CHAPTER ONE

INTRODUCTION

1.1 BACKGROUND TO THE STUDY

Phytochemical screening is a process of tracing the medicinal value of plants constituents

in some chemical substance that produce a definite physiologic action on the human body (Jigna
et al., 2006; Allero and Afolayan, 2006). The most important of these bioactive compounds of
plants are alkaloids, flavonoids, tannins, saponins, glycosides, cardenolides, bufadionolides and
polyphenolic compounds (Erinle, 2012). Knowledge of the chemical constituents of plants is
desirable not only for the discovery of therapeutic agents but also because such information may
be of value in disclosing new sources of such economic materials as tannins, oils, gum,
precursors for the synthesis of complex chemical substances (Erinle, 2012). For decades, the
screening of medicinal plant materials for their therapeutic values has continued to represent
potential sources of new effective medicines. Besides, evidences from epidemiological studies
suggest that high consumption of fruits and vegetables is linked to reduced risk of developing
most oxidative stress – induced diseases (Dani et al., 2008; Wasson et al., 2008; Atrooz, 2009).
Examples of such diseases include cancer, diabetes mellitus, protein energy malnutrition (PEM),
cataract, infections and other degenerative diseases of aging (Dani et al., 2008; Wasson et al.,
2008; Atrooz, 2009; Omoregie and Osagie, 2011; Dhanasekaran and Ganapathy, 2011). Previous
studies have shown that increased production of reactive oxygen species (ROS) may be one of
the underlying causes of these diseases (Bender, 2006; Adesegun et al., 2008; Wasson et al.,
2008; Martin and Appel, 2010). Nevertheless, ROS can be generated during normal metabolism
in the body; and if not removed may lead to any of the diseases. The long term effects of
increased ROS level include damages to important cellular components especially proteins,
nucleic acids and polyunsaturated fatty acids in cell membranes and plasma lipoproteins
(Bender, 2006; Kasote et al., 2011). Reports abound on the antioxidant activities of
phytochemical constituents of medicinal plants (e.g. polyphenols, carotenoids, flavonoids,
phenolics, vitamins C and E). These phytochemicals act as antioxidants by preventing damages
to cell membrane due to cellular oxidative processes that may result in diseases (Oboh and
Rocha, 2008; Wasson et al., 2008; Ebrahimzadeh et al., 2009; Atrooz, 2009; Omoregie and
Osagie, 2011; Kasote et al., 2011). For instance, natural polyphenols from plant vegetables have

1
been found to exert their beneficial effect by removing free radicals, chelating metal catalyst,
activating antioxidant enzymes, etc (Atrooz et al., 2009; Oboh et al., 2009).

Crassocephalum crepidioides, also called ebolo, thickhead, redflower ragleaf, or

fireweed, is an erect annual slightly succulent herb growing up to 180 cm tall. Its use is
widespread in many tropical and subtropical regions, but is especially prominent in tropical
Africa. Its fleshy, mucilaginous leaves and stems are eaten as a vegetable, and many parts of the
plant have medical uses. The tender and succulent leaves and stems of Ebolo are mucilaginous
and are used as a vegetable in soups and stews, especially in West Africaa. It is much
appreciated for its special flavor, which is sharp but not bitter. It is especially popular in South-
western Nigeria, from where the originally Yoruba name ‗Ebolo‘ derives. The nutritional
compositin of Ebolo leaves per 100g edible portion is: water 79.9%, energy 64kcal, protein 3.3g,
fat 0.7g, carbohydrate 14.0g, fibre 1.9g and Calcium 260mg. The leaves are mildly stomachic. In
Southern Nigeri, the leaves of Ebolo are used to treat indigestion and in Congo, the leaf-sap is
taken for upset tummy with colic and flatulence. The leaves prepared as a lotion or a decoction is
also used in Nigeria as an analgesic for headache. (Udomoh, 2019). Generally, fresh leaves of
Ebolo plant are used medicinally as laxatives, to relief stomach ache, colitis, etc. (Oguntona,
1998; Grubben, 2004).

Scent leaf, Ocimum gratissimum is an aromatic perennial herb, with erect stem, much
branched, glabrous and woody at the base often with epidermic peeling in strips. Ocimum
gratissimum is grown for the essential oil in its leaves and stems while engenol and to a lesser
extent thymol extracted from the oil which are substitutes of clove oil and thyme oil. The
essential oil possesses antibacterial as well as anti-oxidant properties and is also an important
insect repellent so also are the leaves when left dry and burnt (Health Facts, 2015). They are used
as vegetables (Sulistiarini, 1999), as spice due to its aromatic nature to spice various kinds of
soup (e.g. pepper soup) and other delicious meals like porridge (Health Facts, 2015). The whole
plant has many applications in traditional medicine especially in Africa and India. The
applications include in the treatment of ringworms, gout and fungal infections, malaria, catarrh,
aches, colon pain. The juice gotten from squeezing its leaf can be used to cure several stomach
related illnesses like cholera, diarrhea, dysentery, vomiting and convulsion (Health Facts, 2015).

