In vitro testing of biological action of Origanum species from Greek flora in various cancer cell lines
The Origanum species (Lamiaceae family), which are commonly used herbs, contain phenolic compounds; however, their estrogenic effects remain unknown. In this study, we investigated the possible estrogenic/antiestrogenic effects of extracts (dichloromethanic, methanolic, aqueous) derived from three Origanum species of Greek origin, (O. dictamnus, O. scabrum, O. microphyllum) by using the appropriate biological markers in various estrogen-dependent cellular systems. We evaluated the potential of (i) dichloromethanic, methanolic and aqueous extracts (at a concentration range of 0.2–125µg/ml), to modulate cell viability of MCF-7 and MDA breast cancer cell lines, Ishikawa endometrial and PC-3 prostate cancer cell lines, by use of the MTT assay and (ii) of methanolic extracts (at a concentration range of 0.1–100µg/ml) to influence the activity of estrogen receptor (ER) in MCF-7 cells transfected with an estrogen response element (ERE)-driven luciferase (Luc) reporter gene. Ishikawa, MDA and PC-3 cell lines showed no response to all Origanum extracts tested. The viability of MCF-7 breast cancer cells showed a small but significant increase when exposed to methanolic extracts. O. dictamnus and O. scabrum extracts (at a concentration range of 2–100µg/ml), in the absence and in the presence of 17β-estradiol (E2), reduced the luciferase activity significantly. O. microphyllum methanolic extract, when alone, increased the basal luciferase activity, whereas its co-incubation with estradiol inhibited significantly the E2-stimulated gene induction. Concluding, the methanolic extracts of the three Origanum species modulate the cellular growth and estrogenic/antiestrogenic potency in MCF-7 cells indicating an impact of this dietary substance on human health.