Antidiabetic Efficacy Of (Vernonia Amygdaline) Bitter Leaf Plant Extracts On Diabetic Albino Rats

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Antidiabetic Efficacy Of (Vernonia Amygdaline) Bitter Leaf Plant Extracts On Diabetic Albino Rats


The study evaluated the efficacies of the ethanolic extracts of the leaf, stem – bark and root of Vernonia amydalina plant on alloxan – induced diabetic allano rats. Twenty (20) albino rats were divided equally into four groups comprising of five (5) animals in each group. Group A was treated with leaf extract, group B was treated with stem – bark extract, group C was treated with root extract.

The effect of aqueous leaf extract of vernonia amygdalina on blood glucose of alloxan induced diabetic albino rats was evaluated. Animals received daily oral administration of aqueous leaf extract of Vernonia amygdalina for 14 days. The effect of 200mg/kg dose was studied during the treatment period.

There was a significant reduction in blood glucose concentration (p < 0.05) with the mean blood glucose of the different groups having 5.3 ± 0.33 for normal control, 7.0 ± 0.40 for diabetic control and 4.5 ± 0.24 for diabetic treated. There was also 15.38 percent reduction in body weight of the rats.

Based on these results, it was suggested that aqueous leaf extract of Vernonia amygdalina has hypoglycemic effect. Further researches are therefore needed to identify all the hypoglycemic inducing compounds in Vernonia amygdalina.

Table Of Contents

Content page

  • Title page
  • Declaration
  • Certification
  • Approval page
  • Dedication
  • Acknowledgements
  • Abstract
  • Table of contents

Chapter One

1.0 Introduction

  • 1.1 Medicinal Plants
  • 1.2 Vernonia Amygdalina (Bitter Leaf)
  • 1.3 Research On Extracts And Chemical Constituents
  • 1.4 Local Uses Of Bitter Leaf

Chapter Two

Literature Review

  • 2.1 Diabetes
  • 2.2 Types Of Diabetes
  • 2.3 Signs And Symptoms Of Diabetes
  • 2.4 Diabetic Emergencies
  • 2.5 Chemotherapeutic Treatment Of Diabetes
  • 2.6 Nutritional Management Of Diabetes

Chapter Three

3.0 Material and Methods

  • 3.1 Methodology
  • 3.2 Collection And Preparation Of Plant Extracts
  • 3.3 Experimental Animals
  • 3.4 Induction Of Experimental Diabetes
  • 3.5 Experimental Design
  • 3.6 Collection Of Sample Analysis

Chapter Four

4.0 Result and Discussion

  • 4.1 Data Presentation And Analysis
  • 4.2 Discussion

Chapter Five

5.0 Conclusion and Recommendations

  • 5.1 Recommendations
  • 5.2 Conclusion
  • References

Chapter One

1.0 Introduction

The use of indigenous plants in the management of diseases has been a common practice over the years. Few of the plants have received adequate scientific scrutiny. The study and understanding of ethno – botanical information, chemical constituents of plants and the therapeutic application of the plant drug will help in understanding efficiency of the plant as a potent remedy; extend our knowledge of their pharmacological activity, active principles, dosage and administration (Unger et al., 2008).

Diabetes mellitus has been defined by the world health organization (WHO), on the basis of laboratory findings as a fasting venous plasma glucose concentration greater than 7.8 mmol/l (140mg/dl) or greater than 11.1 mmol/l (200mg/dl) two hours after a carbohydrate meal or two hours after an oral ingestion of the equivalent of 75g glucose, even if the fasting concentration is normal (Nwanjo and Nwokoro, 2004).

It is a metabolic disease characterized by hyperglycaemia and glycosuria due to absolute or relative lack of insulin (Ononogbu, 1996).Medicinal plants have formed the basis of health care throughout the world since the earliest days of humanity and are still widely used and have considerable importance in international trade (Unger et al., 2008). In certain African countries for instance, up to 90% of the population still relies exclusively on plants as a source of medicines (hostettmann et al., 2000). As a consequences, the World Health Organization (WHO) had in one of its charters in Geneva recommended further investigation into this area, particularly, as it concerns chronic and debilitating disease such as diabetes mellitus (WHO, 1980).

A complex disease like diabetes mellitus, where little is talked about in aspects of prevention and curation, but rather management, there is an increased focus on plants in the search for appropriate hypoglycaemic / antihyperglycaemic agents (Ebong et al, 2008). Firstly, because of leads provided by traditional medicine to natural products that may be better treatments than currently used conventional drugs (Nwanjo et al., 2004). Secondly the plants by secondary metabolic means contain a variety of herbal and non-herbal ingredients that are thought to act on a variety of targets by various modes and mechanisms (Tiwari and Rao, 2002) given the multi-factorial pathogen city of the disorders.

