HPLC Assay of Water-Soluble Vitamins, Fat-Soluble Vitamins ...
Biochemistry Vitamins 1. Water soluble vitamins 2. Fat soluble vitamins.
-
Upload
veronica-long -
Category
Documents
-
view
405 -
download
11
Transcript of Biochemistry Vitamins 1. Water soluble vitamins 2. Fat soluble vitamins.
Biochemistry
Vitamins 1. Water soluble vitamins 2. Fat soluble vitamins
Objectives:
To recognize vitamins by nameTo understand their distribution in various food sourcesTo understand their role in metabolismTo understand the signs and symptoms of diseases resulting from deficiencies
Vitamins
A group of organic nutrients required in small
quantities for a variety of biochemical
functions and which , generally , cannot be
synthesized by body and must therefore be
supplied in the diet.
Water soluble vitamins
1. B-complex vitamins
a) B-vitamins in energy metabolism Thiamine (B1) Riboflavin (B2) Niacin (B3) Biotin Pantothenic acid
b) B-vitamins in methyl group metabolism conversions Folic acid Cobalamin (B12)
c) B-vitamins in metabolic conversions Pyridoxine (B6) Pyridoxal Pyridoxamine
2. Vitamin C
O-
O
O
H3CS
O
H3CCoA CO2+
pyruvate acetyl CoA
pyruvate dehydrogenase complex
Champe and Harvey, p. 106
O
H3C
O
O-
N
N
N+ S
H3C
NH2 H
HO
N
N
N+ S
H3C
NH2 CH
O
P OP O-
O
-OO
-O
H3C OH
N
N
N+ S
H3C
NH2 H
O
P OP O-
O
-OO
-O
CO2
thiamine (B1)
thiamine pyrophosphate TPP
first step in pyruvate dehydrogenase complex
+
Thiamine Food sources and distribution:
Whole grain, meats, legumes (peas, beans and lentils) Signs and symptoms of deficiency
Beri-beri: severe deficiencyPrimarily in areas where polished rice is primary food sourceSymptoms include dry skin, irritability, disorderly thinking and progressive paralysisWet beriberi-cardiovascular symptoms, cardiac failure Infants: onset can be rapid, resulting in tachycardia and death(look to nutritional status of mother)
Wernicke-Korsakoff syndrome: Primarily associated with severe alcoholism.Symptoms include apathy, loss of memoryWandering eye movement
Toxicities, contraindications, and other notes
Only known use in treating deficiencyCommonly given to alcoholics in ER(emergency room)Excess of any one B-vitamin can cause deficiency of others.
Rubin and Farber, Pathology - 2nd edition, p. 329
N
N
N
NH3C
H3C
O
H
O
CH2
OH
OH
OH
OH
CH2
OH
OH
OH
O P
O P
OO
N
NN
N
NH2
OHHO
O
-O
-O
N
N
N
NH3C
H3C
O
H
O
O
N
N
N
NH3C
H3C
O
H
O
H
H
FADH2
riboflavin (B2)
Flavin adenine dinucleotide FAD
Riboflavin
Food sources and distribution:Milk, cheese, meat, leafy vegetables, breads, cereals
Signs and symptoms of deficiency
Sore throat, glossitis, cheilosis (red lips)Anemia, neuropathy
Toxicities, contraindications and other notes
Only known use in treating deficiencyExcess intake can cause yellow urineExcess can interfere with B1 & B6
Rubin and Farber, Pathology - 2nd edition, p. 331
N+
O
NH2
H
N+
O
O-
H
N+
O
NH2
N
NN
N
O
O
NH2
OHHO
OH
OH
O
O
P
P
O
OO-
O
-O
H NADH
N
O
NH2
H H
niacin (B3)
nicotinamide
nicotinamide adenine dinucleotide NAD+
H- = H+ + 2e-
niacin Food sources and distribution:
Fish, meat, poultry, cereal, nutsTryptophan in diet can serve as alternative source
Signs and symptoms of deficiencyPellagra (pella agra: rough skin)3D’s: dermatitis, diarrhea, dementiared, swollen tongueobserved in chronic alcoholics
symptoms reverse within 24H of administration Toxicities, contraindications and other notes
Harnup’s disease: defective renal and intestinal transport of tryptophanFast growing tumors can exhaust tryptophan supplyExcess can cause high BP and uric acid, cardiac arrhythmiasCan lower cholesterol
Rubin and Farber, Pathology - 2nd edition, p. 330
N N
S
O
Enzyme
HHCO2
N N
S
O
Enzyme
HCO
-O
biotin
biotin Food sources and distribution:
Can be synthesized by intestinal bacteriaFound in most foods
Signs and symptoms of deficiency
Very rare, include dermatitis, muscle pain
Toxicities, contraindications, and notesChronic consumption of raw eggs can induce deficiency.Chronic inflammatory bowel disease can cause deficiency.
