to MOLECULAR REDOX
ORP stands for Oxidation-Reduction Potential. In some parts of the world, it is
also known as Redox Potential. The word "oxidation" means, "to combine with oxygen".
When we use the term potential in describing ORP, we are actually talking about electrical potential or voltage.
We are reading the very tiny voltage generated; when a metal is placed in water in the presence of oxidizing and reducing
Chemicals like chlorine, bromine, and ozone are all oxidizers. It is their ability
to oxidize - to "steal" electrons from other substances.
of oxidizing, all of these oxidizers are reduced - so they lose their ability to further oxidize things. They may combine
with other substances in the water, or their electrical charge may simply be "used up."
atom that loses an electron in the process is said to be "oxidized." The one that gains an electron is said to be
"reduced." In picking up that extra electron, it loses the electrical energy that makes it "hungry" for
If we had a body of water in which the concentration of oxidizers exactly
equaled the concentration of reducers then the amount of potential generated at the measuring electrode would be exactly zero.
The World Health Organization adopted an ORP standard for drinking water disinfection of 650 millivolts. That is,
the WHO stated that when the oxidation-reduction potential in a body of water measures 650/1000 (about 2/3) of a volt, the
sanitizer in the water is active enough to destroy harmful organisms almost instantaneously.
Any system or environment
that accepts electrons from a normal hydrogen electrode is a half cell that is defined as having a positive redox potential;
any system donating electrons to the hydrogen electrode is defined as having a negative redox potential. Eh
is measured in millivolts (mV). A high positive Eh indicates
an environment that favors oxidation reaction such as free oxygen. A low negative Eh indicates a strong reducing environment.
Many enzymatic reactions are oxidation-reduction reactions in which one compound is oxidized and another compound is reduced. The ability
of an organism to carry out oxidation-reduction reactions depends on the oxidation-reduction state of the environment, or
its reduction potential (Eh).
aerobic microorganisms can be active only at positive Eh
values, whereas strict anaerobes can be active only at negative Eh
values. Redox affects the solubility of nutrients, especially metal ions.
There are organisms that can adjust their metabolism to their environment,
such as facultative anaerobes. Facultative anaerobes can be active at positive Eh values, and at negative Eh values in the
presence of oxygen bearing inorganic compounds, such as nitrates and sulfates.
Oxygen Radical Absorbance Capacity
Radical Absorbance Capacity (ORAC) is a method of measuring antioxidant capacities in biological samples in vitro.
A wide variety of foods has been tested using this methodology, with certain spices, berries and legumes rated highly. Correlation between the high antioxidant capacity of fruits and vegetables, and the positive impact of diets high
in fruits and vegetables, is believed to play a role in the free-radical theory of aging
The redox potential is a measure (in volts)
of the affinity of a substance for electrons — its electronegativity — compared with hydrogen (which is set at 0).
Substances more strongly electronegative than (i.e., capable of oxidizing) hydrogen have positive redox potentials. Substances less electronegative than (i.e., capable of reducing) hydrogen have negative redox potentials.
electro-negativity of a substance can also be expressed as a redox potential (designated E)
The standard is hydrogen, so its redox potential is expressed as E
Any substance — atom, ion, or molecule —
that is more electronegative than hydrogen is assigned a positive (+) redox potential; those less electronegative
a negative (−) redox potential.
The greater the difference between
the redox potentials of two substances (ΔE), the greater the vigor with which electrons will
flow spontaneously from the less positive to the more positive (more electronegative) substance.
The difference in potential (ΔE) is, in a sense, a measure of the pressure between
the two. ΔE is expressed in volts.
bring two substances of differing E together with a potential path for electron flow between them,
we have created a battery. Although it may be in a mitochondrion, it is just as much a battery as a the lead-acid storage
battery in an automobile.
The greater the voltage, ΔE, between
the two components of a battery, the greater the energy available when electron flow occurs. It is, in fact, possible to quantify
the amount of free energy available.
is the number of moles of electrons transferred and
23.062 is the amount of energy (in kcal) released when
one mole of electrons passes through a potential drop of 1 volt.
every molecule of glucose respired, 24 electrons travel down the respiratory chain to the final acceptor: oxygen molecules.
Carbon reduced to the extent occurring in carbohydrates like glucose (only partially reduced)
has a redox potential of approximately − 0.42 volt.
