Cytotoxic Resibufogenin Transformation Products from Cell Suspension Cultures of Platycodon Grandiflorum

Four biotransformed products of resibufogenin were obtained after 4 days of incubation with cell suspension cultures of Platycodon grandiflorum. On the basis of chemical and spectral data, their structures were elucidated as 3-epi-resibufogenin, marinobufagin, 1β-hydroxy-resibufogenin, and 3-epi-marinobufagin respectively, among which the latter two compounds are new. These compounds were found to exhibit potent cytotoxic activities against Bel-7402, BGC-823, HeLa, and HL-60 human cancer cell lines.