Synthesis, characterization and antitumor activity of rare earth (Y, La) substituted phosphotungstates containing 5-fluorouracil

Two rare earth substituted Keggin-type phosphotungstates containing 5-fluorouracil, K₁₀C₄H₄FN₂O ₂Y(PW₁₁O₃₉)₂10H₂O (FYPW) and K₉(C₄H₄FN₂O₂) ₂La(PW₁₁O₃₉)₂18H₂O (FLaPW) were synthesized in aqueous solution, and the structures were characterized by Fourier transform infrared spectroscopy (FT-IR), element analysis, inductively coupled plasma spectrometry (ICP), X-ray powder diffraction (XRD) and ¹H nuclear magnetic resonance (NMR). Thermal analysis showed that the decomposition processes of the two compounds could be divided into three steps, the loss of crystal water, the decomposition of 5-fluorouracil unit and the decomposition of Keggin-type polyanions. The in vitro cytotoxicities against HEK 293, HeLa and HepG-2 cells were studied by methyl thiazolyl tetrazolium (MTT) assay. The results showed that FYPW and FLaPW had higher antitumor activities than 5-fluorouracil, C₄H ₄FN₂O₂H₂PW₁₂O ₄₀8H₂O and rare earth substituted polyoxometalates K ₁₁Ln(PW₁₁O₃₉)₂nH₂O (Ln=Y, La). It was concluded that introducing 5-fluorouracil and rare earth (Y or La) into its structure was a considerable way to enhance antitumor activities of polyoxometalates.