Antioxidant Activity Evaluation of Methanolic Extracts of
Brassica napus by Different Assays.
A thesis submitted as partial fulfillment of the requirement for
the
Degree of M.Sc. in
Chemistry
By
MUHAMMAD SHOAIB
2006-2008
DEPARTMENT OF CHEMISTRY UNIVERSITY OF SARGODHA SARGODHA,
PAKISTAN
Antioxidant Activity Evaluation of Methanolic Extracts of
Brassica napus by Different Assays.
A THESIS SUBMITTED TO THE
UNIVERSITY OF SARGODHA IN PARTIAL
FULFILLMENT OF THE REQUIREMENT
FOR
THE DEGREE OF M.Sc.
IN
CHEMISTRY
SUBMITTED BY
MUHAMMAD SHOAIB Roll No. 03 SESSION 2006-2008
DEPARTMENT OF CHEMISTRY UNIVERSITY OF SARGODHA SARGODHA,
PAKISTAN
The Fruit of My Work is Dedicated To my Parents Whose Abundant
Affections Patronizing Encouragement And Secret Prayers Have
Enabled Me to Accomplish This Task And
To my Brother, Sister, friends Whose Hands Always Pray For My
Success
APPROVAL CERTIFICATE
This thesis entitled Antioxidant Activity Evaluation of
Methanolic Extracts of Brassica napus by Different Assays submitted
by Mr. Muhammad Shoaib in Partial fulfillment of the requirement
for the degree of Master of Science in Chemistry is hereby
approved.
SUPERVISOR Dr. Rana Shahid Iqbal Asst. Professor (Analytical
Chemistry) Department of Chemistry University of Sargodha
Sargodha
Dr. Ilays Tariq Chairman Department of Chemistry University of
Sargodha Sargodha
ACKNOWLEDGEMENT
Glory is to that Almighty Allah who has, out of a drop of fluid,
created such a variety of creatures, rational and irrational!
Adored be that Creator, who has established such a variety of
forms, statures and vocal sounds among them, though their origin is
the same pure liquid and genuine spirit. In praise of the Prophet
Muhammad, a thousand salutations and
benedictions to his sublime Holiness Muhammad Mustafa, the
chosen, the benefactor the blessing and peace of God be with Him
through whose grace the sacred Quran descended from the most high!
How inadequate is man justly to praise and eulogize Him!
Salutations and blessing also to His companions and posterity! I
feel great pleasure in expressing my deep sense of gratitude to
Dean of Sciences and Technology, Dr. Ghulam Hussain Bhatti and our
respected and chairman, Department of Chemistry, University of
Sargodha, Sargodha, for their constant inspiring leadership and
encouragement. I, with deep emotions of benevolence and gratitude,
am highly thankful to my worthy supervisor Dr. Rana Shahid Iqbal,
Department of Chemistry, University of Sargodha, Sargodha, under
whose dynamic supervision, illustrative advice, keen interest and
sympathetic behavior, the present study was accomplished. I am
grateful for her cordial behavior towards me.
I feel pleasure to express thanks to all teachers of department
for being a source of inspiration for me during my research work. I
offer my sincerest thanks to my affectionate parents, especially my
mother, who always remembered me in her prayers and raised her
hands for me to achieve the highest goal of life. This work was not
possible without their moral and financial support. Words are
inadequate to express my deep sense of gratitude and indebtedness
to my dear class fellows, who passed two years education period of
M.Sc. excellently and my best friend Muhammad Umer Farooq whose
hands always raised for my success. They will remain vibrating for
years in my mind for their unselfish behavior and nice company.
Thanks to all non-teaching staff of Department of Chemistry,
University of Sargodha, Sargodha.
Muhammad Shoaib
Sr. No.
TOPIC
Page No.
CHAPTER NO. 01
INTRODUCTION
1.1 1.2 1.2.1 1.2.2 1.2.3 1.3 1.4 1.5 1.6 1.6.1 1.6.1 1.6.1.2
1.6.1.3 1.6.2 1.6.3 1.7 1.7.1 1.7.2 1.8
Foods Components of Foods Proteins Carbohydrates Lipids Fats and
Oils Importance for Living Organisms
1 1 1 1 2 2 2 2 3 3 3 4 5 5 5 6 6 6 7
Problems with OilsLipid Peroxidation Mechanism of Peroxidation
Initiation Propagation Termination Photo-oxidation Enzymatic
Peroxidation Antioxidants Desirable Qualities of Food Antioxidants
Mechanism of antioxidative action Natural Antioxidants
1.8.1 1.8.2 1.8.3 1.8.4 1.8.5 1.8.6 1.9 1.9.1 1.9.2 1.9.3 1.9.4
1.10 1.11
Vitamin C Vitamin E Coenzyme Q10 Seasamol Gossypol Lecithin
Synthetic Antioxidants Butylated Hydroxyanisole Butylated
Hydroxytoluene Nordihydroguaiaretic Acid Propyl Gallate Superiority
of Natural Antioxidants Over Synthetic Sources of Natural
Antioxidants
7 8 9 9 10 10 10 11 11 11 12 12
12 1313
1.121.12.1 1.13 1.14
BrassicaBrassica napus Literature Review Aims and Objectives of
Work Scope of Work/Study
13 23 23
1.15CHAPTER NO. 2
EXPERIMENTAL
2.1 2.2 2.3 2.4 2.6
Samples Chemicals and Reagents Drying and Grinding Extraction of
Total Antioxidants DPPH Scavenging Assay 24 25
24 24 24
2.7 2.8
Determination of Total Phenolic Contents (TPC) Chelating
Activity
25
25
2.9
Antioxidants Activity Determination in Linoleic Acid System
25
CHAPTER NO. 3
RESULTS AND DISCUSSIONS
3. I
DPPH Radical Scavenging Abilities
26
3.2 3.3 3.4 3.5
Total Phenolic Content (TPC) Chelating Activity Antioxidant
Activity in Linoleic Acid System Total Flavonoid Contents (TFC)
26 27 27
2728
CHAPTER 4
REFRENCES
CHAPTER 1 INTRODUCTION
1.1 FoodFood is any substance, usually composed primarily of
carbohydrates, fats, water and proteins, that can be eaten or drunk
by an animal or human for nutrition. Items considered as food may
be sourced from plants, animals or other categories such as fungus
or fermented products like alcohol [1]. There are around 2,000
plant species, which are cultivated for food [2]. Seeds of
plants may be a good source of food for animals, including
humans because they contain nutrients necessary for the plant's
initial growth. In fact, the majority of food consumed by human
beings is seed-based foods. Edible seeds include cereals (such as
maize, wheat, and rice), legumes (such as beans, peas, and
lentils), and nuts. Oilseeds are often pressed to produce rich
oils, such as sunflower, rape (including canola oil), and sesame
[3]. Some fruits, such as tomatoes, pumpkins and eggplants, are
eaten as vegetables [4].