1.1 Medicinal Plants

  • Aconite (Aconitum spp. also known as Wolfsbane, or Monkshood)
  • Aloe (Aloe vera)
  • American skullcap (Scutellarialateriflora)
  • Arnica (Arnica montana, also known as “Leopard’s Bane” or “Dog’s Bane”)
  • Asian ginseng (Panax ginseng)
  • Bilberry (Vaccinium spp.)
  • Birthwort (Aristolochia spp.)
  • Bitter orange (Citrus x aurantium)
  • Black walnut (Juglansnigra)
  • Betelnut (Areca catechu nuts, wrapped and eaten with Piper betel leaves and lime (calcium hydroxide))
  • Black cohosh (Actaearacemosa)
  • Cat’s claw (Uncariatomentosa or Uncariagulanensis)
  • Greater Celandine (Chelidoniummajus)
  • Lesser Celandine (Ranunculusficaria)
  • Chamomile (Chrysanthemum spp.)
  • Chaparral (Larreadivaricatacoville)
  • Chrysanthemum (Asteraceae spp.)
  • Cinnamon (Cinnamomum spp.)
  • Cloves (Syzygiumaromaticum)
  • Coca leaves (Erythroxylon coca)
  • Coltsfoot (Tussilagofarfara)
  • Comfrey (Symphytumofficinale)
  • Country mallow (Sidacordifolia)
  • Dandelion (Taraxacumspp)
  • Devil’s claw (Harpagophytumprocumbens)
  • Dong quai (Angelica sinensis)
  • Echinacea (Echinacea sppj
  • Eleuthero (Eleutherococcussenticosus)
  • Ephedra (Ephedra sinIca, also known as ma huang)
  • European birthwort (Aristolochiaclematitis)
  • Evening primrose oil (Oenothera spp.)
  • Eyebright (Euphrasia spp.)
  • Feverfew (Tanacetumparthenium)
  • Fennel (Foeniculumvulgare)
  • Garlic (Alliurn sativum)
  • Germander (Teucrium spp.)
  • Ginseng (Panax spp.)
  • Grapefruit seed extract (Citrus x paradisi)
  • Grape seed extract (Vitisvinifera)
  • Green tea (Camellia sinensIs)
  • Groundsel (Senecio vulgaris)
  • Goldenseal (Hydrastiscanadensis)
  • Henbane (Hyoscyamusniger)
  • Horse chestnut (Aesculushippocastanum)
  • Horsetail (Equisetum sp.)
  • Impila (Callilepsislaureola)
  • Jimson weed (Daturastramonium)
  • Kava (Piper methysticum)
  • Licorice (Glycyrrhizaglabra)
  • Lily-of-the-valley (Convallariamajalis)
  • Lobelia (Lobelia inflata)
  • Madder root (Rubiatinctorum)
  • Marijuana (Cannabis spp.)
  • Mate (Ilex paraguariensis)
  • Milk thistle (Silybummarianum)
  • Mistletoe (Viscum album)
  • Mu Tong (Caulis aristolochiae)
  • Neem (Azadirachtaindica)
  • Oil of oregano
  • Oleander (Nerium oleander)
  • Parsley (Petroselinumcrispum)
  • Pennyroyal (Lamiaceae)
  • Peppermint oil (Menthapiperita)
  • Roman chamomile (Chamaemelumnobile)
  • Sassafras (Lauraceae spp.)
  • Saw palmetto (Serenoarepens)
  • Senna (Cassia angustifolia)
  • Siberian ginseng (Eleutherococcussenticosus)
  • Soursop (Annonamuricata)
  • Spinach (Spinaciaoleracea)
  • Squill (Urginea maritime)
  • Stevia (Asteraceae spp.)
  • St. John’s wort (Hypericumperforatum)
  • Tea tree oil (Melaleucaalternifolia)
  • Tobacco (Nicotiana spp.)
  • Valerian (Valerianaofficinalis)
  • Willow bark (Salix spp.)
  • Wintergreen (Gaultheria procumbens)
  • Woad (Isatistinctoria)
  • Wormwood (Artemisia absinthium)

(Kelly, 2000)

1.2 Vernonia amygdalina (BITTER LEAF)

Vernonia amygdalina, a member of the Asteraceae family, is a small shrub that grows in the tropical Africa. V. amygdalina typically grows to a height of 2–5 m. The leaves are elliptical and up to 20 cm long. Its bark is rough. V. amygdalina is commonly called bitter leaf in English because of its bitter taste. African common names include grawa (Amharic), ewuro (Yoruba), etidot (Ibibio), onugbu (Igbo), ityuna (Tiv), oriwo (Edo), chusar-doki (Hausa), mululuza (Luganda), labwori (Acholi), and olusia (Luo) Ndolé (cameroon). Vernonia amygdalina Del (Compositae) popularly known as bitter leaf is a shrub of 2 — 5m tall (Ojiako and Nwajo, 2006). It is popularly called bitter leaf because of its abundant bitter principles. It is cultivated in Nigeria mainly for its nutritional value (Igile et al., 1995). The plant (especially the leaf) has been found useful in the ethnotheraphy of diabetes (Nwajo, 2005), asthma, schistosormiasis, malaria (Masaba, 2000), measles, diarrhea, tuberculosis, abdominal pain and fevers, cough (Ojiako et al., 2006). Phytochemicals contained in V. amygdalina include saponins, sesquiterpenes, lactones and flavonoids, steroid glucosides such as Vernoniosides A1, A2, A3, A4, B1, B2, B3, D and E have been isolated from the plant (Igile et al., 1995) But it is yet to be ascertained which of these are responsible for some observed biological effects of the plant (Haslett et al, 1999). However, there is dearth of scientific data to support the folkloric use of this plant in the treatment of diabetes mellitus disease in Nigeria herbal homes. Therefore, the present work was designed to provide scientific proof of the use of V. amygdalinain the treatment of diabetes mellitus and we hope that the results of this short-term investigation will have important implications for the management of diabetes.

