In vitro cytotoxicity of extracts from Brazilian Asteraceae

Aqueous and organic extracts of Asteraceae (Compositae) collected from the State of Rio Grande do Sul, Brazil, have been tested in vitro for cytotoxic activity against human solid tumour cell lines. Twenty-five species, 125 extracts in total, were screened against HT29 human colon adenocarcinoma cells and NCI-H460 human non-small cell lung cancer cells. Twenty-five extracts from 11 species demonstrated cytotoxicity at 100 mug/ml against one or both of the cell lines tested. Further analysis was performed on the active extracts using three cell lines HT29, NCI-H460, and U373 human glioblastoma cells, to determine the IC50 and the degree of tumour cell line selectivity. Extracts from Baccharis coridifolia, Baccharis ochracea, Eupatorium macrocephalum, Eupatorium pedunculosum and Stenachaenium riedelii all produced IC50 values below 5 mug/ml. Comparison of the IC50 results between cell lines identified that Baccharis coridifolia, Baccharis ochracea, Eupatorium laevigatum and Pluchea sagittalis extracts produced differential sensitivity across the panel of three cell lines. These species are currently under further investigation with the ultimate objective of isolation and identification of the active principles responsible for the anti-proliferative activity.