10 b Flashcards
(4) Glucosinolates
what containing carbohydrate
food sources
sulfur containing carbohydrates (thioglucosides)
- food sources: cabbage , cauliflower, broccoli, radish , mustard seeds, rapeseed/canola, turnips and others
Glucosinolates
Toxicity
to date, no toxicity effects have been correlated with intact glucosinolate consumption by humans
- glucosinolates/breakdown products are considered to be goitrogens compounds that cause an enlargement of the thyroid (hyperthyroid syndrome-> goiter [ insufficient hormone production])
- animal consumption (via feed) physiological disorders in beef cattle/dairy animals, pigs and chickens (e.g. egg production/weights)-> human consumption of animal products?
Glucosinolates — Nitriles
Toxicity
- acute toxicity (HCN) inhibition of cytochrome oxidase ->respiratory enzyme (electron transport)
- organ damage (kidney and liver tissue lesions)
- bind to glutathione -> inhibition of ROS [H2O2] removal from cells (cellular based tripeptide antioxidant)
hemorrhaging and necrosis(tissue loss/death) of the adrenal cortex(hormone production glands) (animal studies)
Glucosinolates — Isothiocyanates
Toxicity
Toxicity
- possess goitrogenic properties increased thyroid weight (indicative of gland/organ damage)-> hormone synthesis disruption
- inactivation of enzymes (glycosidases) in the carbohydrate metabolism pathway (malnutrition)
react with sulfhydryl (RS-H) groups on proteases (i.e. sulfhydryl proteases)-> rendering them inactive (malnutrition)
Correlative evidence: bladder /breast/colon/liver/lung and stomach cancer
Glucosinolates — Isothiocyanates
Allyl isothiocyanate 40mg/100g of brussel sprout
bladder/kidney/pancreas lesions, skin irritation/blisters
- reproductive disorders; teratogen (compound that negatively impacts normal embryo/fetal development)
Glucosinolates — Isothiocyanates
Benefits (correlative evidence)
- phytochemical (“biologically active compound found in plants”; prevention and treatment of: cancer (inactivates carcinogens; protect cells from DNA damage]
- anti-inflammatory and antiviral/antibacterial activities
- treatment of insomnia-> mechanism?
Naturally Occurring Toxic Compounds in Foods
(5) Toxic Amino Acids
Toxicity (general)
enzyme inhibition ‘suicide substrates’- no turnover of the
enzyme-fit in and don’t get out
- reduced cellular transport of essential chemical compounds
- impaired/aberrant (abnormal) protein synthesis (animal)
changes in toxin movement across the blood-brain barrier direct
crossing? Adjuvant behavior?
- Reproductive disorders (animals)
> 200 non-protein amino acids occur naturally in plants most are associated with toxic properties
- seeds are generally the most concentrated source of these compounds forage grains and legumes (gramineae and leguminosae)
Transferred to humans via the
consumption of animal tissue
(e.g. liver)-> safety of free-range meets?
Toxic Amino Acids (examples)
(a) mimosine and canavanine
- similar in structure to arginine and tyrosine
- may be incorporated into proteins by animals ? Impact on animal health-> ? Impact on human health
Toxic Amino Acids (examples)
(b) beta-cyanoalanine
common foods
lathyrogen (present in sweet pea/grass pea/chickpea) neurolathyrism (neurological disorder)-> muscular rigidity , crippling paralysis, death
Not denatured when cooked
Toxic Amino Acids (examples)
(c) selenocysteine and selenomethionine
common foods
common foods (seafoods, eggs) organis selenium complex (SeMet major dietary form) [Brazil NUTS: 500mcg/servinfgs (8 nutes) [ RDA for Se: 55mcg/day
- possibility of selenium poisoning (LD50 [rats] : 12.7 mg/kg bwt) severe hemolytic anemia, kidney/liver/heart damage
Toxic Amino Acids
Benefits
anti-tumor activity (disruption of mitosis)
- treatment of Parkinson’s disease (not b-cyanoalanine; mechanisms unknown)
- antioxidant (mimosine)-> ‘ohenolic’ structure
- antimicrobial activity (broad spectrum; impaired protein synthesis)
- Naturally Occurring Toxic Compounds in Foods
(6) Cyanogens
- a group of chemical compounds which may release hydrogen cyanide (HCN) upon metabolism/decomposition
- naturally present in many plant species (>2000) as cyanogenic glucosides (cassava, corn, flax, lima bean, sweet potato; seeds/kernels of almonds, apples, apricots, cherries, etc.)
- example: linamarin (cassava)
Staple food in Africa, and south and
central America]-> 15-200mg/kg FW (roots
these reactants (physically sepa-rated in plants) only come in contact after physical disruption of cells (bruising, cutting) bamboo shoots and the panda
Cyanogens
Toxicity
treatment
Toxicity
- LC50 for hydrogen cyanide (rats, mice and dogs): 544 ppm (5 min); 169 ppm (30 min) - cyanide has a strong affinity for cytochrome oxidase binding comprimises cellular respiration-> death ( the brain is the most sensitive organ to this inhibition)
Inactivation/Destruction
- moist heat treatment-> b-glucosidase inactivation
