Synthesis and antitumor activities of rare earth substituted phosphotungstates containing 5-fluorouracil

Two novel rare earth substituted phosphotungstates containing 5-fluorouracil, K9(C4H4FN2O2)2Nd(PW11O39)225H2O (FNdPW) and K9(C4H4FN2O2)2Ce(PW11O39)223H2O (FCePW), were synthesized and characterized by elementary analysis, FT-IR spectra, X-ray powder diffraction and 1H NMR. The thermal analysis showed that FNdPW decomposed at 210 and 493 °C, and FCePW decomposed at 223 and 471 °C, both of which had good thermal stabilities. MTT tests were performed to study the antitumor activities against HeLa cells and HepG-2 cells of FNdPW, FCePW, 5-fluorouracil, C4H4FN2O2H2PW12O408H2O and K11Ln(PW11O39)2xH2O (Ln=Nd, Ce), and their cytotoxicities against HEK 293 cells. The results showed that FNdPW and FCePW possessed higher antitumor activities and lower cytotoxicities than those of 5- fluorouracil and C4H4FN2O2H2PW12O408H2O, of which FNdPW exhibited the highest antitumor activates against HeLa cells (EC50=3.41×10−6 mol/L) and HepG-2 cells (EC50=6.24×10−6 mol/L). Thus the introduction of rare earth elements and 5-fluorouracil could significantly enhance antitumor effect of polyoxometalates.