An Overview of Antioxidants in Healthcare

8/3/2019 An Overview of Antioxidants in Healthcare

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An overview of Antioxidants in healthcare - Usesand Estimation

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Kushal H.Sanghvi

An Antioxidant is a molecule capable of slowing or preventing the oxidation of other

molecules. Oxidation is a chemical reaction that transfers electrons from a substanceto an oxidizing agent. Oxidation reactions can produce free radicals, which start chain

reactions that damage cells. Antioxidants terminate these chain reactions by

removing radical intermediates, and inhibit other oxidation reactions by being

oxidized themselves. As a result, antioxidants are often reducing agents such as thiols

or polyphenols.[1]

Although oxidation reactions are crucial for life, they can also be damaging; hence,

plants and animals maintain complex systems of multiple types of antioxidants, such

as glutathione, vitamin C, and vitamin E as well as enzymes such as catalase,

superoxide dismutase and various peroxidases. Low levels of antioxidants, orinhibition of the antioxidant enzymes causes oxidative stress and may damage or kill

cells.

As oxidative stress[7] has been associated with the pathogenesis of many human

diseases, the use of antioxidants in pharmacology is intensively studied, particularly

as treatments for stroke and neurodegenerative diseases. However, it is unknown

whether oxidative stress is the cause or the consequence of such diseases.

Antioxidants are also widely used as ingredients in dietary supplements in the hope of

maintaining health and preventing diseases such as cancer and coronary heart

disease. Although some studies have suggested antioxidant supplements have healthbenefits, other large clinical trials did not detect any benefit for the formulations

tested, and excess supplementation may occasionally be harmful. In addition to these

uses in medicine, antioxidants have many industrial uses, such as preservatives in

food and cosmetics and preventing the degradation of rubber and gasoline.
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Space-filling model of the antioxidant metabolite glutathione.

The yellow sphere is the redox-active sulfur atom that provides antioxidant activity,

while the red, blue, white, and dark grey spheres represent oxygen, nitrogen,

hydrogen, and carbon atoms, respectively.

The oxidative challenge in biology

A paradox in metabolism is that while the vast majority of complex life requires

oxygen for its existence, oxygen is a highly reactive molecule that damages living

organisms by producing reactive oxygen species.Consequently, organisms contain a

complex network of antioxidant metabolites and enzymes that work together to

prevent oxidative damage to cellular components such as DNA, proteins and lipids.In

general, antioxidant systems either prevent these reactive species from being formed,

or remove them before they can damage vital components of the cell.[13].

The reactive oxygen species produced in cells include hydrogen peroxide (H2O2),

hypochlorous acid (HClO), and free radicals such as the hydroxyl radical (OH) and the

superoxide anion (O2-). The hydroxyl radical is particularly unstable and will react

rapidly and non-specifically with most biological molecules. This species is produced

from hydrogen peroxide in metal-catalyzed redox reactions such as the Fenton

reaction. These oxidants can damage cells by starting chemical chain reactions such

as lipid peroxidation, or by oxidizing DNA or proteins.

Damage to DNA can cause mutations and possibly cancer, if not reversed by DNA

repair mechanisms, while damage to proteins causes enzyme inhibition, denaturation

and protein degradation.

The use of oxygen as part of the process for generating metabolic energy produces

reactive oxygen species.In this process, the superoxide anion is produced as a by-

product of several steps in the electron transport chain.Particularly important is thereduction of coenzyme Q[14] in complex III, since a highly reactive free radical is

formed as an intermediate (Q-). This unstato electron "leakage" when electrons jump

directly to molecular oxygen and form the superoxide anion, instead of moving

through the series of well-controlled reactions of the electron transport chain. In a

similar set of reactions in plants, reactive oxygen species are also produced during

photosynthesis under conditions of high light intensity.
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The structure of the antioxidant vitamin ascorbic acid (vitamin C).

Metabolites

Overview

Antioxidants are classified into two broad divisions, depending on whether they are

soluble in water (hydrophilic) or in lipids (hydrophobic). In general, water-soluble

antioxidants react with oxidants in the cell cytoplasm and the blood plasma, while

lipid-soluble antioxidants protect cell membranes from lipid peroxidation. These

compounds may be synthesized in the body or obtained from the diet.The different

antioxidants are present at a wide range of concentrations in body fluids and tissues,

with some such as glutathione or ubiquinone mostly present within cells, while others

such as uric acid are more evenly distributed throughout the body.