2
 Crassocephalum crepidioides and Ocimum gratissimum plants are known to have
common phytochemical compounds which are used in traditional medicine for the treatment of
several ailments and the extracts have been evaluated for their ability to act as anti-oxidant and to
stall the activities of organisms responsible for spoilage of fresh catfish (Clarias gariepinus) by
extending its shelf lif. (Oladosu-Ajayi et al., 2016). It is against this background this study was
carried to determine the anti-oxidant profile properties present in the extracts of scent leaf
(Ocimum gratissimum) and ebolo leaf (Crassocephalum crepidioides).

1.2 JUSTIFICATION OF THE STUDY

The study on the antioxidant profile properties of aqueous extracts in Ebolo and Scent
Leaf is essential for several reasons.

i. Understanding the flavor content of these extracts contributes to the sensory evaluation of
these commonly used herbs, providing valuable insights into their culinary and medicinal
applications.
ii. The investigation of hydroxyl radical and nitrous oxide radical levels in the extracts is crucial
in assessing their potential antioxidant properties. Antioxidants play a pivotal role in
neutralizing free radicals, which are implicated in various health disorders. By determining
the levels of these radicals, we can gauge the effectiveness of Ebolo and Scent Leaf extracts
as natural antioxidants, potentially offering therapeutic benefits.
iii. This study addresses the growing interest in alternative and complementary medicine.
Investigating the antioxidant profile of traditional herbs aligns with the global trend towards
exploring natural sources for health-promoting compounds. The findings from this research
may contribute to the development of antioxidant-rich products or supplements with potential
applications in health and wellness.
iv. Exploring the antioxidant profile properties of aqueous extracts in Ebolo and Scent Leaf
aligns with the need to understand the flavor components, assess the potential health benefits,
and contribute to the broader field of natural antioxidants in the realm of traditional
medicine.

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 1.3 SIGNIFICANCE OF THE STUDY

The investigation into the antioxidant profile properties of aqueous extracts of Ebolo and Scent
Leaf holds significant implications for various fields:

i. Health and Wellness: Understanding the antioxidant properties of these herbal extracts
provides valuable insights into their potential health benefits. This knowledge may contribute
to the development of natural remedies or supplements, promoting overall well-being.
ii. Traditional Medicine Enhancement: This study bridges traditional and scientific
knowledge by scientifically evaluating the antioxidant profile of Ebolo and Scent Leaf. The
findings may validate or enhance the traditional uses of these herbs, fostering a deeper
integration of traditional medicine into contemporary healthcare practices.
iii. Nutraceutical Development: The identification of antioxidant-rich components in these
extracts opens avenues for the development of nutraceuticals. These natural compounds may
find applications in functional foods or dietary supplements, catering to the increasing
demand for natural and health-promoting products.
iv. Culinary and Food Industry: The determination of flavor content contributes to the
culinary understanding of Ebolo and Scent Leaf. This information may be valuable for chefs,
food scientists, and the food industry in incorporating these herbs into recipes, enhancing
both flavor and nutritional value.
v. Ecological Conservation: Investigating the antioxidant profile of specific plant extracts
contributes to the conservation of biodiversity. Understanding the potential health benefits of
these herbs may encourage sustainable harvesting practices and cultivation, ensuring the
preservation of these plant species.

Conclusively, this study holds significance by addressing health, traditional medicine,

nutraceutical development, culinary applications, and ecological considerations. The outcomes
may pave the way for practical applications in various industries, fostering a holistic approach to
the utilization and preservation of natural resources.

1.4 AIM OF THE STUDY

The primary aim of this study is to identify the anti-oxidant profile properties of aqueous extract
in ebolo and scent leaf.

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 1.5 SPECIFIC OBJECTIVES OF THE STUDY

i. To collect, prepare and extract the leaves of Ebolo and Scent plants.
ii. To determine the total phenol and flavonoid content present in the aqueous extract of ebolo
and scent leaf.
iii. To determine the hydroxyl (OH) and nitrous oxide (NO) radicals in the aqueous extract of
ebolo and scent leaf.
iv. To carry out DPPH (free scavenging) analysis on the leaf extracts of Ebolo and Scent plant.

