Vitamins, stability and structural diversity Flashcards
What are the general characteristics of vitamins?
- nutritionally essential
- antioxidants
- diverse
- present in trace amounts in food
what vitamins are fat soluble?
A,D,E and K
Which vitamins occur as single compounds versus classes of compounds?
Some vitamins (e.g., Vitamin C) occur as single compounds, while others (e.g., B-complex vitamins) exist as related compounds
what vitamin is this? provide the common name, specific name and type of vitamin.
Vit B1
-Thiamine
-water soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
Vit C
-ascorbic acid
-water soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
Vit B2
-Riboflavin
-water soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
Vit B3
-Niacin nicotinamide
-water soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
vit B6
-pyridoxol
-pyridoxal phosphate
-water soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
vit B9
-folate / folic acid
-water soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
vit B5
-pantothenic acid
-water soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
B12
-cyanocobalamin
-water soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
vit B7
-biotin
-water soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
Vit A
-retinol
-fat soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
Vit D3
-Cholecalciferol
-fat soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
Vit D2
-ergocslciferol
-fat soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
Vit E
-tocopherol
-fat soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
Vit K1
-phylloquinone
-fat soluble
what vitamin is this? provide the common name, specific name and type of vitamin.
menadione
-fat soluble
How does food processing affect vitamin stability?
Processing (e.g., canning, cooking) can lead to significant losses, with sterilized foods experiencing greater losses than frozen or cooked foods
What are the main forms of Vitamin A?
retinoids (from animal sources) and carotenoids (pro-vitamins from plants, e.g., β-carotene)
What are terpenes? provide examples and draw the structural component on the white board.
Terpenes are a class of organic compounds made from isoprene units
-common in plants
-pine,mint and herby aroma
how are terpenes classified?
monoterpene- two isoprene units
sesuiterpene- three isoprene units (1.5 terpene)
diterpene- four isoprene units
triterpenes- 6 isoprene units
Name some common terpenes and their sources.
Limonene: Found in citrus peel.
Pinene: Found in pine needles and rosemary.
Humulene: Found in hops.
Myrcene: Found in bay leaves and thyme.
what is the terpenome? how many compounds does it account for?
the compendium of all known terpenoids
-accounts for ~1/3 of all compounds in the dictionary of natural products
what terpene pathway is shared by almost all domains of life?
the route from IPP to squalene
What are terpenoids, and how do they differ from terpenes? provide examples.
modified terpenes where functional groups like oxygen are added or structural changes occur
terpenes:
-limonene
-pinen
terpenoids:
-Retinol
-Tocopherol
-Cholecalciferol
what is the relationship between terpenoids and sterols?
terpenoids are precursors to sterols
what kind of terpinoid is retinol?
diterpenoid; made from 4 isoprene units
what is the highest source of Vit A?
cod liver oil
-300mg/kg
what is provitamin A? what are food sources high in this?
dietary precursors of Vit A that can be converted into active Vit A
-carotenoids (spinach, parsley, carrots)
What enzyme converts carotenoids to retinol?
how much retinol is produced?
15,15’-dioxygenase catalyzes the cleavage of β-carotene into retinol
-2 moles of retinol
if beta carotine is not broken in half equally, what impact does this have on the vitamin content? what is produced?
beta carotene that is not cleaved in half produces a product that will have an inactive form, reducing the vitamin content provided
-alpha carontene
-gamma carotene
where must beta carotene be cleaved to yieled the most retinol?
15-15’ position
What is retinol activity equivalent?
RAE is the amount (in μg) of dietary carotenoids providing the activity of 1 μg retinol
-the efficiency with which these compounds are converted into active Vitamin A in the body
why is retinol activity equivalent used?
1) Not all sources of Vitamin A are equally bioavailable or effective at being converted into retinol
2) accounts for differences in bioavailability and conversion efficiency between retinol and carotenoids.
what is the retinol activity equivalent for:
beta carotene
retinol
beta carotene: 12 μg β-carotene = 1 μg RAE
Retinol: 1 μg retinol = 1 μg RAE
what would you expect the retinol activity equivalents to be for a compound with a relative acvtivity of 0 when cleaved at 1515’?
theyre will be no activity and no retinol conversion
Explain what you would expect out of the activity for a carotenoid in cis configuration? when is it in this state?
it would be inactive
-typically, carotenoids are in a trans configuration, though heat or a change in pH, it can result in a cis conformation
what cis isomers of betacarotene have the lowest energy? how does this impact their usage in food?
9 and 13
-they are the most common cis isomer of beta carotene due to their stability
what effect does thermal processing have on all trans beta carotene? what does this do to cis beta carotene? what impact does this have on the vitamin profile?
it will reduce the percentage off all trans beta carotene and some is converted into cis beta carotene
this reduces the provitamin activity (cis conformation has lower levels because they are not as efficiently cleaved by 15-15’ enzyme) which in turn, decreases converion into retinol2
What is retinyl palmitate, and why is it significant?
Retinyl palmitate is a form of Vitamin A commonly added to fortified foods like milk to enhance Vitamin A intake
What are tocopherols and tocotrienols, and how do they differ?
Both are forms of Vitamin E.
Tocopherols: Saturated side chain
- more biologically active
Tocotrienols: Unsaturated side chain
what are food sources high in y-tocopherols vs y-tocotrienols? overall, what are common sources of both?
y-tocopherol: soybean
y-tocotrienol: palm oil
-both found in vegetable oils
What are the different forms of tocopherols, and how do they differ?
Dependent on where the methyl group is
α-Tocopherol (most biologically active)
β-Tocopherol
γ-Tocopherol (abundant in oils)
δ-Tocopherol
What factors influence tocopherol antioxidant activity in oils?
Oil type: Different oils contain varying tocopherol forms
Concentration: Higher tocopherol levels improve activity
Processing temperature: High heat can degrade tocopherols
How do tocopherols act as antioxidants?
Tocopherols stabilize free radicals by donating a hydrogen atom from their chromanol ring
How does natural α-tocopherol differ from synthetic forms?
Natural α-tocopherol (RRR) is more bioactive
Synthetic α-tocopherol contains a mix of isomers, reducing bioavailability
Which form of tocopherol is most biologically active, and why?
α-Tocopherol is the most biologically active due to its superior absorption and interaction with Vitamin E receptors in the body