1.2 Components of FoodFood mainly consists of proteins,
carbohydrates, fats.
1.2.1 ProteinsThe word protein comes from the Greek word
("prota"), meaning "of primary importance." Proteins are large
organic compounds made of amino acids arranged in a linear chain
and joined together by peptide bonds between the carboxyl and amino
groups of adjacent amino acid residues [6]. The end of the protein
with a free carboxyl group is known as the Cterminus or carboxy
terminus, whereas the end with a free amino group is known as the
Nterminus or amino terminus. Protiens have primary, secondary,
tertiary and quaternary structure [7]. Many proteins catalyze
biochemical reactions. Proteins also have structural or mechanical
functions, such as actin and myosin. Other proteins are important
in cell signaling, immune responses, cell adhesion, and the cell
cycle. Proteins are also necessary in animals' diets, since animals
cannot synthesize all the amino acids they need [8].
1.2.2 CarbohydrateCarbohydrates (from 'hydrates of carbon') or
saccharides (Greek meaning "sugar") simple organic compounds that
are aldehydes or ketones with many hydroxyl groups added [9]. The
basic carbohydrate units are called monosaccharides, such as
glucose, galactose, and fructose. If the carbonyl group is an
aldehyde, the monosaccharide is an aldose; if the carbonyl group is
a ketone, the monosaccharide is a ketose. Monosaccharides with
three carbon atoms are called trioses, those with four are called
tetroses, five are called pentoses, six are hexoses, and so on.
They fill numerous roles in living things, such as the storage and
transport of energy (starch, glycogen) and structural components
(cellulose in plants, chitin in animals) [10]. Additionally,
carbohydrates and their derivatives play major roles in the working
process of the immune system, fertilization, pathogenesis, blood
clotting, and development. Two joined monosaccharides are called
disaccharides (sucrose and lactose). Oligosaccharides and
polysaccharides are composed of longer chains of monosaccharide
units bound together by glycosidic bonds [11].
1.2.3 LipidsLipids are broadly defined as any fat-soluble
(lipophilic), naturally-occurring molecule, such as fats, oils,
waxes, cholesterol, sterols, fat-soluble vitamins (such as vitamins
A, D, E and K), monoglycerides, diglycerides, phospholipids, and
others. The main biological functions of lipids include energy
storage, acting as structural components of cell membranes, and
participating as important signaling molecules [12].
1.3 Fats and OilsFats consist of a wide group of compounds that
are generally soluble in organic solvents and largely insoluble in
water. Chemically, fats are generally triesters of glycerol and
fatty acids. Fats may be solid or semi-sold at normal room
temperature, depending on their chemical and composition. Although
the words "oils", "fats", and "lipids" are all used to refer to
fats, "oils" is usually used to refer to fats that are liquids at
room temperature, while "fats" is usually used to refer to fats
that are solids at normal room temperature. "Lipids" is used to
refer to both liquid and solid fats. Examples of animal fats are
lard (pig fat), fish oil, and butter or ghee. They are obtained
from fats in the milk, meat and under the skin of the animal.
Examples of edible plant fats are peanut, soya bean, sunflower,
sesame, coconut, olive, and other vegetable oils. These examples of
fats can be categorized into saturated fats and unsaturated fats
[13].
1.4 Importance for Living OrganismsFats are also sources of
essential fatty acids, an important dietary requirement. Vitamins
A, D, E, and K are fat-soluble compounds, meaning they can only be
digested, absorbed, and transported in conjunction with fats. Fats
play a vital role in maintaining healthy skin and hair, insulating
body organs against shock, maintaining body temperature, and
promoting healthy cell function. They also serve as energy
reservoirs for the body. Fats are broken down in the body to
release glycerol and free fatty acids. The glycerol can be
converted to glucose by the liver and thus used as a source of
energy. They yield a lot of food energy (37MJ /g, or 9 cals/g),
roughly twice as much as carbohydrates [14].
1.5 Problems with Oils
On prolonged storage oils, fats and their products undergo
oxidation and deterioration which results in off-odor and
off-flavor. Oxidative deterioration in oils has been a problem for
common interest for scientist since long. According to Hilfer,
light is perhaps the most important single factor affecting the
stability of oil and fats. Heat and moisture may serve as catalysts
for oxidative deterioration [15].
1.6 Lipid PeroxidationLipid peroxidation is the process whereby
free radicals "steal" electrons from the lipids in cell membranes,
resulting in cell damage. This process proceeds by a free radical
chain reaction mechanism [16]. It most often affects
polyunsaturated fatty acids, because they contain multiple double
bonds in between which lie methylene -CH2- groups that possess
especially reactive hydrogens. As with any radical reaction the
reaction consists of three major steps: initiation, propagation and
termination [17].
1.6.1 Mechanism of PeroxidationThree different mechanisms are
able to induce lipid peroxidation: 1 - Autoxidation This is a
radical-chain process involving three sequences.
1.6.1.1 InitiationIn a peroxide-free lipid system, the
initiation of a peroxidation sequence refers to the attack of a ROS
(reactive oxygen species) able to abstract a hydrogen atom from a
methylene group (CH2-), this hydrogen having very high mobility.
This attack generates easily free radicals from polyunsaturated
fatty acids. .OH is the most efficient ROS to do that attack,
whereas O 2. - is insufficiently reactive.
This peroxidation process is inhibited by tocopherols, mannitol
and formate. The presence of a double bond in the fatty acid
weakens the C-H bonds on the carbon atom adjacent to the double
bond and so makes H removal easier.The carbon radical tends to be
stabilized by a molecular rearrangement to form a conjugated
diene.
Under aerobic conditions conjugated dienes are able to combine
with O 2 to give a peroxyl (or peroxy) radical, ROO
.
1.6.1.2 Propagation
As a peroxyl radical is able to abstract H from another lipid
molecule (adjacent fatty acid), especially in the presence of
metals such as copper or iron, thus causing an autocatalytic chain
reaction. The peroxyl radical combines with H to give a lipid
hydroperoxide (or peroxide). This reaction characterizes the
propagation stage.
