Anticancer agent 3-bromopyruvic acid forms a conjugate with glutathione

Background: 3-Bromopyruvic acid (3-BP), a glycolytic inhibitor and a promising anticancer compound, induces oxidative stress and depletes cells of glutathione (GSH). The causes of GSH loss remain unclear. The aim of this study was to ascertain whether 3-BP forms a conjugate with glutathione. Methods: GSH was incubated with various amounts of 3-BP and the extent of reaction was titrated with H-1 NMR and H-1-H-1 NMR. The reaction outcome was identified by MS/MS. Intracellular formation of the conjugate was assessed in cells treated with 3-BP and 3-BP(C-13) and analyzed using the targeted LC-MS/MS method in negative ionization MRM mode. Results: 3-BP was found to react with GSH in a 1:1 ratio forming an S-conjugate. The same conjugate was formed intracellularly in erythrocytes and MCF-7 cells. Conclusions: 3-BP reacts with GSH in the absence of cells and intracellularly. This reaction appears to be the main cause of GSH loss in 3-BP treated cells. (C) 2015 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Sp. zo.o. All rights reserved.