Mycotoxins Flashcards
What are the two routes of exposure to mycotoxins?
oral (consumption) and inhalation
What are the major concerns in regards to exposure to mycotoxins?
Chronic toxicity in humans, acute toxicity in livestock, economic losses and reduced crop yield and quality
What are some conditions that favour the growth of moulds?
warmth and moisture, insect damage and other diseases-however a period of drought can increase a plants susceptibility to a fungus
What are the two aspergillus and penicillium species discussed in class?
Aflatoxins and Ochratoxins
What species produce aflatoxins?
Aspergillus flavus and aspergillus parasiticus
What are the structures of aflatoxins?
B1, B2, G1 and G2
What is the LD50 of aflatoxin?
0.5-20mg/kg
What are the main sources of alfatoxins?
peanuts, corn, tree nuts, dried fruit and cottonseed
What led to the discovery of aflatoxins?
100,000 turkeys dying in England in the 1960s due to brazil nuts being present in their feed
What is aflatoxins MOA?
binds guanine in DNA which inhibits mRNA synthesis and thus protein production
What are the symptoms associated with acute aflatoxin poisoning in animals?
liver necrosis and hemorrhage, weakness, vomiting, loss of appetite
How is acute aflatoxin poisoning diagnosed?
increased liver enzymes like alkaline phosphatase, AST or ALT, bilirubin and serum bile acids
What are the results of chronic aflatoxin poisoning?
liver fibrosis, cirrhosis, tumors, bile duct hyperplasia
What are the symptoms present in humans after inhalation and ingestion of aflatoxin?
Inhalation-cough, fever, chest pain, hemoptysis
Ingestion-liver damage or cancer
What species produce ochratoxin?
Penicillium verrucosum and aspergillus molds
Where is it found in ?
cereal grains, red wine, coffee beans
What is the most toxic ochratoxin and its MOA?
Ochratoxin A and it competes with phenylalanine in the process of phenylalanyl-tRNA synthesis, or inhibits other enzymes like phenylalanine hydroxylase, inhibits protein synthesis
What are the symptoms of ochratoxin poisoning in humans?
fatigue, chronic pain, GI symptoms, autoimmune, insomnia
What are the symptoms of ochratoxin poisoning in animals?
feed refusal, vomiting, diarrhea and anorexia
What occurs in high vs low does of ochratoxin
high does: kidney damage, low: carcinogenicity and also possibly teratogenic
What are the fusarium toxins discussed in class?
T2, Deoxynivalenol. fumonisins and zearalenone
What are the species that produce T2 toxin?
fusarium poae, fusarium sporotrichioides and fusarium tricinctum (mainly)
What are the physical and structural properties of T2?
non-volatile, low molecular weight sesquiterpenoids
What is the LD50 of T2 in mice?
2-4mg/kg
What is T2’s MOA?
Targeting 60S ribosomal subunit which inhibits protein synthesis leading to apoptosis
What are humans symptoms after being exposed to T2?
vomiting, stomach necrosis, hemorrhage and dermatitis
What are the symptoms present in animals after T2 poisoning?
feed refusal, vomiting, stomach necrosis
What is alimentary toxic aleukia?
leukopenia, agranulocytosis, nectroic angina, sepsis all caused by T2 poisoning-occurred in families in the USSR
What is Vomitoxin and its LD50?
trichothecene mycotoxin, 50-100mg/kg
What is DON’s MOA?
halts protein synthesis by binding to ribosome and activate MAPks ribotoxic stress response causing inflammation (chemokines, cytokines) in low doses or apoptosis in high doses
What are the symptoms of DON toxicity in humans?
nausea, vomiting and diarrhea
What are the symptoms of DON toxicity in animals?
diarrhea and vomiting (pigs)
What animals are most sensitive to DONS?
pigs, rats and mice
Why do we puke when exposed to DON?
damage to enterochromaffin cells, releases serotonin, vagal afferent nerve sends signal to vomit center and posterma in brainstem detects toxin in blood, further amplifying nausea and vomiting signals
What are the symptoms of acute intoxication of fumonisin?
GI
What are the symptoms of chronic intoxication of fumonisin?
cancer of GI (esophagus), neural tube defects and transfer to breast milk
What is equine leukoencephalomalacia?
disease of the CNS that comes from horses, mules and donkey’s eating moldy corn. White matter liquefies- symptoms: drowsiness, apathy, blindness, circling, stumbling, recumbency and pharyngeal paralysis, 8-10ppm
What is porcine pulmonary edema?
fluid leakage into lungs in pigs, symptoms: dyspnea, cyanosis of mucous membranes, weakness and recumbency, occurs 3-6 after consumption of fumonisins of >100ppm
What organisms produce Zeralenone?
F. gra,omearum, F. culmorum, F. cerealis, F. equseti, F. crookwellense, etc.
Where is Zeralenone typically found?
in warmer climates?
What is Zeralenone’s MOA?
binds and activates estrogen receptors, 2-4 times less potent agonist than estradiol
Why is Zeralenone carcinogenic?
affects apoptosis, DNA fragmentation and adduct formation, alters DNA repair mechanisms and could induce cancer cell proliferation
What species produced ergot toxin and what does it infect?
clavicep purpurea-infects cereal grains
What are the three different types of ergot alkaloids?
amine: uterotonic effects
peptide: ergocristine and ergotamine, vasconstrictive
clavine: simpler alkaloids
What are symptoms of ergot poisoning?
hallucinations, severe gastrointestinal distress, convulsion and gangrene
