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BIOL3207 Toxicology > Chapter 2 Mycotoxin > Flashcards

Chapter 2 Mycotoxin Flashcards

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1
Q

What are mycotoxins?

A

Secondary metabolites of fungi which can be toxic to humans/amimals when ingested/inhaled.

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2
Q

What are the features of mycotoxin?

A
  • Low molecular weight; non protein, non-carbohydrate
  • Structural diverse
  • Potent biological effector
  • Wide range of specific toxic effect
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3
Q

Are mycotoxins natural occuring?

A

Yes

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4
Q

Are mycotoxins natural occuring?

A

Yes

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5
Q

Does secondary metabolites directly function in the process of growth and development?

A

No, they are produced to influence a competitive outcome

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6
Q

Where can we find mycotoxins?

A

Maize, wheat, nuts, coffee, cereals…
25% of global argriculture producs

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7
Q

How many mycotoxins are identified? How many of them are toxigenic?

A
  • 10,000 identified
  • 500 toxigenic
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8
Q

Where can the contamination be?

A
  1. during growth of the cereal plant on the field
  2. during storage of the grain
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9
Q

Give example for
1. Field fungi
2. Storage fungi

A
  1. Fusarium sp.
  2. Asperigillus sp.
  3. Penicillium sp.
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10
Q

Mycotoxins can be eliminated by cooking, T/F?

A

False

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11
Q

Rice usually less contain mycotoxins, T/F?

A

True

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12
Q

What are the 2 reasons for mycotoxin production?

A
  1. genetic resistance of the plant cultivar to fungal infection; natural plant-derived detoxification-systems (enzymes)
  2. environmental conditions and stress during growth and at the time of crop harvest
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13
Q

What are the factors for mycotoxin production in storage?

A
  • moisture level of the produce
  • storage conditions (temperature, humidity!) and duration
  • insect damage and infestation
  • The presence of substrate for fungi growth
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14
Q

Name some chemical, environmental and biological factors affecting mycotoxin occurence

A

Biological: Suceptible crops, compatible toxogenic fungus
Chemcial: CO2 O2, composition of substrate, pesticides and fungicides
Environmental: Temp, humidity, injury

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15
Q

What are the 3 types of mycotoxin focused in this chapter?

A
  1. Aflatoxin
  2. Deoxynivalenole (DON)
  3. zearalenone (ZEN)
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16
Q

Give some general characteristics of mycotoxins

A
  1. low molecular weight
  2. varying water solubility
  3. chemically stable
  4. Heat resistant (stabilization through binding to proteins orother compounds)
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17
Q

What is the main way of exposure?

A

oral ingestion of contaminated
food/feed

A kind of direct exposure

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18
Q

Is indirect exposure to mycotoxin also possible?

A

Yes

Some animal derived food has residues. Inhalation and skin contact also

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19
Q

What primarily produces Aflatoxin?

Also give some general features

Study These Flashcards
A

A. flavus & A. parasiticus

Important agent of disease (acute death/ chronic tumour)

20
Q

Give some examples of Aflatoxin incidents

Study These Flashcards
A
  1. “turkey X disease”
  2. Acute poisoning due to presence in rice, Taiwan
  3. Kenya: maize high level of aflatoxin
21
Q

What food is the primary contamination of aflatoxin?

Study These Flashcards
A

High energy content foods

grain, nut and soy products

22
Q

What is the secondary contamination of aflatoxin?

Study These Flashcards
A

Dairy products

23
Q

What is the main cause of toxicity in the metabolic transformation of aflatoxin B1?

Study These Flashcards
A

Aflatoxin-exo 8,9-epoxide

unlikely to be asked

24
Q

What are the 5 toxicities of aflatoxin?

Study These Flashcards
A
  1. Carcinogenicity
  2. Immunotoxicity:Immunosuppressive
  3. Malnutrition
  4. Retarted physical and mental maturity
  5. Reproduction and nervous system disease
25
Why aflatoxin has a high carcinogenicity?
* Aflatoxin B1 is highly mutagenic 1. epoxidation resulting in covalent binding to DNA 2. specific mutation at tumor-suppressor gene p53
26
Why intake estimates are not accurate?
* Recall what they eat * Over/underestimate the actual amount * biased/ non-reliable results
27
What is the relationship between chronic hepatitis B and aflatoxins?
Increase the risk of liver cancer | Synergy
28
Breast milk cannot transmit aflatoxin to infants, T/F?
False, the kids have retarded growth
29
Breast milk cannot transmit aflatoxin to infants, T/F?
False, the kids have retarded growth
30
What family does Deoxynivalenol (DON) belong to?
Trichothecenes | Trichothecenesbelongs to Type B
31
What are the common contaminants of DON?
* cereal crops * processed grains
32
What is the alternative name of DON?
Vomitoxin
33
What are the toxicities of DON?
1. digestive disorders 2. oral and dermal lesions, haemorrhages, necroses 3. reduced productivity and performance 4. **immunosuppression** 5. **Reduced growth**
34
What is the problem of immunosuppression?
Severe adverse health effects could be found in **chronic low level exposure**.
35
What are the consequences of immunesuppression?
1. increased risk of infections 2. more severe disease processes 3. more difficult therapies 4. impaired vaccination response 5. activation of tumor formation 6. impaired health status - decreased productivity
36
Why is immunosupression/DON exposure difficult to detect?
overlaying secondary diseases or infections
36
Why is immunosupression/DON exposure difficult to detect?
overlaying secondary diseases or infections
37
DON and ZEA has synergism, T/F
True | Can be produced by same fungal species F. graminearum
38
ZEA is heat stable and resistant to standard decontamination process, T/F?
True
39
Suggest the direct and indirect contamination of ZEA
* Direct contamination: food or feed infected by fungi * Indirect contamination: Processed food, e.g. Beer, flour, soybean, bread, milk, cheese, meat
40
Why can ZEA cause the “estrogen-like syndrom"?
It acts as an endocrine disrupter cuz has** high sturcture similarity w/ estrogen**
41
What is the toxicokinetics of ZEA for animals?
affecting **primarily the reproductive system **(infertility, abortions, various hyperstrogenism-effects) leading to** reduced performance and reproduction in farm animals**
42
What is the toxicokinetics of ZEA for humans?
* Pre-mature pubertal changes * Scabby grain toxicosis
43
ZEA is classified as a carcinogen, T/F?
False, the carcinogenic properties of ZEA are not yet well defined
44
What are the 3 ways to counteract mycotoxins?
1. Prevention (food production) 2. Decontamination (physical/chem treatments, during food processing) 3. Deactivation ( During food digestion)

BIOL3207 Toxicology (7 decks)

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