Free radicals - Nexus Academic Publishers

Report
FREE RADICAL
and Health
Divya
Sr. Scientist
Avian Nutrition and Feed Technology
CARI, Izatnager Bareilly.
Structure of Atom
An atom consists of an small,
positively charged nucleus
surrounded by a cloud of
negatively charged electrons.
Electrons in every orbital must
be paired and these paired
electrons spin in the opposite
direction.
It is called stable form of an
atom
Stable atoms contain an even number
of paired electrons.
Free radical - what it is?
particles withunpaired electron spinning around the
nucleus. (can be atom, ions, molecule).
Any atom or molecule capable of independent existence
(hence the term ‘free’) that contains one or more unpaired
electrons
 Free radicals are highly reactive and can cause
damage to molecules in the cell
Formation of Free Radical
 Free radical are ionized particle in human body
Free radicals produced in NORMAL cellular
metabolism are vital to certain body functions, such
as fighting disease or injury. When tissue is diseased
or damaged, the body’s immune system sends
disease fighting cells to the site, where they produce
free radicals in an effort to destroy foreign invaders.
Free radicals are also produced by
Pollution
Ultraviolet light and radiation
Toxic substances
cigarette smoke, overexposure to sunlight
•3. H 2 O 2 Hydrogen peroxide 1 O 2 Singlet oxygen NO
Types of Free radicals
There are two major types of free radical species:
reactive oxygen species (ROS)
reactive nitrogen species (RNS).
ROS (reactive oxygen species)
Free radicals
superoxide, O2 · hydroxyl radical, OH ·
peroxyl, ROO ·
alkoxyl, RO ·
hydroperoxyl, HO2 ·
Particals, which are not
free radicals
hydrogen peroxide, H2O2
hypochlorous acid, HClO
ozone, O3
singlet oxygen, 1O2
RNS (reactive nitrogen
species)
Free radicals
nitrogen oxide, NO .
Nitrogen oxide, NO2 .
Particals, which are not free
radicals
nitrosyl, NO+
nitrous acid, HONO
nitogen(III) oxide, N2O3
peroxynitrite, ONOO alkylperoxinitrite, ROONO
Mechanism of radical reactions
Radicals are highly reactive species
Three distinc steps
 initiation (homolytic covalent bonds cleavage)
formation of radicals
 propagation (chain propagation)
in this step required free radical is regenerated
repeatedly as a result of chain reaction
 termination
Free Radical Oxidation
Stable
antioxidant
radical breaks
the cycle
(unstable peroxyl
radical)
R* + O2
ROO*
ROO* + RH
ROOH + R*
Aldehydes, organic acids, alcohols, ketones RO* + RH
(hydroperoxide breakdown products
ROH + R*
contribute off flavors)
Free radicals damage
 Steal electrons from cells,
DNA, enzymes
membranes.
and
cell
 Damage to cell structures,
nucleic acids, lipids and
proteins.
Lipids in cell membranes are very prone to oxidative damage
because some free radicals tend to concentrate in the
membrane and cause oxidative damage, known as lipid
peroxidation
Free radical and diseases
Number of human degenerative diseases.
 Oxidative stress is a harmful condition that occurs when there
is an excess of ROS and/or a decrease in antioxidant
levels, this may caused tissue damage by physical, chemical,
psychological factors that lead to tissue injury in human and
causes different diseases
Free radical and ageing Aging pigments (lipofusin granules)
are
accumulated in the subsarcolmal region of the muscle
fibers and becomes more abundant with increasing age.

Other diseases such as atherosclerosis, Parkinson's disease
and Alzheimer's are also attributed to free radicals.
Need
of antioxidant
 Cell produce defense against excessive free radicals by their
preventative mechanisms, repair mechanisms, physical
defenses and antioxidant defenses.
 Antioxidants prevent cell and tissue damage as
they act as Scavenger.