N
NN
N
O
NH2
OH
OH
O
P
O
P
O
O-O
O O-
N CH3
CH3
OH
O
HO
N
SH
H
OHN CH3
CH3
OH
O
HO
O-
pantothenic acid
coenzyme A: CoA
acceptor site for acetyl group
pantothenic (B5)
Food sources and distribution:UbiquitousEasily destroyed by heating
Signs and symptoms of deficiency
Very rareNeuromuscular degeneration
Toxicities, contraindications and other notes
Megadose can cause diarrhea and water retention
B-complex vitamins in energy metabolism and neuropathologies
Review B-complex vitamins and energy metabolism: Thiamine B1 TPP, pyruvate dehydrogenase Riboflavin B2 FAD, FADH2
Niacin B3 NAD+, NADH Pantothenic acid coenzyme A Biotin decarboxylation reactions (decarboxylase)
N
vitamin B6
OHNH2
OH
CH3
H
+
N
OHOH
OH
CH3
H
+
N
OHO
OH
CH3
H
+
N
OO
OH
CH3
H
+
O-O
-O
pyridoxine
pyridoxamine
pyridoxal
pyridoxal phosphate
vitamin B6 - catalyzed reactions
N
OO
OH
CH3
H
+
O-O
-O
pyridoxal phosphate
R
N
O
O-H
H
N
OO
CH3
H
+
O-O
-O
Schiff base
R
N
O
O-
H
Transamination:
Deamination:
Decarboxylation:
Condensation:
oxaloacetate + glutamate --> aspartate + alpha ketoglutarate
serine --> pyruvate
histidine --> histamine
glycine + succinyl CoA --> gamma-aminolevulinic acid
Pyridoxine (B6) Food sources and distribution:
Meat, whole-grain breads and cereals, vegetables Signs and symptoms of deficiency
Skin lesionsConvulsive disorders resulting from low levels of GABANeeded for NAD+ synthesis
Toxicities, contraindications and other notes
Excess can lead to sensory nerve destruction, loss of feeling in fingers, legsExtra pyridoxine needed when using ISONAZIDE for treatment of TBISONAZIDE binds covalently to pyridoxal phosphate
Champe and Harvey, p. 250
N
N N
N
O
H2N
H CH3
H2N
O
O-
O
O-
O
O-
NH2
6-methylpteridine
para-aminobenzoic acid, PABA
glutamate
N
N N
N
O
H2N
H CH2
HN
O
O
O-
O
O-
NH
+
+
folate, folic acid
5
10
S
H2N
O
ONH2
sulfanilamide
N
N N
N
O
H2N
H CH2
HN
O
O
O-
O
O-
NH
folate, folic acid
5
10
N
N N
N
O
H2N
H CH2
HN
O
O
O-
O
O-
NH
dihydrofolate, DHF
5
10
N
N N
N
O
H2N
H CH2
HN
O
O
O-
O
O-
NH
tetrahydrofolate, THF
5
10
H
H
HH
HH
N
N NH
HN
O
H2N
H CH2
HN
O
O
O-
O
O-
NH
tetrahydrofolate, THF
5
10
OH
NH2
O
O-
serine
N
N NH
HN
O
H2N
H CH2
N
O
O
O-
O
O-
NH
10-hydroxymethyl-THF
5
10
H
NH2
O
O-
glycineH2C
OH
H
H
N
N NH
N
O
H2N
H CH2
N
O
O
O-
O
O-
NH
5,10 methylene-THF
5
10H2C
- H2O
Stryer, Fig 29-16
Folic acid
Food sources and distribution:Fresh green vegetablesCooking can destroy folic acid
Signs and symptoms of deficiency
Hemolytic anemias
Toxicities, contraindications and other notes.Critical for pregnant womenMegadose can interfere with Zinc absorption.May interfere with antiepileptic meds (phenobarbitol)
Rubin E, Pathology, p1379
Goodman Gilman, A. The Pharmacological Basis of Therapeutics, p.1245
Champe and Harvey, p. 327
N
N NH
NO
H2N
H CH2
N
O
O
O-
O
O-
NH
5,10 methylene-THF
5
10H2C
N
N NH
NO
H2N
H CH2
HN
O
O
O-
O
O-
NH
5
10H3C
Methyl loading of methionine
5-methyl-THF
NH2
O
O-
SCH3
NH2
O
O-
SH
homocysteine methionine
methylcobalamin fromvitamin B12
Cobalamin (B12)
Food sources and distribution:Synthesized only by microorganismsDeficiency usually results from absorption problem, not availability
Signs and symptoms of deficiency:
Pernicious anemiaMegaloblastic anemiaNeurologic dysfunctionCan result in abnormal fatty acid accumulation in membranes
Toxicities, contraindications and other notes
Substantial stores of B12 are found in the body.Could take years to develop deficiency.Caution with patients who have had GI(gastro-intestinal) surgery.
