Persin is a fungicidal toxin

Toxin

A toxin is a poisonous substance produced within living cells or organisms; man-made substances created by artificial processes are thus excluded...

 present in the avocado

Avocado

The avocado is a tree native to Central Mexico, classified in the flowering plant family Lauraceae along with cinnamon, camphor and bay laurel...

. It is generally harmless to humans, but when consumed by domestic animals in large quantities it is dangerous. It has been suggested as a treatment for breast cancer

Breast cancer

Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...

.

Persin is an oil-soluble compound structurally similar to a fatty acid

Fatty acid

In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...

, and it leaches into the body of the fruit from the pits. Negative effects in humans seem to be primarily in allergic

Allergy

An Allergy is a hypersensitivity disorder of the immune system. Allergic reactions occur when a person's immune system reacts to normally harmless substances in the environment. A substance that causes a reaction is called an allergen. These reactions are acquired, predictable, and rapid...

 individuals.

Pathology

Consumption of the leaves and bark of the avocado tree, or the skin and pit of the avocado fruit have been shown to have the following effects:

• In birds (which are particularly sensitive to the avocado toxin), the symptoms are: increased heart rate, myocardial tissue damage, labored breathing, disordered plumage, unrest, weakness, and apathy. High doses cause acute respiratory syndrome (asphyxia
  Asphyxia
  Asphyxia or asphyxiation is a condition of severely deficient supply of oxygen to the body that arises from being unable to breathe normally. An example of asphyxia is choking. Asphyxia causes generalized hypoxia, which primarily affects the tissues and organs...
  
  ), with death approximately 12 to 24 hours after consumption.
• Lactating rabbits and mice: non-infectious mastitis
  Mastitis
  Mastitis is the inflammation of breast tissue. S. aureus is the most common etiological organism responsible, but S. epidermidis and streptococci are occasionally isolated as well.-Terminology:...
  
   and agalactia
  Agalactia
  Agalactia is absence of or faulty secretion of breast milk following childbirth.It is commonly associated with Sheehan's syndrome, following post partum haemorrhage....
  
   after consumption of leaves or bark.
• Rabbits: cardial arrhythmia, submandibular edema
  Edema
  Edema or oedema ; both words from the Greek , oídēma "swelling"), formerly known as dropsy or hydropsy, is an abnormal accumulation of fluid beneath the skin or in one or more cavities of the body that produces swelling...
  
   and death after consumption of leaves.
• Cows and goats: mastitis
  Mastitis
  Mastitis is the inflammation of breast tissue. S. aureus is the most common etiological organism responsible, but S. epidermidis and streptococci are occasionally isolated as well.-Terminology:...
  
  , decreased milk production after consumption of leaves or bark.
• Horses: Clinical effects occur mainly in mares, and includes noninfectious mastitis
  Mastitis
  Mastitis is the inflammation of breast tissue. S. aureus is the most common etiological organism responsible, but S. epidermidis and streptococci are occasionally isolated as well.-Terminology:...
  
  , as well as occasional gastritis
  Gastritis
  Gastritis is an inflammation of the lining of the stomach, and has many possible causes. The main acute causes are excessive alcohol consumption or prolonged use of nonsteroidal anti-inflammatory drugs such as aspirin or ibuprofen. Sometimes gastritis develops after major surgery, traumatic...
  
   and colic
  Colic
  Colic is a form of pain which starts and stops abruptly. Types include:*Baby colic, a condition, usually in infants, characterized by incessant crying*Renal colic, a pain in the flank, characteristic of kidney stones...
  
  .
• Cats, Dogs: vomiting, diarrhea
  Diarrhea
  Diarrhea , also spelled diarrhoea, is the condition of having three or more loose or liquid bowel movements per day. It is a common cause of death in developing countries and the second most common cause of infant deaths worldwide. The loss of fluids through diarrhea can cause dehydration and...
  
  .
• Hares, pigs, rats, sheep, ostriches, chickens, turkeys and fish: symptoms of intoxication similar those described above. The lethal dose is not known; the effect is different depending upon the animal species.

Medical uses

Persin has recently been discovered to kill breast cancer

Breast cancer

Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...

 cells. It has also been shown to enhance the effect of the breast cancer fighting drug tamoxifen

Tamoxifen

Tamoxifen is an antagonist of the estrogen receptor in breast tissue via its active metabolite, hydroxytamoxifen. In other tissues such as the endometrium, it behaves as an agonist, hence tamoxifen may be characterized as a mixed agonist/antagonist...

. This could potentially reduce the necessary dosage of current cancer drugs. Persin is however highly insoluble in aqueous solutions and more research will be needed to put it into a soluble tablet form.