1.6 SCOPE OF THE STUDY

This research focuses on the antioxidant profile properties of aqueous extracts derived from
Ebolo and Scent Leaf. The scope encompasses the following key elements:

i. Plant Material: The study concentrates on the antioxidant components present in the
aqueous extracts of Ebolo and Scent Leaf. It involves the collection, identification, and
preparation of plant materials for extraction.
ii. Extraction Process: The research delves into the methodology of obtaining aqueous extracts
from Ebolo and Scent Leaf. Parameters such as extraction time, temperature, and solvent
concentration will be considered to optimize the extraction process.
iii. Flavor Content Analysis: The study involves the analysis of the flavor content in the
extracts. This includes the identification and quantification of aromatic compounds that
contribute to the characteristic flavors of Ebolo and Scent Leaf.
iv. Antioxidant Assays: The investigation covers the assessment of antioxidant properties,
focusing on hydroxyl radicals and nitrous oxide radicals. Various assays will be employed to
determine the antioxidant capacity and potential health-promoting properties of the extracts.
v. Data Analysis: Statistical methods will be applied to analyze and interpret the results
obtained from all experimental analysis. The data analysis aims to provide meaningful
insights into the composition and potential benefits of the studied extracts.
vi. Comparative Analysis: A comparative analysis between the antioxidant profiles of Ebolo
and Scent Leaf extracts will be conducted. This comparison seeks to identify any variations
in antioxidant composition and effectiveness between the two plant species.

5
vii. Practical Applications: The study aims to discuss the practical applications of the findings,
exploring potential uses in traditional medicine, nutraceuticals, culinary practices, and other
relevant fields.

It is important to note that this scope defines the boundaries of the research, focusing specifically
on the antioxidant profile properties of aqueous extracts from Ebolo and Scent Leaf. The
outcomes of the study aim to contribute valuable information to various scientific, health, and
industrial domains.

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 CHAPTER TWO

LITERATURE REVIEW

2.1 EBOLO LEAF (Crassocephalum crepidioides)

Ebolo leaf, Crassocephalum crepidioides, also called thickhead, redflower ragleaf,

or fireweed, is an erect annual slightly succulent herb growing up to 180 cm tall. Its use is
widespread in many tropical and subtropical regions, but is especially prominent in tropical
Africa. Its fleshy, mucilaginous leaves and stems are eaten as a vegetable, and many parts of the
plant have medical uses. However, the safety of internal use needs further research due to the
presence of plant toxins (Grubben, 2004). The species is invasive in New Caledonia.
Crassocephalum crepidioides contains the hepatotoxic and tumorigenic pyrrolizidine alkaloid,
jacobine. However, in another study, it is shown that the antitumor activity and macrophage
nitric oxide produce action (Fu et al., 2002; Grubben, 2004). Ebolo plant is a stout erect herb up
to 1m high; leaves are arranged spirally, flowers are bisexual, equal; corolla tubular, 9 – 11mm
long, yellow or orange with reddish brown top; fruit a ribbed achene c. 2mm long, hairy, dark
purplish, crowned by white, caduceus pappus hairs 9-12mm long. Seedling with epigeal
germination; a weed of cultivation, disturbed land and waste places, occurring across the West
African Region from Guinea to W Cameroons and Fernando Po, and generally distributed over
tropical Africa. The leafy parts are widely used as a vegetable, e.g. in Sierra Leone, Ghana,
Benin, Nigeria, Cameroon, Democratic Republic of Congo and Uganda, and also in Asia. In
tropical Africa, Crassocephalum crepidioides comprises of about 24 species, many of which
have medicinal uses. The genus is placed in the tribe Senecioneae. Seedlings of Ebolo appear 8 –
10 days after sowing. Growth of seedlings is fast. Within 40 – 45 days after sowing, the plants
are ready for the first harvest by uprooting and harvesting for seed can start 15 – 17 weeks after
sowing. The wild plant is collected and sold in Northern Ghana markets, while in Nigeria, it is
said to be cultivated for sale in Lagos.

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 Fig. 2.1: Ebolo Leaf

2.2 SCENT LEAF (Ocimum gratissimum)

Scent leaf, with the scientific name ―Ocimum gratissimum‖ is a plant that is frequently
grown for both culinary and medicinal purposes in West Africa, typically in and around village
huts and gardens. The leaves, which have a potent scent, are frequently used to season meat,
particularly game, and to flavor soup. The leaves are widely used as an essential seasoning in
soups, especially ―pepper soup,‖ and other similar dishes in the southeast of Nigeria and beyond.
A number of researchers have been interested in medicinal plants and their bioactive chemicals
over the past 10 years due to their potential for managing and preventing both life-threatening
and chronic disorders such as arthritis, diabetes, cancer, and stroke (Edo et al., 2022). It is a
common perennial herbaceous plant with a potent aroma that is also commercially viable. Scent
leaf is found in Africa, Asia, and South America and it is a member of the Lamiaceae family
(Ugbogu et al., 2021). Also, scent leaf is used to spice fish, meat, soup, and stew. It is also used
to treat a variety of conditions such as aches, fever, inflammation, anemia, diarrhea and fungal
and bacterial infections (Shedoeva et al., 2019). It has enough number of macronutrients in it that
is valuable to the body. The leaf has a lot of nutritional value when taken in the right quantity
and in moderation.

