Xanthene derivatives were previously reported to complex metals. A series of 9-(substituted phenyl)-2,6,7-trihydroxy-xanthene-3-ones was tested for their metal chelating effect and the results were confirmed in biological models (breast adenocarcinoma cell lines and erythrocytes).
The trifluoromethyl substitution resulted in the strongest chelator. It reduced however as well both iron and copper but protected erythrocytes and even cancer cells against excess copper.