role of free radicals in human diseases. Inside the human cells, there is an effective antioxidant defence system to counter damaging actions of reactive oxygen species. ... Direct damage to structural proteins and DNA inside the cells may result in loss of cell architecture and lack of its ability to restore.

1. ROLE OF FREE RADICAL
ANTIOXDANT IN HUMAN
Shruti gautam
Vidya bharati college of pharmacy

2.  Free Radical’ is an especially reactive atom or group of atoms that has one or more unpaired
electrons; especially : one that is produced in the body by natural biological processes or
introduced from an outside source (such as tobacco smoke, toxins, or pollutants) and that can
damage cells, proteins, and DNA by altering their chemical structure
 Free Radicals are very short-lived, with half-lives in milli-, micro- or nanoseconds
FREE RADICAL

3.  Mitochondria-the intracellular powerhouse which produces the
universal energy molecules Adenosine triphosphate (ATP) normally
consume oxygen in the process and convert it to water
.
GENERATION OF FREE RADICAL

4.  Oxygen free radicals occur just by breathing but excessive
amounts of these free radicals occur when we are exposed
to air pollution and cigarette smoke.
 Secondly, white blood cells destroy parasites, bacteria, and
viruses by using oxidants (free radicals) such as nitric
oxide, Superoxide, and hydrogen peroxide. This is done by
the release of free radicals to destroy invading pathogenic
microbes as part of the body’s defense mechanism against
diseases but with electrons unhinged, free radicals roam
the body wreaking havoc

5.  cellular components called peroxisomes produce hydrogen peroxide as a
by-product of the degradation of fatty acids and other molecules. In
contrast to the mitochondria which oxidizes fatty acids to produce ATP and
water, peroxisomes oxidize fatty acids to produce heat and hydrogen
peroxide. The peroxide is then degraded by an enzymatic antioxidant called
catalase.
 an enzyme in the cells called cytochrome P450 is one of the body’s primary
defenses against toxic chemicals ingested with food. The induction of these
enzymes to prevent damage by toxic foreign chemicals like drugs and
pesticides also result in the production of oxidant by-products. Virtually all
organs and tissues in the body are under constant attack by these free
radicals behaving like biological terrorists ripping through our bodies and
they need to be stopped quickly. To prevent free radical damage, the body
has a defense system called antioxidants

7.  Reactive oxygen species
 Radicals derived from oxygen represent the most important
class of radical species generated in living systems.
Molecular oxygen (dioxygen) has a unique electronic
configuration and is itself a radical. The addition of one
electron to dioxygen forms the superoxide anion radical
(O2•−). Superoxide anion, arising either through metabolic
processes or following oxygen “activation” by physical
irradiation, is considered the “primary” ROS, and can further
interact with other molecules to generate “secondary” ROS,
either directly or prevalently through enzyme- or metal-
catalyzed processes
REACTIVE SPECIES

8.  Reactive nitrogen species (RNS)
 NO• is a small molecule that contains one unpaired electron
on the antibonding 2π orbital and is, therefore, a radical. NO•
is generated in biological tissues by specific nitric oxide
synthases (NOSs), which metabolize arginine to citrulline
with the formation of NO• via a five-electron oxidative
reaction.Nitric oxide(NO•) is an abundant reactive radical
that acts as an important oxidative biological signaling
molecule in a large variety of diverse physiological processes,
including neurotransmission, blood pressure regulation,
defense mechanisms, smooth muscle relaxation and immune
regulation
REACTIVE SPECIES

9. REACTIVE SPEICE SYMBOL HALF LIFE REACTIVITY
Superoxide O2 10-6 s Generated in
mitochondria, in the
cardiovascular system
and others
Hydroxyl Radical OH 10-9 s Very highly reactive,
generated
during iron overload and
such conditions in our
body
Hydrogen Peroxide H2O2 stable Formed in our body by
large
peroxide
number of reactions and
yields potent species
Reactive oxygen species

