Bis diphenylphosphine ethane Gold Complexes

In culture medium (and presumably in vivo), the digold complexes rearrange to form a new species, which is more active than the precursors  

Au(DPPE)2 is stable in serum for 25 hours, and in the presence of glutathione for 8 days. ° The stability and inertness result from two factors, the chelate effect (since DPPE coordinates via two phosphorus donor atoms) and the greater stability of phosphine over thiolate ligands. The complex reacts with Cu(ii), forming Au2(DPPE)j and a precipitate containing Cu and DPPE.  

Structure-function relationships were examined for complexes with a variety of related diphosphine ligands.Generally the phenylphosphine complexes are more active than are ethyl, pyridyl or fluorophenyl derivatives. As would be expected when a cationic complex is the active species, the nature of the anion [e.g. Cl , Br or NO3 ) does not substantially affect the potency of the drug. 

PhjP-C C-PPh2, trans-PhjP-C=C-PPh3, and para-PhjP-CgH -PPhj. 

Substituting PhjAs for PhjP also eliminates the Cu-induced enhancement and the in vivo activity, but not in vitro activity against several cell lines, From these results, Snyder et al. suggested that Cu(l) may function to transport DPPE, or, conversely, that DPPE may transport Cu(i) to the target site, or that the entire Cu-DPPE molecule is necessary for activity.  

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