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 Fig. 2.2: Scent Leaf

The species of basil known as Ocimum gratissimum is sometimes referred to as clove

basil, African basil, and wild basil in Hawaii. It is indigenous to southern Asia, the Bismarck
Archipelago, Africa, Madagascar, and the Bismarck Archipelago. Polynesia, Hawaii, Mexico,
Panama, the West Indies, Brazil, and Bolivia are among its naturalized nations. Ocimum
gratissimum (scent leaf) is most commonly utilized for its leaves in food. Ocimum gratissimum
is a member of the class of plants known as spices. The plant is an upright, little plum with
numerous barnacles that are often no taller than one meter. It belongs to the Labiatea family, and
it is a gratissimum specie. The plant is widespread in the tropics and subtropics, although tropical
Africa and India are where it is most varied. Despite the fact that it is grown commercially in
Vietnam, it is grown as a home garden crop throughout South East Asia. It has different uses. For
instance, its various parts are used for different treatment of diseases like headache, fever,
asthma and others (Taur and Patil, 2011). In various regions of the world, scent leave is used as a
cuisine in salads, soups, pastas, vinegars and jellies. It is well known to the Thai people because
they use it as a flavor for their food (Amit, et al., 2017). Aside from being utilized frequently in
modern medicine, scent leaf extracts are also used traditionally to cure ailments like fever,
cough, and body ache (Ghaleb, 2022). The essential oil of Ocimum gratissimum leaf contains
significant amounts of eugenol (Fig. 2.3), thymol (Fig. 2.4), camphor, pinene, limonene and
other chemical components that are responsible for many of its medicinal properties (Akpoghelie
et al., 2022).

9
Fig. 2.3: Chemical Structure of Eugenol. Fig. 2.4: Chemical Structure of Thymol.

Scent Leaf, just like any other plant, may be toxic if it is not used in the right manner.
Avoid using fragrance leaves if you have any allergies to plants in the mint or basil family. If
you develop hives, swelling or trouble breathing after consuming food made with the leaves, call
emergency authorities (Ademiluyi et al., 2023). Also, Scent leaves contain a lot of vitamin K
which is important for blood clotting. High quantities of vitamin K in food or supplements can
influence how warfarin and other blood thinners work. Therefore, before increasing their
consumption of fragrance leaf or any other variety of basil, anyone using blood thinners should
consult a doctor. One study conducted in Nigeria looked into the use of high doses of scent leaf
(Ocimum gratissimum) leaf extract to induce labor in pregnant women and found encouraging
results (Attah et al., 2012). Therefore, it is suggested that pregnant women avoid consuming
heavy amounts of this herb to prevent premature labor, so it is not toxic to them.

2.3 TAXONOMY

2.3.1 Taxonomy of Ebolo (Crassocephalum crepidioides)

Kingdom: Plantae

Phylum: Magnoliophyta

Class: Magnoliopsida

Subclass: Asteridae

Family: Asteraceae

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 Order: Asterales

Genus: Crassocephalum

Species: Crassocephalum crepidioides (Benth.)S.Moore

Common Name: Redflower Ragleaf

2.3.2 Taxonomy of Scent Leaf (Ocimum gratissimum)

Kingdom: Plantae - Plants

Phylum: Tracheobionta - Vascular plants

Superdivision: Spermatophyta - Seed plants

Division: Magnoliophyta - Flowering plants

Class: Magnoliopsida - Dicotyledons

Subclass: Asteridae

Order: Lamiales

Family: Lamiaceae Martinov - Mint family

Genus: Ocimum

Species: Ocimum gratissimum L.

Common Name: African basilP

2.4 MEDICINAL USES

2.4.1 Medicinal Uses of Ebolo Leaf

The use of Ebolo leaf is widespread in many tropical and subtropical regions, but is
especially prominent in tropical Africa. Its fleshy, mucilaginous leaves and stems are eaten as a
vegetable, and many parts of the plant have medical uses. The tender and succulent leaves and
stems of Ebolo are mucilaginous and are used as a vegetable in soups and stews, especially in

11
West Africa. It is much appreciated for its special flavor, which is sharp but not bitter. It is
especially popular in South-western Nigeria, from where the originally Yoruba name ‗Ebolo‘
derives. The nutritional composition of Ebolo leaves per 100g edible portion is: water 79.9%,
energy 64kcal, protein 3.3g, fat 0.7g, carbohydrate 14.0g, fibre 1.9g and Calcium 260mg. The
leaves are mildly stomachic. In Southern Nigeria, the leaves of Ebolo are used to treat
indigestion and in Congo, the leaf-sap is taken for upset tummy with colic and flatulence. The
leaves prepared as a lotion or a decoction is also used in Nigeria as an analgesic for headache. In
Tanzania, a mixture of the leaf sap of Crassocephalum crepidioides and Cymbopogon giganteus
Chiov is used orally and externally for the treatment of epilepsy. (Udomoh, 2019). Generally,
fresh leaves of Ebolo plant are used medicinally as laxatives, to relief stomach ache, colitis, etc.
(Oguntona, 1998; Grubben, 2004). In Tanzania, the dried leaf powder is applied as a snuff to
stop nose bleeding and smoked to treat sleeping sickness. Tannin found in the roots of the plant
is used to treat swollen lips. The plants are readily eaten by livestock and they are considered a
useful green fodder for poultry. Crassocephalum crepidioides has been used successfully as a
trap plant to collect adult corm weevils in banana plantations (Udomoh, 2019).

