Bufagin

Bufagin is toxic steroid, C24H34O5, found as a component of bufotoxin. It is obtained (in form of marinobufagin) from toad's milk, which refers to secretions from the Cane Toad (Bufo marinus), when it is injured, scared or provoked.

Its effects are similar to poisoning by digitalis, having an effect on the cardiac muscle, causing ventricular fibrillation. It has equally some local anesthetic action. The analgesic effect has also been proven (Wang, Sun et al. 1994), by acting as a Na+/K+-ATPase inhibitor on the binding sites of the cell membrane. The anti-cancer properties in leukemia and melanoma cells, and the inhibition of the proliferation of prostate cancer cells, have also been investigated.

There are several closely related bufagins, such as:
 * The very toxic arenobufagin C25H34O6, obtained from the Argentine Toad (Bufo arenarum)
 * Cinobufagin, from Chusan Island Toad (Bufo gargarizans)
 * Gamabufagin, from the Japanese Toad (Bufo japonicus)
 * Quercicobufagin, from Oak Toad (Bufo quercicus)
 * Regularobufagin, from the Square-marked Toad (Bufo regularis)
 * Vallicepobufagin, from the Gulf Coast Toad (Bufo valliceps)
 * Viridibufagin, from the European Green Toad (Bufo viridis)

These bufagins, and especially cinobufagin, have given rise a large number of derivatives, such as desacetylcinobufagin 16-O-β-D-glucoside, 3-epi-desacetylcinobufagin 16-O-β-D-glucoside, 3-oxo-desacetylcinobufagin 16-O-β-D-glucoside and cinobufagin 3-O-β-D-glucoside.