Vitamins and Minerals 3&4 Flashcards
What do Vitamin E and Selenium partner as?
Antioxidants
What do we need antioxidants for?
Antioxidants scavenge free radicals
What are free radicals?
-are unstable molecules formed when an atom or molecule gains or loses an electron
-highly reactive
Where are free radicals produced?
-in cells during cellular metabolism
What can free radicals affect?
-lipids
-DNA
-proteins in cells
What do free radical produced by cells include?
-Superoxide’s: negatively charged oxygen molecule
-Hydrogen peroxide: not a free radical itself but can produce them
Who can antioxidants donate an electron to?
-a free radical to stabilize it
Will an antioxidant become unstable if it donates an electron to a free radical?
No
Is vitamin E fat or water soluble?
Fat soluble
What group of compounds is vitamin E apart of?
Tocopherols
What is alpha-tocopherol?
-Vitamin E
-the most biologically active of the tocopherols
Can other tocopherols have vitamin E antioxidant activity?
Yes
What are the functions of Vitamin E?
-important as a biological antioxidant
-helps prevent formation of peroxides
What can an antioxidant reduce?
-susceptibility of polyunsaturated fatty acid oxidative degradation
where are polyunsaturated fatty acids founds?
-cell membranes
-organelle membranes
What are peroxides?
-are toxic byproducts of incomplete polyunsaturated fatty acid oxidation
What is an example of a lipophile?
Vitamin E
Since vitamin E is a lipophile what can it be incorporated to? what else is there?
-membranes
-polyunsaturated fatty acids are found in the phospholipids of cell membranes
What are polyunsaturated fats open to attack from? and why?
-free radical
-bc of double binds in the polyunsaturated fatty acid
Symptoms of Vitamin E Deficiency
-reproductive failure
-myopathies
-nutritional muscular dystrophy
muscular weakness
-stiff gait
-white muscle disease
When there is a vitamin E deficiency that causes reproductive failure what happens?
-embryonic degeneration
-some effects in testicles of some species
When there is a vitamin E deficiency that causes nutritional muscular dystrophy what happens?
-muscle defects
-young animals will show stiff gait and weakness
When there is a vitamin E deficiency that causes white muscle disease what happens?
-dystrophic lesions in muscle
-white lesions on muscle show degeneration of skeletal muscle fiber
-degrading in cell membrane
What age group is white muscle disease most common in?
Young and growing animals
Supply and sources of Vitamin E
-Forages (whole plant feeds)
-Cereal grains
-Corn
-milk in mammal
What does corn contain more of?
-more relatively inactive forms of tocopherols
What do moist grains and hay experience during storage?
-loss of Vitamin E
-reduces avability
Do vitamin E requirements increase or decrease with greater polyunsaturated fatty acids in the diet?
-increase
-protection of feed quality as well
When and were was Selenium toxicity first observed?
-In grazing ruminants and horses in the west where high selenium soils caused disease (blind staggers or alkali disease)
-Many areas of US have Se deficient in soil
Can Selenium supplements reduce symptoms of Vitamin E deficiency?
Yes, but can’t fully replace or balance out deficincy
What is Seleniums Functions?
-Selenium is an essential component of the enzyme glutathione peroxidase (GP)
-contains selenocysteine amino acid in the active site of GP
-enzyme destroys hydrogen peroxide protecting cell membranes form peroxidative damage
Symptoms of Selenium Deficiency
-Muscular weakness
-muscle lesions in young ruminants
-very similar to Vitamin D deficiency
Sources of Selenium
-supplemented by injection
-oral dosing
-incorporation into salt blocks
~in Se deficient areas
Is there a large or narrow margin for Selenium?
-narrow margin of safety between the minimum requirement and the maximum requirement tolerable level
-supplement must be managed to avoid excess
What would a Se excess affect?
-liver and kidney damage
-hair loss
-hoof loss
What vitamin do all animals require a source of?
Vitamin A
Does active vitamin A occur in plants?
-No
What can be converted to get Vitamin A?
-Carotenoids from plants, like beta-carotene, can be converted to vitamin A
Characteristics of vitamin A deficiency and excess
-vitamin A deficiency is a widespread problem in animals and humans
-Vitamin A deficiency and excess are both serious hazards
-deficiency leads to disease
What is provitamin A?
-Carotenoids
-not active form
-most abundant and widespread provitamin A in animal feeds is beta-carotene
What is the active form of vitamin A?