Ebola leaf helps lower bad cholesterol (LDL) levels while increasing good cholesterol
(HDL) levels. A balanced cholesterol level is essential for maintaining a healthy heart and
preventing cardiovascular diseases. It is a natural supplement that aids in managing cholesterol
levels and blood pressure. This leaf is traditionally used by people in Southwest, Nigeria, to help
regulate their blood pressure and flush out excess body water. Consuming Ebolo leaf can
significantly improve the digestive health. It is a natural dietary fiber source, promoting regular
bowel movements and preventing constipation. The anti-inflammatory properties of the Ebola
leaf make it an effective remedy for managing irritable bowel syndrome (IBS) symptoms. It
helps reduce abdominal pain, bloating, and discomfort associated with IBS. The anti-
inflammatory properties of Ebolo leaf also makes it an effective remedy for combating
inflammation-related diseases such as arthritis, asthma, and bronchitis. The leaf's positive
attributes aid in diminishing swelling and providing relief from sickness. Ebolo leaf is beneficial
for the liver as it aids detoxification and promotes overall liver health. The antioxidants and anti-
inflammatory compounds present in the leaf protect the liver from damage and help it function
optimally. Ebolo leaf is particularly beneficial for diabetic patients as it helps regulate blood
sugar levels (Oguntona, 1998). It stimulates the secretion of insulin, a hormone responsible for

12
regulating blood sugar, and lowers high blood sugar levels. By managing blood sugar levels,
Ebolo leaf can also help prevent diabetes-related complications such as nerve damage, kidney
problems, and eye disorders. This herb contains a compound called mukuloosides, which helps
lower blood sugar levels and prevent complications associated with diabetes. Ebolo leaf can
provide the body with ample protection against free radicals as a result of its abundant
antioxidants. These antioxidants, which include terpinene, quercetin, and tocopherols, have
immune-boosting, anticancer, anti-inflammatory, and neuroprotective effects. Ebolo leaf is a
natural remedy that fights stress and anxiety. The calming effects of these leaves can be felt after
just one or two sips, making it a popular choice for people who suffer from these conditions
(Udomoh, 2019). The leaves offer an alternative to other remedies like alcohol, which some
people turn to when feeling too anxious or stressed.

2.4.2 Medicinal Uses of Scent Leaf

According to studies, eating the Ocimum gratissimum leaf‘s stem helps prevent bad
breath and keeps one‘s teeth strong due to the presence of oral microorganisms present in scent
leave which helps to fight tooth decay (Mbegbu et al., 2021). Scent leaves have a wide range of
medical advantages. It has calcium and magnesium, both of which work to lower blood sugar
(Okoduwa et al., 2017). The islets that make insulin for the body are shielded by scent leaves. In
addition, it aids the heart to function correctly by removing toxic and cholesterol which the body
does not need. (Ademiluyi et al., 2023). Ocimum gratissimum assists with intestinal evacuation.
It has a relaxing effect on the stomach and speeds up digestion of food (Oppong et al., 2021). It
reduces blood sugar and prevent harm from getting into the pancreatic islets that make insulin
(Ademiluyi et al., 2023). Recent research has shown that Ocimum gratissimum is used as
medication for persons living with AIDS and the Human Immunodeficiency Virus (HIV)
(Ugbogu et al., 2021). Scent leaves can be used to stop stomach aches, dysentery, diarrhea, and
vomiting. It also helps in prompt food digestion (Ademiluyi et al., 2023). Blood sugar levels can
become normal when scent leaves are taken regularly and this is one of scent leaves‘ incredible
health advantages. The harm that nicotine and smoking have done to the body can be repaired by
scent leaves (Agholor et al., 2018).

Furthermore, Ocimum gratissimum provide a wide spectrum of therapeutic benefits that

have been utilized in traditional medicine for a very long time (Akinyemi et al., 2005). Most

