Bioscience Methods 2015, Vol.6, No.2, 1-7
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with oxidative stress, such as cancer and cardiovascular
and neurodegenerative diseases. Furthermore, polyph-
enols, which constitute the active substances found in
many medicinal plants, modulate the activity of a
wide range of enzymes and cell receptors. There is
now overwhelming evidence to indicate that free
radicals and oxygen species causing oxidative damage
to lipid, protein and nucleic acid. Therefore, they have
been implicated in the pathogenesis of many human
sufferings like cardiovascular and pulmonary diseases,
some types of cancer, cataracts, immune / autoimmune
diseases, inflammation, arthritis, atherosclerosis and
brain dysfunction (Parkinson’s, Alzheimer’s, Huntington’s
diseases) (Thamizhvanan et al., 2012).
Allium sativum
extracts are also used as potential
cardiovascular and anticancer agents (Ghasemzadeh et
al., 2010). Mushrooms, white
Brassica oleracea
,
cauliflower and
Allium sativum
have also been shown
to have strong protective activity against a number of
diseases (kamonrat et al., 2010). Extracts of many
vegetables have anti-mutagenic e
ff
ects.
Beta vulgaris
is regarded, as the ‘Brain Food’ needed to avoid
memory loss and Alzheimer disease. Broccoli is a
potential source of glucosinolates having anti-cancero-
us activity (Saffa et al., 2010).
However, numerous studies have conclusively shown
that the majority of the antioxidant activity may be
from compounds such as flavonoids, iso-flavone,
flavones, anthocyanin, catechin and iso-catechin rather
than from Vitamin C, E and b-carotene (Wang et al.,
1996). Epidemiological studies have shown that
consumption of food and beverages rich in phenolic
content can reduce the risk of heart disease by slowing
the progression of atherosclerosis by acting as
anti-oxidants towards low-density lipoprotein (LDL)
(Yafang et al., 2010). Therefore, mostly, the current
focus is on the anti-oxidant action of phenolics. The
anti-oxidant activity of phenolics is mainly because of
their redox properties which allow them to act as
reducing agents, hydrogen donors, singlet oxygen
quenchers and metal chelators (Ljiljana et al., 2009).
Elimination of synthetic anti-oxidants in food applications
has given more impetus to exploring natural sources
of anti-oxidants. In this context a large number of
plant sources including many vegetables and fruits
have been explored for their anti-oxidant potential
(Oviasogic et al., 2009). Mushroom, white
Brassica
oleracea
and cauliflower (Mohammed and Aly, 2008),
Allium sativum
, broccoli, kidney and pinto beans
(Patricia et al., 2008), beans, beet and corn have been
reported to have high anti-oxidant activity. Other
vegetables such as
Brassica juncea
leaves,
Beta
vulgaris
,
Chenopodium album
, alfalfa sprouts, broccoli,
beets, red bell-pepper,
Allium cepa
, corn, and
Cucumis
sativus
are also rich source of anti-oxidant (Kaur et
al., 2002).
Green leafy vegetables (GLV) are rich sources of
many nutrients and form a major category of vegetable
groups that have been designated as ‘nature’s
anti-aging wonders’. Therefore, the objective of the
present study was to determine the antioxidant activity
of these GLV using in vitro models and their
correlation with their total polyphenol, β-carotene
contents. (Kaur et al., 2002) Human have evolved
highly complex anti-oxidant systems (enzyme and
non-enzyme), which work synergistically, and in
combination with each other to protect the cells and
organ systems of the body against free radical
damage. The anti-oxidants can be endogenous or
obtained exogenously e.g. as a part of a diet or as
dietary supplements. Some dietary compounds that do
not neutralize free radicals, but enhance endogenous
activity may also be classified as anti-oxidants (Lien
et al., 2008).
An ideal anti-oxidant should be readily absorbed and
quench free radicals, and chelate redox metals at
physiologically relevant levels. It should also work in
both aqueous and/or membrane domains and effect
gene expression in a positive way. Endogenous
anti-oxidants play a crucial role in maintaining optimal
cellular functions and thus systemic health and well-being.
However, under conditions, which promote oxidative
stress, endogenous anti-oxidants may not be sufficient
and dietary antioxidants may be required to maintain
optimal cellular functions. (Wong et al., 2005) The
most efficient enzymatic antioxidants involve glutathione
peroxidase, catalase and superoxide dismutase.
Non-enzymatic antioxidants include Vitamin E and
C, thiol antioxidants (glutathione, thioredoxin and
lipoic acid), melatonin, carotenoids, natural flavonoids,
and other compounds. Some antioxidants can interact
with other antioxidants regenerating their original
properties; this mechanism is often referred to as the
“antioxidant network”. There is growing evidence to
support a link between increased levels of ROS and
disturbed activities of enzymatic and non-enzymatic
