The cytotoxic effects of water and ethanol extracts of Echinacea purpurea (L.) (EP) and chloroform, ethyl acetate butanol and aqueous fractions from each extract of EP were examined. Every extract and fractoin of EP inhibited the growth of human hepatocarcinoma, human gastric cancer cell, human breast cancer cells and human lung carcunoma in concentration-dependent manners over a concentration range of 0.05~1.0㎎/㎖. Most extracts and fractions with the concentration of 1㎎/㎖ showed strong inhibition of more than 70% for every cancer cell. Only aqueous fractions of each extract showed very weak inhibitons of 12 to 25% on the growth of human normal lung cell with the concentration of 1㎎/㎖ . Overall selectivity of the extrats and fractions on the four human cancer cell lines was over 2.5. These results indicatd that EP has a very potent selective toxicity for cancer cells.

Rehmannia glutinosa shows a high level of resistance to the non-selective herbicide paraquat.To characterize the antioxidant enzyme system of R. glutinosa, we comparatively examined the responses of antioxidant enzymes to UV, wounding and a general elicitor yeast extract in R. glutinosa and soybean. The levels of enzyme activities of the two plant species were drastically different between those per fresh weight (general activity) and per protein (specific activity) bases. The general activities of superoxide dismutase (SOD), peroxidase (POX), catalase (CAT), and glutathione reductase (GR) were lower, but that of ascorbate peroxidase (APX) was higher in R. glutinosa than in soybean. The specific activities of the enzymes, however, were about two-to seven-fold higher in R, glutinosa than In soybean except that of CAT, which was about 12-fold higher in soybean The general and specific enzyme activities of R, glutinosa relative to those of soybean showed a consistent increase in responses to the stresses only in SOD. The specific activities of SOB and AM were higher in R, glutinosa in all stress treatments. The results might suggest a relatively higher contribution of SOD and APX to the stress tolerance.