Screening for cytotoxic activity of plants used in traditional medicine.

A total of 260 extracts have been prepared from 75 medicinal plant species collected in Africa, Panama and Mauritius. Three different concentrations of each extract have been screened in vitro for cytotoxic activity using a colorimetric assay to determine cell survival of human colon carcinoma Co115 cells. Fifteen plants showed ED50 values between 10.0 and 1.0 micrograms/ml but more significant activities were obtained in 11 (ED50 range 1.0-0.1 micrograms/ml) and 3 (ED50 range 0.1-0.01 micrograms/ml) plant specimens. Identification of new active substances may well be aided by pre-selecting plants known to be used empirically by traditional healers.