Transcript Toxins Project

Toxins Project
By
Justin Sona
Cammie Atwater
Margaret Garcia
Zach Cecelic
Fusarium Toxins
Kingdom: Fungi
Phylum: Ascomycota
Genus: Fusarium
Species: Many
General: Why you might want to know
about Fusarium mycotoxins
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Mycotoxins: secondary metabolites produced by fungus
In grains that are consumed by people
In feed grains of animals that are eaten by people
fusarium mycotoxins can be:
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Beneficial for plants
Used as weapons and biological control
Possible carcinogens
Immuno-depressors
Hepatotoxic
Nephrotoxic
A cause of Pre-puberty [i.e. earlier onset of puberty]
(controversial)
 Damaging economically due to crop loss
 Varies among season and region
Introduction
• These toxins are produced by fungi that
grow mainly on corn, wheat, oats, and
other cereals.
• The levels of toxin produced are
influenced by environmental factors
 High levels produced when
 hot dry weather which is fallowed by humidity
 Plants are damaged by insects/birds
• Most are heat resistant
 Even if grains are cooked, mycotoxins still present (FinkGremmels, 1989).
General: Environmental role
• While these mycotoxins are harmful to
mammals, they actually improve root
growth of crops like corn.
• They enable crop plants to survive through
dry conditions and other stresses (Lee 2000).
Ethnobotany
• Indigenous people in the Andes and Amazon
have suffered from mycotoxins which have
compromised plants, such as the coca and
poppy which can be used for medicinal
purposes. (The Sunshine Project 2001)
• Fusarium oxysporum has been known to kill
coca, and has been used by US government in
an attempt to eradicate coca. (Zielonka et al. 2009 )
Fusarium oxysporum
www.answers.com/topic/fusarium-oxysporum
Mycotoxins Produced
• More then 10 forms of fumonisin have
been isolated
• We focused on:
 Trichothecenes
 Desoxynivalenol
 Nivalenol
 Zearalenon
 Fumonisin B1 and B2
Trichothecenes
• Effects of poisoning
 Vomiting, Diarrhea, food rejection, GI
inflammation, tissue necroses and impairment
of: nerves, heart, lymph system, testes, and
thymus
 immunodepression
• LD50: 10.5mg/kg in mice
• Growth
 Mainly on dry grains in warm conditions
Trichothecenes
• Most dangerous of the mycotoxins
• Mechanism
 Inhibits protein synthesis by chemical
inactivation of ribosomes
 Acts like an estrogen and inhibits division of
rapidly growing cells (i.e. intestine lining and
bone marrow) (Obremski et al. 2008).
 Inhibits/weakens effect of blood clotting
Trichothecenes: Weapon Potential
• Intensely irritating effects on the skin
 immediately active upon touching skin (Bunner et al., 1985)
• Attempt to use as topical poison and mucosal
poison
• Used as a component in the weapon known as
“yellow rain” (Croddy et al. 2005).
Trichothecenes: Medical Uses
• Investigated for its treatment of cancerous
tumors
• Found to be too toxic for routine use (Croddy et
al. 2005)
Desoxynivalenol
• A type of Trichothecene
• One of the most common mycotoxins
found on animal feed (Zielonka et al. 2009).
Desoxynivalenol
• Mechanism
 Same as other Trichothecenes
• Effects of poisoning
 In plants
 Growth depression, Immune system suppression
 In humans
 Vomiting, rejection of nutrition, GI inflammation
Nivalenol
• Oral LD50 (for mice): 38.9 mg/kg
 Death seen three days after exposure due to:
 Congestion hemorrhage in the intestine
• Is a B-Trichothecenes
 Trichothecenes contain a tri-cyclic ring system
with various functional groups
 The B group has a carbonyl group on the
eighth carbon that distinguishes it from A, C
and D (Eke et al. 2004)
Nivalenol: Medical Studies
• High levels of nivalenol found in food has
been correlated with areas of high risk for
esophageal cancer in China.
