Non-enzymatic glutathione-mediated conjugation of unsymmetrical bisacridine C-2028 with anticancer activity

The presented data complement the studies on the interplay between C-2028 (anticancer-active unsymmetrical bisacridine) and the glutathione S-transferase/glutathione (GST/GSH) system.
Individual three recombinant human GST isoenzymes (A1-1, M1-1, and P1-1; 0.05 mg/mL) were incubated for 1 h with the tested C-2028 (0.05 mM) in the presence and in the absence of GSH (0.1, 1, and 5 mM) at 37 °C. Then, incubation mixtures were analyzed by RP-HPLC with UV-vis detection and/or diode array and multiple wavelength detection, and monitored by MS.
Elution profiles obtained from the chromatographic separation of incubation mixtures showed two novel peaks eluted at tR = 11.5 min (marked as X1) and tR = 14.0 min (marked as X2). These were observed only at higher concentrations of GSH (5 mM) and their formation did not require the participation of GST enzyme. MS analysis indicated the corresponding ions at m/z 590 and m/z 722, respectively, but the identity of these products remains unknown. To provide additional data on these novel likely non-enzymatic GSH-mediated derivatives of C-2028, additional structure confirmation tools, such as tandem mass spectrometry or NMR, are needed.