Chloro(triphenylphosphine)gold(I) a forefront reagent in gold chemistry as apoptotic agent for cancer cells.

The antiproliferative activity of the gold complex [Au(tpp)Cl] (1) (tpp=triphenyphosphine) against human breast adenocarcinoma cells (MCF-7) and normal human fetal lung fibroblast cells (MRC-5) was investigated. The compound exhibits stronger activity against MCF-7 cells than cisplatin. The apoptotic pathway, especially though the mitochondrion damage was concluded by cell cycle arrest, flow cytometry using Annexin V-Fluorescein IsoThioCyanate (FITC) and Propidium Iodide (PI) as indicators, assays and permeabilization of the mitochondrial membrane tests. The molecular mechanism of action of 1 was further studied by: (i) its catalytic activity on the oxidation of linoleic acid (an acid that partakes in membrane fluidity) to hyperoxolinoleic acid by oxygen and (ii) its binding affinity towards the calf thymus (CT) DNA. Since the deactivation of cisplatin by glutathione (GSH), is related with the development of cell resistance, the reaction of 1 with GSH was investigated by UV absorption spectroscopy. The absence of micronucleus in cells confirms that the complex has no in vitro toxicity. The in vivo genotoxicity caused by 1 was evaluated by Allium cepa test.