Toxic substances

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Toxic substances present real risks:

• causing food intolerance ( intolerance ), toxic for certain individuals,
• causing intoxication , toxic for all individuals.

Substances causing food intolerance:

• allergies (immunological reactions), allergens (immunogens), (do not) induce IgE formation,
  • celiac disease , gluten-free diets (<100 mg/kg gliadin dry weight),
• intolerance (non-immunological manifestations), metabolic disorders, hypersensitivity (anaphylaxis), aversion (idiosyncrasy),
  • lactose intolerance, foods with a low content (<10 g/kg), lactose-free (100 mg/kg),
  • phenylketonuria , hydrolysates without Phe,
  • favism, broad bean ( Vicia faba ).

https://www.wikiskripta.eu/w/Soubor:Toxiny-vicin.jpg

Toxins and other substances causing intoxication

Classification:

• by structure,
• physical properties,
• by origin (plant, animal),
• by effects,
• main groups of toxins,
• alkaloids,
• saponins,
• cyanogens,
• glucosinolates,
• lectins,
• estrogenic substances,
• phototoxic substances,
• amino acids,
• biogenic amines.

Antinutritional and toxic substances of legumes:

• protease and amylase inhibitors,
• α-galactosides,
• substances causing favism,
• lectins ,
• cyanogenic glycosides,
• estrogens ,
• saponins ,
• lathyrogens.

Toxic substances of higher mushrooms:

• proteins ,
• peptides ,
• amino acids ,
• amines,
• hydrazines,
• alkaloids ,
• terpenoids.

Alkaloids

Classification:

• true alkaloids (N-heterocycles, derived from amino acids),
  • pyridine (nicotine) and tobacco,
  • piperidine and pepper,
  • pyrrolizidines and senecias (necines),
  • quinolizidine and. lupins,
  • quinoline and cinchona barks,
• pseudoalkaloids (N-heterocycles, derived from other precursors),
  • purine a. coffee, tea, cocoa,
  • terpenoid (glycoalkaloids) a. potatoes, tomatoes,
• protoalkaloids (not N-heterocycles, derived from amino acids),
  • capsaicinoids and peppers.

Pyridine alkaloids

Nicotine and minor alkaloids (~20 compounds):

• tobacco (obligation to indicate content in tobacco products, warnings).

Piperidine alkaloids

Piperine, homologs, geometric isomers, related substances, pepper (hot substances)

Pyrrolizidine alkaloids

Many related esters (mono-, di-, macrocyclic), hepatotoxic substances.

Quinolizidine alkaloids

A number of related compounds, lupine.

Quinoline alkaloids

Contents in pod.

Legislation: additive, alcoholic beverages 300 mg/l, non-alcoholic (tonics) 75 mg/l (teratogenicity)

Purine alkaloids

a number of related compounds, coffee, tea, cocoa (chocolate), mate, guarana.

• caffeine R 1 = R 2 = R 3 = CH 3
• theobromine R 1 = H, R 2 = R 3 = CH 3
• theophylline R 1 = R 2 = CH 3 , R 3 = H

Steroidal glycoalkaloids

• a number of related compounds, potatoes, tomatoes, eggplant,
• heteroglycosides, aglycone, sugar.

Potatoes

• α-solanine = solanidine + β-solatriose,
• α-chaconine = solanidine + β-chacotriose,

• distribution,
• legislation: 200 mg/kg.

Tomatoes

• tomatine = tomatidine + β-lycotetraose

• legislation: 200 mg/kg, teratogenicity

Capsaicinoids

capsaicin, homologues, paprika (hot substances):

• the effect of technological processing,
• capsaicin, (E)-8-methyl-N-vanillylnon-6-enamide .

Saponins

a number of related compounds, foods of plant origin:

• heteroglycosides, aglycone, sugar,
• aglycon = sapogenin (sapogenol),
  • triterpene alcohols,
  • sterols (4-demethylsterols).

Biological effects:

• hemolysis of erythrocytes , other cells, damage to the intestinal mucosa.

Properties

• toxicity to cold-blooded animals,
• bitter taste,
• detergent effects, emulsion (o/w),
• fungicidal, antioxidant, anticarcinogenic, anticholesterolemic effects.

