CHAPTER ONE

INTRODUCTION

1.0     Background of the study

Medicinal plants have been identified and used throughout human history (Tapsell et al., 2006). Plants have the ability to synthesize a wide variety of chemical compounds that are used to perform biological functions. The chemical compounds in plants mediate their effects on the human body through processes identical to those already well understood for the chemical compounds in conventional drugs (Tapsell et al., 2006). Herbal medicines do not differ greatly from conventional drugs in terms of how they work and this enables them to be as effective as conventional/orthodox drugs, and also gives them the same potential to cause harmful side effects (Lai et al., 2004). Many of the pharmaceuticals currently available to physicians have a long history of use as herbal remedies this includes aspirin, digitalis, quinine and opium (swain et al., 1968). With this upsurge in the use of herbal medicines alongside orthodox medicine, there is a shift in the use of mono-therapy to multi-drug therapy as seen in the treatment of malaria, tuberculosis, cancer, diabetes, etc. This practice has become inevitable as the rise in the use of herbal remedies most especially has gone global with more than 80% of the people in west Africa (Nigeria precisely), Asia and an increasing number in some western countries using this method of treatment. Malaria, a life threatening blood disease caused by the anopheles mosquito, is a major tropical disease with high mortality and morbidity rate. It is responsible for the death of about 1.24 to 1.82 million patients mainly among children and pregnant women (WHO, 2010). Malaria has been shown to be a contributor to the economic burden in communities where it is endemic and is responsible for annual economic loss. Due to the ineffectiveness of anti-malarial drugs in combating malaria, several studies have been made which produced a new and effective anti-malaria drug, artemisinin. Artemisinin can be used alone but this leads to high rate of recrudescence (return of parasites) after which other drugs are required to clear the body of all parasites and prevent recurrence. This led the World Health Organization to recommend artemisinin combination therapies (ACT) to be the first-line therapy for Plasmodium falciparum malaria worldwide. These combinations are effective because the artemisinin component kills the majority of the parasites at the start of the treatment while the partner drug, which is more slowly eliminated, clears the remaining parasites (White, 2004). The artemisinin has a short half-life while the partner drug has a long half-life e.g mefloquin, lumefantrine, piperaquine, amodiaquine and pyronaridine (Krudsood et al., 2010). Despite the recorded success with the use of ACTs, patients often fall back to using herbal therapies in combination prior to after orthodox anti-malaria therapy (Ijarotimi et al., 2010) which is mostly done without the knowledge of a health personnel. Combination of drugs may predispose the body to pharmacodynamic or pharmacokinetic interactions which may result in drug toxicity or therapeutic failure (Fasinu et al., 2012). With regards to malaria, one of the anti-plasmodial herbs often used in combination with orthodox drugs is Hippocratea africana root bark extract alongside Eremomastax speciosa leaf extract which is believed to be anti-anaemic. This combination is commonly practiced by the people of the south-eastern part of Nigeria. The Hippocratea africana root extract has also been used traditionally in the treatment of ailments such as diabetes, fever, malaria, diarrhea, anemia (Okokon et al., 2006). It has been reported to possess anti-plasmodial activities with lethal dosage (LD₅₀) of 2.45 mg/kg body weight in mice (Ndem et al.,2010). Further studies carried out also shows that the ethanolic extract of H. africana possesses promising schizonticidal activity (Ndem et al., 2013). Eremomastax speciosa leaf extract has also been reported to cause increase in hematological parameters and prevent malaria anemia which is common in areas endemic to malaria (Okokon et al., 2007). The leaves are also used to treat fracture, hemorrhoids, irregular menstruation and urinary tract infections (Adjanohoun et al., 1996).

Drug-herb interaction is therefore of clinical significance as an alteration in the pharmacokinetics/pharmacodynamics of the drug by the herb could bring about potentially severe alterations in the body such as bleeding, depression, reduced bioavailability of either of the drugs.

This work would vividly discuss and experiment on the concomitant administration of Artemether Lumefantrine, Hippocratea Africana root barkextract and Eremomastax speciosa leaf extract on Leucocyte panel of normal and plasmodium bergei infected adult Albino mice. This project work would analyze the following parameters in leucocyte panel: Total lymphocyte, white blood cells,Basophils , Eosinophils,Neutrophil, Monocyte.

