Lecture 12: Mycotoxins Flashcards
Mycotoxins
Toxic secondary fungal metabolites that contaminate various food substances and agricultural products and are a serious health risk to humans and animals
Mycotoxicoses
Poisoning due to exposure to mycotoxins, Amy be acute or chronic
Symptoms depend on…
- Type of mycotoxin
- The amount and duration of the exposure
- The age, health and gender of the exposed individual
- Synergic effects
Major mycotoxins
- Aflatoxins
- Ergot alkaloids
- Fumonisins
- Patulin
- Zearalenone
Aflatoxins
Contamination of nuts and grains. pre-harvest linked to drought stress and poor storage conditions
Aflatoxin fungi
Aspergillus flavus and Aspergillus parasiticus
Major groups of Aflatoxins
B1&2 and G1&2
They are fluorescent under UV and chromatographic mobility during TLC
Aflatoxin contamination
- Increased mortality in farm animals
- Lowers value of grains
Milk as indirect source of aflatoxins
Cows biotransform aflatoxin B1 into hydroxylated form aflatoxin M1
Aflatoxins may cause cancer and immune suppression
Which organ does aflatoxins target
Liver
Ergot alkaloids
Includes lysergic acid and pure ergotamine
Fungi that produce ergot alkaloids
Claviceps spp.
Ergotism
- Anthony’s Fire
- Ergot replace seeds in flower spike of grains
- Flour and resulting baked goods contaminated
- Modern grain processing has largely eliminated disease
Convulsive ergotism
- Neural dysfunction
- Severe muscular pIN
- Hot-cold sensations
- Hallucnations
Gangrenous ergotism
- Constriction of blood vessels
- burning pain
- Gangrene/necrosis of limbs
Fumonisins
endophyte of maize
* Analogues A,B,P
Fungi that produce fumonisins
Fusarium spp. (F.verticilliodes)
Fumonisin B1
- Leukoencephalomalacia (Horses)
- Pulmonary oedema syndrome (pigs)
- Toxic to liver, pancreas, kidneys, lungs
- phytotoxic to some plants
- Linked to human oesophageal cancer
Patulin
Soft rot pathogen of apples, pears, cherries and deciduous fruits
* Regularly found in unfermented apple juice
Toxic effects
Oedema, haemorrhage, damage to liver, spleen and kidneys
Fungi that produce Patulin
Penicillium expansum
Zearalenone
Contaminates cereal grain
Fungi that produce zearalenone
Fusarium graminearum
Hyperestrogenism (pigs) symptoms caused by zearalenone
swelling of vulva
Infertility
stillbirths
small litters
Impact of mycotoxin contamination in commercial farming
- Fungicide application
- Controlled storage conditions
- Mechanical dehulling and milling technologies
Impact of mycotoxin contamination in subsistence farming
- High risk of exposure
- Socio-economic factors
- no regulations enforced
Strategies for mycotoxin control
- Awareness
- Use of improved crop varieties
- Technologies and community-based practices to reduce exposure
- Dietary diversity