13
people think of diarrhea as a temporary minor inconvenience. However, for many other people,
diarrhea is a serious, long-term problem. In fact, according to the World Health Organization,
diarrhea diseases are the second leading cause of death in children under five years old
(Mokomane et al., 2018). The usage of scent leaf is one of numerous treatments for diarrhea,
even though it is frequently disregarded. It can be used to treat diarrhea according to recent
studies. Eugenol, a substance with antibacterial and antispasmodic effect is the active component
of Ocimum gratissimum (Das et al., 2020). In other words, it can aid in the killing of germs that
are producing the diarrhea and also ease cramps and bloating that are frequently related to it
(Ukoroije et al., 2018). Scent leaf (Ocimum gratissimum) extract has been traditionally used to
treat ulcers due to its anti-inflammatory, analgesic and anti-ulcer properties (Agholor et al.,
2018). The specific ingredients in scent leaf extract that are believed to be responsible for its
anti-ulcer activity are eugenol and carvacrol, which are both phenolic compounds (Leyva-López
et al., 2017). Eugenol is a natural compound that has been shown to exhibit anti-inflammatory
and antioxidant properties (da Fonsêca et al., 2019). It is also known to inhibit the activity of
cyclooxygenase-2 (COX-2), an enzyme that plays a key role in the development of ulcers
(Prasad and Tyagi, 2015). Carvacrol is another phenolic compound found in scent leaf extract
that has been shown to possess antimicrobial, antioxidant, and antiinflammatory properties
(Mączka et al., 2023). It is believed to protect the gastric mucosa by increasing mucus
production and reducing gastric acid secretion (Mbegbu et al., 2021). Together, these compounds
work in synergy to protect the gastric mucosa from damage and promote healing of existing
ulcers (Hassan et al., 2021). Scent Leaf is also known as the ―fever‖ leaf because of the
antiseptic, antifungal and antibacterial qualities of its oil (Irshad et al., 2020). Scent Leaf is a
remedy for skin ailments because of the presence of antiseptic, antifungal and antibacterial
qualities. It is fights skin diseases such as ringworm when ground into a paste for skin care
(Ademiluyi et al., 2023).

2.5 ANTIOXIDANT IN FOODS

The body‘s trillion or so cells face formidable threats, from lack of food to infection with
a virus. Another constant threat comes from chemicals called free radicals. In very high levels,
they are capable of damaging cells and genetic material. The body generates free radicals as the
inevitable byproducts of turning food into energy. Free radicals are also formed after exercising

14
or exposure to cigarette smoke, air pollution, and sunlight (Helberg J. and Pratt D. A., 2021).
Antioxidants are compounds in foods that scavenge and neutralise free radicals. Evidence
suggests that antioxidant supplements do not work as well as the naturally occurring antioxidants
in foods such as fruits and vegetables. There are hundreds, probably thousands, of different
substances that can act as antioxidants. The most familiar ones are vitamin C, vitamin E, beta-
carotene, and other related carotenoids, along with the minerals selenium and manganese. They
are joined by glutathione, coenzyme Q10, lipoic acid, flavonoids, phenols, polyphenols,
phytoestrogens, and many more. Most are naturally occurring, and their presence in food is
likely to prevent oxidation or to serve as a natural defense against the local environment
(Klemchuk, 2000).

One possible reason many studies on antioxidant supplements do not show a health
benefit is because antioxidants tend to work best in combination with other nutrients, plant
chemicals, and even other antioxidants. For example, a cup of fresh strawberries contains about
80 mg of vitamin C, a nutrient classified as having high antioxidant activity. But a supplement
containing 500 mg of vitamin C (667% of the RDA) does not contain the plant chemicals
(polyphenols) naturally found in strawberries like proanthocyanins and flavonoids, which also
possess antioxidant activity and may team up with vitamin C to fight disease. Polyphenols also
have many other chemical properties besides their ability to serve as antioxidants. There is a
question if a nutrient with antioxidant activity can cause the opposite effect with pro-oxidant
activity if too much is taken. This is why using an antioxidant supplement with a single isolated
substance may not be an effective strategy for everyone (Smirnoff, 2001).

Differences in the amount and type of antioxidants in foods versus those in supplements
might also influence their effects. For example, there are eight chemical forms of vitamin E
present in foods. However, vitamin E supplements typically only include one form, alpha-
tocopherol. Epidemiological prospective studies show that higher intakes of antioxidant-rich
fruits, vegetables, and legumes are associated with a lower risk of chronic oxidative stress-
related diseases like cardiovascular diseases, cancer, and deaths from all causes. A plant-based
diet is believed to protect against chronic oxidative stress-related diseases (Herrera and Barbas,
2001).

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 2.6 TYPES OF ANTIOXIDANT IN FOOD

2.6.1 Antioxidants According to their Mechanism

i. Primary antioxidants: These essentially function as free radical terminators.

ii. Secondary antioxidants: These function by retarding chain initiation and it is also important
preventive antioxidants.
iii. Tertiary antioxidants.

Primary Antioxidants: Primary-antioxidants are important antioxidant enzymes certainly

produced by the body. These internal antioxidant enzymes serve as our body‘s most potent
defense against free radicals and harmful inflammatory reactions. There are only 3 primary-
antioxidants: Catalase (CAT), Glutathione Peroxidase (GPx) and SOD (Kunming, 2022).

