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MARGINALCOMPOUDS
semi vitaminsPresented by
NAGI Moh ELFATIH
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number of organic compounds have clear
metabolic functions; they can be synthesized
in the body ,but it is possible that under some
circumstances endogenous synthesis may not
be adequate to meet requirements
Some were considered as vitamines once but
the most suitable term for them all is quasi
vitamins
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The list of quasi-vitamins includes
Factors required for some species other than
man and required in man in certain conditionsCholine
Carnitine
Myo-inositol
Factors with certain metabolic functions but less
evidence for essentiality
Co Q10
Lipoic acid
bioptreins and others
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CARNITINE
-hydroxy--N,N,N trimethylaminobutyrate
quaternary ammonium compound
two stereoisomers L carnitine and D carnitine
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Biologically active forms
L-carnitine
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sources
Diet
Biosynthesis
Supplements
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biosynthesis
From two essential amino acids
lysine and methionine
primarily in the liver and kidneys Requirements for synthesis
Iron
Vitamins C and B6
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Dietary Sources
Breast milk --- contains 2895 nmol of
carnitine per milliliter
Red meat
Milk and Dairy products
Fish
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materials of plant origin tend to be low in
carnitine, whereas those derived from animals
tend to be rich in the factor
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supplements
L-carnitine most widely available and least
expensive
Acetyl L-carnitine
Propionyl L-carnitine
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metabolism
Absorption
active transport dependent on Na+ co-
transport
Passive diffusion
High efficiency
Rapid uptake
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Transport
released slowly from tissues
High soluble in plasma in both the free and
acetylated forms
3089 M taken up, against concentration gradients, by
peripheral tissues by high-affinity, Na+-
dependent transporters located principally in the skeletal muscle, which
contains some 95% of the bodys carnitine
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The L-carnitine level in healthy adults
umol/L
Plasma free L-carnitine level 40~50
Plasma acetyl-L-carnitine 3~6
Plasma acyl-L-carnitine except acetyl-
L-carnitine
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carnitine concentrations of skeletal muscles
are typically 70-fold that of plasma
turnover of carnitine in muscle is relatively
slow( ~8 days) but increased substantially by
exercise
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Excretion
carnitine is highly conserved by the human
kidney, which reabsorbs more than 90% of
filtered carnitine
Renal excretion of carnitine adapts to the level
of carnitine intake
free form or as short-chain acylcarnitine
esters
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Some conditions increase excretion of
carnitine
Propionic aciduria
Methylmalonic aciduria
Supplemental dietary choline
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Metabolic Function transport of fatty acids (fatty acyl-CoA) from the
cytosol into the mitochondrial matrix foroxidation as sources of energy
The fatty acids with chain lengths of 12 or fewercarbons enter mitochondria without the help of
membrane transporters. Those with 14 or more carbons, the majority of
the FFA obtained in the diet or released fromadipose tissue, cannot pass directly through the
mitochondrial membranesthey must firstundergo the three enzymatic reactions of thecarnitine shuttle
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The carnitine acyltransferases are actually a
family of related enzymes. Six carnitine
acyltransferases with different but overlappingchain-length specificities have been isolated
from mitochondria
At least five carnitine transporters have beencloned
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Hormone function
Carnitine have biological actions similar to
those of glucocorticoids
bind the glucocorticoid receptor and effect the
receptor-mediated release of cytokines
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Physiological effects
Atherosclerosis
There may be a link between dietaryconsumption of carnitine and atherosclerosis
Antioxidant effects
protective effect against lipid peroxidation of
phospholipid membranes and againstoxidative stress induced at the myocardial andendothelial cell level.
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Health effects
Hepatic function
protect against ammonia-induced encephalopathy in cirrhotics
Renal function
studies have suggested that carnitine administration to dialysis
patients can increase hematocrit, allow a lower erythropoietin
dose, and reduce intradialytic hypotension and fatigue
Diabetes A clinical trial found carnitine to reduce fasting plasma glucose
levels and to increase fasting triglycerides in type II diabetics
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Cardiovascular function
benefit cardiac function
produce effects on prostaglandins that are associated withcardioprotection
reduce myocardial injury after ischemia and reperfusion
Neurologic function
studies have shown that acetylcarnitine treatment can induce
the release of acetylcholine in the striatum and hippocampus,
Alzheimers disease patients carnitine attenuate progression
of several parameters of behavior, disability, and cognitive
performance
reduce attention problems and aggressive behavior in boys
with attention-deficit hyperactivity disorder
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Male reproductive function
Epididymal tissue and spermatozoa typically contain high
concentrations of carnitine Studies indicate that carnitine levels are related to sperm
count, motility, and maturation
carnitine supplementation can improve sperm quality
Thyroid function
Carnitine appears to be a peripheral agonist of thyroidhormone action
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Carnitine deficiency
metabolic disorder in which body levels of
carnitine, is less than what is needed for the
normal function of the body.
