Excerpt
Table of Contents
CHAPTER ONE: Introduction
CHAPTER TWO: Literature review
CHAPTER THREE: Material and Method
CHAPTER FOUR: Results
CHAPTER FIVE: Discussions and Conclusions
REFERENCES
CHAPTER ONE: Introduction
1.1 Background of the Study
The leaves, flowers, stems, roots and other components derived from plants have been reported to be effective antibacterial agents. Traditional herbalists in Nigeria use herbal preparations to treat various types of ailments, including diarrhea, urinary tract infections (UTIs), typhoid fever and skin diseases (Sofowora, 2010). The World Health Organization (WHO, 2010) survey indicated that about 70- 80% of the world’s population particularly in developed countries rely on non-conventional medicines mainly of herbal origins for their primary health care. This is because herbal medicines are accessible and cheap (Sofowora, 2010). With the increased usage of herbal preparations in Nigeria, the safety, efficacy and quality of these medicines have been an important concern for health authorities and health professionals (Adeleye et al., 2015).
Antibiotic resistant bacteria have been a source of an ever increasing therapeutic problem (Sheikh et al., 2013). Drug resistant infectious microorganisms have become an important public health concern. Aside from the public health threat drug resistant microorganisms pose, research into newer antibiotics to overcome resistant microbes is usually very expensive and contributes to the higher costs of health care (Adeleye et al., 2015).
Resistant bacteria strains may develop almost anywhere particularly in a pressurized environment containing previously non-resistant bacteria strains as contaminants. One of such environments can be herbal medicinal products (HMPs). Herbal medicinal products have been previously implicated as a pool for such contaminations (Esimone et al., 2017). It is of utmost importance to monitor and ascertain the microbial purity of HMPs given the huge medical and economic implications of any such microbial contamination especially with multiple drug resistant strains. Such surveillance will help to identify microbial contamination of herbal products and slow down or prevent the emergence of drug-resistant strains (Odimegwu et al., 2011).
1.2 Aim of the Study
The aim of this study is to determine the efficacy of herbal mixtures on some selected bacteria, Staphylococcus aureus and Streptococcus pyogene
1.3 Objectives of the Study
The objectives of this study include:
- To determine the antibacterial efficacy of herbal mixtures on some selected bacteria, Staphylococcus aureus and Streptococcus pyogene
- To determine the minimum inhibitory concentration of herbal mixtures some selected bacteria, against Staphylococcus aureus and Streptococcus pyogene.
- To determine the minimum bactericidal concentration of herbal mixtures some selected bacteria, against Staphylococcus aureus and Streptococcus pyogene
CHAPTER TWO: Literature review
2.1 Medicinal Plants in Nigeria with Antimicrobial Activities
Despite the success of antibiotic discovery, infectious diseases are consistently ranked second among causes of death worldwide (Pavithra et al., 2010). The pursuit of new compounds that have therapeutic potential for infectious diseases with no existing remedy such as Lassa fever and others focuses mainly on plants as the best reservoir of drug compounds. The microbial resistance to antibiotics is among the significant problems in the twenty-first century and has necessitated the need for a continuous search for more potent and safe therapeutic agents (Chikezie et al., 2015).
2.1.1 Antibacterial Activity
Tuberculosis (TB) is a life-threatening disease caused by various Mycobacterium species and has been ranked among the leading causes of human death in the developing nations (Okwuosa et al., 2012). In 2013, WHO reported that approximately 8.6 million people incurred TB and 1.3 million died from it, with an estimated 450,000 new cases of multidrug-resistant TB worldwide. Chronic cough is a feature of many common respiratory diseases with the percentage of global occurrence in Oceania (18.1%), Europe (12.7%), America (11.0%), Asia (4.4%), and Africa (2.3%) (Aiyeloja and Bello, 2016). Diarrhea is a killer disease; according to 2015 observatory data of WHO, the occurrence of childhood mortality in developing nations due to diarrhoeal disease between 9% and 34%. Many enteric bacterial pathogens are responsible for diarrhea, which include bacteria such as Vibrio cholera, Campylobacter jejuni, Helicobacter pylori, Salmonella typhi or paratyphi, Shigella flexneri, Clostridium difficile, and Shiga toxin-producing Escherichia coli. Findings of Ogbonnia et al. (2018) and Oladele et al. (2019) stated that the root and leaf extracts of Terminalia glaucescens show appreciable activity against E. coli and S. typhi. The methanol extracts of three Nigerian medicinal plants have antimicrobial activity against five clinical bacterial isolates comprising two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and three Gram-negative bacteria (Pseudomonas aeruginosa, E. coli, and Klebsiella pneumonia) organisms (Chikezie et al., 2015). Acetone and ethanol extracts of bark of Azadirachta indica (A. Juss.), at a concentration of 25–400 mg/ml, showed significant antibacterial activity on all 14 strains of multidrug-resistant Salmonella typhi with zone diameter of 18–31 mm (Okpe et al., 2016). An investigation of the activity of aqueous and ethanolic extracts of Zingiber officinale and Allium sativum extracts on selected foodborne pathogens (Salmonella species, Bacillus cereus, E. coli, and S. aureus) showed multidrug resistance. E. coli sensitive to aqueous extracts, but S. aureus and Salmonella species were sensitive to ethanol extracts (Ola-Fadunsin and Ademola, 2014). The alcoholic extracts from the leaves of two Diospyros spp. (D. barteri and D. monbuttensis) showed potent antibacterial activity against a wide range of Gram-positive and Gram-negative bacteria, while two