Xenobiotics Flashcards
1
Q
What is Xenobiotics?
A
• Foreign chemicals that are not synthesized by the body
• May be occuring chemicals produced by plants, microorganisms, or animals
• Not all xenobiotics are poisonous
2
Q
What are natural toxins?
A
• Naturally present in animals & plants
• Usually, natural toxins are not acutely toxic, except in a few cases in animals
3
Q
Risks of toxins in food
A
• Carcinogenic
• Mutagenic
• General Toxicity
4
Q
Natural Toxins in Foods
A
- Endogenous toxins of plant origin
• Toxic phenolic substances: Tannins
• Cyanogenic Glycosides
• Central Stimulants - Natural Contaminants
• Mixing of edible plants with toxic plants
• Microbial toxins
5
Q
Flavonoids
A
- Generally located in the oil vesicles of the fruit peel
- Nonpolar and readily soluble in the oil
- A well-known mutagenic representative is Quercetin
- Quercetin is the only flavonoid shown to be carcinogenic in mammals
6
Q
Tannins
A
- Heterogenous group of broadly distributed substances of plant origin
- 2 types of tannins can be distinguished on the basis of degradation behavior & botanical distribution is: Hydrolyzable tannins & Condensed Tannins
- Tannic acid has been reported to cause acute liver injury
- Condensed tannins are flavonoids
- Tannins occur in many tropical fruits
- TEA has the highest tannin content
7
Q
MYRISTICIN
A
- Found in spices and herbs: Nutmeg, Black Pepper
- Myristricin contributes to the toxicity of nutmeg. Nutmeg has been abused as a narcotic
8
Q
Cyanogenic Glycosides
A
- Are glycosides from which cyanide is formed by the activity of hydrolytic enzymes
- Can be found in food plants: Cassava, Lime Beans
- Damaged roots can contain even more cyanide
- It can be fatal if those foods are eaten raw or prepared improperly
- Peeling, washing in the running water and cooking can remove or volatilize the cyanide
9
Q
Goitrogens (Glucosinolates)
A
- A particular group of substances, occuring in cruciferous plants: Cabbage, Turnips
- They can be considered as natural toxins, but also as antinutritives
10
Q
Acetylchollinesterase Inhibitors
A
- Have been detected in several edible fruits & vegetables
- Their active components are alkaloids
- The most potent inhibitors are found in potatoes
- The most active cmponent is the glycoalkaloid solanine
- Oral administration of solanine results primarily in gastrointestinal & neurological symptoms
- Most of the alkaloid is concentrated in the skin
- Sprouts may contain lethal amounts of solanine
- Peeling will remove most of the solanine
- Solanine is heat stable and insoluble in water. Hence, toxic potatoes cannot be rendered harmless by cooking
11
Q
Biogenic Amines
A
- Naturally present in animals, plants and microorganisms
- Sources: Fermented Foods
- Mainly caused by the ezymatic decarboxylation of amino acids by microorganism origin
- High conc. in fish and cheese
- The toxicity dose of BA depends on the individual sensitivity and characteristic
12
Q
Mushroom Toxins
A
- Caused by the high content of amatoxins in mushrooms
- Mushrooms identified as containing amatoxin toxins are the species: Galerina autumnalis, A. ocreata
- There are 4 categories of mushroom toxins: Neurotoxins, Protoplasmic poisons, Gastrointestinal irritants, and Disulfiram-like toxins
- Neurotoxins: Cause neurological symptoms - Coma
- Protoplasmic poisons: Cause generalized destruction of cells, which is followed by organ failure
- Gastrointestinal irritants: Produce rapid nausea, abdominal cramping, vomiting, and diarrhea
- Disulfiram-like toxins: Usually nontoxic & produce no symptoms. However, if alcohol is consumed within 72 hours after eating them, they may produce vomiting, nausea
- The first symptoms of mushroom poisoning occur within 6 - 24 hours after ingestion (Phase 1)
- Phase 2 ( Gastrointestinal phase) involves severe vomiting & abdominal cramps
- Phase 3 lasts about 12 - 24 hrs and is characterized by improved clinical symptoms and the beginning of liver necrosis
- Phase 4 (Last Phase) results in hepatic failure, internal bleeding, and acute renal failure
- Patients usually die within 5-20 days after ingestion of the mushrooms
13
Q
Mycotoxins
A
- Secondary metabolites of fungi which can induce acute as well as chronic toxic effects in animals & man
- Often produce by the genera Aspergillus, Penicillium
- Toxic syndromes resulting from the intake of mycotoxins are known as mycotoxicoses
- Highly depends on the environmental conditions that lead to mold growyh and toxin production
- Because of their chemical stability, several mycotoxins persist during food processing, while the molds are killed
- The most important mycotoxins is Aflatoxins
- Aflatoxins can develop at high temp and humidity levels
- Aflatoxins are carcinogenic substances and can cause cancer, cirrhosis of the liver
- The most common commodities contaminated: Peanuts
- TLC method can detect Aflatoxins
14
Q
Heavy Metal
A
a) Mercury
b) Lead
c) Cadmium
15
Q
Mercury
A
• Fish and seafood can be contaminated with mercury
• The primary target for mercury is the Central Nervous System
• Source: Volcanoes, Battery production, Product containing mercury
