There are estimated to be more than 20,000 species of plants in Venezuela, of which more than 1,500 are used for medicinal purposes by indigenous and local communities. Only a relatively small proportion of these have been evaluated in terms of their potential as antitumour agents. In this study, we screened 308 extracts from 102 species for cytostatic and cytotoxic activity against a panel of 6 tumour cell lines using a 24h sulphorhodamine B assay. Extracts from Clavija lancifolia, Hamelia patens, Piper san-vicentense, Physalis cordata, Jacaranda copaia, Heliotropium indicum and Annona squamosa were the most cytotoxic, whereas other extracts from Calotropis gigantea, Hyptis dilatata, Chromolaena odorata, Siparuna guianensis, Jacaranda obtusifolia, Tapirira guianensis, Xylopia aromatica, Protium heptaphyllum and Piper arboreum showed the greatest cytostatic activity. These results confirm previous reports on the cytotoxic activities of the above-mentioned plants as well as prompting further studies on others such as Clavija lancifolia and Hyptis dilatata that have not been so extensively studied.