fungal species investigated in the study, Aspergillus niger and Candida albicans, were resistant to the extracts of both Diospyros spp. (Suleiman et al., 2018). The result of in vitro study of water, methanol, chloroform, and petroleum ether extracts of Senna alata flowers, which examined antimicrobial properties at a final concentration of 500 μg/mL, showed antimicrobial activities against clinical isolates of S. aureus, C. albicans, E. coli, Proteus vulgaris, P. aeruginosa, and B. subtilis (Omotoyinbo and Sani, 2015). Heeria insignis O. Ktze, a member of the family Anacardiaceae, is an indigenous African shrub used in the treatment of diarrhea, schistosomiasis, and venereal diseases. The methanol and dichloromethane extracts of the leaves of H. insignis possessed antibacterial and antidiarrheal activities, while methanol showed a more significant antibacterial activity than dichloromethane (Keyal et al., 2016). However, aqueous extracts of the stem bark of Spondias mombin have outstanding anthelmintic activity at low concentrations (Uzodinma, 2013). Preliminary investigation of the in vitro vibriocidal activities of three medicinal plants (traditional Ogi-tutu, Psidium guajava, and Vernonia amygdalina), using agar cup diffusion assay, showed that V. amygdalina has the highest ameliorative effects in the deterrence and cure of V. cholerae infection (Suleyman and Alangaden, 2016). Moreover, a study has revealed the antibacterial property of T. vulgaris on multiple antibiotic-resistant Vibrio fluvialis and Vibrio parahaemolyticus isolated from shrimps using agar diffusion method (Suleyman and Alangaden, 2016). The examination of Argemone mexicana L. for antimicrobial activity showed that the aerial and root extracts inhibited B. subtilis and K. pneumoniae, but P. aeruginosa and S. aureus were not prone to the aerial and root extracts.
In Nigerian ethnomedicine, Annona senegalensis Pers. (Annonaceae) has been used for the treatment of infectious diseases. Okokon et al. (2017) investigated A. senegalensis using the GC-MS and agar-well-diffusion method and found that lipophilic fraction and kaurenoic acid from A. senegalensis root bark showed potent antibacterial activity. Furthermore, the results of in vivo and in vitro model investigations of the antidiarrheal properties of the stem bark extract of A. senegalensis using mice and isolated rabbit jejunum showed maximum inhibition at a dose of 10 mg/kg. At the same time, intestinal transit time decreased at concentrations of 0.2–3.2 mg/ml, and the extract lessened spontaneous contractions of the jejunum (Cheesman et al., 2017). Ficus exasperata Vahl-Holl (Moraceae) leaves in West Africa are used for the treatment of infectious diseases and inflammatory conditions. However, a more thorough phytochemical analysis of the ethnomedicinal uses of F. exasperata has identified new compounds: apigenin C-8 glucoside, isoquercitrin-6- O-4-hydroxybenzoate, and quercetin-3-O-β- rhamnoside, as some of the constituents of this plant that inhibited the growth of Gram-positive organisms only (Hassan et al., 2016).
2.2 Antimalarial Activity
Malaria, a significant threat to global health, is responsible for the death of millions of people predominantly in sub-Saharan Africa. The occurrence of multidrug-resistant malaria parasites has triggered efforts to develop combined formulations (such as artemether-lumefantrine and sulfadoxine-pyrimethamine) and continuous research toward discovering better therapeutics. An in vitro study by Oladele (2018) on the sensitivity pattern of Plasmodium falciparum to Diospyros monbuttensis (“Egun eja”), Momordica charantia (“Ejirin”), and Morinda lucida (“Oruwo”) recorded the lowest antiplasmodial activity with the ethanolic extract of M. lucida while D. monbuttensis recorded the highest activity. Oladele (2018), investigated the antiplasmodial activity of crude n-hexane and ethanolic extracts of M. oleifera seeds using the cold extraction method and found the highest parasite inhibition activity in crude ethanolic extract. Besides, Landolphia owariensis P. Beauv., a member of the family Apocynaceae, is used in southeast Nigeria for the treatment of malaria. A study has shown that methanol fractions of L. owariensis leaf in early, established, and residual infections in Plasmodium berghei -infected albino mice have the most significant antiplasmodial activity in all the models carried out, due to alkaloids, flavonoids, saponins, and tannins present in the fractions (Butler and Buss, 2016). Allamanda cathartica and Bixa orellana are antimalarial plants (Handa et al., 2018). Moreover, Alchornea laxiflora (Benth.), a member of the family Euphorbiaceae, is used traditionally in the treatment of malaria in Nigeria. Furthermore, the study has shown that root extract A. laxiflora exerted significant antimalarial activity against P. berghei infection while ethyl acetate fraction exerted the highest activity against chloroquine-sensitive (Pf3D7) and -resistant (PfINDO) strains of P. falciparum infection in mice (Conrad et al., 2013). Enantia chlorantha has significant utilization in traditional medicine for the treatment of several diseases which include malaria. However, another study has suggested that oral administration of E. chlorantha at relatively high doses may produce severe toxic effects (Ozioma and Chinwe, 2019). A study on the acute and subacute toxicity of the medicinal plant E. chlorantha carried out in mice showed a mean lethal dose (LD50) of 0.7 g-kg−1 for ethanolic but 43.65 g-kg−1 for aqueous preparations (Ivana et al., 2016). Cajanus cajan (L.) is a member of the family Fabaceae and possesses antimalarial properties. The result of the in vitro investigation of crude methanolic extract of C. cajan leaves, using the multiresistant strain of P. falciparum (K1) and combination of chromatographic techniques, identified cajachalcone (2′,6′-dihydroxy-4-methoxy chalcone) from the ethyl acetate fraction, as one of the biologically active constituents (Subramaniyan et al., 2016).