White Blood Cell (WBC): this is also called Leukocytes or Leucocytes. There are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from multipotent cells in the bone marrow known as Hematopoietic stems cell. Leukocytes are found throughout the body, including the blood and lymphatic systems.  

Total Lymphocyte is one of the sub-types of white blood cells in a vertebrate’s immune system. Lymphocyte include natural killer cells (NK cells) which function in cell _mediated, cytotoxic innate immunity, T cells (for cell mediated, cytotoxic adaptive immunity), and B-cells (for humoral antibody driven  adaptive immunity). They are the type of cells found in lymph, mammalian stem cells, differentiated into several kinds of blood cells within the bone marrow. This process is called haematopoiesis. All lymphocytes originate during this process, from a common lymphoid progenitor before differentiating into their distinct lymphocytes types. The formation of lymphocyte is called lymphopoiesis,B cells mature into B lymphocyte in the bursa equivalent while T-cells migrate and mature in a distinct organ called the thymus .Microscopically, in a Wright ‘s stained peripheral blood smear , a normal lymphocyte  has a large , dark-staining nucleus with little to no eosinophilic cytoplasm.

Basophils are type of white blood cells, they are the least commonof the granulocytes representing about 0.5 to 1% of the circulating white blood cell .They are responsible for inflammatory reactions during immune response ,as well as in the formation of acute and chronic , allergic disease including asthma, anaphylaxis, atopic dermatitis and hay fever. They can perform phagocytosis (cell eating) produce histamine and serotonin that induce inflammation and heparin that prevent blood clotting (khurana, 2009).

Neutrophils (also called neutrocytes) are the most abundant type of granulocytes and the most abundant type of white blood cell ( 40 _75 %) in most mammals .They form essential part of the innate immune system, lts functions vary in different animals (Ermert D, Niemiec M., et al ., 2013). Neutophils are formed from stem cells in the bone marrow. They are short lived and highly motile or mobile as they can enter parts of tissue where other cells cannot .They form part of the polymorph nuclear cells family (PMNs) together with basophiles and eosinophils. Neutrophils are type of phagocyte and are normally found in the blood stream. During the beginning (acute) phase of inflammation,particularly as a result of bacterial infection, environmental exposure and cancers, Neutrophils are the first responders of inflammatory cells to migrate toward the site of inflammation. They migrate through the blood stream then through the interstitial tissue , following chemical signals such as interlukin-8 (IL_8), C5a, leucotriene B4 and H hydrogen peroxide in a process called chemotaxis.[Yoo,Sk, Starnes, Tial, Deng, et al., 2011]

Monocytes: Monocytes are a type of white blood cells 0r leucocytes. They are the largest type of leukocyte and can differentiate into macrophages and myeloid lineage dendritic cells. Monocyte also influences the process of adaptive immunity. Monocytes are amoeboid in appearance and have a granulated cytoplasm. Monocytes are produced by the bone marrow from precursors called monoblast. Monocytes circulate in the blood stream for about one to three s and they move into tissues throughout the body where they differentiate into macrophages and dendritic cells. Macrophages are responsible for protecting tissues from foreign substance. Monocyte performs three functions namely phagocytosis, antigen presentation, and cytokine production.

Eosinophils, sometimes called eosinophiles or less commonly, acidophils, are a  variety of white blood cells and one of the immune system component responsible for combating multicellular parasites and certain infections in vertebrates ,. Along with mast cells and basophils, they also co troll mechanism associated with allergy and asthma. They are granulocytes that develop during haematopoiesis in the bone marrow before migrating into blood stream. Eosinophil is transparent, it is this affinity that causes them to appear brick –red after  staining with eosin, a red dye , using the Romanowisky  method . The staining is concentrated in a small granules with the cellular cytoplasm, which contain many chemical mediator such as histamine and proteins such as eosinophil peroxidase, Ribonuclease (RNase), deoxyribonuclease, lipase, plasminogen. In normal individual, eosinophil make up to about 1-6%  of white blood cells and are about 12-17 micrometers in size  (Young, Barbara,:owe, Joseph o, Connell, 2006). And increase in eposinophils, that is the presence of more than 500 eosinphils/microlitre of blood is called an eosinophilia and is typically seen in people with a parasitic infestation of the intestine, autoimmune and collagen vascular disease  (such as rheumatoid arthritis ) and systemic lupus erythematosus, malignant disease such as eosinophilic leukrmia, clonal hypereosinophilia