study of synergistic and protective effects of three different polar saffron extracts and photon radiation on human colorectal cancer cells (ht-29) and normal human fibroblasts

Background: there are some hypotheses about radiationsensitizing and radiationprotective effects of antioxidants. saffron, dried stigmas of crocus sativus l., is a precious medicinal plant that contains an impressive variety of plant compounds such as crocin, crocetin, and safranal that act as antioxidants. the present study examined the cytotoxic effects of saffron extracts with different polarity and their synergism or protective effects with radiation on a colorectal cancer cell line (ht29) and normal human fibroblasts. objectives: the aim was to find a natural agent to improve radiotherapy efficacy.methods: ht29 colorectal cancer cells and normal human fibroblasts were cultured in rpmi1640 medium, incubated with different concentrations of different saffron extracts (50250 µg/ml), and then were exposed to a dose of 8 gy of xrays. the cytotoxicity effect was determined by the mtt assay.results: saffron extracts decreased cell viability in ht29 colorectal cancer cells and normal human fibroblasts as a concentrationdependent manner. combination radiotherapy with polar saffron extract in most doses showed synergistic effects on ht29 cell death while it did not show any distinctive synergistic effect in normal cells. semipolar and nonpolar extracts just in low doses had synergistic effects on tumor cells. these two extracts did not show any protective effects on normal cells.conclusions: among the various saffron extracts, polar saffron extract and low doses of nonpolar saffron extract in combination with radiation increase radiation sensitivity and cell death in tumor cells, while they do not increase radiation sensitivity in normal cells and even protect normal cells to some extent.