Cytotoxic activity of polyacetylenes and polyenes isolated from roots of 'Echinacea pallida'

Abstract

The n-hexane extracts of the roots of three medicinally used 'Echinacea' species exhibited cytotoxic activity on human cancer cell lines, with 'Echinacea pallida' found to be the most cytotoxic. Acetylenes are present in 'E. pallida' lipophilic extracts but essentially absent in extracts from the other two species. In the present study, the cytotoxic effects of five compounds, two polyacetylenes (namely, 8-hydroxy-pentadeca-(9E)-ene-11,13-diyn-2-one (1) and pentadeca-(9E)-ene-11,13-diyne-2,8-dione (3)) and three polyenes (namely, 8-hydroxy-pentadeca-(9E,13Z)-dien-11-yn-2-one (2), pentadeca-(9E,13Z)-dien-11-yne-2,8-dione (4) and pentadeca-(8Z,13Z)-dien-11-yn-2-one (5)), isolated from the n-hexane extract of E. pallida roots by bioassay-guided fractionation, were investigated and the potential bioavailability of these compounds in the extract was studied.