Antineoplastic agents III:: Steroidal glycosides from Solanum nigrum

By bioactivity-guided fractionation, three known steroidal glycosides, beta(2)-solamargine (1), solamargine (2), and degalactotigonin (3), were isolated from Solanum nigrum. Compounds 1-3 induced morphological abnormality in Pyricularia oryzae mycelia with MMDC (minimum morphological deformation concentration) values of 63.0, 38.5, and 97.2 mu M, respectively. This is the first report on the isolation of 1 from this species and on the cytotoxicity of 1-3 on six cultured human solid tumor cell lines HT-29 (colon), HCT-15 (colon), LNCaP (prostate), PC-3 (prostate), T47D (breast), and MDA-MB-231 (breast) in vitro. The cytotoxic assay indicated that 2 is the main antineoplastic agent in S. nigrum. The structures of 1-3 were elucidated on the basis of chemical evidence and spectral analysis, especially by 2D-NMR analysis.