Use

• foaming agents (cosmetics),
• emulsifiers (cosmetics),
• sweeteners (glycyrrhizin, licorice: 0.2−5.6% saponins).
• 

Cyanogenic glycosides

• a number of related compounds, foods of plant origin,
• HCN content in cyanogens,
• heteroglycosides, aglycone, sugar,
• aglycone = 2-hydroxynitrile (cyanohydrin),
• 2-hydroxy acid nitrile.

Substituents - Chirality:

• aliphatic – acetone, methyl (ethyl) ketone,
• aromatic – benzaldehyde.

Sugar

• usually Glu,
• genciobiosis disaccharides etc.

Properties

• decomposition (β-glucosidase) → HCN, toxicity (inhibition of cytochrome oxidase in the respiratory chain),
• acute intoxication, chronic intoxication (cassava, cassava).

Glucosinolates

• thioglucosides (glucosides of mustard oils), a number of related compounds, foods of plant origin (cruciferous plants),
• names and structure,
• dominant glucosinolates in vegetables,
  • heteroglycosides, aglycone, sugar, aglycone = thiohydroxamate-O-sulfonate, counterion K+

Substituents

• aliphatic,
• aromatic,
• heterocyclic.

Sugar

• exclusively Glc.

Properties

• decomposition (myrosinase) → isothiocyanates, nitriles, etc.,
• toxicity, isothiocyanates and goitrin strumogenic, nitriles hepatotoxic.

Plant phenols

estrogenic substances

• phytoestrogens - foods of plant origin,
  • isoflavones,
  • content in soybeans.

daidzin, R = H aglycon daidzein

genistin, R = OH aglycon genistein

soybeans (0.13−0.42%)

• • pterocarps,
  • lignans.

content in food

coumestrol − sprouting − soybeans

secoisolariciresinol − flax seeds

• mycoestrogens,
• xenoestrogens.

Properties

• simultaneously useful and harmful.

Phototoxic substances

• coumarins,
• furanocoumarins,
• foods of plant origin.
• 

Properties

• phototoxicity (sensitivity of non-pigmented skin, association with skin cancer, acute dermatitis),
• phytoalexins (phytonicides, plant antibiotics, pesticides), blastocolins (inhibits seed germination),
• antimicrobial and other effects.

Phototoxic pigments

• hypericin (St. John's wort), fagopyrin (buckwheat).

Lectins (phytohemagglutinins)

foods of plant origin (seeds and other parts)

Proteins with a non-catalytic center:

• merolectins (1 center, catalytic no),
• hololectins (2 centers, no catalytic),
• chimerolectins (1−2 centers, catalytic yes).

Soy lectin

• metalloprotein, 120 kDa, hololectin, N-acetyl-D-galactosamine binding.

Properties

• precipitation of erythrocytes, interaction with sugars in glycoproteins and glycolipids of membranes (plant protection mechanism against predators, parasites),
• toxic intravenously, some orally, some not at all, some probiotics (garlic).

Amino acids

Lathyrogens:

• foods of plant origin (seeds of vetiver and peas),
• amino acids (peptides, nitriles) -3-(N-oxalyl)-2,3-diaminopropanoic acid

Properties

• structural form with proteinogenic amino acids, metabolic disorders,
• deformation of the lower limbs (osteolathyrism), damage to blood vessels (angiolatyrism), disorders of the nervous system (neurolathyrism), humans, mainly farm animals.

Biogenic amines:

• precursors,
• aliphatic, aromatic, heterocyclic bases with biological activity, fermented and microbially degraded foods of plant and animal origin

Emergence

• from amino acids by microorganisms
  • histamine (His) , cadaverine (Lys)

Properties

• tissue hormones (allergic reactions, anaphylactic shock)
• psychoactive and vasoactive substances

Content

• changes in salami

Links

Internal links

• Natural toxic substances (1. LF UK, NT)

Source

• DAVIDEK, Jiří. 12. NATURAL ANTINUTRITIONAL AND TOXIC SUBSTANCES  [online]. [feeling. 2012-03-13]. < https://el.lf1.cuni.cz/p30693038/ >