ABSTRACT
Methanolic and ethanolic extracts of Moringaoleifera leaves, seeds, roots and Piperguineense (Uziza) leaves were evaluated for antioxidant activity assayed by Total Phenol Content (TPC),1,1 -diphenyl - 2 - picrylhydrazyl (DPPH), 2, 2 – azino – bis 3 –ethyl benthiazoline-6-acid (ABTS), Total Antioxidant Capacity (TAC) and reducing power invitro. Gallic acid was used as standard in total phenol assay. Trolox equivalent was used as standard in ABTS, while ascorbic acid was used in reducing power, DPPH and total antioxidant capacity assays. The antioxidant activity of the extracts ranged from 2.13 to 16.64 µg/g for TPC, 0.24 to 0.89 mg/mL for DPPH, 5.66 to 10.09 µg/mL for ABTS, 3.24 to 6.48 µg/mL for reducing power and 9.76 to 53.25µg/mL for TAC. The highest valueranged from 9.76 ascorbic acid equivalent (AAE) µg/mL in Piper hhhguineense leaf to 53.25 AAE µg/mL in moringa seed while DPPH content was the lowest and ranged from 0.24 mg/mL in Piper guineense leaf to 0.89mg/mL inmoringa seed. In the TPC, moringa leaf extract had the highest value of 16.64 µg/g while the seed extract exhibited the least value of 2.13 µg/g. Also, moringa seed extract had the highest value of 0.89 mg/mL in DPPH and the least value 0.24 mg/mL seen in Piper guineense leaf extract. Piper guineense leaf had the greatest activity since lower values indicate higher activity. The root extract of moringa had the highest value of 10.09µg/mL in ABTS while Piper guineenseleaf extract had the least value of 5.66µg/mL. In the reducing power, the highest value (6.48 µg/mL)observed in moringa leaf while Piper guineense leaf had the least value of 3.24µg/mL. Moringaseed extract had the highest value of 53.25µg/mL in the total antioxidant capacity while Piper guineense seed extract exhibited the least activity. The proximate composition of the extracts ranged from 5.12 to 12.16%, 5.58 to 12.60%, 4.31 to 10.47%, 13.91 to 25.05%, 0.05 to 3.30% and 40.59 to 68.39% for moisture, ash, fibre, protein, lipid and carbohydrate content respectively. Piper guineense leaf extract had the highest moisture content of 12.16% while moringa seed had the least with value 5.12%. Moringa leaf extract exhibited the highest value in ash and fibre content with values of 12.60% and 10.4% respectively. Meanwhile moringa seed extract had the highest carbohydrate content of 68.39 %. In terms of the mineral and vitamin content, the extract of moringa leaf exhibited the highest value in potassium and magnesium content with values of 63.23 mg/100g and 57.01 mg/100g respectively while Piper guineense leaf had the highest value of 48.18mg/100g for calcium. The extract of Piper guineense leaf showed the highest value in β – carotene (pro-vitamin A)and vitamin C content with values 3.14 mg/100g and 134.34 mg/100g respectively. There was significant (p< 0.05) difference in the proximate composition except for moisture content were there was no significant (p> 0.05) difference between two samples, minerals and vitamin contents of moringa leaf, the seed, the root and Piperguineense leaf extracts. From this analysis therefore, moringa leaf and Piperguineense leaf could serve as prospective source of natural antioxidants to food and health industries.
