ABSTRACT
The aim of this research work was to evaluate the effect ofCocosnuciferaand Elaeisguineensisoils on alloxan-induced diabetes mellitus. Virgin coconut oil (VCO) and palm kernel oil (PKO) were extracted using the hot extraction process. Diabetes was induced in rats and the initial glucose level taken before the oils were administered alone and in combination with metformin tothe test animals. Blood was obtained from the tail vein of the test animals in 0, 2, 4, 8, 12, 24 hours, 3days, 7days and 14 days post administration, respectively. The blood glucose level was determined using a fine test glucometer. The result of the analysis revealed that VCO and PKO yielded 15.75 % and 13.50 % w/w oil, saponification values of 267.712 ± 0.07mgKOH/g and 361.377 ± 1.69 mgKOH/g and acid value of 0.804 ± 0.09mgKOH/g and 11.088 ± 0.09 mgKOH/g, respectively. The hypoglycaemic result revealed that the daily doses of PKO was able to cause a reduction in mean blood glucose levels compared to negative control, bringing blood glucose levels down to normal range within 7 days of administration. On the other hand, although the VCO drastically brought down glucose level, it could not bring it down to normal level within 7 days, but the concomitant administration of VCO with metformin showed an improvement on the efficacy of metformin. This study therefore revealed that both PKO and VCO possess hypoglycaemic properties and a concomitant administration of VCO and metformin slightly enhances the efficacy of the drug.
TABLE OF CONTENTS
Title page – – – – – – – – – i
Declaration – – – – – – – – – ii
Certification – – – – – – – – – iii
Acknowledgements – – – – – – – – iv
Abstract – – – – – – – – – v
Table of Contents – – – – – – – – vi
List of Tables – – – – – – – – – ix
List of Figures – – – — – – – – – x
CHAPTER ONE: INTRODUCTION AND LITERATURE REVIEW
1.1 General introduction – – – – – – 1
1.2 Statement of Research problem – – – – – 2
1.3 Justification of the study – – – – – – 3
1.4 Aim of research – – – – – – – 3
1.5 Objectives of study – – – – – – – 3
1.6 Statement of research hypothesis- – – – – – 4
1.7 Literature Review – – – – – – – 4
1.7.1 Diabetes Mellitus – – — – – – – 4
1.7.2 Epidemiology of Diabetes Mellitus – – – – 5
1.7.3 Types of Diabetes Mellitus – – – – – – 5
1.7.3.1 Type 1 Diabetes Mellitus – – – – – – 5
1.7.3.2 Type 2 Diabetes Mellitus – – – – – – 7
1.7.3.3 Gestational Diabetes Mellitus- – – – – – 8
1.7.4 Management of Diabetes Mellitus – – – – – 8
1.7.5 Alloxan-Induced Diabetes Mellitus– – – – – 8
1.7.5.1 Mechanism of Alloxan-Induced Diabetes Mellitus – – 9
1.7.6 Metformin Use in Management of Diabetes Mellitus- – – 10
1.7.6.1 Pharmacokinetic Parameters of Metformin – – – 12
1.7.6.2 Physicochemical Properties of Metformin – – – – 12
1.7.6.3 Mechanism of Antihyperglycaemic Action of Metformin- – 13
1.7.7 Virgin Coconut Oil (VCO)- – – – – – 14
1.7.7.1 Chemical Properties of Virgin Coconut Oil- – – – 14
1.7.7.2 Physicochemical Properties of virgin coconut oil – – 15
1.7.7.3 Mechanism of Action of Virgin Coconut Oil in Glycemic Control- 15
1.7.8 Palm Kernel Oil – – – – – – – 15
1.7.8.1 Chemical and Physicochemical Properties of Palm Kernel Oil- – 16
CHAPTER TWO: MATERIALS AND METHODS
2.1 Materials – – – – – – – – 17
2.2 Methods – – – – – – – – 17
2.2.1 Extraction of VCO – – – – – – – 17
2.2.2 Extraction of PKO – – – – – – – 18
2.2.3 Determination the Physicochemical Properties of the oils- – – 18
2.2.3.1 Determination of Density- – – – – – – 18
2.2.3.2 Determination of Acid value – – – – – 18
2.2.3.3 Determination of Saponification Value – – – – 19
2.2.3.4 Determination of percentage oil yield – – – – 19
2.2.4 Hypoglycaemic Study – – – – – – 20
2.2.4.1 Induction ofAlloxan-Induced Diabetes- – – – – 20
2.2.4.2 Animal Grouping and Administration of PKO, VCO and Metformin- 20
2.2.4.3 Blood Collection and Determination of Fasting Blood Glucose Level- 21
2.2.5 Data and Statistical Analysis – – – – – 21
CHAPTER THREE: RESULTS AND DISCUSSION
3.1 Results – – – – – – – – – 22
3.1.1 Extraction of VCO and PKO – – – – – – 22
3.1.2 Physicochemical Analysis of VCO and PKO- – – – 22
3.1.3 Hypoglycemic Study- – – – – – – – 22
3.2 Discussion- – – – – – – – – 25
CHAPTER FOUR: SUMMARY, RECOMMENDATIONS AND
CONCLUSION
4.1 Summary- – – – – – – – – 29
4.2 Conclusion- – – – – – – – – 29
4.3 Contribution to knowledge – – – – – – 30
4.4 Recommendations – – – – – – – 30
REFERENCES
LIST OF TABLES
Table 3.1: Physicochemical Properties of VCO – – – – 22
Table 3.2: Result of hypoglycaemic study of palm kernel oil and virgin coconut
oil in alloxan-induced rats after 14 days treatment. – – – 22
Table 3.3: Result of the effect of concomitant administration of metformin with
VCO and PKO on the efficacy of metformin after 14 days treatment.- 23
Table 3.4: Comparison of antidiabetic effect of VCO and PKOon blood glucose
levels of alloxan-induced diabetic rats after 14 days treatment. – 24
LIST OF FIGURES
