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Antioxidants: Their health benefits

© CAB International 2014. Phytochemicals of Nutraceutical Importance
248 (eds D. Prakash and G. Sharma)
16.1 Introduction
An important field of research today is the
control of ‘free radicals’ generation or redox’
status with the properties of food and food
components. Reactive oxygen species (ROS)
may interact with cellular macromolecules
and modify several cellular proteins, lipids
and DNA, which results in altered target
cell functions. Oxidative stress occurs in
a cell or tissue when the ROS generation
level exceeds the antioxidant capability
of that cell (Kumar et al., 2011). ROS can be
produced both endogenously and exoge-
nously. Endogenous oxidative stress can
be the result of normal cellular metabolism
and oxidative phosphorylation. Exogenous
sources of ROS can also impact on the over-
all oxidative status of a cell. Drugs, hor-
mones and other xenobiotic chemicals can
produce ROS by either direct or indirect
mechanisms (Kakkar and Singh, 2007).
Several human chronic disease states,
including cancer, have been associated with
oxidative stress produced through either an
increased free radical generation and/or a
decreased antioxidant level in the target
cells and tissues (Rice-Evans and Burdon,
1993). Natural antioxidants present in the
diet increase the resistance toward oxidative
damages and they may have a substantial
impact on human health. It has been
reported that a diet rich in antioxidant
phytochemicals, such as polyphenolics,
carotenoids, terpenoids and flavonoids, pro-
tects against cellular damage due to ability
to quench oxygen-derived free radicals
(Dhakarey et al., 2005; Singh, P., 2008; Singh,
B.N., 2009a). If antioxidant defence systems
are not sufficiently present in critical situa-
tions like oxidative stress, contamination,
UV exposure etc., the production of free
radicals increases significantly (Singh, U.
et al., 2008). Non-enzymatic (vitamin E,
vitamin C, glutathione (GSH), etc.) and
enzymatic (superoxide dismutase, GSH per-
oxides, glutathione-S-transferase and cata-
lase) antioxidant levels in the cell can be
decreased through modification in gene
expression, decreased antioxidant uptake
in the diet, or can be overloaded in ROS pro-
duction, which creates a net increase in the
amount of oxygen free radicals present in
the cell. It has been reported that with the
administration of antioxidants, cells are
protected against carcinogen-induced dam-
age (Kumar et al., 2011). Mechanisms of
protection could be effective against a wide
16 Antioxidants: Their Health
Benefits and Plant Sources
R.L. Singh,1* Sapna Sharma2 and Pankaj Singh1
1Department of Biochemistry, Dr RML Avadh University,
Faizabad, India; 2Division of Nephrology, Department of Medicine,
University of Chicago Medical Center, Chicago, USA
* Email:
Prakash_Ch16.indd 248 11/27/2013 10:07:54 AM
Antioxidants: Their Health Benefits and Plant Sources 249
range of dietary carcinogens possibly influ-
encing several cancer sites. Antioxidant
enzymes are detoxi fication/biotransforma-
tion enzymes that are involved in the
detoxification of toxic substances such as
xenobiotics, carcinogens, free radicals and
peroxides by conjugating these sub-
stances with GSH (Tripathi et al., 2010).
Traditional medicine all over the
world is nowadays being revalued by an
extensive amount of research on different
plant species and their therapeutic princi-
ples. Experimental evidence suggests that
free radicals (FR) and ROS can be involved
in a high number of diseases (Richards and
Sharma, 1991). As plants produce a lot of
antioxidants to control the oxidative stress
caused by sunlight and oxygen, they can
represent a source of new compounds
with antioxidant activity. One of the clini-
cal specialities of Ayurveda is Rasayana.
Rasayana is not only a drug therapy but
is a specialized procedure practised in the
form of rejuvenating recipes and dietary
regimen promoting good habit. The pur-
pose of Rasayana is two-fold: prevention
of disease and counteraction of ageing
processes which result from optimization
of homeostasis. The meaning of the word
Rasayana (rasa: essence, water; ayana:
going) essentially refers to nutrition and
its acquisition, movement, circulation and
perfusion in the body tissues (Singh, 1992).
With regard to Rasayana drug therapy,
Sharma et al. (1992) reported the strong anti-
oxidant activity of any Rasayana: these com-
pounds were found to be 1000 times more
potent than ascorbic acid, a-tocopherol
and probucol.
16.2 Antioxidants
In living cell, two antioxidant defence sys-
tem are present against free radical damage.
The first line of defence includes antioxidant
enzymes (such as superoxide dismutase,
catalase, GSH peroxidase), whereas the sec-
ond defence system includes low molecular
non-enzymatic antioxidants (thioredoxin,
GSH, vitamins A, C, E, lycopene, lutein,
quercetin etc.). These antioxidants inhibit
the formation of FRs by breaking the chain
reaction or can reduce the concentration
of FR by donating hydrogen and an elec-
tron. They also act as peroxide decomposer
(vitamin E), enzyme inhibitor, singlet oxygen
quencher (vitamin E), synergist and metal-
chelating agents (tranferritin). To provide
maximum intracellular protection, antioxi-
dants are strategically compartmentalized
throughout the cell. So that FR is produced
intracellular and extracellular during metab-
olism, both enzymatic and non-enzymatic
antioxidants are able to detoxify FRs.
Certain antioxidant enzymes (super-
oxide dismutase, catalase and GSH) are pro-
duced within the body. Other antioxidant
agents are found in foods, such as green
leafy vegetables, and it is believed that
diets rich in antioxidant (such as b-carotene
and vitamins A, C and E) are beneficial to
human health (Halliwell and Gutteridge,
1989). Therefore, antioxidant naturally pre-
sent in body or supplied in the form of diet
(phytonutrients) plays an important role
to control various diseases resulting from
oxidative stress. Fresh fruits and vegetables
are of more importance than cooked, because
of the high concentration and maximum
absorption of antioxidants. In recent years,
researchers have been researching the
relationship between antioxidants and pre-
vention of some diseases, such as cardiovas-
cular disease and cancer (Kubola and
Siriamornpun, 2008).
As soon as these FRs are generated in
the body, they are trapped by antioxidant
present in extracellular and intracellular
defence system. If the generation of free
radicals is much more than the concentra-
tion of antioxidants then oxidative stress
arises. As a result of oxidative stress, arthri-
tis in joints, emphysema and bronchitis in
lungs, atherosclerosis or heart disease in the
blood vessels, peptic ulcer in the stomach,
ageing and wrinkling in the skin are caused.
In the nucleus, it also alters the sequence
of nucleotide base pair, strand break etc. in
the DNA resulting in transformed and
mutated DNA. Mutated DNA will produce
diseases like cancer, leukaemia and lym-
phoma (Prakash et al., 2012).
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250 R.L. Singh et al.
16.2.1 Antioxidant enzyme
Three groups of enzymes play significant
roles in protecting cells from oxidative stress.
Superoxide dismutase
Superoxide dismutase (SOD) has been recog-
nized to play an important role in the body
defence mechanism against the deleterious
effect of superoxide FR in the biological sys-
tem. It acts on two superoxide molecules and
converts it into hydrogen peroxide and oxy-
gen. The beneficial aspect of this reaction is
that it produces less toxic hydrogen peroxide.
The organisms that resist oxygen toxicity
must have the SOD enzyme. On the basis
of metal cofactor, the organism has three
distinct types of SOD. In eukaryotes, cytosol
has the copper- and zinc-containing form
of SOD while mitochondria and bacterial
cells have the manganese-containing form of
SOD (Table 16.1). Iron-containing SOD is
found in bacteria, cynobacteria and some
plants. Newly discovered forms of SOD, also
found in bacteria, contain nickel as a cofactor.
Interestingly, SODs are inducible enzymes,
i.e. with the increase in the concentration of
oxygen in the environment of the cell, the
concentration of SOD enzyme also increases.
