Molecule of the Week(08): Cytotoxicity of Platinum(II) Compounds

The molecule of the week is fresh out of Leiden University in the Netherlands regarding the cytotoxicity of fluorescent platinum (II) compounds (Brouwer, J.; den Dulk, H.; Kooijman, H.; Marques-Gellego, P.; Reekijk, J.; Roubeau, O.; Spek, A.L.; Teat, S.J., Inorg. Chem., Articles ASAP).  Although the paper describes the synthesis of two platinum(II) compounds, I chose to focus on cis-[Pt(A9opy)Cl2] (molecule 1) because of the intricate way in which the planar ligand conforms itself to bind to the platinum metal ion.  The E-2-[1-(9-anthryl)-3-oxo-3-prop-2-enylpyridine] (aka A9opy in figure 1) ligand coordinates to platinum through three different bonds.  The carbons of the isomerizable carbon-carbon double bond coordinate perpendicularly in an organometallic bond to create a constrained and distorted square planar configuration.  The pyradinium nitrogen also coordinates to the metal ion to create a five-membered chelating ring with platinum and the carbon-carbon double bond.

However I didn’t choose this molecule because it looked “cool”.  I found the molecule’s ability to bind to cancerous cells and fluoresce to be particularly appealing.  Previously, most known platinum (II) anticancer compounds did not flouresce which was promblematic because the best way to study living cells was using a digital fluorescence microscopy technique.  Achieving a fluorescent metal-based molecule allows researchers to study the chemical processes platinum undergoes once it binds to tumor cells, providing better insight to fighting cancer.  In the case of cis-[Pt(A9opy)Cl2], studies showed that upon photolysis, the carbon-carbon double bond remained stable and did not isomerize.  Although the molecule is less effective than cisplatin, the most common metal-based chemotherapeutic drug, it proved to be fairly active against most tumor cells.  Further studies into the synthesis of related compounds and more in-depth biological research will be conducted in order to eventually find a drug that is less toxic and more active against a wider range of tumor lines.

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