 Food plants including fruits, vegetables and spices are the
primary sources of naturally occurring antioxidants for humans
Antioxidant
Antioxidant means "against oxidation." Antioxidants are an
inhibitor of the process of oxidation, even at relatively small
concentration and thus have diverse physiological role in
the body .
Antioxidants are any substance that delay or inhibits
oxidative damage to a target molecule. At a time one
antioxidant molecule can react with single free
radicals and are capable to neutralize free radicals by
donating one of their own electrons, ending the
carbon-stealing reaction.
CLASSIFICATION
Non-Enzymatic antioxidants
Enzymatic antioxidants
superoxide dismutase
Glutathione reductase,
Glucose 6-phosphate
dehydrogenase.
1.
Minerals e.g.-Zinc, Selenium
2. Vitamins e.g.-VitaminA, Vitamin
C, Vitamin E, Vitamin F
3. Carotenoids e.g.--carotene,
Lycopene, Lutein, Zeaxanthin
4. Low molecular weight
Antioxidants e.g.-glutathione,
uric acid
5. Organosulfur compounds e.gAllium, Allyl sulfide,Indoles
6. Polyphenols
Types of natural antioxidant
Photochemical
Phenolic Acids
Anthocyanins
Flavones, Flavanones
Isoflavones
Stilbenes/
Lignans
Flavonoids
Flavonols
Catechins
Flavanols
Epicatechins
sources of Natural antioxidant
Polyphenolic
compounds
Carotenoids
Vitamin-A
Vitamin-C
Vitamin E
. Organosulfur
compounds
Mechanism of action of antioxidants
 Two principle mechanisms-
chain- breaking mechanism by which the primary
antioxidant donates an electron to the free radical present in
the systems--as beta-carotene and vitamins C and E, or it
simply decays into a harmless product.
 Preventive - Antioxidant enzymes like superoxide
dismutase, catalase and glutathione peroxidase prevent
oxidation by reducing the rate of chain initiation. They can
also prevent oxidation by stabilizing transition metal radicals
such as copper and iron.
Three major levels of antioxidant
defense in the cell
Free
radicals
First level of defense
Free
radicals
Second level of defense
Third level of defense
Se-GSH-Px
Uric acid
Glutathione
Lipases, proteases, etc
, Free radicals
Catalase
Vitamins A, E, C,
carotenoids
Metal-binding
proteins
Free
radicals
Levels of antioxidant defense in
the cell
 The first line of defense is the preventive
antioxidants, which suppress the formation of
free radicals.
 The second line of defense is the antioxidants
that scavenge the active radicals to suppress
chain initiation and/or break the chain
propagation reactions
 The third line of defense is the repair and de
novo antioxidants. The proteolytic enzymes,
proteinases, proteases, and peptidases, present
in the cytosol and in the mitochondria of
mammalian cells
Function
 Destroying the free radicals that damage cells.
 Promoting the growth of healthy cells.
 Protecting cells against premature, abnormal
ageing.
 Help fight age-related macular degeneration.
 Provide excellent support for the body’s immune
system.
 prevent the oxidation of unsaturated fats
Antioxidant defense system
 Antioxidants act as
radical scavenger,
hydrogen donor,
electron donor,
peroxide decomposer,
singlet oxygen quencher,
enzyme inhibitor,
metal-chelating agents.
Antioxidants in Human health
 Considerable research demonstrates the human
health benefits of naturally occurring antioxidant
compounds.
 Claims of Various properties
 anti-viral,
anti-inflammatory,
 anti-cancer,
anti-mutagenic,
anti-tumour,
 hepatoprotective
Natural extracts with antioxidant properties
The rate of lipid oxidation can be effectively retarded
by the use of antioxidants.
3
TBA value of chicken nuggets
2.5
2
1days
7 days
1.5
14 days
1
0.5
0
control
Bitter melon-0.50%
Bitter melon-0.75%
TBARS value of chicken nuggets
Bitter melon-1.0%
………….Natural extracts with antioxidant properties
 The antimicrobial properties of essential oils extracted
from plants used against a wide range of microorganisms
have been considered as an alternative to antibiotics in
livestock. Therefore, essential oils are promising as feed
additives to improve feed efficiency and control the
spread of pathogens in livestock
 The human intake of green tea decreases total
cholesterol,
increases
the
high-density
lipoprotein (HDL) fraction, and decreases
lipoprotein oxidation.
Antioxidants in Poultry health
 Hatching time is an environmental stress for the chick. At
this time stress caused by environment is very height.
 Though natural antioxidants level maximum at this stage
but in the cycle process enhance lipid unsaturation in
tissues.
 Low level concentrations of ascorbic acid (can limit
vitamin E recycling) and high temperature and humidity
increase risk of lipid peroxidation
……..Antioxidants in Poultry health
 Effect on egg production
 In the production system time between the egg laid
and cooling is variable. Whatever effort may be
made
some changes are bound to happen in
composition of egg due to high temperature and
time gap.
 Free radical is responsible accelerating these
compositional change and damage to lipids and
proteins. Addition of antioxidant in feed may retard
such changes ultimately improve egg production.
……Antioxidants in Poultry health
Transport of chicks:
 Transportation from hatchery to farm is another source of
stress. For breeding companies where chicken transportation
could involve several thousand miles, a very high degree of
stress would be associated with temperature fluctuation and
dehydration.
 Oxidation of fat in feed: Oxidized fat in the diet can cause
oxidative stress in the intestine increasing antioxidant nutrient
requirements. When a chicken diet includes spent fat after its
high temperature treatment, the fat usually contains
peroxides and hydroperoxides that can contribute
substantially to oxidative stress. It is necessary to evaluate
benefits vs disadvantages of using such fat sources.
……..Antioxidants in Animal health
 Vaccination stress: Vaccination is also a substantial
stress; and in some cases using vitamin E, for example, as
a vaccine adjuvant can help improve vaccination
efficiency.
 Exposure to Mycotoxin: Mycotoxins can substantially
decrease antioxidant assimilation from the feed and
increase their requirement to prevent damaging effects
of free radicals produced as a result of mycotoxin
exposure.
Applications of some antioxidant
in poultry production
 Increased antioxidant supplementation for improvement
of meat quality during storage.
 It is recorded that vitamin E and selenium combination is
very effective to reduce drip loss.
 Decline in egg production due to heat related stress is
increased due to less Vitamin E in feed.
 Increased
antioxidant
mycotoxin toxicity.
supplementation
decreased
continue- Poultry has become a very competitive business and any
addition on coast or change in feed ingredient will affect
the cost of production and quality of the products.
 While adding antioxidant in the feed one has to be
careful about coast, age, feed and food laws of the
country.
 Certainly there are reports available for beneficial effect
of antioxidants improving the immunity system, health
management and quality of the poultry products but all
of them cannot be introduced in poultry feed.
 Most precise study has been undertaken on available
antioxidants and their scope of application in poultry
feed.
continue--
 On the other hand, under conditions of oxidative
stress where free radical production dramatic
increases, then without external help it is difficult to
prevent damage to major organs and systems. This
external help takes the form of increased dietary
supplementation of natural antioxidants. For the
poultry business it need to understand at the time
of feed formulator when and how much fed
additive is needed and economically justified.

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