The main source of naturally occurring SOD
enzyme is green vegetables such as in barley,
broccoli, Brussels sprouts, cabbage, wheat and
most green plants (Gassen and Youdim, 1999).
The catalase activity of mammalian tissue
varies greatly. It is highest in liver and kidney
and low in connective tissue. In the cell, it is
mainly particle bound (in mitochondria and
peroxisomes) whereas in erythrocytes it exist in
soluble state. Catalase activity received much
attention for its role in oxidative metabolism as
well as protective function by acting as H2O2
scavenger. Catalase located in the organelles
acts as regulator of H2O2 levels and, on the other
hand, in erythrocytes, catalase and GSH peroxi-
dase jointly exert a protective function for hae-
moglobin and other SH-protein. It degrades
hydrogen peroxide to water and oxygen, and
hence finishes the detoxification reaction
started by SOD (Gassen and Youdim, 1999).
Glutathione peroxidase
GSH peroxidase is a member of family of
GPx enzymes, whose function is to detoxify
Table16.1. Important enzymatic and non-enzymatic physiological antioxidants.
Antioxidants Location Properties
Superoxide dismutase Mitochondria, cytosol Dismutase superoxide radicals
Glutathione peroxidase Mitochondria and cytosol Removes hydrogen peroxide and organic
Catalase Mitochondria and cytosol Removes hydrogen peroxide
Vitamin E Cell membrane Chain-breaking antioxidant in cell membrane
Vitamin C Aqueous phase of
cell Sap
Acts as free radical scavenger and
recycles vitamin E
a-Lipoic acid Endogenous thiol Effective in recycling vitamin C, may also
be an effective glutathione substitute
Carotenoids Membrane tissue Scavengers of reactive oxygen species,
singlet oxygen quencher
Bilirubin Blood Extracellular antioxidant
Ubiquinones Mitochondria Reduced forms are efficient antioxidants
Metals ions sequestration:
transferrin, ferritin,
Chelating metals ions, responsible for
Fenton reactions
Nitric oxide Free radical scavenger, inhibitor of LP
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Antioxidants: Their Health Benefits and Plant Sources 251
peroxide in the cell. Peroxides decompose to
form highly reactive free radicals, which can
damage the macromolecules like protein,
DNA and lipid. GPx enzyme plays an impor-
tant role in the protection of cell from this
damage, particularly lipid peroxidation. GSH
peroxidase contains selenium as a cofactor.
The synthesis of GSH peroxidase in humans
appears to be very important in scavenging
H2O2 (Cheng et al., 2003).
16.2.2 Antioxidant phytochemicals
There are more than a thousand phytochemi-
cals that have been identified with antioxidant
properties. Plants produce these chemicals to
protect themselves from microorganism and
oxidative stress, but now several evidences
suggest that these phytochemicals also protect
humans against various diseases caused by
FRs. Some of the well-known phytochemicals
are lycopene (tomatoes), isoflavones (in soy),
flavanoids (in fruits, vegetables), allyl sulfides
(onions, leeks, garlic), carotenoids (fruits, car-
rots) and polyphenols (tea, grapes). Medicinal
plant parts are commonly rich in phenolic
compounds, such as flavonoids, phenolic
acids, stilbenes, tannins, coumarins, lignans
and lignins. These compounds have multiple
biological effects including antioxidant activ-
ity (Shukla et al., 2009). The antioxidant activ-
ity of phytochemicals is mainly due to their
redox properties, which can play an impor-
tant role in adsorbing and neutralizing free
radicals, quenching oxygen, or decomposing
Flavonoids are the most common secondary
metabolites in higher plants, and can directly
scavenge the superoxide ion, hydroxyl radi-
cal and H2O2. These include more than
4000 phenolic compounds that occur natu-
rally in plants.
The main flavonol is quercetin, followed
by myricetin, kaempferol, laricitrin, isor-
hamnetin and syringetin. The main sources
of flavonols are onion, kale, broccoli, lettuce,
tomato, apple, grape, berries, tea and red
wine. High contents of flavonols are pre-
sent in greener leaves (Manach et al., 2004).
Flavonols have multiple biological health
benefits. It reduces risk of cardiovascular
diseases, cancer, improve endothelial
function and reduce platelet activity. This
property is mainly attributed due to their
antioxidant properties (Patel, 2008). Furthe-
rmore, flavonols also help to prevent oxida-
tive damage to cells, lipids and DNA. The
antioxidant properties of flavonols are
drawn from the presence of aromatic rings
of the flavonoid molecule, which allows the
donation and acceptance of electrons from
FR species.
Anthocyanins are violet, blue and purple pig-
ments, which are mainly present in fruits,
berries and flowers. The major dietary antho-
cyanins include cyanidin, delphinidin, malvi-
din, pelargonidin, peonidin and petunidin
(Manach et al., 2004). Anthocyanins and their
derivatives have the capacity to scavenge FRs
through a number of mechanisms, thereby
reducing the oxidative stress. Anthocyanins
present in red cabbage reduce the oxidative
stress caused by the toxin paraquat (Igarashi
et al., 2000). Tsuda (2000) reported that cyani-
din, which is found in most fruit sources, has
potential antioxidant activity under in vivo
conditions. In another animal study, Tsuda
(1998) reported that cyanidins protect cell
membrane lipids from oxidation by a variety
of harmful substances.
Tannins are commonly present in fruits
(grapes, persimmon, blueberry, etc.), tea,
chocolate, legume forages and legume trees
(Acacia sp., Sesbania spp. etc.) and grasses
(sorghum, maize, etc.). Tannins include proan-
thocyanidins, gallotannins and ellagitannins.
At high temperatures in alcohol solutions
or in a strong mineral acid, proanthocyanidins
release anthocyanidins, which have antioxi-
dant properties. Gallotannins and ellagitannins
are both hydrolysable tannins. Gallotannins
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252 R.L. Singh et al.
constitute galloyl esters of glucose or quinic
acid whereas ellagitannins are derivatives of
hexahydroxydiphenic acid (HHDP). Another
form of tannin is phloroglucinols, which are
subunits of phlorotannins and present in
marine brown algae only. Tannins give an
astringent or bitter taste to foods and bever-
ages (e.g. some red wines, teas and unripe
fruits). The basic function of tannin is not as a
primary antioxidant (i.e. they donate hydro-
gen atom or electrons) but they act as second-
ary antioxidants (i.e. interfere with the chain
reaction or by chelating the metal ions such as
Fe(II) thereby retarding oxidation or Fenton
reaction). Zhang et al. (2004) showed that
the inhibition of lipid peroxidation by tan-
nin constituents can act via the inhibition of
Phenolic acids
Phenolic acids are a major class of phenolic
compounds, widely occurring in the plant
kingdom. Predominant phenolic acids
include hydroxybenzoic acids (e.g. gallic
acid, p-hydroxybenzoic acid, protocatechuic
acid, vanillic acid and syringic acid) and
hydroxycinnamic acids (e.g. ferulic acid, caf-
feic acid, p-coumaric acid, chlorogenic acid
and sinapic acid) (Wrigstedt et al., 2010).
Ferulic, caffeic and p-coumaric acid are pre-
sent in many medicinal herbs and dietary
spices, fruits, vegetables and grains. Wheat
bran is a good source of ferulic acids.
Hydroxycinnamic acids (non-flavonoid phe-
nolics) are characterized by the C6–C3 struc-
ture. Plants use these compounds in both
structural and chemical defence strategies
against microbial flora as well as oxidative
stress (Cartea et al., 2011). Naturally occur-
ring hydroxycinnamic acids possess high
level of antioxidants in comparison to
hydroxybenzoic acid due to increased possi-
bilities for delocalization of the phenoxy rad-
ical (Beer et al., 2002). Phenolic compounds
have the potential to function as antioxidants
by scavenging the superoxide anion, hydroxyl
radical, peroxy radical or quenching singlet
oxygen and inhibiting lipid peroxidation in
biological systems (Izunya et al., 2010). At
low temperatures during the maturity of
leaves, the leaves have been shown to
increase the phenols and flavonoids content
(Singh, P. et al., 2008; Singh, B.N., 2009c).