The relative importance and interactions between these different antioxidants is a

complex area, with the various metabolites and enzyme systems having synergistic

and interdependent effects on one another. The action of one antioxidant may

depend on the proper function of other members of the antioxidant system. The

amount of protection provided by any one antioxidant therefore depends on its

concentration, its reactivity towards the particular reactive oxygen species being

considered, and the status of the antioxidants with which it interacts.

Some compounds contribute to antioxidant defense by chelating transition metals and

preventing them from catalyzing the production of free radicals in the cell.

Particularly important is the ability to sequester iron, which is the function of iron-

binding proteins such as transferrin and ferritin.Selenium and zinc are commonly

referred to as antioxidant nutrients, but these chemical elements have no antioxidant

action themselves and are instead required for the activity of some antioxidant

enzymes, as is discussed below.

Antioxidant metabolite SolubilityConcentration in human serum

(M)

Concentration in liver tissue

(mol/kg)

Ascorbic acid(vitaminC)

Water 50 60 260 (human)
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Glutathione Water 325 650 6,400 (human)

Lipoic acid Water 0.1 0.7 4 5 (rat)

Uric acid Water 200 400 1,600 (human)

Carotenes Lipid-carotene: 0.5 1

retinol(vitamin A): 1 35 (human, total carotenoids)

-tocopherol(vitamin E) Lipid 10 40 50 (human)

Ubiquinol(coenzyme Q) Lipid 5 200 (human)

Ascorbic acid

(Vitamin-C)

Ascorbic acid or "vitamin C"[3],[29] is a monosaccharide antioxidant found in both

animals and plants. As it cannot be synthesised in humans and must be obtained from

the diet, it is a vitamin. Most other animals are able to produce this compound in

their bodies and do not require it in their diets. In cells, it is maintained in its

reduced form by reaction with glutathione, which can be catalysed by protein

disulfide isomerase and glutaredoxins. Ascorbic acid is a reducing agent and can

reduce and thereby neutralize reactive oxygen species such as hydrogen peroxide. In

addition to its direct antioxidant effects, ascorbic acid is also a that is particularly

important in stress resistance in plants.
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Glutathione

The free radical mechanism of lipid peroxidation.Glutathione is a cysteine-containing

peptide found in most forms of aerobic life.It is not required in the diet and is instead

synthesized in cells from its constituent amino acids.Glutathione has antioxidant

properties since the thiol group in its cysteine moiety is a reducing agent and can bereversibly oxidized and reduced. In cells, glutathione is maintained in the reduced

form by the enzyme glutathione reductase and in turn reduces other metabolites and

enzyme systems as well as reacting directly with oxidants. Due to its high

concentration and its central role in maintaining the cell's redox state, glutathione is

one of the most important cellular antioxidants.[34],[15].


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Melatonin

Melatonin is a powerful antioxidant that can easily cross cell membranes and the

blood-brain barrier. Unlike other antioxidants, melatonin does not undergo redox

cycling, which is the ability of a molecule to undergo repeated reduction and

oxidation. Redox cycling may allow other antioxidants (such as vitamin C) to act aspro-oxidants and promote free radical formation. Melatonin, once oxidized, cannot be

reduced to its former state because it forms several stable end-products upon

reacting with free radicals. Therefore, it has been referred to as a terminal (or

suicidal) antioxidant.[16].

Tocopherols and tocotrienols (Vitamin-E)

Vitamin E is the collective name for a set of eight related tocopherols and

tocotrienols, which are fat-soluble antioxidant vitamins. Of these, a-tocopherol hasbeen most studied as it has the highest bioavailability, with the body preferentially

absorbing and metabolising this form.

The a-tocopherol form is the most important lipid-soluble antioxidant and protects

cell membranes against oxidation by reacting with the lipid radicals produced in the

lipid peroxidation chain reaction. This removes the free radical intermediates and

prevents the propagation reaction from continuing. The oxidised a-tocopheroxyl

radicals produced in this process may be recycled back to the active reduced form

through reduction by ascorbate, retinol or ubiquinol.

The functions of the other forms of vitamin E are less well-studied, although ?-

tocopherol is a nucleophile that may react with electrophilic mutagens, and

tocotrienols may have a specialised role in neuroprotection.[17],[18].