1.3 Research On Extracts And Chemical Constituents

Vernonia amygdalina extracts and isolated chemical constituents have been studied for their potential pharmacological effects, including:

  • Induction of apoptosis as determined in cell culture and animal studies.
  • Enhanced chemotherapy sensitivity – V. amygdalina extracts may render cancerous cells to be more sensitive to chemotherapy.
  • Inhibition of the growth or growth signals of cancerous cells.
  • Suppression of metastasis of cancerous cells in the body by the inhibition of NFkB is an anti-apoptotic transcription factors as demonstrated in animal studies.
  • Reduction of estrogen level in the body by the suppression of aromatase activity.

The involvement of blood estrogen level in the etiology of estrogen receptor (ER) positive breast cancer has been widely reported. Additional source of estrogen production in humans besides the ovary and adrenal gland is the conversion of testosterone to estrogen in a reaction catalyzed by aromatase. Many studies have shown positive correlations between blood estrogen levels and breast cancer risks.( Nwanjo, H.U., and Nwokoro, E.A. (2004).

Therefore, compounds that inhibit aromatase activity are used for the treatment of breast cancer.

  • Antioxidants – V. amygdalina may provide anti-oxidant benefits.
  • Enhancement of the immune system – Many studies have shown that V. amygdalina extracts may strengthen the immune system through many cytokines (including NFKB, pro inflammatory molecule) regulation.
  • Studies conducted using streptozotocin-induced diabetic laboratory animals showed that V. amygdalina administration decreased blood glucose by 50°k compared to untreated diabetic animals.
  • Extracts of V. amygdalina possess in vitro anthelminthic anti-parasitic properties. (Ebong et al., 2008)

1.4 Local Uses Of Bitter Leaf

Bitter leaf (Vernonia amygdalina) is a vegetable used for preparing the popular Bitter leaf soup. It is also known as Onugbu, Shiwaka and Ewuro by the Igbos, Hausa and Yorubas in Nigeria. (Ebong et al., 2008).

Chapter Five

5.0 Conclusion and Recommendations

5.1 Recommendations

  1. From the research and findings it is understood that mechanism of action of the components contained in V. amydalina has not been ascertained. Therefore, it is important for scientific studies to evaluate the possible mode/mechanism of action of the plant and as well further investigate their safety in controlled studies
  2. Apart from traditional and orthodox medications, some practices such as physical activities, exercise and consumption of low sugar diet are hereby recommended for diabetic patients for the control of their blood sugar level.
  3. Owing to the high prevalence of diabetes in the world and its resistance to duration, more in vivo investigations should be carried out in other to validate the anti-diabetic activity of some documented medicinal plant like Vernonia amydalina.

5.2 Conclusion

V. amygdalina Del. Apparently is a plant with diverse potentials. Its chemical constitution makes it ideal for nutritional and medicinal uses its content of virtually all the major food classes, albeit in modest ratios; make it an ideal supplement that can be used to augment the nutrient requirements of Africa and the developing world. The wide spectrum of photochemical ‘bottled up’ in its leaves and other parts could help in salvaging mankind from the present burden of diseases-communicable and otherwise-and help in the preservation of agricultural produce.

However, more has to be done, to transform the large volume of research already done on the plant into practical, ready-made nutraceuticals or phytotherapeutics so that mankind may begin to effectively utilize the plant Ijeh and Ejike 1059 for maximal benefit. It is worrisome that most of the work done so far have not been followed up in such a way as to clear all scientific doubts and determine specific active principles and mechanisms of action – the typical and classical ‘follow your nose’ method of scientific investigation. A good number of the researches done so far on VA have been at best peripheral and haphazard.

These are exemplified in the number of patents on the plant weighed against the number of publications on it.
The usually peddled alibi however, is that a good proportion of the research on VA have been done in sub-Saharan Africa, where state-of-the-art laboratory equipment and facilities are often difficult to come by.

Future research must aim at characterizing the active principle(s) responsible for each effect, and determining if they act singly or synergistically with other principles present in the plant. Only such research would place V. amygdalina Del. in its proper place in nutritional and medical sciences.

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