16.3 Antioxidant Nutrients
16.3.1 Vitamin E
Vitamin E is the main lipid-soluble antioxi-
dant and plays a vital role in protecting
membranes from lipid peroxidation. Primary
function of vitamin E is to trap peroxy radi-
cal formation during lipid peroxidation
in cellular membranes. It is mainly present
in nuts, seeds, vegetables, fish oils, whole
grains (especially wheat germ), fortified
cereals and apricots (Glenville, 2006). Current
recommended daily allowance (RDA) is
15 IU day−1 for men and 12 IU day−1 for women.
16.3.2 Vitamin C or ascorbic acid
Vitamin C or ascorbic acid is a water-soluble
antioxidant that can reduce a variety of free
radicals. It acts as a synergist for tocopherol
by converting the oxidized tocopherols
back to their reduced status. Ascorbic acid
can also act as a pro-oxidant under certain
circumstances and helps regeneration of
membrane-bound oxidized vitamin E.
Vitamin C reacts with the a-tocopheroxyl
radical and is oxidized to dehydroascorbic
acid. Humans lack L-gulono-g-lactone oxi-
dase, which is a key enzyme in ascorbic acid
synthesis, hence it cannot be synthesized in
the body and must be acquired from dietary
sources. Ascorbic acid is mainly present in
citrus fruits and juices, kiwi, cabbage, green
peppers, spinach, broccoli, kale, cantaloupe
and strawberries. The RDA for vitamin C is
60 mg day−1. If taken in high dosages it may
be excreted out due to its water-soluble
nature but may cause adverse side effects in
some individuals. The efficiency of ascorbic
acid as scavenger of superoxide in mamma-
lian tissue is not less than the SOD enzyme.
The ascorbic acid level in extracellular fluids
is higher than those of glutathione. So, ascor-
bate probably plays a predominant role in
extracellular antioxidant protection. Vitamin C
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Antioxidants: Their Health Benefits and Plant Sources 253
reacts with the superoxide radical to form
dehydroascorbic acid and it returns to its
original state (vitamin C) with the help of
gluthathione (Prakash et al., 2012).
16.3.3 Glutathione
Glutathione, a tripeptide (glutamyl-cysteinyl-
glycine) antioxidant, is the most important
intracellular defence against damage by
ROS. It is widely distributed among living
cells and apparently involved in many bio-
logical functions. Glutathione present in the
oxidized (GSSH) form is converted to the
reduced GSH by enzyme glutathione reduc-
tase. It has been reported that reduced GSH is
mainly present in tissue. The free sulfhydryl
(SH) is a very reactive group in cysteine, pro-
viding target for radical attack. Reduced
glutathione is oxidized when it reacts with
free radicals and it gets back to the reduced
state by redox cycle involving GSH reduc-
tase and the electron acceptor NADPH
(Gassen and Youdim, 1999).
16.3.4 Selenium
Selenium, an essential element for antioxida-
tion reactions, is required only in small
amounts in humans and animals (Thomson,
2004). Selenoproteins (proteins containing
selenium) are important antioxidant enzymes.
There are nearly 30 known selenoproteins,
mainly containing selenocysteine. The active
site of GSH peroxidase (the most abun-
dant selenoprotein in mammals) and thiore-
doxin reductase enzyme has selenocysteine.
Thioredoxin reductase not only maintains cell
proteins in a reduced state but also provides
deoxyribonucleases required for DNA syn-
thesis (Holmgren, 1989). At low concentra-
tions it acts as an antioxidant, inhibiting lipid
peroxidation, whereas at higher concentra-
tions it behaves as pro- oxidant, enhancing the
accumulation of lipid peroxidation products.
The antioxidant properties of selenoproteins
help to regulate thyroid function, play impor-
tant role in the immune system and prevent
cellular damage from free radicals (Corvilain
et al., 1993). Selenium deficiency may cause a
form of heart disease, hypothyroidism and a
weakened immune system (Zimmerman and
Kohrle, 2002).
16.3.5 b-Carotene
b-carotene (precursor to vitamin A, retinol) is
present in liver, egg yolk, butter, milk, spin-
ach, squash, carrots, broccoli, tomato, yams,
cantaloupe, peaches and grains. b-carotene is
converted to Vitamin A by the body. The
carotenoids (fat-soluble antioxidant) are one
of the most common pigments found in
nature (Daun, 1988). b-carotene (one of the
best known carotenoids) is necessary for the
synthesis of vitamin A. Some other related
pigments include a-carotene, lutein, lycopene
and astaxanthin. There is evidence that diet
containing fruit and vegetables is associated
with lower incidences of cancer (Giovannucci,
1999). b-carotene has the capacity to quench
reactive oxygen (stop oxidative mechanisms),
making them chemoprotective against cancer.
There is strong evidence that b-carotene
increases the detoxification of carcinogens
present in the liver, thereby reducing the
development of cancer (Solomons, 2001).
16.3.5 Metal-binding protein
Transition metals are tightly bound to vari-
ous proteins that prevent them from reacting
with peroxides to form free radicals. These
include the following.
Ceruloplasmin is an effective antioxidant with
potent peroxidase property. It decomposes
hydrogen peroxide in the presence of reduced
glutathione. Ceruloplasmin is expressed mainly
in the liver but has been found to be expressed
in the lungs (Fleming et al., 1991) and mam-
mary glands. The role of ceruloplasmin as
antioxidant is against organic and inorganic
oxygen radicals from iron and ascorbate.
It contains 90–95% of the circulating copper
in normal mammals. The concentration of
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254 R.L. Singh et al.
ceruloplasmin increases by a factor of 2 to 3
during pregnancy and hormonal conditions.
It also inhibits lipid peroxidation induced by
ferrous ion by way of decomposing lipid per-
oxides (Verma et al., 2005).
Lactoferrin belongs to the iron transporter or
transferrin family of glycoproteins and is
mainly present in whey and exocrine secre-
tions from mammals and is released from
neutrophil granules during inflammation.
Human breast milk may contain as much as
15% lactoferrin while cow’s milk may have
only 0.5% to 1.0%. It has two important roles:
(i) it shows antibacterial, antiviral, antifungal,
anti-inflammatory, antioxidant and immu-
nomodulatory activities; and (ii) lactoferrin
plays an important role in the uptake and
absorption of iron through the intestinal
mucosa. Its ability to bind iron probably con-
tributes to both its antioxidant properties and
its antibacterial action (Gupta et al., 2012).
Metallothionein (MT) consists of four low-
molecular-weight (6000–7000), metal-binding
proteins with high cysteine content. Metal-
lothioneins (MTs) are sulfhydryl-rich pro-
teins, which specifically neutralize hydroxyl
radicals (Viarengo et al., 2000). Antioxidant
properties of MTs are mainly due to sulfhy-
dryl nucleophilicity. In vitro studies have
revealed that it reacts directly with ROS
including superoxide and hydroxyl radicals
and hydrogen peroxide. Binding of transition
metals (Fe, Cu) to the protein reduce the
Fenton reactivity, resulting in reduced oxida-
tive stress.
Transferrin (iron-binding blood plasma gly-
coprotein) has a molecular weight of
approximately 80 kDa and bind iron very
tightly but reversibly and hence control the
level of free iron in biological fluids (Crichton
and Charloteaux-Wauters, 1987). It has two
specific high-affinity Fe(III) binding sites.
Iron present in the body is always found in
protein-bound form and never in a free state.
If iron is being transported or stored it must
be chelated in very specific ways by transfer-
rin or ferritin. Transferrin is mainly present
in serum, but it is also found in other body
fluids at lower concentrations (Chauhan et al.,
2004). The antioxidant activity of transferrin
is due to its reducing properties. It reduces
the concentration of free ferrous ion that
catalyses the conversion of hydrogen perox-
ide to highly toxic hydroxyl radical by Fenton
reaction. Transferrin is a universal iron carrier
and is able to deliver iron to cells without
formation of free radicals.
