Human cancerous and healthy cell cytotoxicity studies of a chiral μ-dicarbene-digold(I) metallamacrocycle.

A novel eighteen membered chiral macrocyclic dicarbene-digold complex [(μ-diNHC)Au(I)]2[OTF]2 (8-(+/-)) was synthesized and characterized. Starting with enantiopure diNHC imidazolium salt ligand precursors enables access to the enantiopure versions of the digold(I) metallamacrocycles, 8-(+) and 8-(-). In vitro cytotoxicity studies indicate 8-(+/-) is moderately cytotoxic to both healthy and cancerous cell-lines, with no specificity. Confocal microscopy indicates the digold metallamacrocycle penetrates the cell membrane and causes cell death via apoptosis, as evidenced by DNA electrophoresis. The complex 8-(+/-) is characterized by a combination of NMR techniques (gDQCOSY, gHSQC, gHMBC and ROESY), single crystal X-ray diffraction, and combustion analysis.