THE ANTIBACTERIAL EFFECT OF ETHANOL AND AQUEOUS EXTRACTS OF GARLIC ON STAPHYLOCOCCUS AUREUS AND PSEUDOMONAS AERUGINOSA

CHAPTER ONE

 

 

INTRODUCTION

1.1        Background to the study

 

Medicinal plants are important elements of traditional medicine in virtually all cultures. The idea that certain plants had healing potential was known long before human beings discovered the existence of pathogens (Ahmed et al., 2019). The therapeutic importance of many indigenous herbal medicinal plants in modern medicine is overwhelming and documented. It is reported that treatment of diseases in most parts of Africa is by the use of herbal medicine, while 65%-80% of world’s population rely on traditional medicine for their health care needs (Ajijolakewu and Awaru, 2017).

In recent years there has been continuous and urgent need to discover new antimicrobial compounds with diverse chemical structures and novel mechanisms of action because there has been an alarming increase in the incidence of new and re-emerging infectious diseases and development of resistance to the antibiotics in current clinical use making the antibiotics impotent (Nair and Chanda, 2008; Basavaraja, et al. 2009; Ahmed et al., 2009). The use of higher plants and their extracts to treat infections is an ancient practice in traditional medicine.

Many plants have been used because of their antimicrobial traits, which are chiefly synthesize during secondary metabolism of the plants (Nabeel et al., 2020). Herbal medication has gained popularity in folklore and in orthordox practice as several medicinal and aromatic herbs are loaded with metabolites that have demonstrated several therapeutic effects (Samuel et al., 2018). A wide number of plant extracts possess antimicrobial properties which are used as natural alternatives to treat several diseases. Scientific studies available on medicinal plants indicate that promising phytochemical can be developed for many health problems [Dhiman et al., 2012]. Their medicinal values lie in their phytochemical composition, which produce physiological changes on the human body (Mann et al., 2016).

The use of garlic as a medicine and condiment predates written history. The oldest recorded literature from the Sumerians is dated at 2600–2100 B.C. In these writings garlic was already widely cultivated, therefore its use must precede this date. It is thought to be of Central Asian origin and features highly in the legends of both India and China but presently grown globally (Iotsor et al 2019). No-one knows exactly where the name garlic comes from, but it is assumed that the Anglo-Saxon ‘gar’ refers to the spear-like foliage and the ‘lic’ is referring to leek. Botanically, Allium sativum is a member of the Lillaceae family, along with onions, chives and shallots (Harris et al., 2001). Allium sativum, garlic (commonly called ‘aayu’ in

Yoruba, ‘ayo-ishi’ in Igbo and ‘tafarunua’ in Hausa) is a perennial bulb-forming plant that belongs to the genus Allium in the family Liliaceae (Eja et al., 2007). Allium is the largest and important representative genus of the Alliaceae family and comprises 450 species, widely distributed in the northern hemisphere (Lonzotti, 2006). Garlic can grow up to 2 feet in height or more. The bulb is the main part of the plant which is used for medicine (Steven, 2015). Each garlic bulb is made up of 4 to 20 cloves. Each garlic clove may weigh about 1 gram in weight. Fresh, aged, dried or garlic can be used garlic supplements (Steven 2015). These species are characterized by a specific flavour and are used for cooking (Tada, 2008). For centuries, garlic (Allium sativum) has played an important dietary and medicinal role. Its therapeutic applications include cardiovascular benefits, antibiotics, anticancer, antiinflammatory, hypoglycemic, and hormone-like effects, common cold, malaria, cough and lung tuberculosis, hypertension, sexually transmitted diseases, mental illness, kidney diseases, liver diseases, asthma, (Tessema, 2016). For thousands of years, garlic extract has been used to treat infections. Its antibacterial activity is based on allicin, which is produced by enzymatic (alliin-lyase) hydrolysis of alliin after cutting and crushing the cloves

(Onyeagba, 2004; Ross, 2011).

1.2        Statement of the Research Problem

Over the past years, there has been a lot of interest in the investigation of natural materials as sources of new antibacterial agents. Literature reports and ethno-botanical records suggest that plants are the sleeping giants of pharmaceutical industry and provide natural source of antimicrobial drugs that provides novel compounds that may be employed in controlling some infections globally. Different extracts from traditional medicinal plants were tested and some natural products were approved as new antibacterial drugs. However, there is still an urgent need to identify novel substances active against pathogens with higher resistance such as Garlic (Allium sativum) and variations in composition of garlic and genetic disparity among Staphylococcus aureus and Pseudomonas aeruginosa. This study therefore, aimed at carrying out in-vitro assessments of the effects of garlic (Allium sativum) extract on clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa in Abuja, Nigeria.

1.3       Justification for the Study

There has been considerable number of studies on effects of garlic (Allium sativum) extract on clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa with vast majority carried out in Southern Nigeria and Ghana respectively. However, in much of Northern Nigeria, little or not much work has been done or reported especially in Abuja as the capital of the nation where there is utilization of such plant. Because of the importance associated with human lives, there is a need to investigate the effects of garlic (Allium sativum) extract on clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa in Abuja Metropolis, which are common encountered pathogenic organisms. The work is intended to give an updated base line data for concentrations of effect of garlic on clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa.

 

1.4       Aim of the Study

This study is aimed at determining the antimicrobial effects of ethanol and aqueous extracts of garlic (Allium sativum) on clinical isolates of Staphylococcus aureus and Pseudomonas aeruginosa in Abuja, Nigeria.

1.5        Objectives of the Study

The objectives of the work will include the following:

1. To extract active component in garlic (Allium Sativum) using ethanol and water as solvent.
2. To determine the phytochemical constituents of the crude extracts of garlic (Allium sativum).
3. To determine the effect of garlic (Allium sativum) on clinical isolates of

Staphylococcus aureus and Pseudomonas aeruginosa.

4. To determine the minimum inhibitory concentrations of the ethanol and aqueous extract of garlic (Allium sativum) against Staphylococcus aureus and Pseudomonas aeruginosa.
5. To determine the minimum bactericidal concentrations of the ethanol and aqueous extracts of garlic (Allium sativum) against Staphylococcus aureus and Pseudomonas aeruginosa.

THE ANTIBACTERIAL EFFECT OF ETHANOL AND AQUEOUS EXTRACTS OF GARLIC ON STAPHYLOCOCCUS AUREUS AND PSEUDOMONAS AERUGINOSA

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