Probable alternative fates of peroxyl radicals are to be
transformed into cyclic peroxides or even cyclic endoperoxides
(from polyunsaturated fatty acids such as arachidonic or
eicosapentaenoic acids)
1.6.1.3TerminationTermination (formation of a hydroperoxide) is
most often achieved by reaction of a peroxyl radical with
a-tocopherol which is the main lipophilic "chain-breaking molecule"
in the cell membranes. Furthermore, any kind of alkyl radicals
(lipid free radicals) L . can react with a lipid peroxide LOO. to
give non-initiating and non-propagating species such as the
relatively stable dimers LOOL or two peroxide molecules combining
to form hydroxylated derivatives (LOH). Some bonds between lipid
peroxides and membrane proteins are also possible.
1.6.2 Photo-oxidationAs singlet oxygen (1O2) is highly
electrophilic, it can react rapidly with unsaturated lipids but by
a different mechanism than free radical autoxidation. In the
presence of sensitizers (chlorophyll, porphyrins, myoglobin,
riboflavin, bilirubin, erythrosine, rose bengal, methylene
blue...), a double bond interacts with singlet oxygen produced from
O2 by light. Oxygen is added at either end carbon of a double bond
which takes the trans configuration. Thus, one possible reaction of
singlet O2 with a double bond between C12 and C13 of one fatty acid
is to produce 12- and 13hydroperoxides. The lifetime of singlet O2
in the hydrophobic cell membrane is greater than in aqueous
solution. Furthermore, photo-oxidation is a quicker reaction than
autoxidation since it was demonstrated that photo-oxidation of
oleic acid can be 30 000 times quicker than autoxidation and for
polyenes photo-oxidation can be 1000-1500 times quicker. Similar
effects have been described in liposomes and in intact membranes.
The inhibition of photosensitized
oxidation is efficiently inhibited by carotenoids, the main
protective role played by these compounds in green plants. The
inhibitory mechanism is thought to be In contrast, tocopherols
inhibit this oxidation by quenching the previously formed singlet
oxygen, this forms stable addition products. Unexpectedly, It was
shown that carotenes are efficient inhibitors in vegetal oils only
if TOCOPHEROLS are also present to protect the former [18].
1.6.3 Enzymatic PeroxidationLipoxygenase enzymes (from plants or
animals) catalyze reactions between O2 and polyunsaturated fatty
acids, such as arachidonic acid (20:4 n-6), containing methylene
interrupted double bonds. When 20:4 n-6 is the substrate, these
hydroperoxides are known as HpETEs which can be transformed into
hydroxy products (HETES). These HETEs are also formed directly via
cytochrome P450 induced reactions (monooxygenases) and sometimes
also via cyclooxygenase enzymes.Six hydroperoxides (5-, 8-, 9-,
11-, 12-, and 15-HpETE) are known to be formed from arachidonic
acid in animal cells. Dihydroperoxy compounds (DiHpETEs) may also
be formed via the action of 5- and 15lipoxygenases. These compounds
are important metabolic intermediates but are also
bioactive.Cyclooxygenase enzymes (in plants and animals) catalyze
the addition of molecular oxygen to various polyunsaturated fatty
acids, they are thus converted into biologically active molecules
called endoperoxides (PGG, PGH), intermediates in the
transformation of fatty acids to prostaglandins.
Among the cytochrome P450 catalyzed reactions, the fatty acid
epoxygenase activity produces epoxide derivatives. Those formed
from 20:4 n-6 (5,6-, 8,9-, 11,12-, 14,15-EpETrE) have been shown to
have prominent biological activities. Furthermore, these
mono-epoxides are susceptible to be metabolized into di-epoxides,
epoxy-alcohols or oxygenated prostaglandins [19].
1.7 AntioxidantsAn antioxidant is a substance capable of slowing
or preventing the oxidation of other molecules. Antioxidants are
used to preserve the edible oils and fats. An antioxidant gives
hydrogen to the free radical. When the free radicals take the
hydrogen atoms from antioxidant the chain is broken and reaction is
stopped. In this way antioxidants are useful for the preservation
of edible oils [20].
1.7.1 Desirable Qualities of Food AntioxidantsAn ideal
antioxidant should satisfy the following requirements. It should be
active in very low concentration i.e.01-.001% The used compound
should be non-toxic and so for oxidation products. It should be
easily incorporated into the substrate. It should impart no foreign
flavor, odor and color to food even after prolonged heating and
storage. Its antioxidant activity should not be limited to the fats
or oils in which it is incorporated, but should be transmitted to
the foods and subsequently might be prepared from this fat. It
should be easily available and cost so little that its use should
not significantly increase the price of food. To control its use in
food, the antioxidant should be easy to detect, identify and
measure [21].
1.7.2 Mechanism of Antioxidative ActionAntioxidation can be
represented by a chain reaction as given below.
R-H_________________R +H
.
. ..
R +O=O____________ROO
.
ROO +R-H_________ROOH+R R +R
.
.
.______________
R-R
Hence there are two ways in which this chain reaction reaction
can be initiated, on the one hand, addition of reagents which
retard the formation of free radicals, and on the other hand the
addition of free radicals accepters called antioxidants. The
general principles of chain termination by free radical accepters
in autoxidation reactions have been clearly recognized by
Backstrom. The first detailed kinetic study was carried out by
Balland.their system consisted of autoxidizing ethyllinoleate
containing benzoyl peroxide and ethyl lioleate hydroperoxide as an
initiator and hydroquinone as an inhibitor.
1.8 Natural AntioxidantThey work together to provide the
ultimate protection. When a natural antioxidant grabs a free
radical, it becomes a weak free radical itself, and another
antioxidant will help regenerate it. There are 5 basic natural
antioxidants: Vitamin C Vitamin E Coenzyme Q 10 Lipoic acid
Glutathione
1.8.1 Vitamin CEssential for the production of collagen, the
cellular glue that keeps cells attached together. It strengthens
the connective tissue. Thought to protect against cataract, against
lipid oxidation Essential for immune system health. Has the
important job of recharging fat-soluble vitamin E when it becomes a
free radical itself [22].
The pharmacophore of vitamin C is the ascorbate ion. In living
organisms, ascorbate is an antioxidant, since it protects the body
against oxidative stress, and is a cofactor in several vital
enzymatic reactions [23].
1.8.2 Vitamin EVitamin E is a family of molecules composed of
four different tocopherols and four different tocotrienols, all
nearly identical in structure. Particularly high levels of vitamin
E can be found in the following foods [24]. Wheat germ, Red Palm
Oil, Corn, Nuts, Seeds, Olives Spinach and other green leafy
vegetables.