10. REACTIVE SPEICE SYMBOL HALF LIFE REACTIVITY
Peroxynitrite ONOO 10-3 s Formed from NO. and
superoxide, highly
reactive
Peroxynitrous ONOOH Protonated form of
ONOO- acid
Reactive nitrogen species (RNS)

11.  Superoxide- Ion Radical (O2 )
 Superoxide anion radical is the most important widespread ROS formed by the
enzymatic process, auto oxidation reaction and by a nonenzymatic electron
transfer reactions in which an electron is transferred to molecular oxygen
 O2 + e- → O 2
–
 O2 + Fe2+ →Fe+3 + O 2
- (auto-oxidation)
 Hydroxyl Radical (OH•)
 Hydroxyl radical is the neutral form of hydroxide ion and is a highly reactive
free radical. It can strongly react with both organic and inorganic molecules
including DNA, proteins, lipids, and carbohydrates and cause severe damage to
the cells than any other ROS can do.
 Fe+2 + H2O2 →Fe+3 + OH (Fenton reaction)
 O2 + H2O2 → O2+ OH + OH - (Haber-Weiss reaction)
Properties of Some Free Radicals

12.  The ROS can be produced from either endogenous or exogenous
sources. The endogenous sources of ROS include different cellular
organs such as mitochondria, peroxisomes, and endoplasmic
reticulum, where the oxygen consumption is high.
 Mitochondria
 Most of the intracellular ROS are derived from mitochondria. The
superoxide radicals are produced at two major sites in the electron
transport chain, namely complex I (NADH dehydrogenase) and
complex III (ubiquinone cytochrome c reductase). The transfer of
electrons from complex I or II to coenzyme Q or ubiquinone (Q)
results in the formation of a reduced form of coenzyme Q (QH2).
SOURCES OF FREE RADICAL

14.  Peroxisomes
 In peroxisomes, the respiratory pathway involves the transfer of
electrons from various metabolites to the oxygen leads to the H2O2
formation but is not coupled to oxidative phosphorylation to
produce ATP instead free energy is released in the form of heat. The
other free radicals produced in peroxisomes include H2O2, O2 •-
OH• and NO•.
SOURCES OF FREE RADICAL

16.  Endoplasmic Reticulum
 The enzymes of endoplasmic reticulum such as cytochrome p-450
and b5 enzymes and diamine oxidase con- a tribute to the formation
of ROS. Another important thiol oxidase enzyme, Erop1p catalyzes
thet ransfer of electrons from dithiols to molecular oxygen results in
the formation of H2O2.
SOURCES OF FREE RADICAL

18.  Free radicals perform many critical functions in our bodies in controlling the
flow of blood through our arteries, to fight infection, to keep our brain alert and
in focus.
 Phagocytic cells involved in body defense produce and mobilize oxygen free
radicals to destroy the bacteria and other cells of foreign matter which they
ingest.
 DEFENSIVE SYSTEM AGAINST FREE RADICAL
 All aerobic forms of life maintain elaborate anti-free-radical defense systems, also
known as antioxidant systems
 The human body has a natural antioxidant defense mechanism to counteract the FR
produced which when present at very low concentrations compared with those of an
oxidizable substrate, significantly delays or prevents oxidation of that substrate".
The word oxidizable substrate includes almost everything (except H2O) found in
foods such as oil and fat; in living tissues, it include carbohydrate, lipid , protein &
DNA
FREE RADICAL IN BENEFICAL ROLE & DEFENSIVE SYSTEM
AGAINST FREE RADICAL

19. FREE RADICALS AND HUMAN DISEASE

20.  Antioxidants are defined as the substances which protect cells from
reactive oxygen species, when present in low concentration inhibit
the oxidative stress, by oxidizing themselves.
ANTIOXIDANT

22. Antioxidant compound Food containing antioxidant
Vitamine C Fresh fruit and vegetables
Vitamine E Vegetable oil
Polyphenolic antioxidant Tea ,coffee ,soy ,fruits, olive oil
Carotenoids Fruits vegetable and egg
Natural antioxidant

23.  Butylated hydroxyanisole
 Butylated hydroxytoluene
 Propylgallate
Synthetic antioxidant

24. Thank you