Bufagin

Bufagins are a class of toxic steroids found as components of bufotoxin. They can be obtained (in form of marinobufagin, for example) from toad's milk, which refers to secretions from the Cane Toad ("Bufo marinus"), when it is injured, scared or provoked.

Some bufagins have effects similar to poisoning by digitalis, having effects on the cardiac muscle, causing ventricular fibrillation. Some also have equally some local anesthetic action. The analgesic effects have also been proven, [Wang, G., G. Sun, et al. (1994). "The application of traditional Chinese medicine to the management of hepatic cancerous pain." J-Tradit-Chin-Med 14(2): 132-8.] by acting as Na+/K+-ATPase inhibitors 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. [Jiun-Yih Yeh, William J. Huang, Shu-Fen Kan, Paulus S. Wang (2002) - Effects of bufalin and cinobufagin on the proliferation of androgen dependent and independent prostate cancer cells: The Prostate - Volume 54, Issue 2 , Pages 112 - 124] [Jing, Y., H. Ohizumi, et al. (1994). "Selective inhibitory effect of bufalin on growth of human tumor cells in vitro: association with the induction of apoptosis in leukemia HL-60 cells." Jpn-J-Cancer-Res 85(6): 645-51]

There are several closely related bufagins, including:
* 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.

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