Synthesis, crystal structure and pH dependent cytotoxicity of (SP-4-2)-bis(2-aminoethanolato-κ2N,O)platinum(II) – a representative of novel pH sensitive anticancer platinum complexes

Solid tumors are often hypoxic and consequently the pH in the tumoral tissue is decreasing with increasing tumor size (pH 5.5–7.4 in solid tumors versus pH 7.4 in normal tissues). This marked difference in pH value is a problem for weak base organic drugs and could advantageously be used for the introduction of pH sensitive anticancer platinum drugs. Synthesis and structure determination of (SP-4-2)-bis(2-aminoethanolato-κ2N,O)platinum(II), its binding behavior to 5′-GMP and its cytotoxicity against cisplatin sensitive cell lines under standard pH screening conditions (pH 7.4) as well as in acidified cell culture medium (pH 6.0) mimicking the conditions in a number of solid tumors is presented. There is evidence that this concept in anticancer platinum therapy, namely administration of rather unreactive drugs and activation under acidic pH conditions, can be realized.