Phytochemical screening of Garlic and its antimicrobial Effects on Staphylloccocus aureus

CHAPTER ONE
INTRODUCTION
Historically, garlic has been used for centuries worldwide by various societies to combat infectious disease. Garlic can be provided in the form of capsules and powders, as dietary supplements, and thus differ from conventional foods or food ingredients. Louis Pasteur was the first to describe the antibacterial effect of onion and garlic juices (Srinivasan et al., 2001). Garlic is a strong antibacterial agent against both Gram-positive and Gram-negative bacteria such as E. coli, Salmonella spp., Streptococcus spp., Staphylococcus aureus, Klebsiella spp., Proteus mirabilis, Shigella senteriae, Pseudomonas aeroginosa and Helicobacter pylori,( Indu et al., 2006), also it's effective even against those strains that have become resistant to antibiotics (Ross Z. et al., 2001). For a long period of time, plants have been a valuable source of natural products for maintaining human health, especially in the last decade, with more intensive studies for natural therapies.The medicinal value of plants has assumed a more important dimension in the past few decades. This is due largely to the discovery that extracts from plants contain not only minerals and primary metabolites but also a diverse array of secondary metabolites with antioxidant potentials (Bayan L, Koulivand P. H. and Gorji A., 2011 & Okigbo et al. 2009). The use of plant extracts in traditional medicine is a worldwide practice. Medicinal plants form the basis of primary health care for majority of the people living in the rural and remote areas in Nigeria and other third world countries (Awosika, 1993). A number of medicinal plants have been found and put into use in ethnomedicine by traditional healers in the management of many diseases. According to Bayan L, Koulivand P. H. and Gorji A. (2011), African medicinal plants rank highest among plants used in the investigations of antimicrobial properties. This could be due to their high traditional medicinal use and also the ease of carrying out such tests. Among medicinal plants of African origin are Psidium guajava (guava), Azadirachta indica (neem), Vernonia amygdalina (bitter leaf), Anacardium occidentales (cashew), Allium cepa (onion) and A. sativum (garlic). The organs or parts used in these plants vary from one plant to the other and these include the leaves, bark, roots, stem, flowers, fruits and even the seeds (Farombi, 2003, Nguelefack et al., 2005). While garlic is primarily used as a herb to enhance many food dishes in various cultures, it contains many substances which studies have shown act together to prevent disease and age-related conditions (Anon, 2009). According to Johnson et al. (2008), biodiversity provides mankind enormous direct benefits and
indirect essential services through natural ecosystem function and stability. Initial reports of antimicrobial activity of garlic showed that allicin (allyl 2-propene thiosulfinate), a notable flavonoid in garlic is formed when garlic cloves are crushed (Ross et al., 2000). Allicin formation follows the action of an
enzyme, allinase of the bundle sheet cells upon the alliin of the mesophyl cells. When crushed, A. sativum yields allicin, a powerful antibiotic and antifungal compound (phytoncide). However, due to poor bioavailability, it is of limited use for oral consumption. Garlic also contains some sulphur-containing compounds such as alliin,
ajoene, diallylsulphide, dithin, S-allylcysteine and enzymes as well as some non sulphur-containing compounds including vitamin B, proteins, minerals, saponins and flavonoids. Yukihiro et al., (2002), have reported a phytoalexin called allixin in garlic.
1.2 Statement of the problem
Infectious disease is one of the biggest health problems not only in Nigeria but the world at large. Infectious disease is also one of the leading causes of death in the world. Other than virus, bacteria can also cause infectious disease (Alli et al., 2011) Centers for Disease Control and Prevention (CDC), America, estimates that in the United States alone around 23,000 people die each year due to antibiotic-resistant infections. In 2014, World Health Organization (WHO) estimates 20% of people with antibiotic resistance occur in recurrent cases. Antibiotic-resistant bacterial infection with recurrent cases are Staphyloccoccus aureus (or MRSA, the resistant variant), Pneumonia, Escherichia coli, urinary tract infections and gonorrhea. (Borlinghaus et al.,2014). With high cases of resistance due to side effects of antibiotics, researchers tried alternative medicines that acted as natural antibiotics from medicinal plants. Staphylococcus aureus bacterial infectious diseases such as pneumonia, UTI and gonorrhea can be managed with pharmacology, in the form of antibiotics and nonpharmacology.
The use of antibiotics has the disadvantage of causing resistance because of incorrect
indications and dosage usage (Amagese et al., 2014 & Borlinghaus et al.,2014). On the other hand, the use of non-pharmacology such as plants or traditional medicine made by natural ingridients have minimal or no side effects (Amagese et al., 2014 & Bayan et al., 2014). Garlic (Allium sativum) is a plant-based food which is consumed everyday and is known to have strong natural antibiotic with a wide spectrum. Phytochemical contents that act as antibacterial include essential oils, allicin, ajoene and flavonoids. Essential oils and allicin inhibits the synthesis of RNA, DNA and bacterial proteins. Ajoene plays a slow role in inhibiting bacteria while flavonoids play a role in denaturing proteins to inhibit bacterial growth. All four of the phytochemical contents above effectively eradicate the bacterial wall (Amagese et al., 2014; CDC 2014 & Safitri et al., 2014 ). As such study of this nature becomes very imperative in order to device a less resistant antibiotics to reduce the prevalence of staphylococcus aureus in Nigeria and the world at large.
1.3 Objectives of the study
The aim of this study is to:
Screen the phytochemical constituent of Garlic and the Anti-microbial effect of Garlic extract on Staphylococcus aureus.
1.4 Specific objectives
The specific objectives of the study is to:
1. Screened the phytochemical constituents of Garlic
2. Determine the anti-microbial effect of Garlic extract on Staphylococcus aureus
3. Carryout biochemical tests and identification of the organisms isolated
1.5 Significance of the study
This study shall be of immense importance to health practitioners most especially nutritionists and pharmacists. This study will also be of great importance to students of knowledge who may desire to carry out research in this area and also it shall contribute to the various literature already published in this area. Lastly the findings of this study will educate the general public on the importance of Garlic and its health benefits.
1.6 Scope of the study
This study will be carried in gombe state polytechnic Bajoga and it will majorly focus on examining the phytochemical constituent of Garlic and also examining the effect of garlic extract on the bacteria: Staphylococcus aureus.
1.7 Definition of terms
Phytochemical: are plant-based bio-active compounds produced by plants for their protection.
Staphyloccocos aureus: is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin.
Screening: theevaluation or investigation of something as part of a methodical survey, to assess suitability for a particular role or purpose.
Garlic: is a species of bulbous flowering plant in the genus Allium. Its close relatives include the onion, shallot, leek, chive, Welsh onion, and Chinese onion.
Extract: a preparation containing the active ingredient of a substance in concentrated form.
 