CH3 HO CH3 H3C CH3 O CH3 CH3 CH3 CH3
Most vitamin supplements contain only one kind of Vitamin
E-alpha-tocopherol but not the others [25]. Many fats and oils are
quite stable to oxidative rancidity. Oils containing antioxidants
when mixed with other fats, tends to protect the fats from
oxidation. For example, the tocopherol (, beta, gamma and delta)
appear to be principal antioxidants in a number of vegetable oils.
They are effective stabilizer for animal fats but have little
antioxigenic effect when added to vegetable fats. The alpha isomer
has the greatest antioxidant activity than others [26]. Alpha
tocopherol
CH3 HO H3C CH3 O CH3 CH3 CH3 CH3 CH3
Beta tocopherol
CH3 HO O CH3 CH3 CH3Gamma tocopherol
CH3
CH3 CH3
HOH3C
CH3 O CH3 CH3
CH3
CH3 CH3
Delta tocopherol
HO O CH3
CH3 CH3
CH3
CH3 CH3
1.8.3 Coenzyme Q10This vitamin-like substance is, by nature,
present in most human cells except red blood cells and eye lens
cells. Ninety-five percent of all the human bodys energy
requirements (ATP) are converted with the aid of CoQ10. CoQ10
Because of its ability to transfer electrons and therefore act
as an antioxidant, Coenzyme Q is also used as a dietary supplement
[27].
1.8.4 SeasamolSeasamol seed oil exhibits antioxidant property
when added to other fats. The active antioxidant of oils is
seasamol which is present in unsaponifiable matter of sesamol seed
oil [28].
O O
OH
1.8.5 GossypolCrude cotton oil contains the natural antioxidant
gossypol. However, the toxic property of gossypol prevents its use
as an antioxidant in edible oils and fats [29].
O HO OH HO HO OH O OH
H3C CH3 CH3 H3C
CH3
1.8.6 LecithinLecithin is one of the first antioxidant to
receive serious consideration in the united state for use in edible
oils. Commercial lecithin preparation have been found to be
somewhat effective in vegetables oils like cotton seed oil but are
relatively ineffective in lard [30]
CH2 CH3 H3C N+
CH2
CH2
CH2 CH2
CH
CH2 CH2 CH2
CH2 CH2
CH2
CH3
OH CH2 CH2 O P+ HO O
O
C
CH2 CH OH
CH2
CH
CH2
CH3
CH2HC CH2 O C O CH2 CH2 CH2 CH2 CH2 CH2 CH CH CH2 CH2 CH2 CH2
CH2
CH2 CH3
1.9 Synthetic Antioxidants
Most of the antioxidants occurring naturally in food stuff
exhibit comparatively weak antioxigynic properties. Consequently a
number of substances possessing marked antioxigenic properties have
been developed and put in the market for use in food. Different
antioxidants vary in their effectiveness to stabilize fats or fats
products are used which are discussed as under.
1.9.1 Butylated Hydroxyanisole (BHT)This commercial product is a
mixture of 2-tert-butyl-4-methoxyphenol and
3-tert-butyl-4methoxyphenol. These compounds do not occur naturally
but can readily synthesize by butylation of para methoxy
phenol.
OCH3
OCH3H3C
CH3 CH3
CH3 CH3
OH H3C
OH
They are very soluble in fats and oils but practically insoluble
in water. The antioxidant property of 3-BHA is greater than 2-BHA.
The most important property of BHA which accounts for its great
popularity as a food antioxidant is its ability to remain effective
in baked and in fried foods. It is used in low concentration due to
its phenolic smell [31].
1.9.2 Butylated Hydroxy Toluene (BHT)Butylated hydroxyl toluene,
commonly known as BHT is 2,6-di-tert-butyl-4-methyl phenol or
2,6-di-tert-butyl-p-cresol. It is also synthetic antioxidant,
originally developed for use in petroleum products and rubber,
which has been adopted for use in food products. Like BHA, BHT
belongs to group of compounds called hindered phenols [32]
H3C H3C
CH3 OH H3C
CH3 CH3
CH3
1.9.3 Nordihydroguaiaretic AcidThis acid commonly known as NDGA
was isolated in 1942 from a desert plant larrea divaricata. Pure
NDGA is white crystalline solid melts at 184-1850C and very
slightly soluble in water and dilute acid NDGA is effective in
preventing oxidative rancidity in fat aqueous system [33].
1.9.4 Propyl GallateIt is an antioxidant approved by the meat
inspection division, US department of agriculture use as edible oil
in concentration .01%.. Propyl gallate is the one of the most
widely used antioxidant at present and is a component of many
commercial antioxidant preparations.OH HO O HO O CH3
1.10 Superiority of Natural Antioxidants Over SyntheticThe oils
with higher content of unsaturated fatty acids, especially
polyunsaturated FA, are most susceptible to oxidation. In order to
overcome the stability problems of oils and fats synthetic
antioxidants, such as butylate hydroxyanisole (BHT), butylated
hydroxy tolune (BHT), tertiary butyl hydroquinone (TBHQ) have been
used as food additives. But resent reports reveal that these
compounds may be implicated by health risks, including canceer and
carcinogenesis [34]. Therefore the most poweful synthetic
antioxidant (TBHQ) is not allowed for food application in Japan,
Canada and Europe. Similarly, BHA has also been removed from the
generally recognised as safe (GRAS) list of compounds [35]. Due to
these safty concerns, there is an increasing trend among food
scientists to replace these synthetic antioxidants with natural
ones, which in general are supposed to be safer.
1.11 Sources of Natural AntioxidantsThe effectiveness of
different natural sources in stablizing vegetable oils has been
previously studied [36]. Jung, Lee, Hun, Kyung and Chung (2001)
evaluated the effect of natural lecithin on the stability of borage
oil. Shahidi and Wanasundara (1992) investigated the stabilization
of canola oil with canola meal. Fruits, vegetables, nuts, seeds,
and bark are being investigated for their antioxidatnt potential
(Pratt and Hudson, 1990). Peschel, W.et al (2007) searched natural
antioxidants from vegetable and fruit wastes. Eleven fruit and
vegetable byproducts and two minor crops were screened for
antioxidant activity. . Esposito, F.et al (2007) worked on
antioxidant activity and dietary fiber in durum wheat bran
by-products. . Abdalla, A.E.M. et al (2006) collected Egyptian
mango seeds as wastes from local fruit processing units and checked
their antioxidant potential. Anna.P.et al (2009) evaluated of
antioxidant properties of pomegranate peel extract in comparison
with pomegranate pulp extract. Maier, T.et al (2009) observed
antioxidant potential of seven grape seed samples originating from
mechanical seed oil extraction. Besides these, search of newer
sources of natural antioxidants from economical materials,
agricultural wastes is hot area of research in recent years. As a
step towards series of investigations in the said dimension,
antioxidant potential of Brassica napus has been studied in this
project.
