Gold(III) compounds of 1,4,7-triazacyclononane showing high cytotoxicity against A-549 and HCT-116 tumor cell lines

Two gold(III) compounds Au(TACN)Cl(2)]Cl (1) and Au(TACN)Cl(2)]AuCl(4)] (2) (where TACN=1,4,7-triazacyclononane), have been synthesized and characterized by electrospray ionization mass spectrometry (ESI-MS), (1)H NMR spectroscopy and elemental analyses. The structure of compound 2 was determined by X-ray crystallography, in which TACN coordinates to the gold(III) center in a bidentate mode and the unbound amine group forms a very short intramolecular Au-H(-N) contact (1.91A). Biological activity data showed that compound 1 is more cytotoxic than cisplatin against A-549 and HCT-116 tumor cell lines. The interactions of compound 1 with CT-DNA were studied by UV-Vis, fluorescence and CD spectroscopy, which suggests that compound 1 can induce the distortion of DNA double helix.