Secondary Antioxidants: Secondary antioxidants frequently known as hydro peroxide

decomposers, act to convert hydro peroxides into non-radical, non-reactive and thermally stable
products. To yield synergistic stabilization effects, they are often used in combination with
primary antioxidants. Glucose-6-phosphate dehydrogenase, Glutathione reductase, ubiquinone
and glutathione-s-transferase, are the secondary antioxidants. Iron, copper, zinc, manganese and
selenium also increase the antioxidant enzyme activities (Kunming, 2022).

Tertiary Antioxidants: Tertiary oxidants by repairing the oxidized molecules and there function
takes place (some enzymes of DNA, proteolytic enzymes, etc.) through sources like consecutive
antioxidants or dietary (Kunming, 2022).

2.6.2 Antioxidants According to their Nutrients and Food Sources

Vitamin C: Broccoli, Brussels sprouts, cantaloupe, cauliflower, grapefruit, leafy greens (turnip,
mustard, beet, collards), honeydew, kale, kiwi, lemon, orange, papaya, snow peas, strawberries,
sweet potato, tomatoes, and bell peppers (all colors).

Vitamin E: Almonds, avocado, Swiss chard, leafy greens (beet, mustard, turnip), peanuts, red
peppers, spinach (boiled), and sunflower seeds.

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Carotenoids including beta-carotene and lycopene: Apricots, asparagus, beets, broccoli,
cantaloupe, carrots, bell peppers, kale, mangos, turnip and collard greens, oranges, peaches, pink
grapefruit, pumpkin, winter squash, spinach, sweet potato, tangerines, tomatoes, and watermelon.

Selenium: Brazil nuts, fish, shellfish, beef, poultry, barley, brown rice.

Zinc: Beef, poultry, oysters, shrimp, sesame seeds, pumpkin seeds, chickpeas, lentils, cashews,
fortified cereals.

Phenolic compounds: Quercetin (apples, red wine, onions), catechins (tea, cocoa, berries),
resveratrol (red and white wine, grapes, peanuts, berries), coumaric acid (spices, berries),
anthocyanins (blueberries, strawberries).

2.7 ANTIOXIDANT METABOLITES

The antioxidant networks in the body are complex and are composed of several
components. These may be endogenous factors such as Glutathione, thiols, haem proteins,
Coenzymes Q, bilirubin and urates. These may also be endogenous enzymes like GSH reductase,
GSH transferase, GSH peroxidises, Superoxide dismutase and Catalases (Ananya, 2023).

2.7.1 Dietary Factors

Some nutritional and dietary factors also function as antioxidant metabolites or parts of
the antioxidant metabolic pathways. These include Ascorbic acid or vitamin C, Tocopherols or
vitamin E, beta carotenes and retinoids, Selenium, Methionine etc. (Ananya, 2023).

2.7.1.1 Vitamin C or Ascorbic Acid

This is a monosaccharide antioxidant found in both animals and plants. This is one of the
essential nutrients for living organisms like humans. It must be obtained from the diet of humans
and is a vitamin. Most other animals are able to produce this compound in their bodies and do
not require it in their diets. The vitamin is maintained in its reduced form by reaction with
glutathione within the cell. It can be catalysed by protein disulfide isomerase and glutaredoxins.
Since it exists as a reduced agent, it can neutralize reactive oxygen species such as hydrogen
peroxide. Ascorbic acid also is a substrate for the antioxidant enzyme ascorbate peroxidise. This
is important for preventing oxidative stress particularly in plants (Ananya, 2023).

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2.7.1.2 Vitamin E or Tocopherols

Vitamin E includes around eight related tocopherols and tocotrienols. These are fat-
soluble vitamins with antioxidant properties. Of these, alpha tocopherol is the most studied
component as it has the highest bioavailability. The body absorbs this vitamin along with fats. It
has been claimed that the α-tocopherol form is the most important lipid-soluble antioxidant. This
vitamin protects membranes from oxidation by reacting with lipid radicals produced in the lipid
peroxidation chain reaction. The reaction removes free radical intermediates and prevents the
propagation reaction. Once completed the oxidised α-tocopheroxyl radicals can be recycled back
to the active reduced form through reduction by other antioxidants, such as ascorbate, retinol or
ubiquinol. This α-tocopherol protects glutathione peroxidase 4 (GPX4)-deficient cells from cell
death (Ananya, 2023).

2.7.1.3 Glutathione

This is an endogenous antioxidant factor. Glutathione contains cysteine and is a peptide

found in most forms of aerobic life. It is not required in the diet and is instead synthesized in
cells from its constituent amino acids. Glutathione contains a thiol group in its cysteine moiety
which is a reducing agent and can be reversibly oxidized and reduced. In cells, glutathione is
maintained in the reduced form by the enzyme glutathione reductase. This reduced glutathione
reduces other metabolites and enzyme systems, such as ascorbate in the glutathione-ascorbate
cycle, glutathione peroxidases and glutaredoxins (Ananya, 2023).