True carnitine deficiency is not known to occur
in healthy people
Primary
Secondary
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primary carnitine deficiencyis a rare genetic
disorder caused by a mutation in the protein
that transports carnitine
presents in childhood and can be fatal without
treatment.
Other names for these conditions includecarnitine palmitoyltranserase I or II deficiency
and carnitine-acylcarnitine translocase
deficiency.
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Secondary carnitine deficiency, more
common than primary deficiency,
people at risk
strict vegetarians
protein-energy malnutrition
administration of the anticonvulsant valproic
acid and other drugs
metabolic organic acidemias acidurea
premature infants
patients undergoing hemodialysis
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Signs and Symptoms of Deficiency
Some people with primary carnitine deficiency
are asymptomatic
Symptomatic disease appears as
liver dysfunction
Cardiomyopathy and cardiomegaly
Muscle fatigue and weakness
abdominal cramps
Hypoketotic hypoglycemia
Diarrhea
Anemia
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Diganosis of carnitine deficiency
Measurement of plasma carnitine levels of individuals
with carnitine deficiency will show extremely reducedplasma free carnitine levels (
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Treatment of carnitine deficiency
high dose carnitine supplementation, which
must be continued for life.
Individuals who are identified and treated at
birth have very good outcomes, including the
prevention of cardiomyopathy
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CHOLINE
2-hydroxy-N,N,N-trimethylethanaminium
quaternary ammonium compound
freely soluble in water and ethanol, but
insoluble in organic solvents.
strong base
methyl donor ==prominent feature of itschemical structure due to its triplet of methyl
groups
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Dietry forms widely distributed in foods
mostly in the form ofphosphatidylcholine
(lecithin),
Some dietary choline is present as thefree
base or sphingomyelin
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sources in diets
egg yolk
glandular meats
(e.g., liver, kidney, brain)
soybean products,
wheat germ
peanuts
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supplements
Available as choline salts
Added to infant formula also
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metabolism
Digestion
Choline is released from phosphatidylcholine by
hydrolysis in the intestinal lumen, an action of
phospholipases 3 type of phospholipases act on phosphatidylcholine
Phospholipase A2
Phospholipase A1 Phospholipase B
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O CH2C R
O
CHOCR
O
H2C O P O X
O
Phospholipase A1
Phospholipase A2
Phospholipase C Phospholipase D
Cleavage sites of phospholipases
PhospholipaseB
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most of the phosphatidylcholine that is ingested
is absorbed as lysolecithin
lysolecithin is reacylated to phosphatidylcholine in theintestinal mucosal cells
30% of dietary phosphatidylcholine is absorbed intact
into the lymphatic system bound to chylomicron
the resr is converted to glycerylphosphorylcholine in the
intestinal mucosa and to free choline in the liver
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When free choline is consumed a large amount (e.g.,
nearly two-thirds) is catabolized by intestinal
microorganisms to the end product trimethylamine
The remaining portion is absorbed intact
Choline is absorbed in the upper portion of the small
intestine by a saturable, carrier-mediated process
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Hgffd
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Tissue distribution
present in all tissues as an essential
component of phospholipids in membranes of
all types.
stored in the greatest concentrations in brain,
liver, kidney in forms of phosphatidylcholine
and sphingomyelins
Placenta accumulate large amounts ofacetylcholine
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Biosynthesis
three ways of phosphatidylcholine
biosynthesis:
Methylation of ethanolamine,
Reaction of cytidine diphosphate
Phospholipid base exchange
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Choline is released in free form in the tissues
by the actions ofphospholipase C peripheral tissues also contain phospholipase
B activity and can therefore produce
glycerylphosphorylcholine The brain also contains phospholipase D,
which cleaves free choline directly
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Metabolic Functions
As phosphatidylcholine
A structural element of biological membranes
A promoter of lipid transport (as a lipotrope)
Surfactant
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As acetylcholine, it is a neurotransmitter, occurring
primarily in the parasympathetic nervous system
,autanomic ganglia, neuromusclar junction and CNS
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As a component of platelet-activating factor
it is important in clotting, inflammation,
uterine ovum implantation, fetal maturation,
and induction of labor
As a component of plasmalogen, it has a role
in myocardial function
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As a source oflabile methyl groups, after its
irreversible oxidation to betaine,
it is a source of labile methyl groups fortransmethylation reactions in the formation of
methionine from homocysteine,
This function links choline to folate metabolism
choline constitutes an important dietary source of
labile methyl groups for homocysteine
transmethylation
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Health Effects
choline loading may be beneficial to patients with diseasesinvolving deficiencies of cholinergic neurotransmission
1. enhance cognitive performance,
2. increase electrophysiological responsiveness;
3. provide some protection against alcohol and otherneurotoxic agents
4. help in the treatment of tardive dyskinesia
5. success to improve free memory in subjects without
dementia6. diminish short-term memory losses associated with
Alzheimers disease
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deficiency
Risk of deficiency
Poor nutrition, imbalance in the diet
liver disease
methionine,folic acid and vitamin B-3
deficiency
Methotrexate
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Mild choline deficiency can cause
fatigue,
insomnia,
frequent memory loss,
and nerve-muscle imbalances.