1.12 BrassicaKingdom Division Class Order Family planate,
magnolipophyta magnolyopsida capparales, brasicacae.
The four important species of brassica are namely brassica
napus, brassica juncea, brassica oleraceae and brassica
compestriss. Brassica has 350 genera and 2500 species.
1.12.1 Brassica NapusIt is also known as rapeseed, rapa (Latin
for turnip .i.e. rapum, or rapa) and canola from Can-O-L-A
(Canadian oil seed low acid). Leading producer include Canada, USA,
Australia, China, India and Pakistan. This plant has flat leaves
12-20 inches long and 8-25 inches wide all stand 2-4 feet tall at
most and yellow flowers with 4-petals [37]. Pharmaceutically leaves
are used as potherb. Oil of napus seed is used in the production of
erucic acid which is in turn used in the manufacture of other
chemicals. Seed powdered with salt is used to be a folk remedy for
cancer [38]. .Rape oil is used in massage and oil baths which is
beleaved to be strengthen the skin and keep it cool and healthy.
With camphor it is applied for rheumatism and stiff joints. Roots
are used for chromic coughs and bronchial catarrhs. Roots are used
as emollient and diacritic. Canola oil is rich with omega-6 and
omega-3 fatty acids in the ratio of 2:1and has been reported to
reduce cholesterol level lower serum, triglyceride level and keep
platelets by sticking together [39].Per 100 g, the leaf is reported
to contain 61 calories, 83.3 g H2O, 2.9 g protein, 1.7 g fat, 11.2
g total carbohydrate, 1.8 g fiber, 0.9 g ash, 136 mg Ca, 38 mg P,
4.6 mg Fe, 2680g carotene equivalent, 0.08 mg thiamine, 0.15 mg
riboflavin, 0.5 mg niacin, and 120 mg ascorbic acid [40].
1.13 Literature Review
Many literature reports have been published demonstrating
antioxidant potential of pomegranate fruit and peel. Many
antioxidative compounds have been reported from these parts of
pomegranate. For example:
Li.Y.et al (2009) Evaluated of antioxidant properties of
pomegranate peel extract in comparison with pomegranate pulp
extract .They found that pomegranate peel had the highest
antioxidant activity among the peel, pulp and seed fractions of 28
kinds of fruits commonly consumed in China. The contents of total
phenolics, flavonoids and proathocyanidins were also higher in peel
extract than in pulp extract. The large amount of phenolics
contained in peel extract may cause its strong antioxidant ability
[41]. Maier, T.et al (2009) observed antioxidant potential of seven
grape seed samples originating from mechanical seed oil extraction.
The results of the present study confirm the press residues of
grape seed oil production still to be a rich source of
polyphenolics with strong antioxidant activity. Additionally, the
effects of different solvents on the yields of phenolic compounds
were determined. Maximum yields were obtained using methanol/0.1%
HCl (v:v), water [75 C] and a mixture of ethanol and water [3:1;
v:v], respectively, whereas pure ethanol resulted in poor
polyphenol extraction [42]. Astadi, I. R. et al (2008) measured
antioxidant activity of anthocyanins of black soybean seed coat in
human low density lipoprotein (LDL).they examined antioxidant
activity of extract against DPPH radical and LDL oxidation. These
results suggest that black soybean seed coat has high levels of
phenolic and anthocyanin, and also demonstrated considerable
antioxidant activity of black soybean seed coat [43]. Ng, T. B. et
al (2008) examined antioxidative activity of natural products from
plants. A variety of flavonoids, lignans, an alkaloid, a bisbenzyl,
coumarins and terpenes isolated from Chinese herbs was tested for
antioxidant activity. The flavonoids baicalin and
luteolin-7-glucuronide-6methyl ester, the lignan
4-demethyldeoxypodophyllotoxin, the alkaloid tetrahydropalmatine,
the bisbenzyl erianin and the coumarin xanthotoxol exhibited potent
antioxidative activity in lipid peroxidation [44]. Luther, M. et al
(2008) examined Inhibitory effect of Chardonnay and black raspberry
seed extracts on lipid oxidation in fish oil and their radical
scavenging and antimicrobial properties. They were also tested for
radical scavenging activity against DPPH and peroxyl radicals
as
reflected in oxygen radical absorbance capacity (ORAC), and
total phenolic content (TPC). Both tested seed flour extracts
suppressed lipid oxidation and rancidity development in fish oil.
Black raspberry seed flour extract significantly reduced the
degradation of biologically important n 3 PUFA under accelerated
oxidative conditions. Both seed flour extracts exhibited DPPH
radical quenching activity. The data from this study suggest the
potential for developing natural food preservatives from these seed
flours for improving food stability, quality, safety, and consumer
acceptance [45].
Zhou,K. et.al (2007) measured total phenolic contents, chelating
capacities, and radicalscavenging properties of black peppercorn,
nutmeg, rosehip, cinnamon and oregano leaf against cation (ABTS +),
DPPH , peroxyl (ORAC) and hydroxyl (HO ) radicals. The extracts of
all botanical samples showed significant radical-scavenging
capacities, TPC and chelating abilities. The 50% acetone extracts
of black peppercorn and cinnamon showed higher ABTS+-scavenging,
ORAC, Fe+2 chelating ability and TPC value. (ESR) measurements
demonstrated that cinnamon had the strongest HO -scavenging
activities [46].
