Abstract

Bioassay guided fractionation of the roots of Cyathostemma argenteum using the brine shrimp resulted in the isolation of two uncommon flavanones, 2,5-dihydroxy-7-methoxyflavanone 1 and 2,5-dihydroxy-6,7-dimethoxyflavanone 2 while the stem bark yielded the related compounds 5-hydroxy-7-methoxyflavone 3 and 5-hydroxy-6,7-dimethoxyflavone 4. The alkaloids liriodenine 5 and discretamine 6 as well as benzyl benzoate 7 were isolated from the roots and 6 was also isolated from the stembark. In cytotoxicity tests using four human breast cancer cell lines, 1 and 2 were weakly toxic to MCF-7 cells (IC 50 = 19.6 and 19.0 μm, respectively) but showed little activity against MCF-7 cells resistant to doxorubicin or against two oestrogen receptor-deficient cell lines. Compound 5, but not 6 and 7, was moderately cytotoxic against all four cell lines. These results are discussed in the context of the traditional use of C. argenteum in the treatment of breast cancer. Copyright © 2004 John Wiley & Sons, Ltd.