Five new bufadienolides, 3 beta -formyloxyresibubgenin (1), 19-oxobufalin (
2), 19-oxodesacetylcinobufagin (3), 6 alpha -hydroxycinobufagin (4), and 1
beta -hydroxybufalin (5), have been isolated together with the previously k
nown bufadienolides 6-20 from the Chinese traditional drug "Ch'an Su". The
structures were elucidated employing spectroscopic methods. Bufadienolides
1-5 provided significant inhibitory activity against the EB and HL-60 cance
r cell lines. In addition, bufadienolide 1 was found active against the MH-
60 cancer cell line.