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The free radical mechanism oflipid peroxidation.

Pro-oxidant activities

Antioxidants that are reducing agents can also act as pro-oxidants. For example,

vitamin C has antioxidant activity when it reduces oxidizing substances such as

hydrogen peroxide, however, it can also reduce metal ions which leads to thegeneration of free radicals through the Fenton reaction.[8],[23].

2 Fe3++ Ascorbate 2 Fe2+ + Dehydroascorbate

2 Fe2++ 2 H2O2 2 Fe3+ + 2 OH + 2 OH-

The relative importance of the antioxidant and pro-oxidant activities of antioxidants

are an area of current research, but vitamin C, for example, appears to have a mostly

antioxidant action in the body. However, less data is available for other dietary

antioxidants, such as polyphenol antioxidants, zinc, and vitamin E.[23].

Dietary Antioxidants

A substance in food that significantly decreses the adverse effects of reactive

species,such as reactlive oxygen and nitrogen species,on normal physiological

functions in humans.
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Reactive Species Includes:

Hydroxyl radicals (.OH), Superoxideanions (O2-), Singlet oxygen(1O2), Hydrogenperoxides (H2O2), Organic peroxides (R-OOH), Nitric oxide, Peroxynitrite


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Diversity in Dietary Antioxidants

Essential

Vitamin E (tocopherol)

Vitamin C (ascorbic acid)

Vitamin A (retinol andcarotenoids)

Numerous minerals-Cu, Mn, Zn, Se, Fe

Non-essential

Glutathione

small peptides

host ofphytochemicals(thousands in food supply)

Enzymatic pathway for detoxification of reactive oxygen species.Overview

As with the chemical antioxidants, cells are protected against oxidative stress by an

interacting network of antioxidant enzymes. Here, the superoxide released by

processes such as oxidative phosphorylation is first converted to hydrogen peroxide

and then further reduced to give water. This detoxification pathway is the result of

multiple enzymes, with superoxide dismutases catalysing the first step and then

catalases and various peroxidases removing hydrogen peroxide. As with antioxidant

metabolites, the contributions of these enzymes can be hard to separate from one

another, but the generation of transgenic mice lacking just one antioxidant enzymecan be informative.[13],[7].

Superoxide dismutase, catalase and peroxiredoxins

Superoxide dismutases (SODs) are a class of closely related enzymes that catalyse the

breakdown of the superoxide anion into oxygen and hydrogen peroxide. SOD enzymes

are present in almost all aerobic cells and in extracellular fluids. Superoxide

dismutase enzymes contain metal ion cofactors that, depending on the isozyme, can

be copper, zinc, manganese or iron. In humans, the copper/zinc SOD is present in the

cytosol, while manganese SOD is present in the mitochondrion. There also exists a

third form of SOD in extracellular fluids, which contains copper and zinc in its active

sites. The mitochondrial isozyme seems to be the most biologically important of these

three, since mice lacking this enzyme die soon after birth. In contrast, the mice


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lacking copper/zinc SOD are viable but have lowered fertility, while mice without the

extracellular SOD have minimal defects. In plants, SOD isozymes are present in the

cytosol and mitochondria, with an iron SOD found in chloroplasts that is absent from

vertebrates and yeast.[19],[20].

Catalases are enzymes that catalyse the conversion of hydrogen peroxide to waterand oxygen, using either an iron or manganese cofactor. This protein is localized to

peroxisomes in most eukaryotic cells.

Catalase is an unusual enzyme since, although hydrogen peroxide is its only substrate,

it follows a ping-pong mechanism. Here, its cofactor is oxidised by one molecule of

hydrogen peroxide and then regenerated by transferring the bound oxygen to a

second molecule of substrate. Despite its apparent importance in hydrogen peroxide

removal, humans with genetic deficiency of catalase "acatalasemia" or mice

genetically engineered to lack catalase completely, suffer few ill effects.[20].