• Has been known to induce both benign
and malignant tumors in mice.
• Studies in mice continue, to see if
nivalenol must be ingested (vs skin
contact) to have effects. (Hsia et al. 2004)
Zearalenone
• LD50 is >4000 up to >20,000 mg/kg
 Carcinogenic effect is assumed
• Binds to estrogen receptors
 Leads to disturbances in fertility in mice, rats, guineapigs, hamsters, and rabbit
• High levels in farm animals causes serve
morphological and function disorders of
reproductive organs (Mirocha, C.J., and C.M. Christensen)
• May lead to pre-puberty in humans
(Mitterbauer et. al 2003).
Zearalenone: Affect on
Ethno-botanical Medicine
• Tribulus terrestris is an herb grown in India and
Sri Lanka for medicinal purposes.
• The storage conditions of this plant are often not
controlled, allowing toxigenic fungi to grow.
• Zearalenone is often produced by the growing
fungi
• Mycotoxins and their effects on stored medicinal
plants is an area yet to be studied (Abeywickrama et al. 1992).
Fumonisin B1 & B2
• FB1 Most prevalent Fusarium toxin
produced (Kim et al. 2008)
• Mechanism shared by FB1 and FB2
 Inhibits sphingosine biosynthesis
 Sphingolipids are lipids found in neural tissue
 Hepatoxic (Shepard et al., 1995)
 Nephrotoxic
 Suspected to be carcinogenic in humans
Sunshine Project 2001).
(The
Fumonisin B1 & B2
• FB2 is derived by the polyketide pathway
• FB2 is mainly produced by F. verticilloides
and F. proliferatum (Apsimon, 2001)
• Found mostly in maize-based human food
and animal feeds (Visconti, 1996).
• Most common fungus associated with corn
intended for human consumption (Marasas, 2006)
Fumonisin B1 and B2
• Recently shown to be produced by
Aspergillus niger in Thai coffee beans (Noonim
et al. 2009)
• Natural occurrence in corn found all over
the world, from Argentina to Egypt to
Nepal (Marasas, 2006)
Fumonisin B1 and B2
Fumonisin produced by Fusarium
Maize in West Africa containing
aflatoxin, dexoxynivalenol and
fumonisin
Other Examples of toxic effects
Wheat heads with symptoms of Fusarium
head blight. Diseased spikelets become (a)
bleached or tan in appearance
Vulvar prolapse caused by mycotoxin Zearalenone contamination
Photos from www.cas.psu.edu
www.engormix.com/images/e_articles/1127_02.jpg
Grain produced in heads damaged by
Fusarium head blight is often shriveled,
white, and chalky in appearance.
Summary
• We presented a background on mycotoxins,
specifically those of the genus Fusarium.
• Then, we moved on to the specific toxins, their
mechanisms, their toxicities and their ecological
and ethnobotanical roles.
• It is clear that this genus is a prolific producer of
toxins and that it has a tremendous impact on
humans and non-humans who eat grains that
contain these fungi.
Conclusion
• Fungus is among us, and with lots of secondary
metabolites that are harmful.
• As Americans we consume
(nationmaster.com)
 ~33,203 metric tons of wheat
 ~221,726 metric tons of coarse grains
• What amount of mycotoxins are we
accumulating by eating the grains, and the meat
raised on these grains?
Possible future research
• How do agricultural practices influence the
mycotoxins present and infection in crops (ie.
Use of transgenic seeds, herbicides,fertilizers)?
• How do you reduced toxicity of mycotoxins in
contaminated food, since there may be more
than one toxin present? These toxins all have
different characteristics.
• How will climate change affect plants and their
relationship with these and other fungi that
produce mycotoxins?
Works Cited
Abeywickrama, K., Bean G. A. (1992) Cytotoxicity of Fusarium species mycotoxins and culture filtrates of Fusarium
species isolated from the medicinal plant Tribulus terrestris to mammalian cells. Mycopathologia. 120: 189-193.
