Avocado

1. Avocado Name 1

2. Introduction • I wanted to research the avocado plant due to the multiple benefits andtoxic effects the plant expresses. • I will include the following information about the avocado plant: - The Origin and common facts about the avocado. - Health Benefits that the avocado plant provides.

3. Introduction • Medicinal Benefits. • Toxic affects due to animal ingestion of the avocado plant. - Therapeutic breast cancer affects from the toxin of avocado plants .

4. Origins of the Avocado • Avocado (Persea Americana) • Locality: Avocado tree is native to Mexico, Central and northern South America. • The trees were cultivated by the Incan civilizations with archeological evidence dating back to 750 B.C. • The word “avocado” comes from the Aztec word ahueketl which means testicle or “fertility fruit” , a reference to the shape of the fruit.

5. Health Benefits • Ounce for ounce avocado provides the most beta-carotene, potassium, magnesium, folic acid, thiamin, riboflavin, niacin, biotin, pantothenic acid, vitamin E and K, and protein than any other fruit. • Avocado plants contain oleic acid which is a monosaturated fat that helps lower cholesterol.

6. Health Benefits • Avocado provides a good source of potassium which helps regulate blood pressure.

7. Medicinal Benefits • Indians in tropical America use the avocado plant for a variety of medicinal purposes including: • The skin is used as an antibiotic and remedy for dysentery. • The leaves are chewed as a remedy for pyorrhea. • Leaves can be heated and applied to the forehead to relieve neuralgia.

8. Medicinal Benefits • In Cuba the people use the new shoots of the plant as a cough remedy. • The seed in powdered form can cure dandruff. • The exact mechanism of action of how the plant provides various medicinal benefits is not yet known.

9. Avocado is Toxic • Despite the promising health and medicinal benefits towards humans, the consumption of avocado is lethal to many animals. • The toxic principle that causes positive health benefits in humans and negative effects in animals is known as Persin.

10. Persin is a polyketide which is similar in structure to the omega-6 fatty acid, linoleic acid. Researchers have isolated Persin from specialized cells found in the avocado plant called idioblast oil cells. Persin appears to be a defensive compound to protect avocado from predators such as insects and fungi. Persin

11. Persin • Researchers have found through experiments that Persin is responsible for deterring feeding from insects such as the beet armyworm, spodoptera exigua ( Rodriguez-Saona et al. 1998). • Avocado poisoning in animals has been reported as early as 1942 and Persin was identified as the toxic component.

12. Toxic Effects • High concentrations of Persin are found in the leaves, bark, seeds, skin, and pits of the avocado and are the most toxic to animals. • Toxic Effects include: • Horses: Clinical effects occur mainly in mares, and includes noninfectious mastitis, as well as occasional gastritis and colic.

13. Toxic Effects • Cattle: inflammation of the mammary glands, decreased milk production. • Rabbits: inflammation of the mammary glands, decreased milk production, difficulty breathing, fluid around heart, heart rhythm problems, death. • Goats: inflammation of the mammary glands, decreased milk production, difficulty breathing, fluid around heart, heart rhythm problems, and death. • Mice: inflammation of the mammary glands, and necrosis of the myocardium. • Birds: difficulty breathing, fluid around heart, heart rhythm problems, death. • Dogs, cats: vomiting, diarrhea. (ASPCA, 2010)

14. Persin: Variability in Toxic Effects • Both the Guatemalen and Mexican varieties of the avocado are toxic to animals. • The most toxic variety due to a higher concentration of persin is found in the Guatemalen and Nabal varieties of the avocado. • The Mexican Variety is the least toxic containing the least amount of Persin.

15. It seems plausible from our lectures in class that the avocado plants that are the most toxic most likely have the highest predator rate of insects and fungi living in their region. However, this has not yet been studied scientifically. Guatemalan varieties of avocado have a dark rough skin. Persin: Variability in Toxic Effects

16. Persin toxin is identified • Researchers conducted an experiment in which they isolated Persin and administered a single dose of 100mg/kg of Persin to mice on the 8th day of lactation (arrow) (Butt J. Alison et al., 2006).

17. Persin toxin is identified • Pup body weight was measured after the dose was given and this was used as an indirect indicator of mammary gland function and milk production. • Persin treated dams showed a decrease in volume of milk production and pups who were feeding on Persin treated dams showed reduced weight compared with untreated dams (Butt J. Alison et al., 2006).

18. Persin toxin is identified • Histologically, it was witnessed that Persin treated dams had variable degrees of necrosis and apoptosis of alveolar epithelium in the breast tissue. • On the right is a photomicrograph staining of mammary epithelium from a normal lactating dam and dam treated with single dose of Persin. There were no visible effects on other tissues examined (Butt J. Alison et al., 2006).

19. Persin toxicity leads to new discovery • Although the toxic compound that causes animals to become sick after ingesting avocado has been found, the specific mechanism of action is still yet to be known. • However, researchers were surprised by the specific effect Persin had on the mammary tissue of most animals.

20. Persin toxicity leads to new discovery • The specificity of Persin targeting breast tissue in animals lead researchers to question how Persin would affect human breast tissue and breast cancer cells.

21. Persin Extermination • Researchers first began by administering doses of Persin to normal human breast cell lines in vitro. All of the mammary epithelial cell lines showed total resistance to the cytotoxic effects of Persin. • Next, three human breast cancer cell lines were examined for their response to Persin.