Peroxiredoxins are peroxidases that catalyze the reduction of hydrogen peroxide,

organic hydroperoxides, as well as peroxynitrite. They are divided into three classes:

typical 2-cysteine peroxiredoxins; atypical 2-cysteine peroxiredoxins; and 1-cysteine

peroxiredoxins. These enzymes share the same basic catalytic mechanism, in which a

redox-active cysteine (the peroxidatic cysteine) in the active site is oxidized to a

sulfenic acid by the peroxide substrate. Peroxiredoxins seem to be important in

antioxidant metabolism, as mice lacking peroxiredoxin 1 or 2 have shortened lifespan

and suffer from hemolytic anaemia, while plants use peroxiredoxins to remove

hydrogen peroxide generated in chloroplasts.

Thioredoxin and glutathione systems

The thioredoxin system contains the 12-kDa protein thioredoxin and its companion

thioredoxin reductase. Proteins related to thioredoxin are present in all sequenced

organisms, with plants such as Arabidopsis thaliana having a particularly great

diversity of isoforms. The active site of thioredoxin consists of two neighboring

cysteines, as part of a highly-conserved CXXC motif, that can cycle between an active

dithiol form (reduced) and an oxidized disulfide form. In its active state, thioredoxin

acts as an efficient reducing agent, scavenging reactive oxygen species and

maintaining other proteins in their reduced state.After being oxidized, the active

thioredoxin is regenerated by .[22].

The glutathione system includes glutathione, glutathione reductase, glutathione

peroxidases and glutathione S-transferases.This system is found in animals, plants and

microorganisms. Glutathione peroxidase is an enzyme containing four selenium-

cofactors that catalyzes the breakdown of hydrogen peroxide and organic

hydroperoxides. There are at least four different glutathione peroxidase isozymes in


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animals. Glutathione peroxidase 1 is the most abundant and is a very efficient

scavenger of hydrogen peroxide, while glutathione peroxidase 4 is most active with

lipid hydroperoxides.

Surprisingly, glutathione peroxidase 1 is dispensable, as mice lacking this enzyme

have normal lifespans. but they are hypersensitive to induced oxidative stress. Inaddition, the glutathione S-transferases are another class of glutathione-dependent

antioxidant enzymes that show high activity with lipid peroxides. These enzymes are

at particularly high levels in the liver and also serve in detoxification metabolism.

Decameric structure of AhpC, a bacterial 2-

cysteine peroxiredoxin fromSalmonella typhimurium.

Role In Diseases

Oxidative stress in disease

Oxidative stress is thought to contribute to the development of a wide range of

diseases including Alzheimer's disease, Parkinson's disease, the pathologies caused by

diabetes., rheumatoid arthritis, and neurodegeneration in motor neurone diseases. In

many of these cases, it is unclear if oxidants trigger the disease, or if they are

produced as a consequence of the disease and cause the disease symptoms; as a

plausible alternative, a neurodegenerative disease might result from defective axonal

transport of mitochondria, which carry out oxidation reactions. One case in which thislink is particularly well-understood is the role of oxidative stress in cardiovascular

disease. Here, low density lipoprotein (LDL) oxidation appears to trigger the process

of atherogenesis, which results in atherosclerosis, and finally cardiovascular

disease.[27].
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A low calorie diet extends median and maximum lifespan in many animals. This effect

may involve a reduction in oxidative stress. While there is good evidence to support

the role of oxidative stress in aging in model organisms such as Drosophila

melanogaster and Caenorhabditis elegans, the evidence in mammals is less clear.

Diets high in fruit and vegetables, which are high in antioxidants, promote health andreduce the effects of ageing, however antioxidant vitamin supplementation has no

detectable effect on the ageing process, so the effects of fruit and vegetables may be

unrelated to their antioxidant contents.[7][11].

Measurement and levels in food

Fruits and vegetables are good sources of antioxidants. Measurement of antioxidants

is not a straightforward process, as this is a diverse group of compounds with different

reactivities to different reactive oxygen species. In food science, the oxygen radical

absorbance capacity (ORAC) has become the current industry standard for assessing

antioxidant strength of whole foods, juices and food additives.Other measurement


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tests include the Folin-Ciocalteu reagent, and the trolox equivalent antioxidant

capacity assay. In medicine, a range of different assays are used to assess the

antioxidant capability of blood plasma and of these, the ORAC assay may be the most

reliable.[4][9][25].

Antioxidants are found in varying amounts in foods such as vegetables, fruits, graincereals, legumes and nuts. Some antioxidants such as lycopene and ascorbic acid can

be destroyed by long-term storage or prolonged cooking. Other antioxidant

compounds are more stable, such as the polyphenolic antioxidants in foods such as

whole-wheat cereals and tea. In general, processed foods contain less antioxidants

than fresh and uncooked foods, since the preparation processes may expose the food

to oxygen.