Maisuthisakul, P.et al (2007) obtained ethanolic extracts from
various parts of 26 Thai indigenous plants and examined for
phenolic constituents and free radical scavenging capacity, Total
phenolic content and total flavonoid content were evaluated
according to the FolinCiocalteu procedure, and a colorimetric
method, respectively. The results showed that total phenolic
compounds and flavonoid content were higher in seed extracts of
berries used in wine production, while the levels in extracts
obtained from herbs and vegetables were lower. Chewing plants which
have significantly higher total phenolic content and flavonoid
content [47]. Khan, M.A. et al (2007) compared the effects of
natural and synthetic antioxidants on the oxidative stability of
borage and evening primrose triacylglycerols. Results suggest that
tocopherols are more effective antioxidants at 500 ppm than at 200
ppm. The most effective natural antioxidant was Tenox GT-2 followed
by - and -tocopherols, while, among synthetic antioxidants, (TBHQ)
was more effective than (BHA) and (BHT) and served as the strongest
antioxidant in borage and evening primrose oil TAG [48]. Nuutila,
A.M.et al (2007) compared antioxidant activities of onion and
garlic extracts in methanol by inhibition of lipid peroxidation and
radical scavenging activity against
diphenylpicrylhydrazyl radical.They showed that onions had
higher radical scavenging activities than garlic, red onion being
more active than yellow onion. The skin extracts of onion possessed
the highest activities [49]. Esposito, F.et al (2007) worked on
antioxidant activity and dietary fibre in durum wheat bran
byproducts.They investigated, two commercial products Bran &
Brain 50 and 70. The antioxidant activity of some durum wheat
by-product fractions is comparable to that of widespread fruits and
fresh vegetables, likely due to the presence of fibre-bound phenol
compounds [50]. Aguirrezabal, M. M. et al (2007) observed the
effect of paprika, garlic and salt on rancidity in dry sausages.
Spanish paprika and salt showed antioxidant and prooxidant
properties, respectively. Paprika was even able to inhibit the
prooxidant effect of salt. Also, four batches of chorizo were made
to compare the antioxidant effect of the spices (garlic and
paprika) with a mixture of nitrate, nitrite and ascorbic acid. In
this respect, paprika and garlic were as effective as the mixture
of additives in inhibiting lipid oxidation [51].
Lambropoulos, I.et al (2007) observed antioxidant activity of
Xinomavro red wine phenolic extracts towards oxidation of corn oil.
. One wine extract, rich in phenolic acids and flavonols, inhibited
the oxidation of corn oil stripped of tocopherols to a greater
extent than butylated hydroxyanisole, at 200 mg/L.Other extract, at
100 mg/L total phenolics, rich in flavanols, flavonols and tyrosol,
also exhibited high inhibitory action.Results indicated that some
red wine phenolics - such as phenolic acids, flavonols or flavanols
- may be strong antioxidants in corn oil [52]. Iqbal, S.et al
(2007) measured antioxidant properties and components of some
commercially available varieties of rice bran in Pakistan. Five
indigenous rice bran varieties were, i.e. Rice bran-Super kernel
(RB-kr), Rice bran-Super 2000 (RB-s2), Rice bran-Super Basmati
(RB-bm), Rice bran-Super-386 (RB-86) and Rice bran-Super fine
(RB-sf). The overall order of antioxidant activity was RB-kr >
RB-s2 > RB-bm > RB-86 > RB-sf. However, according to the
chelating activity and conjugated dienes assays the antioxidant
efficacy of RB-sf was higher than RB-bm and RB-86 [53]. Han,J.
et.al (2007) examined antioxidants in a Chinese medicinal herb
Lithospermum erythrorhizon.They isolated Seven compounds,
deoxyshikonin (1), ,-dimethylacrylshikonin (2), isobutylshikonin
(3), shikonin (4),
5,8-dihydroxy-2-(1-methoxy-4-methyl-3-pentenyl)-1,4-
naphthalenedione (5), -sitosterol (6) and a mixture of two
caffeic acid esters (7). Antioxidant activities, assessed by
Rancimat method and reducing power, decreased in the following
order, respectively: compound 7 > 4 > BHT > 2 > 3 >
5 > 1 > 6 [54]. Martn-Diana, A. B. et al (2007) used Green
tea extract as a natural antioxidant to extend the shelf-life of
fresh-cut lettuce. Optimal GT treatment (0.25 g 100 mL 1 at 20 C)
was compared with chlorine (120 ppm at 20 C). High GT
concentrations (0.5 g 100 mL 1 and 1.0 g 100 mL 1) maintained
better prevent ascorbic acid and carotenoid loss than 0.25 g 100 mL
1 GT and chlorine [55]. Peschel, W.et al (2007) searched natural
antioxidants from vegetable and fruit wastes. Eleven fruit and
vegetable byproducts and two minor crops were screened for
antioxidant activity.Extracts with the highest activity, economic
justification and phenolic content were obtained from apple, pear,
tomato, golden rod and artichoke. Apple, golden rod and artichoke
byproducts were extracted at pilot plant scale and their
antioxidant activity was confirmed by determination of their free
radical scavenging activity (DPPH) and the inhibition of stimulated
linoleic acid peroxidation (TBA and Rancimat methods). This study
demonstrated the possibility of recovering high amounts of
phenolics with antioxidant properties from fruit and vegetable
residuals not only for food but also cosmetic applications [56].
Anna,P.(2007) focused on the content, composition, and antioxidant
capacity both lipid- and water-soluble antioxidants in raw Brassica
vegetables, which include different genus of cabbage, broccoli,
cauliflower, Brussels sprouts, and kale, are consumed all over the
world [57].
Sultana,B.et al (2007) examined antioxidant potential of corncob
extracts for stabilization of corn oil subjected to microwave
heating.Extracts were prepared in n-hexane, ethyl acetate, acetone,
ethanol, and methanol and was assessed for total phenolics content
(TPC), DPPH radical scavenging activity and % inhibition of
peroxidation in linoleic acid system. . Methanolic extract offered
the highest yield (19.5%), and also exhibited superior antioxidant
activity. The results of different antioxidant parameters
investigated that corncob is a potent source of natural
antioxidants that might be explored to prevent oxidation of
vegetable oils [58].
Nedyalka et.al (2006) obtained natural antioxidants from herbs
and spices (ground materials or extracts) and reported the
structure of the main antioxidatively acting compounds isolated
from them.They studied antioxidative effects of rosemary, sage,
oregano, thyme, ginger, summer savory, black pepper, red pepper,
clove, marjoram, basil, peppermint, spearmint, common balm, fennel,
parsley, cinnamon, cumin, nutmeg, garlic, coriander, etc. Among
these rosemary is extensively studied its extracts are the first
marketed natural antioxidants [59].
Wong, S.P, et al (2006) examined antioxidant properties of 25
edible tropical plants using DPPH (1,1-diphenyl-2-picrylhydrazyl
free radical) scavenging and reducing ferric ion antioxidant
potential (FRAP) assays.They suggested that polyphenols in the
extracts were partly responsible for the antioxidant
activities.While TEACDPPH, (Trolox equivalent antioxidant capacity)
TEACFRAP and TPC contributed to the total variation in the
antioxidant activities of the plants [60].
