Lipophilic extracts of Echinacea roots were screened for their cytotoxic activity on human cancer cell lines and E. pallida was found to be the most active. Ten polyacetylenes and polyenes were then isolated by bioassay-guided fractionation from E. pallida, characterized and tested for cytotoxic activity. (8Z,13Z)-Pentadeca-8,13-dien-11-yn-2-one was the most active constituent, particularly on the colonic COLO 320 cancer cells (IC50 = 2.3 ± 0.3 uM). The cytotoxicity of this compound was also tested on breast carcinoma MCF-7 (IC50 = 2.5 ± 0.7 uM), melanoma MeWo (IC50 = 28.6 ± 2.3 uM) and pancreatic MIA PaCa-2 cancer cells (IC50 = 32.2 ± 3.9 uM). Apoptotic cell death was found to be involved in its mechanism of action. The total synthesis of this secondary metabolite was also described. A HPLC stability study of this polyenic compound indicated that the cytotoxic activity can be mainly attributed to the genuine not oxidized molecule.
Isolation, structure elucidation, synthesis and cytotoxic activity of polyacetylenes and polyenes from Echinacea pallida / Pellati, Federica; A., Chicca; B., Adinolfi; Orlandini, Giulia; Prati, Fabio; P., Nieri; Benvenuti, Stefania. - ELETTRONICO. - Fall 2010:(2010), pp. 27-28. (Intervento presentato al convegno Agricultural and Food Derived Natural Products for Preventing and Combating Disease, 240th ACS National Meeting & Exposition tenutosi a Boston, MA, USA nel 22-26 Agosto 2010).