-Retinol
-retinol includes a hydroxyl that allows it to be esterifies to a fatty acid
What is the structure of vitamin A?
-All trans form: geometric orientation of the double bonds
-The hydroxyl (OH) group at the end is the side where fatty acids can be added using an ester bond
-half of beta carotene
What is the structure of retinoic acid?
-Presence of carboxylic acid (OOH) group at the end where the hydroxyl (OH) group is on retinol
How is vitamin A metabolized?
-Vitamin A and provitamin A carotenoids are absorbed with lipids from the small intestine
-Vitamin A is esterified (retinyl esters) for transport in chylomicrons into the lymph and bloodstream
Where does most of the conversion of beta-carotene to vitamin A occur?
-intestinal mucosa
Simple characteristics of vitamin A metabolism
-incorporated into mix micelles
-go to enterocytes (absorbed here)
-Into the lymph
-chylomicrons export into circulation
How is vitamin A stored?
-about 90% of the body’s vitamin A is stored in the liver mainly in ester form
-carotenoids that escape conversion to vitamin A can be stored in tissues
Why is Vitamin A storage important?
-for periods of dietary shortage
-deficiency might not produce symptoms for months bc of storage
What happens to carotenoids (pigments including beta-carotene) that escape conversion to vitamin A
-Fat soluble vitamin so adipose tissue is one location
-humans, horses, cattle can all have yellow pigmented fat depending on carotenoid intake
Where is a lot of carotenoids stored? and how?
-liver
-in ester form
-vitamin A droplets
When will retinol be mobilized?
-low dietary intake
What are the functions of Vitamin A?
-Vision
-cell growth and differentiation
-Retinoic acid
What is vitamin A an essential precursor for? and what is it?
-the formation of rhodopsin
-rhodopsin is a visual pigment in the retina of the eye
What is the primary event in visual excitation of the retina is the isomerization?
-the isomerization of cis isomer leading to conformational changes in rhodopsin
-hyperpolarization of the retinal rod cell
-extremely rapid transmission of electrical activity to the brain via the optic nerve
Why is Vitamin A important for vision?
-trans-retinal is isomerized to cis-retinal in the dark, which associates with opsin to regenerate rhodopsin
Why is vitamin A important to cell growth and differentiation?
-through the acid form of vitamin A you get retinoic acid
How is retinoic acid formed? and what does it interact with?
-formed in cells from retinol taken up from the blood
-interacts with a cellular protein receptor to turn on (or off) genes in the nucleus of cells
~including skin and gut cells, bone, ovary, testis
~especially important for embryonic cell differentiation
Whay are symptoms of Vitamin A deficiency?
-Night blindness: diminished ability to see in dim light
-Epithelial tissue defects
~diarrhea: gut
~kidney and bladder stones: urinary system
~rough, hairy, scaly skin
-Anormal bone development of fetus and neonates
What are sources of vitamin A fat soluble?
-fish oils, milk fat, egg yolk are good sources from animals
-as long as animals producing them were not vitamin deficient
What are sources of provitamin A carotenoids?
-green forages are good sources for grazing livestock
-grains have little beta-carotene
-yellow corn has ahigh proportion of non-beta-carotenoids with less vitamin A value than beta-carotene
What happens to carotene content of forages with maturity and storage?
-carotene content of forages declines with maturity and declines with storage for hays and silage
Symptoms of Vitamin A toxicity?
-high levels of Vitamin A can cause skeletal malformation, spontaneous fractures, internal hemorrhage, and other symptoms
What are the safe levels of Vitamin A?
-upper safe levels are 4-10 times requirements in nonruminants
-30 times requirements in ruminants
What can in influenced by other minerlas?
-availability, absorption, and sometime post-absorption utilization of essential minerals
Well know mineral-mineral interaction?
-Na and K
-Ca and P
-Cu, Mo, and S (ruminants)
What type of minerals are Cu, Mo and S?
-S (sulfur) is a macro mineral
-Mo (molybdenum) and Cu (copper) are trace minerals
What is the most common imbalance?
-Induced copper deficiency from relatively high Mo and/or S levels
-induced copper with low Mo and or S levels
What is the site of actions for the Cu-Mo-S mechanism interaction?
-rumen
What can high levels of S or Mo cause?
-inhibits absorption
-high levels of both severely limits availability
What does the Cu-Mo-S interaction cause?