Antioxidant compounds Foods containing high levels of these antioxidants

Vitamin C (ascorbic acid) Fruitsandvegetables

Vitamin E (tocopherols,tocotrienols) Vegetable oils

Polyphenolic antioxidants (resveratrol,flavonoids) Tea,coffee,soy, fruit ,chocolate,oreganoandred

Carotenoids(lycopene,carotenes) Fruitandvegetables

Some antioxidants are made in the body and are not absorbed from the intestine. One

example is glutathione, which is made from amino acids. As any glutathione in the gut

is broken down to free cysteine, glycine and glutamic acid before being absorbed,

even large oral doses have little effect on the concentration of glutathione in the

body. Ubiquinol (coenzyme Q) is also poorly absorbed from the gut and is made inhumans through the mevalonate pathway.[17][18][29]
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Fruits and vegetables are good sources of antioxidants.

A list of some Antioxidants found in Food

Bilberries

Bilberries are rich in flavonoids - antioxidant nutrients which may help to protect the

body's cells from damage by excess free radicals.

CarnosineCarnosine is a multi-potent super-antioxidant which stabilizes and protects the cell

membrane. Specifically, as a water-soluble free radical scavenger it prevents lipid

peroxidation within the cell membrane. Many antioxidants (like vitamins E and C) are

aimed at preventing free radicals from entering the tissues, but have no effect after

this first line of defense is broken. Free radicals cause oxidative stress in the

body.Carnosine is not only effective in prevention, but it is also active after free

radicals react to form other dangerous compounds, like lipid peroxides and and

secondary products. So, it protects the tissues from these damaging 'second-wave'

chemicals.Carotenoids

Carotenoids are perhaps best known for their ability to be converted to vitamin A,

which is essential for healthy vision and reproduction, and for maintaining body

tissues. Carotenoids are also powerful antioxidants on their own right.

Co-Enzyme Q10
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Co Q10 is involved in the body's metabolic processes, particularly in the release of

energy from food. It is also a potent antioxidant. Antioxidants can mop up damaging

chemicals (free radicals) in the body and guard against many chronic diseases,

especially in the heart.[14]

Green Tea

Green tea is an excellent source of potent polyphenols, a strong antioxidant and

inhibitor of harmful Angiogenesis.

Vitamin A

Vitamin A, is a fat-soluble vitamin and is involved in the formation and maintenance

of healthy skin, hair, and mucous membranes. Vitamin A helps us to see in dim light

and is necessary for proper bone growth, tooth development, and fertility and has

been well documented for decades. It is also an important antioxidant.

Selenium

Doctors have dismissed the mineral as humbug, while others recommend it as a

valuable component in preventative medicine, or even prescribe it as part of a course

of treatment. Veterinary surgeons, on the other hand, have been using adjunct

selenium therapy for many years.[28][22]

Soy & Isoflavones Research suggests that soy may offer a number of health benefits

related to:

menopause symptom relief

osteoporosis

cardiovascular disease

immunity

cancer

Zinc

Zinc is vital to about 200 different enzymes, to the formation of bone tissue, in the

healing of wounds and sores, to the production of proteins, the regulation of

ribosomal, ribonucleic acid synthesis and insulin and in the carbohydrate metabolism.Zinc is also an antioxidant.[28]

Antioxidants a key to 'long life'

Boosting the body's levels of natural antioxidants could be the key to a long life,

according to US scientists.Mice engineered to produce high levels of an antioxidant

enzyme lived 20% longer and had less heart and other age-related diseases, they


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found.If the same is true in humans, people could live beyond 100 years.The

University of Washington work in Science Express backs the idea that high reactive

oxygen molecules, called free-radicals, cause ageing.

Long life

Free-radicals have been linked with heart disease, cancer and other age-related

diseases.Dr Peter Rabinovitch and colleagues bred mice that over-expressed the

enzyme catalase.By intervening in the underlying ageing process, we may be able to

produce very significant increases in healthy lifespan .Catalase acts as an antioxidant

by removing damaging hydrogen peroxide, which is a waste product of metabolism

and is a source of free-radicals.Free radical damage can lead to more flaws in the

cell's chemical processes and more free radicals, making a vicious cycle.

