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

Two novel rare earth substituted phosphotungstates containing 5-fluorouracil, K-9(C4H4FN2O2)(2)Nd(PW11O39)(2)center dot 25H(2)O (FNdPW) and K-9(C4H4FN2O2)(2)Ce(PW11O39)(2)center dot 23H(2)O (FCePW), were synthesized and characterized by elementary analysis, FT-IR spectra, X-ray powder diffraction and H-1 NMR. The thermal analysis showed that FNdPW decomposed at 210 and 493 degrees C, and FCePW decomposed at 223 and 471 degrees 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, C4H4FN2O2H2PW12O40 center dot 8H(2)O and K(11)Ln(PW11O39)(2)center dot xH(2)O (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 C4H4FN2O2H2PW12O40 center dot 8H(2)O, of which FNdPW exhibited the highest antitumor activates against HeLa cells (EC50=3.41x10(-6) mol/L) and HepG-2 cells (EC50=6.24x10(-6) mol/L). Thus the introduction of rare earth elements and 5-fluorouracil could significantly enhance antitumor effect polyoxometalates.