-involves formation of insoluble Cu salts in the rumen
-sulfides and thiomolybdates (sulfides and molybdate salts combination)
-poorly absorbed
What do B vitamins do?
-support enzyme reactions
-each has a distinct specific role
What does oxidative decarboxylation require?
Coenzymes from
-thiamin (B1)
-riboflavin (B2)
-nicotinamide (niacin)
-pantothenic acid
What does oxidative decarboxylation involve? What does it join?
-removal of a carboxyl (COO-) group from an organic acid
-joins the rest of the molecule with coenzyme A, forms CO2, and hydrogenated NADH
What is Pantothenic Acid? What does it do?
-peptide of a butyric acid derivative and beta-alanine
-readily absorbed and circulates in blood plasma as the free acid
What is Coenzyme A?
Pantothenic acid is a component of coenzymes A
What enzymatic reactions utilize coenzymes A?
-pyruvate dehydrogenase
-propionate CoA carboxylase
-fatty acid synthetase
Symptoms of Pantothenate Deficiency
-Reduce growth rate
-Dermatitis in chicks
-Fatty acid infiltration of the liver; fatty acids acclimate in liver
-Nervous system problems in pigs
What happens to the nervous system in pigs with a pantothenate deficiency?
-peculiar gait: goose steeping
-results from nerve degeneration
What is Niacin/Nicotinic Acid/Nicotinamide? What is it produced by?
-pyridine 3-carboxylic acid
-Niacin can be produced from tryptophan (essential amino acids) if available in excess of protein synthesis requirements
~limited efficiency: 60 units of tryptophan to produce 1 unit of niacin in pigs
What are the two coenzymes of Niacin?
-NAD: nicotinamide adenine dinucleotide
-NADP: nicotinamide adenine dinucleotide phosphate
What is Niacin and its coenzymes (NAD and NADP) important for?
-the transfer of hydrogen from substrates to oxygen: producing water
-lots of substrates are dehydrogenated by enzymes using these coenzymes to reduce the hydrogen ions
~receive H in dehydrogenated
Symptoms of Niacin Deficiency?
-reduce growth
-reduce appetite
-diarrhea
-vomitting
-dermatitis
Niacin Deficiency in specific animals
-ulcerated intestine are manifestation in pigs
-poultry can have poor feathering
-Dogs can get mouth lesions and darkening of tongue
Where can Niacin be found?
-in grains, but can be bond and unavailable for absorption in non-ruminants
What is Thiamin (B1)?
-Thiamin is phosphorylation in the liver to form thiamin pyrophosphate (TPP)
-TPP is an essential cofactor for decarboxylation enzymes including pyruvate dehydrogenase
Symptoms of Thiamin Deficiency?
-disrupts carbohydrate and lipid metabolism
-decarboxylation is reduced and acetyl-CoA doesn’t enter the cycle (polyneuritis)
-Bradycardia (slow heart rate)
What is a key metabolic for the citric cycle?
Pyruvate
What is polyneuritis?
-a classical sign in chicks
-retraction of the head and ridigity of the legs
-Also reduced growth
What id Riboflavin (B2)?
-ribose + isoalloxazine
-precursor required for flavin adenine dinucleotide (FAD) and flavin mono nucleotide (FMN)
What is FAD responsible for?
-transferring H to NAD during pyruvate decarboxylation reaction
-FADH recycled (returns) to FAD so it is not shown in reaction
FAD and FMN Synthesis Reactions
-riboflavin + ATP -> (flavokinase) FMN + ADP
-FMN + ATP -> (FAD pyrophosphorylase) FAD + pyrophosphate
Symptoms of Riboflavin Deficiency
-reduced growth is apparent
-Poultry have curled-toe paralysis with deficiency: results from degeneration of myelin sheaths on nerves
-Lesions of the mouth, anorexia, loss of hair, stillbirth of piglets
B Vitamins in Ruminants
-Microbes in the rumen produce B vitamins to support their own metabolism
-For Adult ruminants, microbes exiting the rumen and entering the small intestine provide sufficient B vitamins to meet requirements
Is B vitamin supplementation necessary in ruminant young animal?
-Not really, B vitamin come from rumen, but in young animals most come from milk from mom
-If calf on formula, then yes supplement
Is B vitamin supplementation necessary in non-ruminants?
-Yes, supply vitamin B to baby pigs bc have no rumen, but should be getting vitamin B from milk from mom
