Bufagins are a class of toxic steroids found as components of bufotoxin

Bufotoxin

Bufotoxins are a family of toxic substances found in the parotoid glands, skin and venom of many toads ; other amphibians; and some plants and mushrooms. The exact composition varies greatly with the specific source of the toxin. It can contain: 5-MeO-DMT, bufagins, bufotalin, bufotenine,...

. They can be obtained (in form of marinobufagin, for example) from toad's milk, which refers to secretions from the Cane Toad

Cane Toad

The Cane Toad , also known as the Giant Neotropical Toad or Marine Toad, is a large, terrestrial true toad which is native to Central and South America, but has been introduced to various islands throughout Oceania and the Caribbean...

 (Bufo marinus), when it is injured, scared or provoked.

Some bufagins have effects similar to poisoning by digitalis

Digitalis

Digitalis is a genus of about 20 species of herbaceous perennials, shrubs, and biennials that are commonly called foxgloves. This genus was traditionally placed in the figwort family Scrophulariaceae, but recent reviews of phylogenetic research have placed it in the much enlarged family...

, having effects on the cardiac muscle

Cardiac muscle

Cardiac muscle is a type of involuntary striated muscle found in the walls and histologic foundation of the heart, specifically the myocardium. Cardiac muscle is one of three major types of muscle, the others being skeletal and smooth muscle...

, causing ventricular fibrillation

Ventricular fibrillation

Ventricular fibrillation is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly. Ventricular fibrillation is a medical emergency and most commonly identified arrythmia in cardiac arrest...

. Some also have equally some local anesthetic action. The analgesic

Analgesic

An analgesic is any member of the group of drugs used to relieve pain . The word analgesic derives from Greek an- and algos ....

 effects have also been proven, by acting as Na+/K+-ATPase inhibitor

Enzyme inhibitor

An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...

s on the binding sites of the cell membrane

Cell membrane

The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

. The anti-cancer properties in leukemia

Leukemia

Leukemia or leukaemia is a type of cancer of the blood or bone marrow characterized by an abnormal increase of immature white blood cells called "blasts". Leukemia is a broad term covering a spectrum of diseases...

 and melanoma

Melanoma

Melanoma is a malignant tumor of melanocytes. Melanocytes are cells that produce the dark pigment, melanin, which is responsible for the color of skin. They predominantly occur in skin, but are also found in other parts of the body, including the bowel and the eye...

 cells, and the inhibition

Enzyme inhibitor

An enzyme inhibitor is a molecule that binds to enzymes and decreases their activity. Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used as herbicides and pesticides...

 of the proliferation of prostate cancer

Prostate cancer

Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...

 cells, have also been investigated. Some of the bufagin toxins are used in low doses in traditional Chinese medicine

Traditional Chinese medicine

Traditional Chinese Medicine refers to a broad range of medicine practices sharing common theoretical concepts which have been developed in China and are based on a tradition of more than 2,000 years, including various forms of herbal medicine, acupuncture, massage , exercise , and dietary therapy...

 for similar applications as digoxin

Digoxin

Digoxin INN , also known as digitalis, is a purified cardiac glycoside and extracted from the foxglove plant, Digitalis lanata. Its corresponding aglycone is digoxigenin, and its acetyl derivative is acetyldigoxin...

 is used for in Western medicine (i.e. treatment of heart conditions such as atrial fibrillation

Atrial fibrillation

Atrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...

).

There are several closely related bufagins, including:

• The very toxic arenobufagin
  Arenobufagin
  Arenobufagin is a cardiotoxic bufanolide steroid secreted by the Argentine toad Bufo arenarum. It has effects similar to digitalis, blocking the Na+/K+ pump in heart tissue....
  
   C₂₅H₃₄O₆, obtained from the Argentine Toad (Bufo arenarum)
• Cinobufagin
  Cinobufagin
  Cinobufagin is a cardiotoxic bufanolide steroid secreted by the Asiatic toad Bufo gargarizans. It has similar effects to digitalis and is used in traditional Chinese medicine....
  
  , 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.