2.7.2 Classification of Antioxidant Metabolites

Antioxidant metabolites are further classified as soluble in water (hydrophilic) or in lipids

(hydrophobic). Water-soluble antioxidants react with oxidants in the cell cytosol and the blood
plasma. On the other hand lipid-soluble antioxidants protect cell membranes from lipid
peroxidation. The actions of each of these metabolites are dependent on each other as the
metabolic pathways are complex. Selenium and zinc are commonly referred to as ''antioxidant
nutrients''. These alone do not have antioxidant properties but are required for the activity of
some antioxidant enzymes (Ananya, 2023).

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2.8 USE OF ANTIOXIDANT IN TECHNOLOGY

2.8.1 Food Preservatives

Antioxidants are used as food additives to help guard against food deterioration.
Exposure to oxygen and sunlight are the two main factors in the oxidation of food, so food is
preserved by keeping in the dark and sealing it in containers or even coating it in wax, as with
cucumbers. However, as oxygen is also important for plant respiration, storing plant materials in
anaerobic conditions produces unpleasant flavors and unappealing colors (Kader et al., 1989).
Consequently, packaging of fresh fruits and vegetables contains an ≈8% oxygen atmosphere.
Antioxidants are an especially important class of preservatives as, unlike bacterial or fungal
spoilage, oxidation reactions still occur relatively rapidly in frozen or refrigerated food (Zallen et
al., 1975). These preservatives include natural antioxidants such as ascorbic acid (AA, E300) and
tocopherols (E306), as well as synthetic antioxidants such as propyl gallate (PG, E310), tertiary
butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA, E320) and butylated
hydroxytoluene (BHT, E321) (Iverson, 1995).

2.8.2 Cosmetics Preservatives

Antioxidant stabilizers are also added to fat-based cosmetics such as lipstick and
moisturizers to prevent rancidity. Antioxidants in cosmetic products prevent oxidation of active
ingredients and lipid content. For example, phenolic antioxidants such as stilbenes, flavonoids,
and hydroxycinnamic acid strongly absorb UV radiation due to the presence of chromophores.
They reduce oxidative stress from sun exposure by absorbing UV light (Débora et al., 2019).

2.8.3 Industrial Uses

Antioxidants may be added to industrial products, such as stabilizers in fuels and

additives in lubricants, to prevent oxidation and polymerization that leads to the formation of
engine-fouling residues (Boozer et al., 1955). Antioxidant polymer stabilizers are widely used to
prevent the degradation of polymers such as rubbers, plastics and adhesives that causes a loss of
strength and flexibility in these materials. Polymers containing double bonds in their main
chains, such as natural rubber and polybutadiene, are especially susceptible to oxidation and
ozonolysis. They can be protected by antiozonants. Oxidation can be accelerated by UV

19
radiation in natural sunlight to cause photo-oxidation. Various specialised light stabilisers, such
as HALS may be added to plastics to prevent this. Synthetic phenolic and aminic antioxidants are
increasingly being identified as potential human and environmental health hazards . (Liu and
Mabury, 2020).

2.9 HEALTH BENEFITS OF ANTIOXIDANTS

Antioxidants can prevent or slow cell damage caused by free radicals, which are unstable
molecules that the body produces as a reaction to environmental and other pressures.
Antioxidants are said to help neutralize free radicals in our bodies, and this is thought to boost
overall health. The damage caused by oxidative stress has been linked to cancer, atherosclerosis,
and vision loss. It is thought that the free radicals cause changes in the cells that lead to these and
possibly other conditions, an intake of antioxidants is believed to reduce these risk (Lobo et al.,
2010). According to Lobo et al. (2010), Antioxidants act as radical scavenger, hydrogen donor,
electron donor, peroxide decomposer, singlet oxygen quencher, enzyme inhibitor, synergist, and
metal-chelating agents. Antioxidant supplements may help reduce vision loss due to age-related
macular degeneration in older people. However, there is a lack of evidence that a higher intake of
specific antioxidants can reduce the risk of disease. In most cases, results have tended to show no
detrimental effect (Lobo et al., 2010).

A diet high in antioxidants may reduce the risk of many diseases (including heart disease
and certain cancers). Antioxidants scavenge free radicals from the body cells and prevent or
reduce the damage caused by oxidation. The protective effect of antioxidants continues to be
studied around the world. For instance, men who eat plenty of the antioxidant lycopene (found in
red fruits and vegetables such as tomatoes, apricots, pink grapefruit and watermelon) may be less
likely than other men to develop prostate cancer. Lycopene has also been linked to reduced risk
of developing type 2 diabetes mellitus. Lutein, found in spinach and corn, has been linked to a
lower incidence of eye lens degeneration and associated vision loss in the elderly. Research also
suggests that dietary lutein may improve memory and prevent cognitive decline. Studies show
that flavonoid-rich foods prevent some diseases, including metabolic-related diseases and cancer.
Apples, grapes, citrus fruits, berries, tea, onions, olive oil and red wine are the most common
sources of flavonoids (Better Health Channel, 2023).

20
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