Stability Tests of Alkynygold(I)(NHC) Complexes by HPLC-DAD-MS
Gold organometallic compounds have been extensively investigated as potential anticancer metallodrugs and have shown a high potential regarding antiproliferative effects [Hickey, 2008; Andermark, 2016; Meyer, 2012; Schmidt, 2019]. Enhanced stability is a driving argument for the design of gold complexes with N-heterocyclic carbene (NHC) ligands. The more surprising is the lack of methods of pharmaceutical analytics for their stability and solution chemistry. Such analytical methods are important key elements for future metabolomic investigations and will help to ensure a better understanding of the biological behavior of the complexes [Kostiainen, 2003]. We selected complexes of the type of alkynylgold(I)(NHC) for detailed stability studies by HPLC-DAD-MS, in comparison to the well-known antirheumatic drug Auranofin. A RP-based chromatographic method was established to separate possible degradation products of alkynylgold(I)(NHC) complexes. The stability studies were performed at 37°C over 24h using dimethylformamide (DMF), dimethyl sulfoxide (DMSO), water and Dulbecco`s modified eagle medium (DMEM) solutions of each compound. Furthermore, interaction experiments of alkynylgold(I)(NHC) complexes with acetylcysteine are under way with the same set-up as the stability tests [Albert 2012]. ESI (+) and (-) ionisation with a quadrupole analyser was used for mass spectrometry. The first results indicate that alkynylgold(I)(NHC) complexes are stable in the analysed solvents with no significant changes in their AUCs [Fig 2].