TABLE OF CONTENTS
Title page i
Declaration ii
Certification iii
Table of Contents iv
List of Tables vii
Abstract viii
CHAPTER 1: INTRODUCTION
1.1 Background of the Study 1
1.2 Statement of the problem 4
1.3 Objectives of the study 5
1.4 Justification of the study 5
CHAPTER 2: LITERATURE REVIEW
2.1 Origin and Distribution of Moringa Plant 6
2.2 Nutritional value of Moringa Plant 6
2.2.1 Nutritional value of fresh moringa leaves 7
2.2.2 Nutritional value of dry moringa leaf powder 8
2.2.3 Nutritional value of cooked moringa leaves 10
2.2.4 Medicinal benefits or disease treatment and
prevention of moringa 12
2.2.4.1 Cancer
prevention 13
2.2.4.2 Moringa and diabetes 13
2.2.4.3 Moringa’s anti-aging compound 14
2.3 Role of Antioxidants in the inhibition of oxidation 14
2.4 Free Radicals 19
2.5 Health effect of antioxidants related to
diets 19
2.6 Adverse Effects; Antioxidative Stress 20
2.7 Uses of Antioxidants in Technology and
Food Preservation 22
2.8 Polyphenolic Antioxidants 23
2.9 Antioxidant Vitamins 25
2.9.1 Vitamin C 26
2.9.2 Vitamin E 26
2.10 Non-Vitamin Antioxidants 28
2.11 Antioxidant Activity Determination
Assays/Principles and Theories 29
2.11.1 Total phenol content 29
2.11.2 1,1-diphenyl-2-picrylhydrazyl(DPPH) 30
2.11.3 Reducing power of moringa leaves, roots, seeds
and Piperguineense leaves 30
2.11.4 Total antioxidant capacity 31
2.11.5 2,2 – azino – bis 3 – ethyl
benthiazoline-6-acid (ABTS) 31
2.12 Moringa and its Antioxidant Galore 31
2.13 Piperguineense 32
2.13.1 Piperguineense
and its medicinal benefits 32
2.13.2 Antioxidant and antioxidant activity of Piperguineense 34
2.13.3 Chemical composition of Piperguineense 34
CHAPTER 3: MATERIALS AND METHODS
3.1 Sample Collection 36
3.2 Sample Preparation 36
3.2.1 Flour production of flour from moringa
leaves 36
3.2.2 Production of moringa seed powder 36
3.2.3 Production of moringa root powder 37
3.2.4 Production of powder from Piperguineense leaf 37
3.3 Extraction of Plant Material 40
3.4 Antioxidant Determination 41
3.4.1 Determination of Total Phenol Content 41
3.4.2 1,1-diphenyl -2 – picrylhydrazyl (DPPH) radical scavenging assay 41
3.4.3 Total antioxidant capacity (TAC) 42
3.4.4 2, 2 –
azino – bis 3 –ethyl benthiazoline-6-acid
(ABTS)
radical scavenging activities 42
3.4.5 Reducing power of moringa leaves, roots,
seeds and Piperguineense leaves 43
3.5 Proximate Determination 44
3.5.1 Determination of moisture content 44
3.5.2 Determination of ash content 45
3.5.3 Determination of crude fibre content 45
3.5.4 Determination of crude protein content 46
3.5.5 Determination of fat content 47
3.5.6 Determination of carbohydrate content 48
3.6 Determination of Total Vitamins and
Minerals 48
3.6.1 Determination of beta - carotene 48
3.6.2 Determination of ascorbic acid 49
3.6.3 Determination of calcium, potassium and
magnesium 50
3.7 Statistical Analysis 50
CHAPTER
4: RESULTS AND DISCUSSION
4.1 Antioxidants Compostion of Moringa
Leaves, Seeds, Roots and Piper
Guineense
Leaves 51
4.1.1 Total phenol content (TPC) 51
4.1.2 1,1- diphenyl-2-picrylhydrazyl (DPPH)
radical scavenging 52
4.1.3 2, 2 – azino – bis 3 –ethyl benthiazoline-6-acid
(ABTS) scavenging activity 53
4.1.4 Reducing power of moringa leaves, roots,
seeds and Piperguineense leaves 54
4.1.5 Total antioxidant capacity 55
4.2 Proximate Composition 57
4.3 Mineral Composition 62
4.4 Vitamin Composition 63
CHAPTER
5: CONCLUSION AND RECOMMENDATION 75
References 77
LIST OF TABLES
2.2.1 Mean nutritional values of 100g Fresh
Moringa leaves 8
2.2.2 Mean nutritional values of 100g Moringa leaf
powder 9
2.2.3 Analysis
of nutritional value of Moringa pods, fresh leaves
and dried leafy powder per 100g of
edible portion 11
2.9.2 List
of antioxidants and polyphenol antioxidant; measurement and levels in food 24
2.11.1 List of antioxidant vitamins, their benefits
and food sources 25
2.14.3 Mean nutritional values of Piperguineense leaf powder per 100g 28
2.14.4 Phytochemical constituents of Piperguineense 35
4.1 Antioxidant activity of ethanol and
methanol extracts of Moringaleaf,
seed,
root,
and Uziza leaf 35
4.2 Proximate
composition of Moringa leaf, Moringaseed, Moringaroot and
Uziza leaf 56
4.3 Mineral
composition of Moringa leaf, Moringaseed, Moringaroot
andUziza leaf 61
4.4 Vitamin
composition of Moringa leaf, Moringaseed, Moringaroot
andUziza leaf 63
LIST
OF FIGURES
2.1 Initiation stage of oxidation action on
lipids 15
2.2 Propagation stage of oxidation action on
lipids 16
3.1 Flow diagram for the production of
Moringa leaf powder 38
3.2 Flow
diagram for the production of Moringa seed powder 39
3.3 Flow
diagram for the production of Moringa root powder 39
3.4 Flow
diagram for the production of Piperguineense(uziza)
leaf powder 40
CHAPTER 1
INTRODUCTION
1.1 BACKGROUND OF THE
STUDY
Moringa
(Moringa oleifera) plant has become famous in tropical and subtropical areas
of the world although it is a plant native India subcontinent. The tree is
known by such regional names as Benzoline, Drumstick tree, Horse raddish tree,
Maranga and Sajna (Fahey, 2005). The tree is known as one of the world’s most
useful trees because every part of Moringa tree is beneficial for either food,
medication or industrial purposes (Khalafalla, et al., 2010). The tree has the ability to increase the quality of
nutrition, foster rural development and boost food security (Hsu, 2006). The leaves have great nutritional value such
as vitamins, minerals and amino acids as shown in studies from Nigeria and
other countries (Anwar et al., 2007).