22. Persin Experimentation • The Estrogen receptor positive breast cancer cell lines (T-47D, MCF-7) were significantly effected by the cytotoxic effects of Persin. • However, the Estrogen receptor negative breast cancer line (MDA-MB-231) showed resistance to the effects of Persin. • The graph on the right shows proliferation of Estrogen positive breast cancer cell lines were significantly reduced as compared to the control group and Estrogen receptor negative breast cancer cell line.

23. Persin Experimentation • The effects Persin has on Estrogen receptor positive breast cancer cell lines are due to an induction of a caspase-dependent apoptosis of the cells signaled by Persin. • More research found that the sensitivity of the apoptotic effects of Persin was associated with expression of the Bim protein, which acts as an apoptotic activator. This was found out when Persin-induced apoptosis of breast cancer cells was inhibited following specific knockdown expression of Bim expression in the cancer cells. • This made sense that the Estrogen receptor negative breast cancer line (MDA-MB-231) showed a resistance to Persin because of the low levels of Bim expressed by these types of cells. • These results provided support to further evaluate Persin and researchers wanted to find out if Persin could work together and enhance the benefits of the common breast cancer drug Tamoxifen.

24. Tamoxifen • Tamoxifen is the most common drug used now to treat breast cancer. • Most breast cancer cells are Estrogen receptor positive, which means estrogen can bind to a receptor protein and promote the proliferation of more cancer cells. • Tamoxifen works against the effects of estrogen on these cells and other cells by competitively binding to estrogen receptor cells which inhibits the effects of estrogen. • Studies have shown that Tamoxifen is only effective in treating Estrogen receptor positive breast cancers.

25. Combining effects of Persin and Tamoxifen • Researchers conducted a series of experiments to find out the effects of a synergistic approach in combining the anti cancer agents Persin and Tamoxifen. • To investigate the interaction between Persin and Tamoxifen researchers examined the effects of combined doses on the long term survival of human breast cancer cells.

26. Results • The diagram on the right shows the survival of the Estrogen positive receptor breast cancer cells (MCF-7 and T-47D) treated with single and combined doses of Persin and Tamoxifen(4-OHT). • Treatment with concentrations of Persin or Tamoxifen(4-OHT) resulted in a small change in survival. • However, there was a significant decrease in survival when the agents were combined.

27. Results • Researchers then wanted to see if the combined effects were effective on Estrogen negative receptor breast cancer cells (SK-br3). • The graph on the right shows Estrogen negative receptor breast cancer cells were relatively resistant to the cytotoxic effects of Persin and Tamoxifen (4-OHT) alone, but there was a significant induction of apoptosis when treatment was combined with Persin.

28. Mechanism of Action • From the results shown it has been evident that human breast cancer cell lines of both Estrogen positive and negative receptors have an enhanced response to the cytotoxic effects of Persin and Tamoxifen when the two agents are combined. • Researchers have concluded that this suggests that Persin has the ability to modulate the response to antiestrogens by a parallel, Estrogen receptor pathway of the drug Tamoxifen.

29. Mechanism of Action • More studies found that Persin mediates its cytotoxic effects in human breast cancer cells due to the generation of ceramide, and pro apoptotic synergy is achieved by addition of Tamoxifen(4-OHT) to inhibit ceramide glycosylation. The resulting increase in intracellular ceramide triggers apoptosis using the Bim dependent signaling cascade (Butt J. Alison et al, 2007).

30. Mechanism of Action • A picture of the combined parallel mechanism of Action pathway of Persin and Tamoxifen(4-OHT). • Persin acts as a signal to produce ceramide. • Tamoxifen inhibits the production of Glucosylceramide. • This causes an increase in intracellular ceramide levels. • Increased ceramide levels activate the Bim protein to trigger a cascade event that ends in celllular apoptosis.

31. Mechanism of Action

32. Summary • After viewing the presentation, one should have a better understanding of the positive and negative effects that Persin can have on humans as well as animals. • This recent research is very important towards the treatment of cancer cells and may be used in cancer drugs in the future due to its promising synergistic effects with the breast cancer drug Tamoxifen.

33. Conclusion • In conclusion, I feel this research is important towards finding possible future cures of cancer in which drugs can provide effective treatment as well as the lowest minimum side effects. • I feel the researchers could try to find out more about exactly why Persin adversely effects animal mammary cells as opposed to human cells.

34. References • Butt AJ, Roberts CG, Seawright AA, et al. A novel plant toxin, persin, with in vivo activity in the mammary gland, induces Bim-dependent apoptosis in human breast cancer cells. Mol Cancer Ther 2006;5:2300-9. • Butt AJ, Roberts CG, Sutherland RL, et al. Synergistic cytotoxicity between tamoxifen and the plant toxin persin in human breast cancer cells is dependent on Bim expression and mediated by modulation of ceramide metabolism. Mol Cancer Ther 2007;6(10):2777-85. • Rodriguez-Saona C, Millar JG, Trumble JT. Isolation, Identification, and Biological Activity of Isopersin, a new compound from idioblast oil cells. Dept. of Entomology 1998;61:1168-1170. • Knight AP, Walter RG. A guide to plant poisoning of animals in north america.2002. • Morton J. Avocado Fruits of Warm Climates.1987:91-102. • ASPCA Website http://www.aspca.org/pet-care/poison-control/plants/avocado.html • National Cancer Institute Website http://www.cancer.gov/cancertopics/factsheet/Therapy/tamoxifen • Takano J. Health Benefits of Avocado http://www.pyroenergen.com/articles07/avocado-health-benefits.htm • Chilean Hass avocados. http://www.chileanavocados.org/chilean-avocados/