Apsimon, J.W. 2001. Structure, synthesis and biosynthesis of Fumonisin B1 and related compounds. Environmental
Health Perspectives 109: 245-249.
Croddy, E., Wirtz J.J., Larsen J.A. Weapons of mass destruction: an encyclopedia of worldwide policy, technology, and
history. ABC-CLIO, 2005.
Eke, Z., Kende A., and Torkos, K. 2004. Simultaneous detection of trichothecenes A and B by gas chromatography with
flame ionization or mass selective detection. Microchemical Journal 78: 211-216.
Fink-Gremmels, J. (1989). The significace of mycotoxin assimilation for meat animals. Dtsch. Tierarztl. Worchensschr
96: 360-363.
Hsia, C. C., Wu, Z. Y., Li, Y. S., Zhang, F., Sun, Z. T. (2004) Nivalenol, a main Fusarium toxin in dietary foods from
high-risk areas of cancer of esophagus and gastric cardia in China, induced benign and malignant tumors in mice.
Oncology Reports. 12: 449-456.
Kim,B., Ejaz, S.,Chekarova,I., Sukura, A., Ashraf,M., Lim, C.W. (2008) Cytotoxicity of fumonisin B-1 in spheroid and
monolayer cultures of rat hepatocytes. Drug and Chemical Toxicology: an International Journal for Rapid
Communication 31: 339-352.
Lee, J. Corn Seed Pretreatment Reduces Fusarium. Agricultural Research. 2000.
Works Cited Cont.
Marasas, W. 2006. Fumonisins: Their implications for human and animal health. Natural Toxins 3: 193-198.
Mirocha, C.J., and C.M. Christensen. (1974). Estrogeneic mycotoxins synthesized by Fusarium, p 129-148. In I.F.H. Purchased (ed.),
Mycotoxins. Elsevier, Amsterdam, The Netherlands.
Mitterbauer, R., Weindorfer, H., Safaie, N., Krska, R., Lemmens, M., Ruckenbauer,P., Kuchler, K., and Adam,G. (2003) A sensetive and
inexpensive yeast bioassay for the mycotoxin zearalenone and other componds with estrogenic activity. Applied and Environmental
Microbiology 69: 805-811.
Noonim, P., Mahakarnchanaku, W., Nielsen, K.F., Frisvad, J.F., and Samson, R.A. 2009. Fumonisin B2 by Aspergillus niger in Thai coffee
beans. Food Additives and Contaminants 26: 94-100.
Obremski, K.; Zielonka, L.; Gajecka, M. (2008) Histological estimation of the small intestine wall after administration of feed containing
deoxynivalenol, T-2 toxin and zearalenone in the pig. Polish Journal of Veterinary Sciences 11:339-345.
Risks of using Biological Agents in Drug Eradication. The Sunshine Project: A Briefing Paper with Emphasis on Human Health. 2001.
Shepard, G.S., Thiel, P.G., Sydenham, E.W., Snijman, P.J. 1995, “Toxicokinetics of the mycotoxin fumonisin B2 in rats” Food Chemistry and
Toxicology., 33: 591-595,
Visconti A. Solfrizzo M:, Doko M.B., Boenke A., and Pascale M. 1996. Stability of fumonisins at different storage periods and temperatures in
gamma irradiated maize. Food Additives and Contaminants 13:929-938.
Zielonka, L., Wisniewska, M., Gajecka, M. 2009. Influence of low doses of deoxynivanol on histopathology of selected organs of pigs. Polish
Journal of Veterinary Science 12:89-95.
“Agriculture Statistics.” Nation Souce. 28 April 2008. Web. 28 Apr.
2009.<http://www.nationmaster.com/graph/agr_gra_coa_gra_con_percap-coarse-grain-consumption-per-capita>