Antioxidant therapies for cystic fibrosis (CF).

Antioxidants may have a role in the slowing or prevention of CF lung disease. Ahealthy diet, including fruit and vegetables supplemented by fat-soluble vitamins, can

boost the CF patients antioxidant protection. However, in people with CF, the

digestion does not always guarantee proper nourishment since mucus tends to clog

the pancreas. Therefore, researchers are looking for alternative ways to deliver

antioxidants to CF patients. One compelling strategy is to supplement the fat-soluble

vitamins A, D, E and K. Another strategy is to administer oral N-acetylcysteine, or

NAC, which is a building block for the antioxidant glutathione.[34]

Coenzyme Q10 as an antioxidant

A substance found in most tissues in the body, and in many foods. It can also be madein the laboratory. It is used by the body to produce energy for cells, and as an

antioxidant. It is being studied in the treatment of cancer and in the relief of side

effects caused by some cancer treatments. Also called Q10, CoQ10, vitamin Q10, and

ubiquinone.[14].

Coenzyme Q 10 is a compound that is made naturally in the body. The body uses it for

cell growth and to protect cells from damage that could lead to cancer.Animal studies

have shown that coenzyme Q10 helps the immune system work better and makes the

body better able to resist certain infections and types of cancer.Clinical trials have

shown that coenzyme Q10 helps protect the heart from the damaging side effects ofdoxorubicin, a drug used to treat cancer.In 3 small studies of coenzyme Q10 in breast

cancer patients, some patients appeared to be helped by the treatment. Weaknesses

in study design and reporting, however, made it unclear if benefits were caused by

the coenzyme Q10 or by something else.

Estimation Of Antioxidant Activity


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An end-point method for estimation of the total antioxidant activity in plant material

The 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) radical can be

generated by the enzymatic system formed by hydrogen peroxide and horseradish

peroxidase. This ABTS radical (ABTS+), a chromogen, is stable at room temperature

but is unstable above 35C and/or at pH values of above 7.5. Nevertheless, the mostimportant factor in its stability is the ABTS/ABTS+ concentration ratio in the medium.

The radical reacts with the antioxidant, L-ascorbic acid, with a high rate constant,

the stoichiometry of the reaction being 1 mol of L-ascorbic acid per 2 mol of

ABTS+reduced. Based on these considerations, a spectrophotometric end-point

method has been developed to evaluate L-ascorbic acid in aqueous media, and this

represents an improvement over the lag-method previously reported. Under optimal

conditions of temperature, pH and reagent concentration, the end-point method was

capable of determining L-ascorbic acid with a limit of quantification of 0.38 nmol. In

the assay described here, this ability is used to evaluate the total antioxidant activityof commercial citrus juices, in which ascorbic acid is a principal component.[32]

Estimation of the Antioxidant Activities of Flavonoids from Their Oxidation

Potentials

A simple electrochemical method for estimating the antioxidant activity (AA) of

flavonoids has been developed. The proposed method is based on a measurement of

the half-wave potential (E1/2) of the first oxidation wave of flavonoids by using flow-

through column electrolysis. At the same time, the lipid peroxidation (LPO) inhibiting

effects of these flavonoids were determined. A quantitative structure-activity

relationship was obtained to describe the AA of flavonoids: IC50(M) = 30.36 +151.50E1/2 (V) - 12.63log P (r = 0.852), where IC50 represents the concentration for

50% inhibition of LPO, and P represents the octanol/water partition coefficient. This

method is expected to be useful for the quick screening of flavonoid antioxidants, and

evaluating the AA of flavonoid-containing foods and medicinal plants.[32]

In Vitro Antioxidant Bioassays

DPPH Radical Scavenging Assay

The DPPH Radical Scavenging Effect Was Carried Out According To Method Used By

Blois (1958).4 Ml Of Each Sample (0.5mg/Ml)Was Added To 1.0 Ml DPPH MethanolSolution(0.000015 M) And Left Room Temperature For 10 Minutes. Absorbance Of The

Solution Was Measured At 520nm By Using A Spectrophotometer. Methanol(4 Ml) Plus

DPPH (1 Ml)Was Used As A Negative Control While The Ascorbic Acid (4 Ml , 5mcgml)

