Fig. 6.

LC-MS/MS analysis of the RU486-GSH conjugates G753 isolated from human liver microsomes. Incubation conditions and extraction/analysis procedures were as described under Materials and Methods. A, extracted ion chromatogram of the MH⁺ ions at m/z 753. B, MS/MS spectrum of G753 eluting at 21.1 min. C, MS/MS spectrum of G753 eluting at 22.5 min. The spectra were obtained in positive mode and analyzed using the eXcalibur software. Right, proposed structures. The sites of fragmentation are indicated by dashed lines and explained in the text.