Zeise’s Salt Could Be A Cancer Fighter

Zeise’s salt, K[PtCl₃(C₂H₄)], is a curious transition-metal complex in which an ethylene molecule binds side-on to the platinum atom. Although Zeise’s salt has been known for nearly 200 years, a team led by Ronald Gust of the University of Innsbruck, in Austria, is just now conducting a thorough investigation of its bioactivity (Angew. Chem. Int. Ed. 2015, DOI: 10.1002/anie.201410357). The researchers have found that the compound strongly inhibits cyclooxygenase (COX) enzymes, but it shows low cytotoxicity against cancer cells. The observation indicates that Zeise’s salt works differently than Peyrone’s salt, an analog better known as the potent chemotherapy drug cisplatin, PtCl₂(NH₃)₂. Cisplatin is mostly inactive against COX enzymes but operates by binding and damaging cancer cell DNA. Because COX overexpression is associated with some cancer tumors, the team thinks Zeise’s salt could be a starting point for developing new chemotherapy drugs. Many more experiments are needed before Zeise’s salt could be used as a drug lead, comments cisplatin researcher Pernilla Wittung-Stafshede of Umeå University, in Sweden. “But this study shows that one does not always need to design elaborate new molecules or seek out unusual natural products—sometimes old molecules can be hidden gems to follow up on.”