As a result of this, the leaves have been used to combat malnutrition
especially among infants and nursing mothers. The Moringa plant (Moringa
oleifera) is known worldwide for its nutritional and medicinal benefits and
industrial uses such as: leaves - nutritional, forage, biomas, medicinal,
flowers - nutritional, medicinal, honey,
fruits - nutritional, medicinal, roots - medicinal, seeds - cosmetics, food,
water treatment, medicinal and wood - paper, alcohol production, animal feed
and medicinal.
Moringa
leaf powder is an excellent source for many of the nutrients such as
carbohydrates, fat, fibre, magnesium, calcium, vitamins A, C, and E, potassium
and protein (Anjorin et al., 2010).
In addition, compared to most other plant food sources (that has generally
about 10%), the leaves have a high dry matter content of about 20-25%. This
makes it even more beneficial as a fresh vegetable source. There are some
factors that can alter the values of these nutrients. They include
environmental conditions (soil, climate), farming methods (irrigation,
fertilizers), maturity of the leaves, harvesting season, the generic background
of the trees as well as the processing methods (Sauveur and Broin, 2010). If
leaves should be dried in an area not protected from light, there is the
tendency of the leaves to lose vitamins. Moringa powder is dried at a
temperature of about 50 – 55oC. The leaf powder still constitutes a
very rich nutritional supplement even if a large amount of vitamins are lost
during drying and storage (Anwar et al.,
2007). As for Moringa roots and seeds, the extract of the roots contain several
procyanidin which exhibited strong in -
vitro antioxidant activity. The
extract of the leaves contains chlorogenic acid, alkaloids, polyphenols,
flavonoids, tannins, saponins, anthraquinones and secondary metabolites (Wang, et al.,
2016). The antibiotic properties of the seeds make them valuable in treatment
of infections and also in reduction of the frequency of epileptic fits and
treatment of arthritis and rheumatoid disorders (Wang et al., 2016).
Antioxidants
are molecules capable of decreasing or preventing the oxidation of substrate
molecules. Oxidation reaction subsequently can cause a large number of
cardiovascular diseases in humans such as atherosclerosis, diabetes mellitus,
chronic inflammation, neurode - generative disorders, aging and certain types
of cancer (Valkoot et al., 2004).
Moringa
contains antioxidants such as campesterol, beta – carotene, chlorophyll, vitamin
C, zanthophyll and zeaxanthin (Asaolu and Omotayo, 2007). Zeatin for example is
a plant hormone derived from purine ademine. It has been reported to have
several in – vitro anti – agency effects on the human fibroblasts (Anonymous,
2010). These antioxidants help to protect the body against “free radicals”
which are unstable molecules that cause damage to the body.
Piper guineense
(African black pepper or Uziza) is a West African spice plant with medicinal
property that belongs to the piperacear
family and widely used traditionally in the treatment of various ailments. It
also contains proteins, carbohydrates, fat, vitamins and minerals. Piper guineense (Uziza leaf) is a known
spice extensively used in some communities of Nigeria for seasoning of soups,
sauces and pepper soup. Traditionally, it is used to prepare food for nursing
mothers because it is believed to be very useful in cleansing the uteral lining
after birth, used in treating diarrhea, used as antimalarial and anticonvulsant
and also as antifungal drugs (Uba, 1997). Phenols are synthesized through the
Shikimic acid pathway, a metabolic route used by plants for the biosynthesis of
aromatic amino acids such as phenylalanine, tyrosine and tryptophan. Piper guineense is said to possess these
phenolic compounds which are known to have anti – fungal and anti – microbial
effects. Piper guineense is one of
the most pungent and flavourful of all other leafy vegetables and this is the
reason why the leaves are used as spices for preparing soups for post –
parturient women (Stephen et al., 2016). According to Ojimelukwe and
Ukom, 2017, it is also belived that Piper
guineense leaf or its restorative soup serves some important roles for
lactation, after – birth cleansing of woman’s womb and restoration of the
woman’s womb and tummy to shape after child birth within a period of three
months.