Ozturk, S.et al (2006) examined the effect of antioxidants on
butter in relation to storage temperature and duration. Natural (
-tocopherol) and synthetic (BHA and BHT) antioxidants were added to
the butter samples at two concentrations (50 and 100 ppm). .
Peroxide value (PV) and thiobarbituric acid (TBA) number and the
residual antioxidants of the samples were examined at 30-day
intervals.The use of -tocopherol is recommended as a natural
antioxidant to suppress the development of rancidity in butter
[61].
Abdalla, A.E.M. et al (2006) collected Egyptian mango seeds as
wastes from local fruit processing units, the kernels were
separated and dried. The antioxidan and antimicrobial activities of
mango seed kernel extract and oil were investigated. The results
indicated that combination of both mango seed kernel extract and
oil had optimum antioxidant potency higher than each one alone
[62]. Pike, P. R. et al (2006) observed antioxidant activity of oat
malt extracts in accelerated corn oil oxidation.They used methanol
to isolate the crude antioxidants.Antioxidant ability was compared
with synthetic antioxidant butylated hydroxytoluene (BHT).Oat malt
extracts showed remarkable antioxidant activity [63].
Serra, A.T. et al (2006) used olive- and grape-based natural
extracts as potential preservatives for food. Results suggested
that the natural extracts may have important applications in the
future as natural antimicrobial agents for food industry as well as
for medical use. The natural extracts showed more antimicrobial
activity than shown by the selected antioxidants alone against all
microorganisms [64]. Amin.I.et al. (2005) determined the total
antioxidant activity and phenolic content of Kale, spinach,
cabbage, swamp cabbage and shallots. Shallots showed the highest
total antioxidant activity followed by spinach, swamp cabbage,
cabbage and kale [65]. Descalzo, A.M. et al (2005) worked on
natural antioxidants and their effects on oxidative status, odor
and quality of fresh beef produced in Argentina. Pasture samples
typically have higher levels of -tocopherol, -carotene, ascorbic
acid and glutathione than feedlot samples. These compounds retard
lipid and protein oxidation in fresh and stored meat, and preserve
the color and odor quality of beef [66]. Wanasundara, U.N.et al
(2005) detrmined the antioxidative activity of ethanolic extracts
of canola meal at 100, 200, 500 and 1000 ppm on refined-bleached
(RB) canola oil and compared with commonly used synthetic
antioxidants, such (BHA), (BHT), BHA/BHT/monoglyceride citrate
(MGC) andtert-butyl-hydroquinone (TBHQ). Stability of RB oil was
monitored under Schaal oven test conditions at 65C over a 17-d
period. Progression of oxidation was monitored by weight gain,
peroxide, conjugated diene, 2-thiobarbituric acid and total
oxidation values. Canola extracts at 500 and 1000 ppm were more
active than BHA, BHT and BHA/BHT/MGC and less effective than TBHQ
at a level of 200 ppm [67]. Pinelo, M. et al (2005) took pine
sawdust and almond hulls, for extraction of natural antioxidants
under different experimental
conditions.1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical was used
for measuring antioxidants activity. Ethanol, methanol and water
were used as extracting solvents.Pine sawdust offered the best
results, with a 310 times higher (0.1122 g/100 g in dry basis)
total phenolics content than almond hulls [68]. Yingming, P.et al
(2004) examined antioxidant activities of several Chinese medicine
herbs. The antioxidant activity (AA) of ethyl acetate extracts of
Caesalpinia sappan, Lithospermum erythrorhizon, Anemarrhena
asphodeloides, Paris polyphylla and Illicium verum were tested in
refined peanut oil at 60 0.5 C. All of C. sappan, L. erythrorhizon
extracts and their combinations were found to be high effective in
peanut oil. But the extracts of A. asphodeloides,
P. polyphylla and I. verum slightly decrease the formation of
peroxides in peanut oil as compared with pure oil [69]. Gramza.A.et
al (2004) studied Tea constituents (Camellia sinensis L.) as
antioxidants in lipid systems.They concluded that tea contain
polyphenols which act as antioxidants [70].
Batifoulier, F. et al (2004) isolated a novel type of
antioxidant from leaf wax of Eucalyptus globulus leaves and
identified as n-tritriacontan-16, 18-dione. The antioxidant showed
remarkable antioxidative activity in a water/alcohol system and was
more effective than tocopherol and BHA [71]. Yin, et. al (2004)
examined nonenzymatic Antioxidant Activity of Four Organosulfur
Compounds Derived from Garlic.The compounds were diallyl sulfide
(DAS), diallyl disulfide (DADS), S-ethyl cysteine (SEC), and
N-acetyl cysteine (NAC). On the basis of the observed nonenzymatic
antioxidant protection, these organosulfur compounds are potent
agents for enhancing lipid stability [72]. Iqbal,S.et al (2004)
examined antioxidant properties and components of bran extracts
from selected wheat varieties commercially available in
Pakistan.They slected five wheat varieties indigenous to Pakistan,
i.e. Punjab-96, Bhakkar-2002, Uqab-2000, SH-2002, and Pasban-90.
All the varieties exhibited appreciable antioxidant potential and
significant differences were observed among the varieties in
different systems of antioxidant activity evaluation [73].
Desmarchelier, C et.al (2003) studied antioxidant and free radical
scavenging properties of bark extracts of Anadenanthera macrocarpa
Brenan (Fabaceae), Astronium urundeuva Engl. (Anacardiaceae),
Mimosa verrucosa Benth. (Fabaceae) and Sideroxylon obtusifolium
T.D. Penn. (Sapotaceae).They used aqueous and methanolic
extracts.They tested antioxidant activity on
2,2-azo-bis(2-amidinopropane) as a peroxyl radical source. The
highest activity was observed in the methanolic extract of A.
macrocarpa (TRAP=302895 M) [74]. Batifoulier, F. et al (2003)
observed Influence of vitamin E on lipid and protein oxidation in
microsomal membranes from turkey muscle. Lipid oxidation was
estimated by TBARS and protein oxidation was measured by an
estimation of carbonyl groups and free thiols. Vitamin E protected
free thiols from oxidation but had only a small effect Vitamin E
supplementation significantly protected free thiols from oxidation
but had only a small effect (non significant) on carbonyl group
formation.on carbonyl group formation [75].