Ferritin (a globular protein complex consist-
ing of 24 protein subunits) is a ubiquitous
intracellular protein that stores iron and
releases it in a controlled fashion. Ferritin is
synthesized by almost all living organisms,
including algae, bacteria, higher plants and
animals. Intracellular iron is stored in the fer-
ritin in both prokaryotes and eukaryotes and
released into cells when needed; hence it acts
as buffer against iron deficiency. Ferritin that
is not combined with iron is called apoferri-
tin. Ferritin converts ferrous (Fe2+) to ferric
(Fe3+) form by ferroxidase activity, thereby
reducing the chance of the deleterious reac-
tion that occurs between ferrous iron and
hydrogen peroxide known as the Fenton
reaction, which produces the highly damag-
ing hydroxyl radical (Sarma et al., 2010).
16.4 Some Commonly Measured
Analytes with Antioxidant and
Pro-oxidant Activities
16.4.1 Gamma-glutamyltransferase
Gamma-glutamyl transpeptidase (also known
as g-glutamyltransferase, GGT, GGTP, gamma-
GT) (EC is an enzyme that transfers
g-glutamyl functional groups. It is the first
enzyme of the g-glutamyl cycle that regulates
the antioxidant glutathione; hence it is a criti-
cal enzyme in glutathione homeostasis. GGT
is present in the cell membrane of many
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Antioxidants: Their Health Benefits and Plant Sources 255
tissues, including the kidney, bile duct, pan-
creas, gallbladder, spleen, heart, brain and
seminal vesicle (Sarma et al., 2010).
16.4.2 Uric acid
Uric acid, the end product of purine metabo-
lism, works as an antioxidant. It is the most
abundant aqueous antioxidant in humans
and contributes as much as two-thirds of all
free-radical scavenging capacity in plasma. It
is particularly effective in quenching hydroxyl,
superoxide and singlet oxygen and peroxyni-
trite radicals and may play a protective physi-
ological role by preventing lipid peroxidation.
The major antioxidant role of uric acid is its
ability to bind and inactivate peroxynitrite.
At physiological concentrations, urate pro-
tects erythrocyte ghosts against lipid peroxi-
dation leading to lysis of erythrocytes. Urate
is found to be about as effective an antioxi-
dant as ascorbate in these experiments. Urate
is much more easily oxidized than deoxynu-
cleosides by singlet oxygen and is destroyed
by hydroxyl radicals at a comparable rate
(Nieto et al., 2000).
16.4.3 Bilirubin
Bilirubin, the end product of haem metabo-
lism, has the ability to function as an antioxi-
dant in the brain, scavenging free radicals and
reducing oxidative damage. It is reported that
bilirubin protects oxidation of lipids such as
linoleic acid and vitamin A. Stocker et al. (1987)
demonstrated that bilirubin has more of an
antioxidant effect than vitamin E towards lipid
peroxidation. It has also been experimentally
proved that higher concentration of serum bili-
rubin increases its antioxidant capacity.
16.4.4 High-density lipoprotein
High-density lipoprotein (HDL) has long
been known as the ‘good cholesterol’, protect-
ing against heart disease and atherosclerosis.
It has been experimentally found that HDL
has powerful antioxidant properties, similar
to vitamin C and vitamin E. An enzyme related
to synthesis of HDL cholesterol, lecithin-
cholesterol acyltransferase, is a powerful anti-
oxidant enzyme that blocks the oxidization of
low-density lipoprotein (LDL) cholesterol.
Cholesterol is beneficial if it is not oxidized.
Barter et al. (2007) suggested that a low level
of HDL increases the risk of diseases even
in people with very low LDL levels. Jafri
et al. (2010) suggested that there is an inverse
relationship between high HDL and cancer
16.4.5 Nitric oxide
Nitric oxide is an uncharged lipophilic mole-
cule that behaves like amphoteric molecule,
i.e. NO could function as an electron donor
(oxidant) or an electron acceptor (antioxi-
dant) (Drew and Leeuwenburgh, 2002). It
contains a single unpaired electron (NO•),
which reacts with other molecules, such as
oxygen, GSH and superoxide radicals. They
prevent free radicals from stealing electrons
from other molecules.
16.5 Sources of Natural Antioxidants
Dietary antioxidants include ascorbate, toco-
pherols, carotenoids and bioactive plant
phenols. The health benefits of fruits and
vegetables are largely due to the antioxidant
vitamins supported by the large number of
phytochemicals, some with greater antioxi-
dant properties. Sources of tocopherols,
carotenoids and ascorbic acid are well
known and there are plenty of publications
related to their roles in health. Exogenous
dietary antioxidants capable of scavenging
free radicals are of great interest in combat-
ing oxidative stress-induced cell damage.
Plants containing a high content of polyphe-
nols and flavanoids are considered as poten-
tial antioxidants and can be used as adjuvant
therapy. These plant polyphenols and flava-
noids are multifunctional and can act as
reducing agents, hydrogen donors, singlet
oxygen quenchers and metal ion chelators
(Gassen and Youdim, 1999).
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256 R.L. Singh et al.
Several natural antioxidants such as sily-
marin, grape seed extract, resveratrol, cur-
cumin etc., are known to reduce oxidative
stress and protect from hepatic damage.
Ulusoy et al. (2012) reported antioxidant and
anti-apoptotic effects of proanthocyanidine
from grape seed extract. Silymarin, a flavonoid
complex from Silybum marianum, has been
used in the treatment of hepatitis, liver cirrho-
sis, viral hepatitis and fatty liver. It has been
shown to have antioxidant, antilipid peroxida-
tive, anti-inflammatory and liver regenerative
effects. Lupeol, a pentacyclic triterpenoid,
found in many plants such as crataeva, mango,
olive etc., received much attention due to its
wide spectrum of medicinal properties that
include antiprotozoal, anti-inflammatory, anti-
carcinogenic, cardioprotective and antimicro-
bial activities. Hepatoprotective action of
lupeol against aflatoxin B1-induced toxicity
has been reported by Preetha et al. (2006).
Cymbopogon citratus D. Stapf., commonly
known as lemongrass, contains volatile oil
consisting of citral, a monoterpene (a mixture
of two isomeric aldehydes, neral and geranial
in the ratio of 2:3), as a major component,
which is used in various perfume and cos-
metic industries (Rauber et al., 2005). The
plant is reported to possess antifungal, mos-
quito repellent, insecticidal, antidiabetic, anti-
septic, antimutagenic and anticarcinogenic
activity (Masuda et al., 2008).
Fumaria parviflora Lam. (Fp) is used for
dermatological diseases, stimulation of liver
function and gall bladder, as antiscabies, anti-
scorbite, antibronchite, diuretic, expectorant,
antipyretic, diaphoretic, appetizer and anti-
neoplastic agent. Its antinoceceptive effect
has also been worked out (Heidari et al.,
2004). Phytochemical analysis of Fp indicated
presence of organic acids and isoquinoline
alkaloids, namely: fumaric acid, protropine,
cryptopine, sinactine, stylopine, dihydro-
fumariline, per-fumidine and dihydrosan-
guirine (Suau et al., 2002). Acetyl-cholinesterase
and butyrylcholinesterase inhibitory activity
of Fp has also been reported (Orhan et al.,
2004). Significant oral antipyretic activity has
been shown by hexane-chloroform and water-
soluble extracts of Fp in rabbits (Akhtar et al.,
1984). A 50% ethanolic extract of Fp was also
tested to discover the role of mitochondria
and ROS/oxidative stress in cytotoprotective
and anti-apoptotic effects against nimesulide-
induced hepatotoxicity (Tripathi et al., 2010).
