Health = Oxidant / Antioxidant Balance - Meet Dr. ROS Jeckyll
Dr. ROS Jeckyll
- In biological systems, REDOX reactions using the
ability of Reactive Oxygen Species (ROS) are essential to body’s functions maintaining life
When we say
Oxygen "OXIDIZES" Food, What Does that Mean?
Oxygen Molecule (3
) "Activated" to Produce ROS by 2 Different Mechanisms
ROS production in the body can be Enzymatically or
are produced continuously in cells
either as by-products of metabolism or deliberately as in immune system
They are also by-products of circulation, respiration, digestion and
This chemical term refers to a two-way reaction in
One atom or molecule
away an electron (REDuces)
Another atom or
TAKES an electron (OXidizes).
When we say Oxygen "OXIDIZES" Food, What Does that Mean?
responsible for providing energy for the cell in a process called “cellular
which takes place in the cell
mitochondria (“energy factories’).
“oxidant” in this REDOX reaction)
( removes electrons from)
(Electrons are transferred
from the sun's radiant energy to glucose in
food, via chlorophyll) -
and then uses the 4 electrons it acquires to produce energy.
Electrons are removed from glucose in a series of enzyme-assisted steps,
which pass them along an “Electron Transport Chain” until they are finally
accepted by oxygen,
producing water. Glucose is the “reductant”
in this redox reaction, since glucose
“reduces” (gives away electrons
The energy gained in this process is stored
(via a process called
molecules - the form of energy that cells use to function.
The Oxygen Molecule
May be "Activated" to Produce
in the body by 2 Different Mechanisms
Atmospheric Oxygen (3
absorbs sufficient energy to reverse
the spin of one of its unpaired electrons,
it will form
in which its two unpaired electrons
have opposite spins.
does not then
have the spin restriction of
triplet oxygen, and
can thus participate in reactions involving the simultaneous transfer of two
electrons (divalent reduction). Since paired electrons are common in organic
is much more reactive towards organic molecules than
can be introduced into the body by various
therapies E.g. Ozone therapy, Hydrogen peroxide therapy,
(Photodynamic Therapy – provides benefit of
light therapy on photosensitive molecules purposefully introduced to target
areas off body)
In the body,
are more typically produced by
the progressive reduction of
and finally water.
The energy-producing cellular
respiration chain in the mitochondria
(the energy "factory" of cell)
uses more than 90% of the body's
oxygen, in a 4-step process that takes
place one electron-transfer at a time,
ultimately producing water, carbon dioxide (CO2) and energy.
The summary process of how cells produce energy from glucose in the presence of
sufficient oxygen is:
+ 6 3
These partial equations show the
ROS produced during this 4-step
Adding 1e- to molecular oxygen
Hydroperoxyl Radical (highly reactive)
Adding H to Superoxide
Hydrogen Peroxide (poorly reactive)
Adding 2 e- to molecular oxygen
Adding 1e- to Hydrogen peroxide
ROS production in the body can be
enzymes that catalyze the reaction
when oxygen is the acceptor of hydrogen
to form water or H2O2
Hydroperoxidases and peroxidases:
or ROOH as
catalyse dehydrogenation of a substrate using NAD+
incorporate oxygen into substrate
A variety of enzyme systems are capable of
generating significant amounts of
activated in ischemia / reperfusion (reduction / restoration of blood supply to
an organ or tissue caused by constriction or obstruction of the blood vessels,
as after a heart attack).
enzymes catalyze reactions between
and PUFAs (polyunsaturated fatty
acids), such as arachidonic acid (AA), containing methylene interrupted double
When AA is the substrate, these Hydroperoxides are known as HpETEs
which can be transformed into Hydroxy products (HETEs).
(COX) enzymes catalyze the addition of
to various PUFAs, converting
them into biologically active molecules called endoperoxides (PGG,
- intermediates in the transformation of fatty acids to prostaglandins.
produced in neutrophils, monocytes and newly activated macrophages,
oxidation of chloride ions into the powerful oxidant
hypochlorous acid (HOCl)
Amino acid oxidase.
Autoxidation is a by-product of the aerobic internal milieu -
molecules that undergo autoxidation include:
Myoglobin (in heavily exercised
Rreduced cytochrome C
Autoxidation of any of the above molecules in a reaction results in the
and the formation of ROS -
Superoxide is the primary radical formed.
ferrous ion (Fe II)
can have its electron stolen from it by oxygen to produce superoxide and Fe III
- by the process of autoxidation (Fridovich, 1983 and 1995).