Bufalin and cinobufagin are cardiotonic steroids extracted from Chansu, a galenical preparation of the dried white venom of
Chinese Bufo gargarizans (Asiatic toad). Chansu is also one of the major components of Kyushin, a traditional Chinese medicine. It has been shown
that bufalin and cinobufagin increase vascular resistance, vasoconstriction, and blood pressure via an inhibition of Na+,K+-ATPase. This evidence indicates that bufalin and cinobufagin are endogenous digitalis-like factors. Since bufalin, cinobufagin,
and digoxin share the similarity in the chemical structure, it is not surprising that bufalin and cinobufagin have digoxin-like
effects. It is well-known that bufalin, cinobufagin, and digoxin as well as ouabain are specific blockers of the sodium pump.
The digoxin-like immunoactivity has been observed in Chansu. It has been shown that bufalin and cinobufagin possess antitumor
effects on human lung adenocarcinoma cells, leukemia cells, pancreatic cancer cells, gastric cancer cells, prostate cancer
cells, endometrial cancer cells, ovarian cancer cells, and hepatocellular carcinoma via induction of growth inhibition, cell cycle arrest and/or apoptosis. Reactive oxygen species-dependent Bax translocation,
PI3K/Akt and apoptotic modulators including Bax, cytochrome c, and caspases are involved in bufalin-induced apoptosis or anticancer
pathways. In the present chapter, we shall review antitumor effects of bufalin on human cancer cells. Although in most studies,
human carcinoma cells or cell lines were employed, we expect that more in vivo studies and clinical trials will be performed in the near future.