Cell and cell-free mechanistic studies on two gold(III) complexes with proved antitumor properties

AuL10 [AuIIICl2DMDT] (DMDT: N,N-dimethyldithiocarbamate) and AuL12 [AuIIIBr2ESDT] (ESDT: ethylsarcosine dithiocarbamate) are two extremely promising gold-based anticancer compounds. Their mechanisms of action are still largely unknown although some specific hypotheses were put forward. To shed light on reactivity with probable biological targets we report here on their interactions with serum albuminand with calf thymus DNA taken as model biomolecules. Quite unexpectedly, spectrophotometric investigations revealed substantially different patterns of interaction for these two gold complexes with the mentioned biomolecules, probably arising from differences in redox chemistry. Afterwards, AuL12 was tested against A549 human non-small-cell lung carcinoma cells, evaluating its real-time profile of cell-growth inhibition by the xCELLigence Real-Time Cell Analysis (RTCA) system. Measures of the impedance at the base of each well by non-invasive gold microelectrodes point out that this gold complex inhibits cell proliferation after only 4 hours of treatment, producing its cytotoxic effects probably at the membrane level.