And DPPH ( 1 Ml) As A Positive Control.The Results Were calculated taking the mean

of triplicate values.[32]

Xanthine/Xanthine Oxidase Superoxide Scavenging System


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The reaction mixture is prepared by dissolving Sodium carbonate(0.53g),EDTA(0.004g)

and xanthine(0.05g) in 100 ml distilled water and then 10 ml NBT solution (0.025 mM)

is added.Inm 5 mcL of each sample(50 mg/ml),995 mcL of reaction mixture and 0.1

mcL of xanthine oxidase(0.1 mL) are added.the solution is mioxed and the absorbance

is taken at 560 nm.th reaction mixture (1000 mcL) and xanthine(0.1 mcL) are used asnegative control.superoxide dismutase (5 mcL),reaction mixture (995 mcL) and

xanthine oxidase are used as positive control.[32]

Antioxidant activity assay

Free radical scavenging capacity was measured using the radical chromogen 2,2-

diphenyl-1-picrylhydrazyl(Dpph)photometric assay.each sample stock solution

(1mg/mlMeOH)was diluted to final concenterations of 0.75,0.25,and 0.1mg/ml.a total

of 2.9ml of a 0.1Mm DPPH MeOH solution was added to 0.1ml of sample solution at

different concenterations and allowed to react at r.t.After 30mins ,the absorbance

values were spectrophotometrically measured at 517 nm to monitor thedisapperanceof the radical chromogen,and converted into the percentage antioxidant activity by

using the following equation:

%antioxidant activity=1-(Ab of sample/Ab of blank) x 100.

The positive controls were DPPH solution plus butylated hydroxyanisole(BHA),a

synthetic antioxidant compound,at the same concenterations as those of the

samples.[32]

Conclusion

An antioxidant is a molecule capable of slowing or preventing the oxidation of othermolecules. Oxidation is a chemical reaction that transfers electrons from a substance

to an oxidizing agent. Oxidation reactions can produce free radicals, which start chain

reactions that damage cells. Antioxidants terminate these chain reactions by

removing radical intermediates, and inhibit other oxidation reactions by being

oxidized themselves. The chief role of antioxidants in biology focused on their use in

preventing the oxidation of unsaturated fats, which is the cause of rancidity.

Antioxidants are almost used in all pharmaceutical products to prevent them from

degradation. Antioxidants are also widely used as ingredients in dietary supplements

in the hope of maintaining health and preventing diseases such as cancer andcoronary heart disease. The diet that is high in anti -oxidants neutralizes free radicals

.though there are lots of benefits of free radicals they can cause damage to healthy

cells as well. The diet that is high in anti-oxidants reduces free radicals there by

fighting ageing. Antioxidants have many industrial uses, such as preservatives in food

and cosmetics and preventing the degradation of rubber and gasoline.


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This review article is aimed to assist researchers conducting further research on

antioxidant activity of certain drugs. Till date there has been no marketed antioxidant

formulation and this project will serve as a base for anyone trying to come out with

such a formulation and thus simplify the use of antioxidants

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About Authors:

Kushal H.Sanghvi

Third B. Pharm Student, MAEERS Maharashtra Institute of Pharmacy, Pune - 411038

E-mail [email protected]

Miss. Vaishali M. Sampat

Third B. Pharm Student, MAEERS Maharashtra Institute of Pharmacy, Pune - 411038

Mr.Sutar A.S.

Lecturer, MAEERS Maharashtra Institute of Pharmacy, Pune - 411038
http://www.pharmainfo.net/thinkofkushalhttp://www.pharmainfo.net/thinkofkushalmailto:[email protected]://www.pharmainfo.net/vaishalihttp://www.pharmainfo.net/vaishalimailto:[email protected]://www.pharmainfo.net/thinkofkushal


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Mr.Kannur D.M.

Senior Lecturer , MAEERS Maharashtra Institute of Pharmacy, Pune - 411038

Pharmacy Student Articles
http://www.pharmainfo.net/dayanandkannurhttp://www.pharmainfo.net/dayanandkannurhttp://www.pharmainfo.net/pharmacy-student-articleshttp://www.pharmainfo.net/pharmacy-student-articleshttp://www.pharmainfo.net/pharmacy-student-articleshttp://www.pharmainfo.net/dayanandkannur

An Overview of Antioxidants in Healthcare

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