Glycyrrhiza glabra (liquorice) possesses
triterpene, saponins, glycyrrhizin/glycyrrhi-
zic acid and glycyrrhetic acid. Glycyrrhizic
acid (GA), a biologically active constituent of
liquorice root with a structure of 20b-carboxy-
copyranosiduronic acid, is believed to be partly
responsible for anti-ulcer, anti-inflammatory,
antidiuretic, anti-epileptic, anti-allergic, anti-
dote, antitumour, antiviral, antihypotensive
and several other properties of the plant
(Baltina, 2003). Hypocholesterolaemic and
hypoglycaemic activities have also been
reported (Sitohy et al., 1991).
Bacopa monnieri Linn. (syn. Herpestis mon-
nieri Linn. H.B. and K) is used as a nerve tonic,
brain tonic, memory enhancer, laxative, astrin-
gent, antipyretic, anti-inflammatory and lep-
rosy healer. It is also useful in renal disorders,
blood diseases, cough, anaemia and poison-
ing. The plant also finds various applications
in central nervous system depressant activity.
Its major constituents including two saponins
(bacoside A and bacoside B) have been isolated
and characterized (Chowdhuri et al., 2002).
Geraniol, an acyclic monoterpenoid, is an
important constituent of essential oils of gin-
ger, lemon, lime, lavender, nutmeg, orange,
rose and palmarosa. It is reported to prevent
cancer. Camphene, another component, is a
bicyclic monoterpene with a pungent smell.
It constitutes a minor part of many essential
oils including turpentine oil, cypress oil, cit-
ronella oil, ginger oil etc., and is known to
possess antilithic and expectorant properties.
Camphene is also present in apricot, carrots,
cinnamon, ginger, cumin seed, nutmeg, car-
damom and turmeric. It is used as a food
additive for flavouring as well as in the prep-
aration of fragrances, plasticizers for resins
and lacquers (Verschueren, 2001).
Free radicals generated in diabetes may
lead to several kinds of diabetic complica-
tions including nephropathy, neuropathy,
cardiopathy and many more. Many herbal
medicines as single agents or in different
oral formulations have been recommended
for diabetes mellitus due to the fact that
they are less toxic than oral hypoglycaemic
Prakash_Ch16.indd 256 11/27/2013 10:07:55 AM
Antioxidants: Their Health Benefits and Plant Sources 257
agents such as sulfonylureas, metformin, etc.
(Ponnachan et al., 1993).
Anthocyanins have been shown to be
natural anti-inflammatory agents and pain
relievers. Chronic inflammation has also
been associated with an increased risk of can-
cer, but anti-inflammatory drugs are not
effective for reducing this type of inflamma-
tion (Singh, B.N. et al., 2009b). Some impor-
tant sources of antioxidants are presented in
Table 16.2.
16.6 Roles of Antioxidants in the
Prevention of Diseases
Plants have numerous natural antioxidants to
control the oxidative stress induced by these
free radicals (Pacher et al., 1997; Sarma et al.,
2010). Free radicals have been implicated in the
pathogenesis of over 100 human diseases such
as cancer, heart disease, stroke, Alzheimer’s
disease, diabetes, premature ageing, high
blood pressure and sepsis, to name a few.
16.6.1 Cancer
Antioxidants protect DNA thereby reducing
the oxidative DNA damage caused by the
free radical and ultimately control the
increased abnormal cell division, the main
characteristic of carcinogenesis. Experimenta l
evidence using cell culture and animal mod-
els indicate that antioxidants either slow or
prevent the development of cancer through
its action as free-radical scavenger (Rock
et al., 1996). Using in vitro and an animal
model system, it was experimentally found
that plant-derived phytochemicals, such as
allyl sulfides, isothiocyanates and sulfora-
phene, inhibit the various step of tumour
development (Milner, 1994). Blot et al. (1993)
and Sardas (2003) reported that a combina-
tion of b-carotene, vitamin E and selenium
significantly reduces the chance of cancer
development especially in the case of gastric
cancer. Experimental evidence also suggests
that b-carotene with a-tocopherol/retinol
significantly reduced the chance of lung can-
cer (Omenn et al., 1994).
16.6.2 Alzheimer’s disease
Alzheimer’s disease (AD) is characterized by
progressive loss of memory as the major clini-
cal manifestation. Studies on free radicals
suggest that oxidative stress causes neurode-
generative disorders, including AD. Metal
ion also plays an important role in the devel-
opment of AD. Nutraceutical antioxidants
such as b-carotene, curcumin, lutein, lyco-
pene, turmerin etc., showed positive effects
by reducing oxidative stress, mitochondrial
dysfunction and various forms of neural
degeneration (Glenville, 2006). It has been
observed that a lower activity of antioxidant
enzyme such as superoxide dismutase is
related to occurrence of Alzheimer’s disease
in humans (Thome et al., 1997). Kontush et al.
(2001) reported that supplementation with
vitamins E and C to the patient significantly
increases the concentration of vitamins in
plasma and decreases the oxidation of lipo-
protein, while vitamin E alone does not have
any significant effects. High intake of nutraceu-
tical postpones the development of demen-
tias such as AD (Haider and Bhutta, 2006).
16.6.3 Atherosclerosis
Atherosclerosis is a common cardiovascular
disease, which occurs due to deposition of
oxidized fatty acid to the arteries in the form
of plaque. Approximately two-thirds of the
serum cholesterol pool in a normal subject is
low-density lipoprotein-cholesterol (LDL-C),
which is believed to play an important role
in the development of atherosclerosis (Shukla
et al., 2011).
Flavonoids and other plant-derived poly-
phenols, present in fresh fruits and vegetables,
have been shown to be powerful antioxidants
capable of preventing LDL oxidation induced
by free radicals. Recommended daily allow-
ance for the flavonoids is 1 g in an ordinary
diet, which is sufficient for the antioxidant
defence system. Interestingly, it has been
found that the antioxidant activity of some of
flavonoids synergistically increases when they
are supplemented with ascorbic acid to pre-
vent LDL oxidation. The beneficial properties
Prakash_Ch16.indd 257 11/27/2013 10:07:55 AM
258 R.L. Singh et al.
Table 16.2. Some important sources of antioxidants.