f
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Extreme choline deficiency can cause
liver dysfunction,
cardiovascular disease,
impaired growth,
abnormalities in bone formation,
lack of red blood cell formation,
infertility,
respiratory distress and failure to thrive in newborns,
kidney failure, anemia, and high blood pressure.
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Toxicity
very low
Appears as symptoms of
Growth depression,
impaired utilization of vitamin B6
dizziness, nausea, and diarrhea
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Myo inositol
Inositol is a carbohydrate
It is sugar alcohol
water-soluble hydroxylated, cyclic six-carbon
compound
nine possible stereoisomeric forms
Myo inositol is the only biologically active
form
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Dietary Sources
occurs in foods and feedstuffs in three forms:
free myo-inositol,
phytic acid and
Inositol containing phospholipids
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The richest sources ofmyo-inositol are the
seeds of plants
Predominant form occurring in plant materials
isphytic acid
Because most mammals have little or no
intestinal phytase activity, phytic acid is poorlyutilized as a source of either myo-inositol or
phosphorus
I i l d t i it l i f f
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In animal products, myo-inositol occurs in free form
as well as in inositol-containing phospholipids
The richest animal sources of inositol are organmeats
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Human milk is relatively rich in myo-inositol
(colostrum, 200500 mg/liter; mature milk,
100200 mg/liter) It is added to many prepared infant formulas
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Biosynthesis
from Glucose 6 phosphate
in the kidneys 4 g/day
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supplements
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Absorption
active transport
uptake ofmyo-inositol from the small intestine iscomplete
absorption of phytic acid, however, depends onthe ability to digest that form and on theamounts of divalent cations in the diet/meal
Dietary cations (particularly Ca2+) can reduce the
utilization of phytate by forming insoluble (and,thus, nondigestible and nonabsorbable) phytatechelates
Absorption of phospholipid m o inositol is
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Absorption of phospholipid myo-inositol; is
probable that it is analogous to that of
phosphatidylcholine
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Transport
Transported in the blood predominantly in the freeform;
A small but significant amount of phosphatidylinositol
(PI) is found in association with the circulating
lipoproteins
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Tissue uptake
Free myo-inositol appears to be taken up
by active transport process in some tissues
(kidney, brain)
by carrier-mediated diffusion in others (liver).
The active process requires Na+ and energy,
and is inhibited by high levels of glucose.
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Metabolism Free myo-inositol is converted to PI within cells either by
de novo synthesis by reacting with the liponucleotide
cytidine diphosphate (CDP)-diacylglycerol,or by an
exchange with endogenous PI
Phosphatidylinositol sequentially phosphorylated to themonophosphate (phosphatidylinositol 4-phosphate, PIP)
and diphosphate (phosphatidylinositol 4,5-diphosphate,
PIP2) forms by membrane kinases
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i it l t i i h h li id i h d i
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myo-inositol-containing phospholipids enriched in
stearic acid at sn1-position and arachidonic acid at
sn2-position
turnover of the myo-inositol phospholipids
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turnover of the myo inositol phospholipids
cellular phosphomonoesterases catabolize PIPs to yield
PI.
