Cytotoxicity of some medicinal plant extracts used in Tanzanian traditional medicine.

Using the ethnomedical data approach, some Tanzanian plants that are used in Tanzanian traditional medicine for cancer or non-cancer diseases were collected and evaluated for cytotoxic activity. The antiproliferative effect of the methanolic extracts (10 and 100 microg/ml) of 47 plants was evaluated in vitro on three human cell lines (HeLa, cervical carcinoma; HT29, colon adenocarcinoma; and A431, skin carcinoma). From the nine plants that are used to treat cancer, two plants (22%) exhibited pronounced cytotoxic effect (<25% cell proliferation) at least in one of the tested cell lines. For the 38 plants that are used to treat non-cancer diseases, 14 plants (37%) exhibited pronounced cytotoxic effect (<25% cell proliferation). Cell type cytotoxic specificity was observed in some extracts. Overall, the A431 cells were much more sensitive to most of the extracts than the other cell lines. For the plants that are used as anticancer herbal drugs, our results indicate that there is no correlation between the reported use of these plants and their cytotoxic activity obtained in this study. However, plants that have shown pronounced cytotoxic activity will be evaluated further for the possible isolation of active antitumor compounds.