摘要
Six indigenous folk medicinal plants growing wild in the area of Tabuk, Saudi Arabia which were selected for the study of their phytochemistry as well as their biological activities as antitumor and antifolate agents. Antitumor activities of methanol extracts of the six plants were measured in vitro using three human tumor cell lines （breast, lung and CNS cancers） while antifolate activities were assessed using commercial dihyrofolate reductase obtained from Sigma Co. Among the six plant extracts tested, the most remarkable were those of Caralluma sinaica and Fagonia tenuifolia. Caralluma extract showed strong antitumor activity （low GIso） against the three human tumor cell lines. Fagonia extract, on the other hand, was quite inhibitory to the growth of CNS cancer and breast cancer cell lines but much less so against lung cancer cells. Extracts of both Sonchus oleraceus and Caralluma sinaica were strongly inhibitory to DHFR. These results suggest that the mechanism of anticancer activity of Caralluma plant is through DHFR inhibition but that of Fagonia may follow a different path.