PI synthetase functions (in the reverse direction) to
break down that form to yield CDP-diacylglycerol and
myo-inositol
The kidney perform most of the catabolism ofmyo-inositol, first clearing it from the plasma and converting
it to glucose and, then, oxidizing it to CO2 via the
pentose phosphate pathway
Metabolic Functions
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Metabolic Functions
active form is phosphatidylinositol,
effecter of the structure and function ofmembranes
enzyme modulater
source of arachidonic acid for eicosanoidproduction
mediator of cellular responses to externalstimuli
e ec er o e s ruc ure an unc onof membranes
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of membranes
activator of a microsomal Na+,K+ ATPase
effective anchor for the hydrophobic attachment of proteins
to membranes
Regulation of Vesicle Transport
Rearrangement of actin cytoskeleton Recruitment of Tyrosine kinases
mediator of cellular responses tol i li
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external stimuli
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enzyme modulater
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en yme modulater
constituent of acetyl-CoA carboxylase
stimulator of tyrosine hydroxylase
Factor bound to alkaline phosphatase and 5-nucleotidase
membrane anchor for acetylcholinesterase
Li i A id
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Lipoic Acid
organosulfur compound derived fromoctanoic acid.
contains two sulfur atoms (at C6 and C8)
connected by a disulfide bond
Di t S
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Dietary Sources present in a wide variety of foods but generally at low levels.
The best sources are tissues rich in mitochrondia (e.g., heart,
kidney)
tissues rich in chloroplasts (i.e., dark green leafy vegetables)
M t b li F ti
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Metabolic Functions
Coenzyme essential cofactor for the oxidative decarboxylations of -
keto acids where, linked to the -amino group of a lysine
residue of the enzyme dihydrolipoyl transacetylase, it is one
of several prosthetic groups in multienzyme complex. In thatcatalysis, the amide form, lipoamide, undergoes reversible
acylation/deacylation to transfer acyl groups to CoA as well as
reversible redox ring opening/closing, which is coupled with
the oxidation of the -keto acid
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Antioxidant
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The ability to undergo
interconversion between disulfide(lipoic acid) and sulfhydryl(dihydrolipoic acid) forms enablesthis metabolite to function as a
metabolic antioxidant, quenchingreactive oxygen species and otherfree radicals and chelating prooxi-dant metal ions. Its function in thisregard is related to those of other
metabolic antioxidants in thenetwork of protection againstoxidative stress.
Antioxidant
H lth Eff t
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Health Effects
it has been proposed that lipoic acid may have valuein the prevention and/or treatment of other chronic
dis-eases associated with oxidative stress
Recent interest has centered on the prospective
benefits of lipoic acid in diabetes andneurodegenerative diseases
Coenzyme Q
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Coenzyme Q10
Ubiquinone
tetra-substituted 1,4-benzoquinone
derivativeswith isoprenoid side
chains of variable length
essential component of themitochondrial electron transport
chains of most prokaryotic and all
eukaryotic cells
sources
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sources
Rich sources of dietary coenzyme Q10 include mainly
meat, poultry, and fish. Other relatively rich sources
include soybean and canola oils, and nuts. Fruits,
vegetables, eggs, and dairy products
Supplements
Biosynthesis
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Biosynthesis
Coenzyme Q10 is synthesized in most tissues.
Requierment
mevalonate,
tyrosine,
molecular oxygen,
S-adenosylmethionine.
endogenous tissue biosynthesis is sufficient to
support membrane saturation levels
Metabolism
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Metabolism
Absorption
ubiquinones are absorbed, transported andtaken up into cells by mechanisms analogousto those of the tocopherols
Tissue distribution
In all membranes in the cell.
Relatively great concentrations of CoQ10are
found in the liver, heart, spleen, kidney,pancreas, and adrenals.
Tissue ubiquinone levels increase under the
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influence of oxidative stress, cold acclimation,
and thyroid hormone treatment, and decrease
with cardiomyopathy, other muscle diseases, and
aging
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Metabolic Function
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Metabolic Function
Mitochondrial respiratory chain component
electron acceptors for complexes I and II of
mitochondrial electron transport chains. They pass
electrons from flavoproteins (e.g., NADH or succinic
dehydrogenases) to the cytochromes via cytochrome
b5
They perform this function by undergoing reversible
reduction/ oxidation to cycle between the 1,4-quinone (oxidized) and 1,4-dihydroxybenzene
(reduced) species
Antioxidant
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membrane-bound antioxidant
protects and thus spares -tocopherol in subcellularmembranes.
Along with -tocopherol, -carotene, and selenium,
CoQ10 has been shown to provide significant
protection from lipid peroxidation in animals.
In some tissues (e.g., liver) its effect appears to be
greater than those of the other antioxidant nutrients.