The
phytochemical studies of Piper guineense
revealed the presence of alkaloids, steroids glycosides, saponins, flavonoids,
tannins and phenolic compounds (Elizerbeth et
al., 2016). The flavonoids have the
ability to scavenge free radicals and are also potent water – soluble
antioxidants and free radical scavengers thus, preventing oxidative cell
damage. They also have some anti – cancer and anti – ulcer activities and
protection against different levels of carcinogenesis (Becky, 2017). The
alkaloids are one of the most therapeutically efficient significant bioactive
substances in plants. The seed of Piper
guineense contains piperine which gives it a spicy heat and is also
reported to dramatically increase the absorption of selemium and vitamin B
content (Nalini et al., 2006). This medicinal plant has
been known to contain chemical substances. Among others are alkaloids which are
medicinally important and have most of the valuable drugs. Piper guineense also contain tannins and due to their astringent
characteristics, they are used in medicine. Alkaloids and tannins are known to
possess anti – herbivore defense function in plants (Harbone, 1998) and as a
result of this, their presence in medicinal plants could be very important and
serving as a deterrent to grazers (Edeoga and Eriata, 2011). Saponins which are
glycosides are found in this plant, and are also widely occurring in a variety
of plants. Saponins are useful as an expectorant and emulsifying agent in
medicine and also in preventing invasion of diseases (Basu and Rastogi, 1967).
Flavonoids also found in Piper guineense are
the commonest phenolic constituents generally distributed throughout the plants
kingdom (Harbone, 1998). Some flavonoids have antibacterial properties and
their gram – positive species are more sensitive to isoflavanones when compared
to their negative counterpart.
1.2 STATEMENT
OF PROBLEM
It
has not been established clearly among the different parts of Moringa, the
particular part of the plant that offers antioxidant properties or if the
different parts can be used as alternatives to the other. Furthermore, it has
not been established between the duo which would offer the best antioxidant
activity, with a more comparably appropriate extraction method for such. The
use of different parts of moringa in dried forms is common and widely known in
many regions, as well as the use of fresh Piper
guineense in soups as vegetable
and spices but since the leaves are more easily perishable, it is therefore
necessary to evaluate the possibility of that offering a comparatively
favorable retention of the antioxidant properties.
Moreover,
the natural antioxidants from these plants are believed to be safe as they
prevent oxidative damages, carcinogenic attributes and other toxic properties
caused by synthetic antioxidants such as butylated hydroxyanisole(BHA),
butylated hydroxytoluene (BHT) and propyl gallate (PG) used in food products to
prevent oxidative damage.
1.3 OBJECTIVES
OF THE STUDY
The
broad objective of this study is to assess the antioxidant properties of Moringa
leaves, seeds, roots and Piper guineense leaf.
The specific objectives were to:
(i)
extract phenolic (antioxidant)
compounds from Moringa leaves, seeds, roots and Piper guineense leaf.
(ii)
determine the total phenol
content in Moringa leaves, seeds, roots and Piper
guineense leaf extracts.
(iii)
determine the antioxidant
activities of Moringa leaves, seeds, roots
and Piper guineense leaf extracts
assayed by DPPH, ABTS, TAC and reducing power.
(iv)
determine the proximate,
minerals and vitamins composition of Moringa leaves, roots, seeds and Piper guineense leaves.
1.4 JUSTIFICATION OF THE
STUDY
Antioxidants
are molecules that help prevent the body against free radicals that leads to
oxidation. Plants possess these antioxidants that protect themselves but recent
research demonstrates that they can also protect humans against diseases. There
has been evidence that Moringa and Piper
guineense have strong antioxidant
properties which can help annihilating the health prosper of many.
This
research work will give people knowledge on how natural antioxidants can improve
the shelf life of food products, curb the effect of free radicals in the human
system which results as chronic inflammation, neuro - degenerative disorders
and atherosclerosis.
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