Ferrocenyl β-diketonate compounds: Extended ring systems for improved anticancer activity

A library of ferrocenyl β-diketonate compounds with varying degrees of aromatic functionality have been synthesized and fully characterized. This includes cyclic voltammetry and the analysis of four new structures by single crystal X-ray diffraction. The compounds cytotoxic potential has been determined by MTT screening against pancreatic carcinoma (MIA PaCa-2), ovarian adenocarcinoma (A2780), breast adenocarcinomas (MDA-MB-231 and MCF-7) and normal epithelial retinal (ARPE-19). The compounds show a general trend, where increasing the number of aromatic rings in the molecule yields an increase in cytotoxicity and follows the trend anthracenyl>naphthyl>phenyl>methyl. The compounds are particularly sensitive to the triple negative cancer cell line MDA-MB-231, and the potential modes of action have been studied by production of reactive oxygen species using fluorescence microscopy and cell morphology using Scanning Electron Microscopy. All assays highlight the ferrocenyl β-diketonate with an anthracenyl substituent to be the lead compound in this library. The decomposition of this compound was also observed within cells, yielding a cytotoxic fluorescent molecule, which has been visualized by confocal microscopy.