Health effects
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Clinical trials with humans have indicated benefits ofsupplemental CoQ10 of several types
Modest improvements in symptoms with Parkinsons diseasepatients.
reduce headache frequency
reduce dyspnea, edema, and the frequency of hospitalization
in Congestive heart failure decrease systolic and diastolic blood pressure in hypertensive
patient
reduce subsequent myocardial events and cardiac deathsafter myocardial infarction
improve endothelial function of peripheral arteries ofdyslipidemic patients with type II diabetes.
Tetrahydrobiopterin
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y p
Tetrahydrobiopterin can be synthesized from GTP
It is the coenzyme for mixed function oxidases:
phenylalaninehydroxylases ,
tyrosine hydroxylases, tryptophan hydroxylases;
alkyl glycerol monoxygenase,
nitric oxide synthase
. In addition to its coenzyme role, tetrahydrobiopterin has adirect effect on neurons, acting to stimulate dopamine release
via a cAMP-dependent protein kinase and a calcium channel
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A deficit in tetrahydrobiopterin biosynthesis and/or
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regeneration can result inphenylketonuria (PKU)
from excess phenylalanine concentrations or
hyperphenylalaninemia (HPA).
The chronic presence of PKU can result in severe
brain damage, including symptoms of mental
retardation, microcephaly, speech impediments suchas stuttering, slurring, and lisps, seizures or
convulsions, and behavioral abnormalities, among
other effects
Glutathione
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Glutathione
Glutathione (gamma-glutamyl-cysteinyl-glycine )
Tripeptide
It is an antioxidant, preventing damage to
important cellular components caused by
reactive oxygen species such as free radicals
and peroxides
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gamma peptide linkage between the amine
group of cysteine (which is attached by normalpeptide linkage to a glycine) and the carboxyl
group of the glutamate side-chain
Biosynthesis
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Biosynthesis
not an essential nutrient (meaning it does not have to beobtained via food), since it can be synthesized in the body
from the amino acids L-cysteine, L-glutamic acid, and glycine.
all cells in the human body are capable of synthesizing
glutathione,
liver is the main organ of glutathione synthesis
Glutathione exists in both reduced (GSH) and
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oxidized (GSSG) states
Food sources
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Food sources
Foods containing glutathione and glutathione-stimulating chemicals
Tomatoes, garlic, onions and green peppers
Function
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Function
Glutathione has multiple functions:
It is the major endogenous antioxidant
produced by the cells, participating directly in
the neutralization of free radicals and reactiveoxygen compounds, as well as maintaining
exogenous antioxidants such as vitamins C and
E in their reduced (active) forms
GSH is known as a substrate in both
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GSH is known as a substrate in both
conjugation reactions and reduction reactions,
catalyzed by glutathione S-transferaseenzymes in cytosol, microsomes, and
mitochondria. However, it is also capable of
participating in non-enzymatic conjugationwith some chemicals.
It is used in metabolic and biochemical
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It is used in metabolic and biochemical
reactions such as
DNA synthesis and repair,
protein synthesis,
prostaglandin synthesis,
amino acid transport,
and enzyme activation.
Regulation of the nitric oxide cycle which is
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Regulation of the nitric oxide cycle, which is
critical for life but can be problematic if
unregulated
It has a vital function in iron metabolism.
Glutathione as antioxidant
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Glutathione as antioxidant
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HHHH
phytochemicals
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p y oc e ca s
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Functions
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Hormonal action - Isoflavones, found in soy, imitate human estrogensand help to reduce menopausal symptoms and osteoporosis.
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and help to reduce menopausal symptoms and osteoporosis.
Stimulation of enzymes - Indoles, which are found in cabbages,
stimulate enzymes that make the estrogen less effective and couldreduce the risk for breast cancer. Other phytochemicals, whichinterfere with enzymes, are protease inhibitors (soy and beans),terpenes (citrus fruits and cherries).
Interference with DNA replication - Saponins found in beans interfere
with the replication of cell DNA, thereby preventing the multiplicationof cancer cells. Capsaicin, found in hot peppers, protects DNA fromcarcinogens.
Anti-bacterial effect - The phytochemical allicin from garlic has anti-bacterial properties.
Physical action - Some phytochemicals bind physically to cell wallsthereby preventing the adhesion of pathogens to human cell walls.
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There are currently many phytochemicalsin clinical trials for a variety of diseases.
Lycopene from tomatoes, for example, has beentested in human studies for cardiovascular
diseases and prostate cancer. These studies,however, did not attain sufficient scientificagreement to conclude an effect on any disease.
Lutein and zeaxanthin are suspected to
inhibit macular degenerationand cataracts, therewas insufficient scientific evidence from clinicaltrials for such specific effects or health claims.
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