Plant Antioxidants References
Medicinal plants
Terminalia chebula (Bahera) Casuarinin, chebulanin and chebulinic acid Cheng et al., 2003
Cassia fistula (Amaltas) Lupeol, b-sitosterol, hexacosanol, kaempferol, proanthocyanidin,
bianthraquinone glycoside, anthraquinones, flavonoids,
flavan-3-ol derivatives, sennoside A, sennoside B
Akiremi et al., 2000
Withania somnifera
Withanolides, cuscohygrine, anahygrine, tropane, pseudotropine,
anaferine, dl-iso-pllatierine, withanine, withasominine, withaninine,
somniferin, pseudowithanine, tropanol, pseudotopanol,
cuscokygrene, 3-tigioyloxytropana, isopelletierine
Sangwan, 2004; Mohammad and Elisabeth, 2009;
Kushwaha and Karanjekar, 2011
Berries (Sarashphal) Flavanols, hydroxycinammic acids, hydroxybenzoic acids,
Wang and Lin, 2000; Yanishlieva-Maslarova and
Heinonen, 2001
Citrus fruits Flavanones, flavonols, phenolic acids Yanishlieva-Maslarova and Heinonen, 2001;
Manach et al., 2004
Black grapes Anthocyanins, flavonols Belitz and Grosch, 1999; Yanishlieva-Maslarova
and Heinonen, 2001
Cherries Hydroxycinnamic acids, anthocyanins Belitz and Grosch, 1999; Yanishlieva-Maslarova
and Heinonen, 2001
Plums (Jamun), apples,
Hydroxycinnamic acids, catechin Belitz and Grosch, 1999; Yanishlieva-Maslarova
and Heinonen, 2001
Allium sativum (Garlic) Aliin, allicin, ajoene, allylpropyl disulfide, diallyl trisulfide, sallylcysteine,
vinyldithiines, S-allylmercaptocystein, S-allylcysteine, S-allyl
mercaptocysteine and saponins
Kemper, 2000; Amagase, 2006
Allium cepa (Onion) Phenolic acids, flavonoids, cepaenes, thiosulfinates, anthocyanins,
sulfur compounds, saponins, quercetrin
Singh, B.N. et al., 2009a; Panduranga Murthy
et al., 2011
Trigonella foenum-graecum
Coumarin, fenugreekine, nicotinic acid, sapogenins, phytic acid,
scopoletin, trigonelline, L-tryptophan-rich proteins and saponins
Yoshikawa et al., 1997
Daucus carota (Carrot) Carotol, daucene, germacrene D, bergamotene, selinene, carotol,
daucol, copaenol
Ozcan and Chalchat, 2007
Sweet potato leaves Flavonols, flavones, Chu et al., 2000
Yellow onion Flavonols Manach et al., 2004
Beans Flavanols Manach et al., 2004
Spinach Flavonoids, p-coumaric acid Bergman et al., 2001
Prakash_Ch16.indd 258 11/27/2013 10:07:55 AM
Antioxidants: Their Health Benefits and Plant Sources 259
Oats, wheat, rice Caffeic, ferulic acids Yanishlieva-Maslarova and Heinonen, 2001
Orange juice Flavanols Manach et al., 2004
Coffee Hydroxycinnamic acids Manach et al., 2004
Chocolate Flavanols Manach et al., 2004
Red wine Flavan-3-ols, flavonols, anthocyanins Manach et al., 2004
Herbs and spices
Sage, carnosol Carnosic acid, lateolin, rosmanul, rosmarinic acid Yanishlieva-Maslarova and Heinonen, (2001)
Foeniculum vulgare (Fennel) Essential oil (trans-anethole, α-phellandrene, α-pinene), dipentene,
methyl chavicol, feniculun, anisaldehyde and anisic acid
Piccaglia and Marotti, 2001; Mimica-Dukic et al.,
2003; Araque et al., 2007
Rosemary Carnosic acid, carnosol, Rosmarinic acid rosmanol Yanishlieva-Maslarova and Heinonen, 2001;
Ibanez et al., 2003
Thyme Thymol, carvacrol, flavonoids, lubeolin Exarchou et al., 2002
Ginger Gingerol and related compounds Moure et al., 2001; Yanishlieva-Maslarova and
Heinonen, 2001
Prakash_Ch16.indd 259 11/27/2013 10:07:56 AM
260 R.L. Singh et al.
of certain plants may be explained by the pres-
ence of some especially effective flavonoids
like resveratrol, which has also been found in
red wines. Probucol, a hypocholesterolaemic
drug, has significant antioxidant activity and
in vivo study on rabbit showed that it has pro-
tective effects against atherosclerosis. In ani-
mal studies, aspirin has also been shown to
prevent atherosclerosis (Jaichander et al., 2008).
16.6.4 Heart diseases
There are several factors such as high choles-
terol level, hypertension, diabetes, cigarette
smoking etc. that provide a platform for the
development of heart disease. Oxidation of
low density lipoprotein (LDL-cholesterol)
causes deposition of fatty acid in arteries lead-
ing to development of atherosclerosis, which
ultimately causes heart disease (Anderson
et al., 1995). Heart disease is acquired with age
because oxidized fatty acid gets more ‘sticky’
and easier to adhere to the artery walls. It is
believed that high intake of ascorbic acid
reconstitutes the endothelial dysfunctions
(Ting et al., 1997) and protects the circulating
lipoprotein from free radicals.
16.6.5 Diabetes
Diabetes mellitus (DM) is characterized by
hyperglycaemia (Grill and Bjorklund, 2000).
Oxidative stress due to lack of antioxidant
defences may also cause diabetes (Cross et al.,
1987; Maxwell et al., 1997; Keaney and
Loscalzo, 1999; Bonnefont-Rousselot et al.,
2000; West, 2000). It is hypothesized that if
ROS are involved in the genesis of diabetes,
then antioxidants may be an effective approach
in prevention of diabetes (Giugliano et al.,
1996). Reaven (1995) revealed that supplemen-
tation of vitamin E reduces the sensitivity of
LDL to in vitro oxidation and availability of
oxidized LDL in type-2 diabetics as well as in
healthy subjects (Liao et al., 1995). It is hypoth-
esized that imbalance between generation and
scavenging of free radicals is the main cause
associated with diabetes. Insulin increases
the uptake of vitamin C in to the cell but in
hyperglycaemic conditions this process is
inhibited resulting in a condition known as
‘tissue scurvy’. Supplementation of vitamin C
alone controls the blood glucose level,
improves endothelium-dependent vasodila-
tion and increases the resistance of lipoprotein
towards oxidation in the patient with either
type-1 or type-2 diabetes mellitus (Ting et al.,
1996; Timimi et al., 1998; Kawano et al., 1999).
16.6.6 Parkinson’s disease
Parkinson’s disease (PD) results from damage
in neuronal cells in certain regions of the
brain, and is characterized by muscle rigidity,
shaking and difficulty in walking (Losso,
2003). Latif et al. (2007) reported that vitamin E
in food may be protective against PD.
Glutathione has also shown some promising
results in preliminary studies to treat PD but
appropriate long-term dosing, side-effects and
the most effective method of administration
are not yet clear.
16.7 Conclusions
Antioxidants may be a promising source for
the prevention and or treatment of free radical-
generated diseases such as atherosclerosis,
hypertension, diabetes, cancer, Parkinson’s
and Alzheimer’s diseases etc. Evidence also
indicates that antioxidants protect/cure the
diseases by involving a number of biological
processes, including signal transduction path-
ways, activation of antioxidant defences, cell
proliferation, cell survival-associated gene
expression, differentiation and preservation
of mitochondrial integrity. To protect the cells
and organ systems of the body against reac-
tive oxygen species, humans have evolved a
highly sophisticated and complex antioxidant
protection system. It involves a variety of anti-
oxidant components, both endogenous and
exogenous in origin, that function interac-
tively and synergistically to neutralize free
radicals. Increasing dietary intake of antioxi-
dants may help to maintain an adequate anti-
oxidant status and, therefore, the normal
physiological function of human beings.
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... Through chromatographic separation, the methanolic extract of S. dulcificum leaves revealed presence of eight compounds including a mixture of b-sitosterol and stigmasterol, pheophytin-a, pheophytin-b, lupeol, lupenone, lupeol acetate, and a-tocopheryl quinone among which major ones are beneficial for health. For instance ''lupeol'' is reported to exhibit antiprotozoal, anti-inflammatory, anticarcinogenic, cardioprotective, antimicrobial, and hepatoprotective activities ( Singh et al. 2014). Similarly, the methanolic extract of the stem was reported to contain six pure compounds namely: propane-1,2,3-triol; 2,5-dimethoxyphenol; 3,4,5-trimethoxybenzoic acid; nicotinic acid; b-sitosterol, and stigmasterol ( Cheng et al. 2012). ...
Introduction - Conservation and management of recalcitrant-seeded species are a major concern, particularly for socio-economically important species such as Synsepalum dulcificum in which seed viability and storage behavior are not sufficiently documented. Materials and methods - In order to improve the seed propagation management of S. dulcificum, we investigated the effects of seed provenance, short-term storage, culture medium, and pulp removal on viability, germinability, germination speed, and seedlings growth. A first experiment following a complete randomized block design consisted of two treatments (intact fruit or depulped fruit). In a second experiment we used a split-split-plot design with 16 treatments of a factorial combination of 2 provenances (Houéyogbé and Toffo), 2 culture media (soil and sawdust) and 4 storage times (0, 1, 2, and 7 days). Results and discussion - The seed viability remained high (85%) on the second day of storage at ambient condition and decreased to 0% when seeds were stored for 7 days. It was affected by the type of culture medium. All factors, except pulp removal, affected germinability and germination speed with percentages ranging from 44 to 99% at two months after sowing. Seedling growth was extremely slow and was affected by the seed provenance, substrate, and storage time. Conclusion - The time of storage is a major limiting factor for S. dulcificum seed viability whereas successive use of sawdust and soil for germination and seedling growth, respectively, is recommended to improve seedling production in the nursery.