Litridou M.et al (2003) fractionated phenolic compounds in olive
oils and checked their antioxidants activity. The polar fraction of
virgin olive oil was separated into two main parts (A and B) using
solid phase extraction. The two parts tested for their antioxidant
activity showed relatively high protection factors in safflower oil
stored at 80C. Part B was found to contribute more than part A to
the stability of the oil [76]. Xing, Y.et al (2003) identified and
quantified methanolic extracts of groats and hulls from Ogle oat by
usings GC-MS. Extracts from groats and hulls at levels of 0.05,
0.1, 0.2, and 0.3% w/w, based on total phenolic content, were added
to soybean oil, and their antioxidant effectiveness was compared
with that of 0.02% w/w tertiary butylhydroquinone (TBHQ) by
measuring peroxide values. During 20 d of storage, the groat
extract (0.3%) was not significantly different from TBHQ after day
16, and hull extracts (0.2 and 0.3%) were not significantly
different from TBHQ on day 20 [77]. Duh, P.D.et al (2003) studied
antioxidant efficacy of methanolic extracts of peanut hulls in
soybean and peanut oils. . Results showed that the oils with 0.12,
0.48, and 1.20% MEPH had significantly
(PSPI>FGK>AV>M>WPC>S>-tocopherol>R>TC>BHA/BHT
[81].
Wanasundara, U. N.et al (2001) stabilized seal blubber and
menhaden oils with green tea catechins. The antioxidant activity of
isolated catechins was compared with those of tocopherol, (BHA),
(BHT), (TBHQ), all at 200 ppm. Oils treated with tea catechins
showed excellent oxidative stability as compared with samples that
contained commonly used antioxidants [82]. Amarowicz, R. et.al
(2001) examined free-radical scavenging capacity and antioxidant
activity of selected plant species from the Canadian prairies.
Ethanolic extracts from the roots of wild licorice (Glycyrrhiza
lepidota), narrow-leaved echinacea (Echinacea angustifolia), senega
(Polygala senega), leaves of bearberry (Arctostaphylos uva-ursi)
and aerial parts of two varieties of horsetail (Equisetum spp.)
were prepared and evaluated for their free-radical scavenging
capacity and their antioxidant activity. The bearberry-leaf extract
consistently exhibited the highest antioxidant activity based on
the tests performed, and seems to be a promising source of natural
antioxidants [83]. Pokorny, J. et. al (2000) obtained natural
antioxidants from herbs and spices and their effect on the
keepability of foods [84]. Farag R. S. et al (1999) examined
Influence of thyme and clove essential oils on cottonseed oil
oxidation. Three methods were used to follow cottonseed oil
oxidation, i.e., coupled oxidation with-carotene, the TBA test and
hydroperoxide number. The results illustrated that clove and thyme
oils at various concentrations exhibit antioxidant activity and
this phenomenon for clove oil is superior to that of thyme oil
[85]. George, B.et al (1999) studied bio-antioxidant content and
antioxidant activity of 12 tomato genotypes. Significant
differences were found between lycopene, ascorbic acid and phenolic
contents among various genotypes [86]. Mohamed H. M. A et al (1999)
isolated sesame oil unsaponifiable matter from two different
coloured seed varieties (white and brown). The brown variety
contained higher amounts of total sterols and tocopherols but lower
amounts of sesamin, sesamolin than the white variety.Both were
added in sunflower oils and their effectiveness was compared with a
control (no additives) at 63 C. Results indicated that both had
antioxidant activity which increased with increasing concentration
[87].
Kang, M.H. et al (1999) used sesame lignans in protecting
lowdensity lipoprotein against oxidative damage. Sesaminol
inhibited the Cu2+-induced lipid peroxidation in LDL. Sesaminol was
a more effective scavenger than either -tocopherol or probucol in
reducing the peroxyl radicals [88].
Osawa, T (1999) reviewed functions of dietary antioxidants which
were obtained from foods [89]. Chen, X.et al (1998) noticed
antioxidant activities of six natural phenolics against lipid
oxidation induced by Fe2+ or ultraviolet light.They used
thiobarbituric acid-reactive substances (TBARS) method to determine
lipid oxidation. The antioxidant activities of the six phenolics
against UVinduced lipid oxidation were as follows: quercetin >
rutin = caffeic acid = ferulic acid = sesamol > catechin.And
against Fe2+-induced lipid oxidation was in the order quercetin
(1.7 M) > rutin (10.3 M) > catechin (14.9 M) > sesamol
(18.5 M) > caffeic acid (19 M) > ferulic acid (>250
M).Quercetin was more efficient than butylated hydroxytoluene (BHT)
(2.9 M) [90]. Shahid.S.A.et al (1998) examined antioxidant activity
of different solvent extracts of rice bran at accelerated storage
of sunflower oil. The antioxidant activity of different extracts of
rice bran (var. Super Kernel) prepared using a number of solvents
(100% methanol, 80% methanol, 100% acetone and 80% acetone) were
evaluated in sunflower oil (SFO) under accelerated storage
conditions. The overall order of antioxidant efficacy of rice bran
extracts as determined by various antioxidant assays was 80%
methanolic extract, >100% methanolic extract, >80% acetone
extract and >100% acetone extract [91]. Edwin N.et al (1998)
reported antioxidants in lipid foods and their impact on food
quality.They observed that tocopherols and ascorbic acid are
present in edible oils. These antioxidants can interrupt lipid
autoxidation by interfering with either the chain propagation or
the decomposition processes [92].
Ganthavorn, C.et al (1997) inhibited of soybean oil oxidation by
extracts of dry beans (Phaseolus vulgaris). Polyphenolic compounds
were extracted from pinto, kidney, white (Great Northern), pink,
and black beans by hot methanol extraction and added to soybean
oil. Oil oxidation was assayed by (TBARS). Bean extracts
effectively inhibited iron-catalyzed oxidation of soybean oil
[93].
Bin, Z.et al (1997) examined antioxidant activity of raisin
extracts in bulk oil, oil in water emulsion, and sunflower butter
model systems. Peroxide values and hexanal content were measured on
a half day, 2 or 3 day basis for the emulsion, sunflower butter,
and bulk oil, respectively. The RE had the best antioxidant
activity in the bulk oil system [94]. Suja, K. P. et al (1997)
observed antioxidant efficacy of sesame cake extract in vegetable
oil protection. Antioxidant activity of methanolic extract of
sesame cake was evaluated in soybean, sunflower, and safflower
oils, using the Schaal oven method and differential scanning
calorimetry (DSC) analysis. Results showed that sesame cake extract
(SCE), at concentrations of 5, 10, 50 and 100 ppm in vegetable
oils, could significantly (P