Cytotoxic effects of Echinacea purpurea flower extracts and cichoric acid on human colon cancer cells through induction of apoptosis

Ethnopharmacological relevance: Echinacea is a top-selling herbal supplement that acts as immunostimulant. It has been used to treat common cold, coughs, bronchitis and upper respiratory infections. It is also a popular product used in anticancer therapy. The cytotoxic effects of Echinacea on cancer cells are still not clear. The aims of this study were to provide a preliminary validation of the effects of 50% aqueous ethanol extract of Echinacea purpurea flowers and its major compound, cichoric acid, on human colon cancer cells Caco-2 and HCT-116. Materials and methods: The cytotoxic effects of Echinace flower extracts and cichoric acid on cell viability, telomerase activity, DNA fragmentation, beta-catenin, caspase-9, and cleavage of poly-ADPribose polymerase (PARP) of human colon cancer cell were examined. Results: The results showed a significant inhibition of proliferation in E. purpurea flower extract and cichoric acid in a dose- and time-dependent manner. Cichoric acid treatment decreased telomerase activity in HCT-116 cells. Moreover, cichoric acid effectively induced apoptosis in colon cancer cells, which were characterized by DNA fragmentation, activation of caspase-9, cleavage of PARP and downregulation of beta-catenin. Conclusions: Our data indicate that cichoric acid has a strong growth-inhibitory effect against colon cancer cells, presumably resulting from the reduced telomerase activity and the induction of apoptosis. The exact mechanism of action should still be determined in future studies. Overall, the effects of 50% aqueous ethanol extract of E. purpurea flowers and cichoric acid may have provided in vitro evidence for the use as chemotherapeutic agents. (C) 2012 Elsevier Ireland Ltd. All rights reserved.