... Arts et al. (2005) reported that epidemiologic studies tend to confirm the protective effects of polyphenol consumption against cardiovascular diseases. Glutathione: Dolas and Gotmare (2015) reported that Glutathione protects cells from toxins such as free radicals. The human body produces glutathione from the synthesis of three key amino acidscysteine , glycine and glutamic acid. ...
Full-text available
Antioxidants are man-made or natural substances that may prevent or delay some types of cell damage. Antioxidants are found in many foods, including fruits and vegetables. Although oxidation reactions are crucial for life, they can also be damaging; plants and animals maintain complex systems of multiple types of antioxidants, such as glutathione, vitamin C, vitamin A, and vitamin E as well as enzymes such as catalase, superoxide dismutase and various peroxides. Traditional herbal medicines, dietary foods were the main source of antioxidant for ancient peoples that protected them from the damage caused by free radicals. Antioxidants are widely used in dietary supplements and have been investigated for the prevention of diseases such as cancer, coronary heart disease and even altitude sickness. Although initial studies suggested that antioxidant supplements might promote health, later large clinical trials of antioxidant supplements including beta-carotene, vitamin A, and vitamin E singly or in different combinations suggest that supplementation has no effect on mortality or possibly increases it. These are also use in the food industry in the form of preservatives in foods and cosmetics and to prevent the degradation to rubber and gasoline.
... Through chromatographic separation, the methanolic extract of S. dulcificum leaves revealed presence of eight compounds including a mixture of b-sitosterol and stigmasterol, pheophytin-a, pheophytin-b, lupeol, lupenone, lupeol acetate, and a-tocopheryl quinone among which major ones are beneficial for health. For instance ''lupeol'' is reported to exhibit antiprotozoal, anti-inflammatory, anticarcinogenic, cardioprotective, antimicrobial, and hepatoprotective activities (Singh et al. 2014). Similarly, the methanolic extract of the stem was reported to contain six pure compounds namely: propane-1,2,3-triol; 2,5-dimethoxyphenol; 3,4,5-trimethoxybenzoic acid; nicotinic acid; b-sitosterol, and stigmasterol (Cheng et al. 2012 ). ...
Full-text available
Synsepalum dulcificum, an African native shrub, is a valuable species. All plant parts are of medicinal importance whereas the fruit known as magic berry, miracle berry, or sweet berry is consumed fresh. Surprisingly, very little is known on the species in terms of genotypes utilization and breeding. In this review we recalled the uses and importance of the species and suggested research avenues for an accelerated growth and fruit production. Synsepalum dulcificum is rich in glycoprotein and is an excellent natural sweetener and also a good candidate for the synthesis of drugs against diabetes. Furthermore, S. dulcificum has high content in phytochemical substances (e.g. (?)-epi-syringaresinol, vanillic acid, cyanidin-3-monogalactoside, and quercetin-3-mono-galactoside) with various health and food benefits. Data on the nutrient content are limited. Likewise, knowledge on the reproductive biology and mating system is still narrow, combined with poorly developed horticultural practices. To fully exploit the potential of S. dulcificum prospective actions include: (1) improving the propagation and growth abilities of the species, (2) improving knowledge of floral biology and genetic diversity, (3) understanding the pheno-logical phases of the species, gene expressions and how this contributes to metabolites accumulation and (4) improving genotypes for beverages, cosmetics and pharmaceutical industries and other value chains.
... Through chromatographic separation, the methanolic extract of S. dulcificum leaves revealed presence of eight compounds including a mixture of b-sitosterol and stigmasterol, pheophytin-a, pheophytin-b, lupeol, lupenone, lupeol acetate, and a-tocopheryl quinone among which major ones are beneficial for health. For instance ''lupeol'' is reported to exhibit antiprotozoal, anti-inflammatory, anticarcinogenic, cardioprotective, antimicrobial, and hepatoprotective activities (Singh et al. 2014). Similarly, the methanolic extract of the stem was reported to contain six pure compounds namely: propane-1,2,3-triol; 2,5-dimethoxyphenol; 3,4,5-trimethoxybenzoic acid; nicotinic acid; b-sitosterol, and stigmasterol (Cheng et al. 2012 ). ...
Full-text available
Synsepalum dulcificum, an African native shrub, is a valuable species. All plant parts are of medicinal importance whereas the fruit known as magic berry, miracle berry, or sweet berry is consumed fresh. Surprisingly, very little is known on the species in terms of genotypes utilization and breeding. In this review we recalled the uses and importance of the species and suggested research avenues for an accelerated growth and fruit production. Synsepalum dulcifum is rich in glycoprotein and is an excellent natural sweetener and also a good candidate for the synthesis of drugs against diabetes. Furthermore, S. dulcificum has high content in phytochemical substances (e.g. (+)-epi-syringaresinol, vanillic acid, cyanidin-3-monogalactoside, and quercetin- 3-monogalactoside) with various health and food benefits. Data on the nutrient content are limited. Likewise, knowledge on the reproductive biology and mating system is still narrow, combined with poorly developed horticultural practices. To fully exploit the potential of S. dulcificum prospective actions include: i) improving the propagation and growth abilities of the species, ii) improving knowledge of floral biology and genetic diversity, iii) understanding the phenological phases of the species, gene expressions and how this contributes to metabolites accumulation and iv) improving genotypes for beverages, cosmetics and pharmaceutical industries and other value chains.