CHAPTER TWO
INTRODUCTION
2.1 PHYTOCHEMICALS
Phytochemicals (Greek: phyton = plant) are chemical compounds naturally present in the plants attributing to positive or negative health effects (Silva GO, Abeysundara AT, and Aponso M. M, 2017). Medicinal plants used in different diseases and ailments are the richest bio reservoirs of various phytochemicals. The medicinal properties of the plants are determined by the phytochemical constituents (Ezeonu C. S. and Ejikeme C. M., 2016). Some of the important phytochemicals include alkaloids, flavonoids, phenolics, tannins, saponins, steroids, glycosides, terpenes, etc. which are distributed in various parts of the plants (Sheel R., Nisha K., and Kumar J., 2014). Nature is a unique source of structures of high phytochemical diversity representing phenolics (45%), terpenoids and steroids (27%) and alkaloids (18%) as major groups of phytochemicals (Saxena M., Saxena J., Nema R., Singh D., Gupta A., 2013) .
Although, these compounds seem to be non-essential to the plant producing them, they play a vital role in survival by mediation of ecological interactions with competitors, protect them from diseases, pollution, stress, UV rays and also contribute for colour, aroma and flavour with respect to the plant. The metabolites produced by the plants to protect themselves against biotic and abiotic stresses have turned into medicines that people can use to treat various diseases (Njoku O. V., and Obi C,.2009 & Kocabas A., 2017) .
Phytochemicals can be separated from the plant material by various extraction techniques. The most commonly used conventional methods include maceration, percolation, infusion, digestion, decoction, hot continuous extraction (Soxhlet extraction) etc., recently, eco-friendly techniques such as Ultrasound-Assisted Extraction (UAE), Microwave-Assisted Extraction (MAE), Supercritical Fluid Extractions (SFE) and Accelerated Solvent Extraction (ASE) have also been introduced (Azwinda N.N., 2015 & Dhanani T. et al., 2017). Different types of solvents viz. water, ethanol, methanol, acetone, ether, benzene, chloroform etc. are used in the extraction process ( Tiwari P. et al., 2011). Extraction of phytochemicals from plant materials is affected by pre-extraction factors (plant part used, its origin and particle size, moisture content, method of drying, degree of processing etc.) and extraction-related factors (extraction method adopted, solvent chosen, solvent to sample ratio, pH and temperature of the solvent, and length of extraction) ( Azwinda N.N., 2015 & Tiwari P. et al., 2011).

    Date: 2026-08-02 00:00:00.000000