Oxygen, as the most electronegative
substance in the system, naturally has the largest E: + 0.82 volt
The difference (ΔE) is thus 1.24 volts. Allowing 24 moles of electrons to pass through
this potential gives us a free energy yield of − 686 kcal:
ΔG = −
(24)(23.062)(1.24) = − 686 kcal
Free radicals are cellular molecules which cause damage by "oxidizing" other cellular molecules, where
'oxidation' refers to how the radicals "steal" elecrons from other molecules. They call this process 'oxidation'
due to how the most well known free radicals are "active oxygen species" (please keep this term in mind for the
upcoming research paper abstracts). 'Antioxidants' on the other hand, fight free radical damage, where these antioxidants
are simply vitamins like beta carotene, vitamin C, A, E and others. The antioxidants prevent free radicals from destroying
cellular molecules by 'reducing' the free radicals by giving electrons to the free radicals. Again, a reduced free
radical is one which has gained electrons from the antioxidants, where 'reduction' is the opposite of the free radical's
destructive 'oxidation' process of stealing electrons.
Water ionizers operate by filtering
and then electrolyzing tap water:
Acidic water is a very strong oxidant which can destroy
the cellular structures of microbes and bacteria, and it has a widespread use as a potent disinfectant in especially Japan.
The oxidizing acidic electrolyzed water's molecules steal electrons from their cellular molecules of germs and bacteria.
The alkaline water produced is a 'reducing' agent which can which can supply electrons
to oxidizing agents such as free radicals, according to the research, opposed to the 'oxidizing' acidic water that can destroy microbial cells. The alkaline electrolyzed water is a reducing
agent due to its increased molecular and atomic hydrogen concentration.
Reactive Oxygen Species (ROS)
Reactive oxygen species
(ROS) are reactive molecules that contain the oxygen atom. They are very small molecules that include oxygen ions and peroxides and can be either inorganic or organic. They are highly reactive due to the presence of unpaired valence shell electrons. ROS form as a natural byproduct of the normal metabolism of oxygen and have important roles in cell signaling. However, during times of environmental stress (e.g. UV or heat exposure) ROS levels can increase dramatically, which can
result in significant damage to cell structures. This cumulates into a situation known as oxidative stress. ROS are also generated by exogenous sources such as ionizing radiation.
// Damaging effects
Cells are normally
able to defend themselves against ROS damage through the use of enzymes such as superoxide dismutases, catalases, lactoperoxidases, glutathione peroxidases and peroxiredoxins. Small molecule antioxidants such as ascorbic acid (vitamin C), tocopherol (vitamin E), uric acid, and glutathione also play important roles as cellular antioxidants. Similarly, polyphenol antioxidants assist in preventing ROS damage by scavenging free radicals. In contrast, the antioxidant ability of the extracellular space
is less — e.g., the most important plasma antioxidant in humans is probably uric acid.
Effects of ROS on cell metabolism have been well documented in a variety of species.
These include not only roles in apoptosis (programmed cell death), but also positive effects such as the induction of host defence genes and mobilisation of ion transport systems. This is implicating them more frequently with roles in redox signaling or oxidative signaling. In particular, platelets involved in wound repair and blood homeostasis release ROS to recruit additional platelets to sites of injury. These also provide a link to the adaptive immune system via the recruitment of leukocytes.
Reactive oxygen species are implicated in cellular activity to a variety of inflammatory
responses including cardiovascular disease. They may also be involved in hearing impairment via cochlear damage induced by elevated sound levels, ototoxicity of drugs such as cisplatin, and in congenital deafness in both animals and humans. Redox signaling is also implicated in mediation of apoptosis or programmed cell death and ischaemic injury. Specific examples include stroke and heart attack.
Generally, harmful effects of reactive oxygen species on the cell are most often:
damage of DNA
of polydesaturated fatty acids in lipids (lipid peroxidation)
Oxidations of amino acids in proteins
inactivate specific enzymes by oxidation of co-factors
In aerobic organisms the energy needed to fuel biological functions is produced in the mitochondria via the electron transport chain. In addition to energy, reactive oxygen species (ROS) are produced which have the potential to cause cellular damage. ROS can damage DNA, RNA, and proteins which theoretically contributes to the physiology of ageing.
ROS are produced as a normal product of cellular metabolism. In particular, one major contributor to oxidative damage is hydrogen peroxide (H2O2) which is converted from superoxide that leaks from the mitochondria. Within the cell there is catalase and superoxide dismutase that help to minimize the damaging effects of hydrogen peroxide by converting it into oxygen and water, benign molecules, however this conversion is not 100% efficient, and residual peroxides persist in the cell.
are produced as a product of normal cellular functioning, excessive amounts can cause deleterious effects. Memory capabilities decline with age, evident in human degenerative diseases such as Alzheimer’s disease which is accompanied by an accumulation of oxidative damage. Current studies demonstrate that the accumulation of ROS can
decrease an organism’s fitness because oxidative damage is a contributor to senescence. In particular, the accumulation of oxidative damage may lead to
cognitive dysfunction as demonstrated in a study where old rats were given mitochondrial metabolites and then given cognitive tests, results showed that the rats performed better after receiving the metabolites, suggesting that the metabolites reduced oxidative damage and improved mitochondrial
Accumulating oxidative damage can then affect the efficiency of mitochondria and further increase
the rate of ROS production. The accumulation of oxidative damage and its implications for aging depends on the particular tissue type where the damage is occurring.