Background: Multiple-micronutrient (MMN) deficiencies often coexist among women of reproductive age in low- to middle-income countries. They are exacerbated in pregnancy due to the increased demands, leading to potentially adverse effects on the mother and developing fetus. Though supplementation with MMNs has been recommended earlier because of the evidence of impact on pregnancy outcomes, a consensus is yet to be reached regarding the replacement of iron and folic acid supplementation with MMNs. Since the last update of this Cochrane review, evidence from a few large trials has recently been made available, the inclusion of which is critical to inform policy. Objectives: To evaluate the benefits of oral multiple-micronutrient supplementation during pregnancy on maternal, fetal and infant health outcomes. Search methods: We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (11 March 2015) and reference lists of retrieved articles and key reviews. We also contacted experts in the field for additional and ongoing trials. Selection criteria: All prospective randomised controlled trials evaluating MMN supplementation with iron and folic acid during pregnancy and its effects on the pregnancy outcome were eligible, irrespective of language or the publication status of the trials. We included cluster-randomised trials, but quasi-randomised trials were excluded. Data collection and analysis: Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. The quality of the evidence was assessed using the GRADE approach. Main results: Nineteen trials (involving 138,538 women) were identified as eligible for inclusion in this review but only 17 trials (involving 137,791 women) contributed data to the review. Fifteen of these 17 trials were carried out in low and middle-income countries and compared MMN supplements with iron and folic acid versus iron with or without folic acid. Two trials carried out in the UK compared MMN with a placebo. MMN with iron and folic acid versus iron, with or without folic acid (15 trials): MMN resulted in a significant decrease in the number of newborn infants identified as low birthweight (LBW) (average risk ratio (RR) 0.88, 95% confidence interval (CI) 0.85 to 0.91; high-quality evidence) or small-for-gestational age (SGA) (average RR 0.92, 95% CI 0.86 to 0.98; moderate-quality evidence). No significant differences were shown for other maternal and pregnancy outcomes: preterm births (average RR 0.96, 95% CI 0.90 to 1.03; high-quality evidence), stillbirth (average RR 0.97, 95% CI 0.87, 1.09; high-quality evidence), maternal anaemia in the third trimester (average RR 1.03, 95% CI 0.85 to 1.24), miscarriage (average RR 0.91, 95% CI 0.80 to 1.03), maternal mortality (average RR 0.97, 95% CI 0.63 to 1.48), perinatal mortality (average RR 1.01, 95% CI 0.91 to 1.13; high-quality evidence), neonatal mortality (average RR 1.06, 95% CI 0.92 to 1.22; high-quality evidence), or risk of delivery via a caesarean section (average RR 1.04; 95% CI 0.74 to 1.46).A number of prespecified, clinically important outcomes could not be assessed due to insufficient or non-available data. Single trials reported results for: very preterm birth < 34 weeks, macrosomia, side-effects of supplements, nutritional status of children, and congenital anomalies including neural tube defects and neurodevelopmental outcome: Bayley Scales of Infant Development (BSID) scores. None of these trials reported pre-eclampsia, placental abruption, premature rupture of membranes, cost of supplementation, and maternal well-being or satisfaction.When assessed according to GRADE criteria, the quality of evidence for the review's primary outcomes overall was good. Pooled results for primary outcomes were based on multiple trials with large sample sizes and precise estimates. The following outcomes were graded to be as of high quality: preterm birth, LBW, perinatal mortality, stillbirth and neonatal mortality. The outcome of SGA was graded to be of moderate quality, with evidence downgraded by one for funnel plot asymmetry and potential publication bias.We carried out sensitivity analysis excluding trials with high levels of sample attrition (> 20%); results were consistent with the main analysis except for the findings for SGA (average RR 0.91, 95% CI 0.84 to 1.00). We explored heterogeneity through subgroup analyses by maternal height and body mass index (BMI), timing of supplementation and dose of iron. Subgroup differences were observed for maternal BMI for the outcome preterm birth, with significant findings among women with low BMI. Subgroup differences were also observed for maternal BMI and maternal height for the outcome SGA, indicating a significant impact among women with higher maternal BMI and height. The overall analysis of perinatal mortality, although showed a non-significant effect of MMN supplements versus iron with or without folic acid, was found to have substantial statistical heterogeneity. Subgroup differences were observed for timing of supplementation for this outcome, indicating a significantly higher impact with late initiation of supplementation. The findings between subgroups for other primary outcomes were inconclusive. MMN versus placebo (two trials): A single trial in the UK found no clear differences between groups for preterm birth, SGA, LBW or maternal anaemia in the third trimester. A second trial reported the number of women with pre-eclampsia; there was no evidence of a difference between groups. Other outcomes were not reported. Authors' conclusions: Our findings support the effect of MMN supplements with iron and folic acid in improving some birth outcomes. Overall, pregnant women who received MMN supplementation had fewer low birthweight babies and small-for-gestational-age babies. The findings, consistently observed in several systematic evaluations of evidence, provide a basis to guide the replacement of iron and folic acid with MMN supplements containing iron and folic acid for pregnant women in low and middle-income countries where MMN deficiencies are common among women of reproductive age. Efforts could focus on the integration of this intervention in maternal nutrition and antenatal care programs in low and middle-income countries.
Several vegetables were selected to study their flavonoid contents and antioxidant activities. The results showed that both green and purple leaves of sweet potatoes (185.01 and 426.82 mg kg(-1) respectively) and the outer leaves of onion (264.03 mg kg(-1)) possessed higher amounts of flavonoids, and more than 85% of free radical scavenging activities were evaluated by using 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals. In addition, green leaves of sweet potatoes and the outer leaves of onion showed higher reducing power and higher antioxidant activity in a Linoleic acid system as compared to cabbage, spinach, potato and crown daisy. Blanching of green leaves of sweet potatoes for 30-60 s retained more flavonoids and higher free radical scavenging activities as compared to more than 1 min of blanching. The storage test showed that green leaves of sweet potatoes stored at 4-10 degrees C maintained better quality than those stored at room temperature. (C) 2000 Society of Chemical Industry.
Free radicals react with biological molecules and destroy the structure of cells, which eventually causes free-radical induced disease such as cancer, renal failure, aging, etc. In this study, 6 extracts and 4 pure compounds of Terminalia chebula RETZ. were investigated for anti-lipid peroxidation, anti-superoxide radical formation and free radical scavenging activities. The superoxide radical scavenging of the 4 pure compounds was further evaluated using electron spin resonance (ESR) spectrometry. The results showed that all tested extracts and pure compounds of T chebula exhibited antioxidant activity at different magnitudes of potency. The antioxidant activity of each pure compound was derived from different pathways and was suggested to be specific.
Approximately 90% of all cancer cases correlate with environmental factors, including one’s dietary habits (Armstrong and Doll 1975; Wynder and Gori 1977; Doll 1992; Potter 1992). Manipulating dietary intakes appears to be one of relatively few realistic approaches to bring about a significant cancer risk reduction. While major limitations exist in defining the precise role of food constituents in the cancer process, their likelihood of significance is emphasized in both The Surgeon General’s Report on Nutrition and Health (1989) and the National Academy of Sciences report on Diet and Health (1989). Although published data suggest that about 60% of cancers in women and more than 40% in men relate to food habits (Doll and Peto 1981), the actual percentage probably depends on a number of factors, including the type of tumor examined and the relative intake of both essential and nonessential nutrients. More recent estimates from crosscultural and epidemiologic studies suggest that approximately 35% of all cancer deaths may relate to diet (Eddy 1986).
Herbal remedies are increasingly used by general public to replace or supplement conventional medicine and to protect from diseases caused by reactive oxygen species. This study was aimed to explore the antioxidant and nutraceutical aspects of agrowaste part of three citrus plant varieties. In all the tested samples the ascorbic acid content ranged between 12.86 - 145.39 mg / 100 g of fresh weight (FW), carotenoid content ranged between 0.12 - 5.77 μg / g of FW. The total phenolic content (TPC) was found between 22.7 - 70.04 mg of GAE / g of dry weight (DW), whereas the protein and carbohydrate content was found between 62.46 - 221.90 and 29.93 - 314.41 mg / g of DW, repectively. The results showed that agrowaste part of citrus fruit plants, specially fruit peel of all three varieties may serve as a good nutraceutical source for pharmaceutical and food industries. ® 2009 The Academy of Environmental Biology, India.
In order to assess the antioxidant potential, leaves of 21 species of Rhododendron were studied for their moisture, total phenolic contents (TPC), flavonoids, antioxidant activity (AOA) and free radical scavenging capacity. Out of these, R. baileyii, R. camellieflorum, R. campanulatum, R. cilliatum, R. cinnabarinum, R. griffithianum, R. lepidotum, R. niveum, R. sallignum and R. virgatum were found to have high TPC (91.4-208.9 mg/g GAE), high AOA (73.5-97.2%) and efficient free radical scavengers as evident by their low IC50 (0.07 to 0.19 mg/ml), low EC50 (3.28 to 8.26 mg/mg DPPH), high ARP (antiradical power) (12.10 to 30.48) and high reducing power expressed as ascorbic acid equivalent (ASE/ml) (0.46 to 1.43) as compared to standard quercetin. The promising species were further assayed for their composition of phenolic acids and flavonoids through high performance liquid chromatography. Free radicals can cause damage to cellular bio-molecules leading to several diseases. Rhododendron species with high amounts of phenols, a major group of phytochemicals with antioxidant properties, can help to inactivate them.
Ficus glomerata Roxb (Family: Moraceae) is an evergreen tree found throughout India and other parts of the world. The lipid lowering action of hydroethanolic fruit extract Ficus glomerata has been studied in triton induced hyperlipidemic rats. Serum lipids were found to be lowered by Ficus glomerata (200mg/kg b. w.) in triton WR-1339 induced hyperlipidemia in vivo. The hypolipidemic activity of the extract is compared with gemfibrozil (100mg/kg) a known lipid lowering drug and in vitro antioxidant activity of this extract shown potent inhibition of superoxide anions, hydroxyl redicals and microsomal lipid peroxidation and scavenger of oxygen free redicals.