Bioactive compounds Flashcards
What is a bioactive compound?
A secondary metabolite with biological activity on other organisms than the one in which it was produced.
What is the classification of bioactive compounds based on chemical structure?
Phenolic compounds (approx 8000 types) Terpenes and terpenoids (approx 25000 types) Alkaloids (approx 12000 types)
Characteristics of terpenes
Compounds containing carbons in multiples of five (isoprene units). Volatile, smelly.
What are terpenoids?
oxygen-containing terpenes
what are terpenes used for?
perfumes, insect repellants, air fresheners, varnish, medicinal value
what are some of the medicinal benefits of terpenes?
anti-inflammatory effects by inhibiting various proinflammatory pathways in ear edema, bronchitis, KOL, skin inflammation, osteoarthrities (beta-pinene). limonene: probably reduces allergic lung inflammation
what are potential adverse effects of overdosing terpenes(ingested or inhaled)?
depressive effects on CNS and respiratory disorders
what are some biological functions of terpenes in plants?
attract pollinators and scare away grazers, allelopathy
what class of bioactive compounds do cyanogenic glycosides belong to?
terpenes
why are cyanogenic glycosides toxic?
upon disruption of plant structure, cyanogenic glycosides in vacuole come into contact with enzymes stored elsewhere in the plant cell and hydrogen cyanide is formed
why is hydrogen cyanide poisonous?
it inhibits cytochrome oxidase thus disrupting respiration
what are alkaloids?
heterocyclic, nitrogen containing compounds, usually with potent activity in the nervous system and with bitter taste
why do alkaloids affect the nervous system?
they are similar to hormones or signal substances and bind to receptors in the brain, ex. caffeine binds antagonistically to adenosine receptors decreasing fatigue and increasing wakeness.
solanins belong to what type of bioactive compounds?
alkaloids.
how can you identify if a potato contains solanin?
if it is green, chlorophyll has formed due to exposure to light. solanins also form from light exposure.
what happens with toxic glycoalkaloids in the gut?
they are hydrolyzed to less toxic aglycones. glycoalkaloids are also generally poorly absorbed by the gastrointestinal tract of mammals.
what is a typically toxic alkaloid that can cause problems in grazing animals?
pyrrolizidine alkaloids present in ragwort
what are phenolic compounds?
compounds with an -OH group attached to an aromatic carbon.
what are the 2 classes of phenolic compounds?
flavonoids and non-flavonoids
what compounds are classified as flavonoids?
isoflavones, flavanols, flavonols, flavones, anthocyanidins and flavanones
what compounds are classified as nonflavonoids?
phenolic acids, stilbenes, lignans and coumestans
the predominant form of flavonoids in plants is
as glycosides. poor bioavailability in this state, needs to be hydrolyzed to increase bioavailability.
how are polyphenols taken up by the body?
in small intestine hydrolyzed by intestinal enzymes, aglycones taken up by epithelial cells and sent to liver., in large intestine hydrolyzed by microbial enzymes, aglycones taken up and sent to liver.
how much of polyphenols in diet are taken up by the body?
5-10%
how are polyphenol aglycones metabolized in the liver?
phase 1 metabolism: addition or unmasking of polar groups ex -OH to increase polarity. these metabolites go to tissues, excreted through kidneys or go to phase 2 metabolism. in phase 2 metabolism, conjugation reactions happen ex. to glucuronic acid or to a sulfate group.
what enzyme is responsible for addition of polar groups in liver metabolism of polyphenols?
Cytochrome p450
what are some potential positive effects of polyphenolic compounds?
antioxidants, anti-carcinogenic, antibacterial, antiviral, antiallergic, antiinflammatory etc
what are some potential negative effects of polyphenolic compounds?
cytotoxicity, toxicity, pro-oxidants
what are tannins?
polyphenolic componds
what are potential positive effects of tannins?
antibacterial and antiinflammatory in low concentrations
what are potential negative effects of tannins?
they can complex with proteins, starch, cellulose and minerals which may decrease nutrient uptake. can also have bad taste.
what are two groups of tannins?
hydrolyzable tannins and condensed tannins (proanthocyanidins)
how can bioactivity of bioactive compounds be categorized?
as hormone-like or enzyme-like
what classes of polyphenols have phytoestrogenic traits?
stilbenes (resveratrol), lignans (cesamin), coumestans (coumestrol) and isoflavones
how are phytoestrogens metabolized?
hydrolyzed by intestinal microflora. produces 2 compounds: p-ethyl-phenol and the active metabolite eqoul. in ruminants it is hydrolyzed in the rumen.
how does phytoestrogen activity relate to endogenous estrogenic activity?
phytoestrogens like eqoul can bind to estrogen receptors instead of estrogen binding. they have lower estrogenic activity than the endogenous estrogen and may stabilize estrogen levels in both high-estrogen and low-estrogen individuals
what are some types of enzyme-modulating action?
ACE (angiotensin converting enzyme) inhibitory bioactive peptides (lower blood pressure) - modulation of detoxification enzymes(various flavonoids) - modulation of steroid hormone metabolizing-enzymes
where can ACE-inhibitory bioactive peptides be found?
in wheat, peas, mushrooms, soybeans, walnuts, date seed flour, bitter melon seeds and spinach
what is generally believed to happen to bioactive compounds in food processing?
decreasing amounts
beneficial or adverse effects of bioactive compounds generally depend on…
the amount eaten/inhaled etc
