Quercetin : Antitumor activity and pharmacological manipulations for increased therapeutic gains

In the present study, we examined antiproliferative activity of quercetin in vitro and in vivo . Antiproliferative activity was demonstrated against MCF7 cell line in a dose and time dependent manner with IC50 value found to be 10 µg/ml. Further quercetin arrested MCF7 cells in G2/M phase of cell cycle in a dose and time dependent way. MCF-7 cells exposed to quercetin beta cyclodextrin complex showed reduced cell survival. Quercetin has found to act as an antiangiogenic molecule with concentrations up to 10 µg but had damaging effect on chick embryo chorioallantoic membrane at 25 µg. In animal studies quercetin inhibited tumor growth by more than 58% in mice grafted with mammary carcinoma and prolonged survival period of sarcoma 180 bearing mice by 2.3 times, respectively. We also evaluated whether quercetin enhances the therapeutic effect of mitomycin C, especially on mammary tumor growth. These studies indicated that quercetin markedly enhances the ability of mitomycin C to inhibit tumorigenicity in mammary adenocarcinoma. These effects are mediated in part by the often poorly vasalarized and hypoxic regions of tumors.