Figure 1: Chemical Structure of Metformin – – – – – 10
Figure 2: Graph of hypoglycaemic study of palm kernel oil and virgin coconut
oil in alloxan- induced rats after 14 days treatment. – – – – 23
Figure 3: Graph of the effect of concomitant administration of metformin with
VCO and PKO on the efficacy of metformin after 14 days treatment.- 23
Figure 4: Antidiabetic effect of VCO and PKOon blood glucose levels of
alloxan-induced diabetic rat for 14 days treatment. – – 24
CHAPTER ONE
1.0 INTRODUCTION AND REVIEW OF RELATED LITERATURE
1.1Introduction
Natural products have been an essential part of healthcare and disease management. Many of these products have been identified, studied and found to be very useful in the treatment and management of several disease conditions. Natural products have a wide range of diversity of multi-dimensional chemical structures; in the meantime, the utility of natural products as biological function modifiers has also won considerable attention (Yuan et al., 2018).
Diabetes mellitus is a group of metabolic diseases characterized by chronic hyperglycaemia due to insufficient insulin action which leads to abnormalities in almost the entire metabolic system including carbohydrate, protein and lipid metabolism (Seino et al., 2010). Chronic hyperglycaemia affects several organs in the body causing them to dysfunction and failure of the organ may result.
The aetiology of diabetes mellitus varies significantly but always includes defects in insulin secretion, response or both in the course of the disease. Mostly, patients with diabetes mellitus have either type 1 diabetes mellitus (which immune mediated or idiopathic) or type 2 diabetes mellitus (formerly known as non-insulin dependent diabetes mellitus). Diabetes can also be related to gestational hormonal environment, genetic defects, other infections and certain drugs (Baynest, 2015).
There is a great challenge for healthcare providers and research scientist in addressing the increased demands for management of chronic illnesses such as diabetes mellitus. It is therefore imperative that several management strategies be implemented and novel ideas and products introduced to curb or slow down the progress and also improve the patients’ quality of life. This has led to the progression in diabetes mellitus management from solely the use of insulin therapy to the use of other means such as oral hypoglycaemic agents, dietary modifications and use of natural exclusively or in combination with oral hypoglycaemic agents such as that embarked upon by this work, which is seeking to explore the hypoglycaemic effect of virgin coconut oil (VCO) and palm kernel oil (PKO) alone and their synergistic effect when combined with hypoglycaemic drug of choice, metformin, in the treatment of alloxan induced diabetes in rat.
1.2 Statement of research problem
Hypoglycaemic agents or oral anti glycaemic agents have been employed extensively in the management and control of diabetes mellitus (type 2) with good therapeutic outcomes. However, there are evidences of the use of natural products in the management of this disease and foods rich in lipids have been shown to improve the therapeutic effect of some hypoglycaemic agents. Some of these products are rich in fatty acids especially the medium and long chain fatty acids. VCO and PKO are known to be rich in these classes of fatty acids. These oils are readily available in the local market and can be accessed by low income and high income popularities. Besides, food is commonly prepared with these oils and eaten by many people including diabetics. To the best of my knowledge, there is very little documentation on the hypoglycaemic activity of VCO whereas nothing is reported about PKO and the concomitant effect of these oils with any hypoglycaemic agent. So it became imperative to investigate the hypoglycaemic effects of these oils as well as their combined effect with a common and readily affordable drug of choice (metformin) widely used in the management of diabetes.
1.3 Justification of the study
VCO and PKO have been shown to aid weight loss and function in the treatment of cardiovascular diseases among other things. These are two areas of concern to diabetics. Besides the readily availability of the extracted oils, the fruits abound everywhere and a good quantity of the oil can also be taken by eating the palm kernel or the meat of the coconut. There is ample opportunity that a diabetic patient may eat food containing these oils and some may even be on antidiabetic drugs while eating the palm kernel or the coconut meat. So there is need to evaluate the antidiabetic effect of VCO and PKO. It is widely recognised that metformin improves glycaemic control with good safety profile, weight neutrality, lack of associated hypoglycaemia, reduced cardiovascular mortality and low cost (McCreightet al., 2016) combination with PKO and VCO with similar characteristic would potentiate this outcome.
