S-transferase (GST) isozyme (human GSTA1-1) from a GSH-agarose column. The finding of an electrophilic metabolite of GSH suggests that alteration of cellular GSH concentrations, irreversible nonreducible glutathionylation of proteins, and interference with GST function may contribute to the toxicity of busulfan. (Published Abstract Provided)

Date Published: December 1, 2008