Nastaran Nikounezhad

Parabens are a group of preservatives that have vast indications in pharmaceuticals, cosmetics and food industries. Recently, there have been reports about the estrogenic effects of these compounds which raised concerns about the possibility of involvement of parabens in estrogen-responsive cancers. In the current study, the effect of methylparaben (MP) and propylparaben (PP) was assessed on the growth pattern of human breast adenocarcinoma cell line, MCF-7. 17-ß-estradiol (EST) and tamoxifen (TAM) were used as estrogenic and anti-estrogenic compounds. EC50 of EST and IC50 of TAM were calculated to be 1.206 and 7.017 µg/ml, respectively, based on trypan blue dye exclusion assay in a 5-day exposure. Proliferation kinetics of MCF-7 cells in a 10 day exposure to these compounds showed that EST (1.206 µg/ml) could induce cell proliferation, while exposure of MP or PP (at the same dose) did not change the growth curve of MCF-7. TAM, on the other hand could decrease the proliferation rate of MCF-7. This inhibition was more exacerbated when MP and PP were added to the culture media, suggesting a competitive binding of these compounds to receptors. In conclusion, the data propose the probable estrogenic effect of MP and PP with less potency compared to EST and less competitive binding to ERs compared to TAM.

Medicinal herbs are significant sources of chemotherapeutic drugs and play a vital role in the prevention and treatment of cancer. Mentha pulegium L. from Labiatae family was traditionally used as an anticancer agent. In this study, aerial parts including leaves of this plant were extracted by methanol and fractionated extracts have been produced by petroleum ether, ethyl acetate, acetone, methanol and distilled water. For the purpose of cytotoxic evaluation of methanolic extract and its fractions on human ovary carcinoma cells (C13), human hepatocarcinoma cells (HepG2) and human lung carcinoma cells (A549), clonogenic assay was performed. Briefly, 200 cells were seeded in each well of 6 well plates in RPMI 1640 with 10% FBS media. After 24 hours incubation, 0-50μg/ml of methanolic extract and its fractions were exposed to the cells. Finally, colonies with more than 50 cells were counted after 7 days. In each case, a control row was set by the exposure of cells to compounds-free solvents. LC50 values were calculated using nonlinear regression analysis on Graphpad prism® software. The result showed that the methanolic extract and its fractions are cytotoxic on all three studied human carcinoma cell lines at different degrees. Human ovary carcinoma cell line (C13), which is resistant to many other chemotherapeutic agents (e.g. cisplatin), is the most sensitive cell line to methanolic extract and its fractions compared to two other cell lines. Further complementary cellular and animal studies are recommended for these anticancer candidates.