Biotransformations of N-heterocyclic carbene gold(I) complexes in cancer cells from speciation studies by X-ray absorption spectroscopy

Linear, two-coordinate gold(I) complexes comprising an N-heterocyclic carbene (NHC) ligand and various other coligands have been found to display anticancer properties related to the nature of the ancillary ligand. Since gold(I) compounds are known to act as prodrugs, undergoing activation via ligand(s) exchange, uncovering the still unknown biotransformation pathways sustained by NHC-gold(I) complexes will provide complementary data regarding their mechanism of action. Following previous experiments at the BM16 beamline (exps. LS-3235 and LS-3432), we successfully determined the speciation of biphenyl gold(III) complexes in cancer cells from cryo-X-ray absorption spectroscopy (XAS) measurements. We now apply for beamtime at BM16 in order to investigate the intracellular speciation of five different NHC-gold(I) compounds to try and draw a relationship between their structure, biotransformation and cytotoxic activity.