2.3 Antifungal Activity
Infections caused by fungi are termed fungal infections or mycoses. Fungal infections have been considered a serious health problem and life-threatening diseases in recent years, especially in immunodeficiency conditions (Ogbole et al., 2018) Severe fungal diseases result from other health challenges such as human immunodeficiency virus (HIV), asthma, cancer, organ transplantation, and corticosteroid treatments (Okigbo et al., 2019). In Nigeria, fungal infections (cryptococcal antigenemia, subclinical histoplasmosis) have been implicated in HIV/AIDS patients and neonatal intensive care babies (Ajaiyeoba et al., 2013). In Cameroun, esophageal candidiasis, cryptococcal meningitis, Pneumocystis pneumonia, disseminated histoplasmosis, and invasive aspergillosis were prevalent in adults, while tinea capitis prevalent among school children (Odelola and Okorosobo, 2010). In Mozambique, disseminated Emergomyces and recurrent Candida vulvovaginitis were common among HIV patients (Jebashree et al., 2011). Some hospitalized patients are at risk of contracting fungal infections (Vambe et al., 2018). Besides, emerging and reemerging fungal infections due to recent therapies for autoimmune and cancer-related diseases (hematopoietic stem cell transplant) are becoming public health concern (Lockhart and Guarner, 2019). Different parts of Calotropis procera, a flowering plant that belongs to the family Asclepiadaceous, have been utilized in traditional medicine for the treatment of infections which include eczema, cutaneous infections, leprosy, and syphilis, as well as malaria. In a study on antifungal activity of C. procera, there complete inhibition of Microsporum and Trichophyton species after ten days of inoculation with water extract at different concentrations (Ugboko et al., 2016). Crude methanolic extract of Spondias mombin (bark and leaves) found to exhibit anti-candidal effects with diameters of 11.00 ± 0.47 mm and 15.00 ± 0.47 mm, respectively. The extracts have varying degrees of phytochemical compositions such as terpenoids, alkaloids, glycosides, saponin, and flavonoids (Agbaje and Onabanjo, 2010). Psidium guajava extracts were active on Candida albicans isolates from caries infected patients (Adeniyi et al., 2015). Additionally, Alchornea laxiflora leaf extracts have antibacterial and antifungal activities due to flavonoids, alkaloids, saponins, tannins, and reducing sugars as major phytochemicals (Aiyegoro and Okoh, 2019).
2.4 Antiviral Activity
Human immunodeficiency virus type 1 (HIV-1) encodes reverse transcriptase which functions in the process of the viral genome reverse transcription, a fundamental step in the HIV-1 replication cycle and promising target in the antiretroviral drug development (Tiwari et al., 2011). A study conducted in Nigeria by Taiwo and Igbeneghu (2014) on the antiviral activities of 27 medicinal plant extracts, belonging to 26 different plant species, against echovirus 7, 13, and 19 serotypes (E7, E13, and E19, respectively) revealed the highest antiviral activity from methanolic extract of Macaranga barteri leaves on E7 and E9, respectively, followed by Ageratum conyzoides leaves extract on E7 and E19 and Mondia whitei leaves extract on E7 and E19. In China, Rheum palmatum and Rheum officinale extracts along with their main single isolated constituents’ anthraquinone derivatives inhibited both HIV-1 reverse transcriptase-associated DNA polymerase (RDDP) and ribonuclease H activities (Nayak et al., 2011). The screening of some plants showed antiretroviral activities. For instance, Ancistrocladus korupensis and Ancistrocladus congolensis produced michellamine A and B, Ancistrocladus congolensis (Boyd et al., 2016).
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