Rubin and Farber, p. 1020
Vitamin C Food sources and distribution:
Citrus fruits, potatoes Signs and symptoms of deficiency:
Scurvy results from deficiency in collagen hydroxylationResults in spongy gums, loose teeth and bleeding under the skin
Toxicities and contraindications:
Can cause oxidation, particularly in presence of free metalsCan be toxic with hemodialysis patients, iron storage diseasesAscorbate is metabolized to oxalate which can form insoluble precipitates with Ca++Result in low Ca++, kidney stones, heart deposits.
OO
OH
OH
HO OH
vitamin C: ascorbic acid
O
NHN
O
HN
O
NHN
O
HN
OH
proline hydroxyproline
sugar attachment site
Vitamin C and collagen synthesis
Rubin and Farber, Pathology - 2nd edition, p. 333
2 H2O2
HO
Vitamin C and hydroxyl radical formation
H2O2 + Fe2+ Fe3+ + HO + HO-
2 O2- + 2 H+ H2O2 + O2
superoxide hydrogen peroxide
superoxide dismutase
2 H2O + O2
catalase
Fenton reaction
ascorbic acid
DNA damage
lipid peroxidation
Review: Diseases associated/resulting from deficiencies in water soluble vitamins: BeriBeri: Vit B1 Wernicke-Korsakoff syndrome: Vit B1 Pellagra: Vit B3 Pernicious anemia: B12 Megaloblastic anemia: B12 Scurvy: Vit C
Fat-soluble vitamins
Vitamin A
Vitamin D
Vitamin E
Vitamin K
Vitamin A
Food sources and distribution:Low fat dairy products, deep yellow, orange vegetables
Function: Vitamin A(retinol) is the precursor of retinel, the light-sensitive group in rhodopsin and other visual pigments.
Signs and symptoms of deficiency:Night blindness, dry eyes and skinSlow growth in childrenLowered resistance to infection
Toxicities and contraindications:
Overdose can result in dry skin, headacheCan result in birth defects in pregnant womenCan cause liver damage
Vitamin A derivatives (isotretinoin, accutane) can cause
birth defects and has been associated with suicide.
CH3
CH3CH3
CH3 CH3
CH3 CH3 CH3
H3C
H3C
CH2OH
CH3
CH3CH3
CH3 CH3
-carotene
all-trans-retinol
Rubin and Farber, Pathology - 2nd edition, p. 328
http://www.cnn.com/2002/US/01/08/plane.suicide.mother/index.html
Goodman and Gilman, The Pharmacological Basis of Therapeutics, p. 1599
Vitamin D
Food sources and distribution:Egg yolks, fortified milk, fish oil, sun exposure
Function: A metabolite of vitamin D is a hormone that regulates the metabolism of calcium
and phosphorus.
Signs and symptoms of deficiency:Rickets in childrenOsteomalacia (osteoporosis) in adults
Toxicities and contraindications:
The most toxic of vitamins in excessCalcium deposits in heart, hypertension, high cholesterolFragile bones
HO
HO
UV light
7-dehydrocholesterol
cholecalciferol (vitamin D3)
OHHO
(acts as a hormone-transcription factor activating expression of Ca++-binding proteins in intestine and bone)
liver hydroxylation
kidney hydroxylationactivated by parathyroidhormone when Ca++ is low
Vitamin D
1,25 dihydroxy
1
25
Robbins, Pathologic Basis of Disease – 5th Edition, p. 1221
Vitamin E
Food sources and distribution:Poultry, seafood, seeds, nuts, whole wheat
Function: Reacts with and neutralizes reactive oxygen species such as hydroxyl , radicals before they can oxidize unsaturated membrane lipids, damaging cell structure(antioxidant)
Signs and symptoms of deficiency: very rare , Unknown in humans, in animal may cause infertility Toxicities and contraindications:
Excessive bleeding, reduced sexual function
vitamin E
O
CH3
CH3
HO
H3C CH3H3C
-tocopherol
Vitamin K Food sources and distribution:
Made by intestinal bacteriaSpinach, leafy vegetables, oats, bran, potatoes
Function: required for normal blood clotting(blood coagulation)
Signs and symptoms of deficiency:Excess bleeding, bleeding gums
Toxicities and contraindications:
Jaundice in infants
O
O
vitamin K
menaquinone (vitamin K2)
required for the carboxylation of glutamate to -carboxyglutamate
allows proteins to bind calcium
N
OH
O-
O-
O
O
Ca++
important in blood clottingnewborn infants usually get a vitamin K shot