Internal Free Radicals
radicals are also produced inside (and also released towards the cytosol) organelles, such as the mitochondrion. Mitochondria convert energy for the cell into a usable form, adenosine triphosphate (ATP). The process in which ATP is produced, called oxidative phosphorylation, involves the transport of protons (hydrogen ions) across the inner mitochondrial membrane by means of the electron transport chain. In the electron transport chain, electrons are passed through a series of proteins via oxidation-reduction reactions, with each acceptor protein along the chain having a greater reduction potential than the
last. The last destination for an electron along this chain is an oxygen molecule. Normally the oxygen is reduced to produce
water; however, in about 0.1–2% of electrons passing through the chain(this number derives from studies in isolated
mitochondria, though the exact rate in live organisms is yet to be fully agreed upon), oxygen is instead prematurely and incompletely
reduced to give the superoxide radical,·O2-, most well documented for Complex I and Complex III. Superoxide is not particularly reactive by itself, but can inactivate specific enzymes or initiate lipid peroxidation in
its HO2· form. The pKa of the protonated superoxide is 4.8, thus at physiological pH the majority will exist as hydrogen peroxide (H2O2). If too much damage is caused to its mitochondria, a cell undergoes apoptosis or programmed cell death.
Bcl-2 proteins are layered on the surface of the mitochondria, detect
damage, and activate a class of proteins called Bax, which punch holes in the mitochondrial membrane, causing cytochrome C
to leak out. This cytochrome C binds to Apaf-1, or apoptotic protease activating factor-1, which is free-floating in the cell’s
cytoplasm. Using energy from the ATPs in the mitochondrion, the Apaf-1 and cytochrome C bind together to form apoptosomes.
The apoptosomes binds to and activates caspase-9, another free-floating protein. The caspase-9 then cleaves the proteins
of the mitochondrial membrane, causing it to break down and start a chain reaction of protein denaturation and eventually
phagocytosis of the cell.
Cause of aging
to the Free-radical theory, oxidative damage initiated by reactive oxygen species is a major contributor to the functional decline that is characteristic
of aging. While studies in invertebrate models indicate that animals genetically engineered to lack specific antioxidant enzymes
(such as SOD) generally show a shortened lifespan (as one would expect from the theory), the converse, increasing the levels
of antioxidant enzymes, has yielded inconsistent effects on lifespan (though some well-performed studies in Drosophila do show that lifespan can be increased by the over-expression of MnSOD or glutathione biosynthesizing enzymes). In mice,
the story is somewhat similar. Deleting antioxidant enzymes generally yields shorter lifespan, though over-expression studies
have not (with some recent exceptions), consistently extended lifespan.
Superoxide dismutases (SOD) are a class of enzymes that catalyze the dismutation of superoxide into oxygen and hydrogen peroxide. As such, they
are an important antioxidant defense in nearly all cells exposed to oxygen. In mammals and most chordates, three forms of
superoxide dismutase are present. SOD1 is located in the cytoplasm, SOD2 in the mitochondria and SOD3 is extracellular. The
first is a dimer (consists of two units), while the others are tetramers (four subunits). SOD1 and SOD3 contain copper and
zinc, while SOD2 has manganese in its reactive centre. The genes are located on chromosomes 21, 6 and 4, respectively (21q22.1,
6q25.3 and 4p15.3-p15.1).
The SOD-catalysed dismutation of superoxide may be written with the following half-reactions :
M(n+1)+ − SOD
+ O2− → Mn+ − SOD + O2
− SOD + O2− + 2H+ → M(n+1)+ − SOD + H2O2.
M = Cu (n=1) ; Mn (n=2) ; Fe (n=2) ; Ni (n=2).
In this reaction the oxidation state of the metal cation oscillates between n and n+1.
Catalase, which is concentrated in peroxisomes located next to mitochondria, reacts with the hydrogen peroxide to catalyze the formation of water and oxygen. Glutathione peroxidase reduces hydrogen peroxide by transferring the energy of the reactive peroxides to a very small sulfur containing protein
called glutathione. The selenium contained in these enzymes acts as the reactive center, carrying reactive electrons from the peroxide to the
glutathione. Peroxiredoxins also degrade H2O2, within the mitochondria, cytosol and nucleus.
H2O2 → 2 H2O + O2 (catalase)
+ H2O2 → GS–SG + 2H2O (glutathione peroxidase)