Thesis Abstract

Abstract
Plants have played a significant role in traditional medicine systems around the world for centuries. The diverse array of phytochemicals present in plants has been utilized for their medicinal properties. In recent years, there has been a growing interest in exploring the potential of plant-based natural products in the treatment of diseases caused by microorganisms. This research aims to investigate the role of plants in combating microbial infections and the mechanisms by which plant compounds exert their antimicrobial effects. The study will focus on identifying specific plant species known for their antimicrobial properties and analyzing the bioactive compounds present in these plants. Various extraction methods will be employed to isolate these bioactive compounds, which will then be tested against a panel of microorganisms including bacteria, fungi, and viruses. The antimicrobial activity of these plant compounds will be evaluated through in vitro assays to determine their efficacy in inhibiting the growth of different pathogens. Furthermore, this research will explore the mechanisms of action of plant compounds against microorganisms. It will investigate whether the antimicrobial activity is due to the disruption of microbial cell membranes, inhibition of essential enzymes, or interference with microbial DNA replication. Understanding the mode of action of plant compounds can provide valuable insights for the development of new antimicrobial agents. In addition, the study will assess the potential synergistic effects of combining plant compounds with conventional antimicrobial drugs. By exploring the interactions between plant compounds and existing antibiotics, this research aims to enhance the efficacy of current treatment strategies and potentially reduce the development of antimicrobial resistance. Overall, this research project seeks to expand our knowledge of the therapeutic potential of plant-based natural products in treating diseases caused by microorganisms. By elucidating the antimicrobial properties of plant compounds and their mechanisms of action, this study aims to contribute to the development of novel antimicrobial agents with improved efficacy and safety profiles. Ultimately, the findings from this research could pave the way for the development of plant-based therapies for infectious diseases, offering sustainable and cost-effective solutions for global health challenges posed by microbial infections.

Thesis Overview

INTRODUCTION1.1 BACKGROUND OF STUDY1.1.1 PhyllantusThis is a genus of the family Euphorbiaceae. It was first identified in Central and Southern India in 18th century. It is called carry me seed, stone-breaker, wind breaker, gulf leaf flower or gala of wind, (Bharatiya 1992).There are over 300 genera with over 5,000 species in the Euphorbiaceae world wide. The Phyllantus is one of the genus that falls under this enormous family. Phyllantus has about 750-800 species, found in tropical and subtropical regions. Green medicine is safe and more dependable than the costly synthetic drugs, many of which have adverse side effects (Joseph and Raj, 2010). The use of medicinal plants by man for the treatment of diseases has been in practice for a very long time. Screening of compounds obtained from plants for their pharmacological activity has resulted in the isolation of innumerable therapeutic agents.Over 50% of all modern chemical drugs are of natural plant product origin and is essential in drug development programs of the pharmaceutical industry (Burton et. al 1983).1.1.2 Phyllantus amarus (P. amarus) P. amarus is an erect annual herb of not more than one and half feet tall and has small leaves and yellow flowers. It is a broad medicinal plant that has received world-wide recognition (Srividiya and Perival, 1995).In herbal medicine, P. amarus has reportedly been used to treat jaundice, diabetes, otitis, diarrhea, swelling, skin ulcer, gastrointestinal disturbances and blocks DNA polymerase in the case of hepatitis B virus during reproduction, (Oluwafemi, and Debiri, 2008).In Nigeria, it is called -Oyomokeisoamankedem” in Efik, -Iyin Olobe” in Yoruba and -Ebebenizo” in Bini (Etta, 2008). In traditional medicine, it is used for its hepatoprotective, anti-diabetic, antihypertensive, analgesic, anti-inflammatory and anti- microbial properties (Adeneye et al; 2006). The plant is also used in the treatment of stomach disorders, skin diseases and cold (Kokwaro, 1976; Iwu, 1993). It has anti-diarrhoea effect (Odetola and Akojenu, 2000). Its anti-viral activity against hepatitis B virus has been established (Thyagarajan et al; 1988, Wang et al; 1995), anti- carcinogenic (Joy and Kuttan, 1998), anti mutagenic activities (Joy and Kuttan, 1998), antiplasmodial (Soh et al. 2009).Plants contain numerous constituents, some tend to possess some level of toxicity. Cases of this toxicity in plants have been reported (Santox et al; 1995, Shaw et al; 1997, Kaplowitz, 1997). P. amarus has been classified among plants with a low potential for toxicity, with an LD50 averaging 2000mg/kg 1day (Krithika and Verma, 2009).1.1.3 Phyllantus niruri (P. niruri)P. niruri is commonly called stone breaker, also known as -Chanca piedra”. It belongs to the family Euphorbiaceae. P. niruri is similar to P. amarus. It is a wide spread tropical plant commonly found in coastal areas that grows 40-70cm tall (Chukwuma, 2012).In Nigeria, it is called enyikwonwa and ngwu in Ibo, Oyokeso amanke edem in Efik, geeron- tsemtsaayee in Hausa, ehin olobe and yin-olobe in Yoruba (Chukwuma, 2012).Although P. niruri is considered a problematic weed to formers it is a valuable medicinal plant. (Oudhia and Tripathi, 2002), and holds a reputed position in both Ayurvedic and Unani system of medicine. Recently, it has attracted the attention of researchers, because of its hepatoprotective (ability to prevent damage to the liver) properties. No effective specific therapy is available for viral Hepatitis but P. niruri has shown clinical efficiency in viral Heptatis B (Paranjape, 2001).P. niruri is an annual plant, its stem is angular with numerous distichous, ellipticoblong leaves. Flowers are yellow and very numerous; monoecious with 1-3 staminate flowers and solitary pistillate flower borne axillary. Fruits capsule, very small, globose, smooth, seeds 3-gonous, longitudinally ribbed on the back. Seed to seed cycle occurs in two or four weeks (Caius 1986), (Agharkar 1991). Its root, leaves, fruits, milky juice and whole plants are used as medicine. According to Ayurvedic system of medicine it is considered acrid, cooling, aleixipharmic and useful in thirst, bronchitis, leprosy, anemia, urinary disharge, anuria, boiliousness, asthma, for hiccups, and as a diuretic. According to Unani system of medicine, it is stomachic and good for sores and useful in Chromic dysentery. Fruits useful for tubercular ulcers, wounds, sores, scabies and ring worm (Agharkar 1991, Krishanamurty 1993). The fresh root is believed to be an excellent remedy for jaundice.In many parts of India, it is commonly used for the treatment of snake bite. The active compounds phyllanthin and hypophyllanthim, nirtetralin and phyltetralin have been isolated from leaves, (Rastogi and Mehrotra, 1991). The plant is used as a fish poison. In many parts of India especially in deserts, the roots mixed with Commiphora mukul are given to camels to cure indigestion. The decoction of leaves and stem are used for dying cotton black, (Singh et al; 1996).P. niruri is one of the medicinal plants used to treat malaria in India and Nigeria. P. niruri has been used traditionally to treat various illnesses including renal stones, gastrointestinal disturbance, cough, hepatitis, gonoorhea, fever and malaria. It has also been reported to posses hypoglycemic activity (Hukuri, et al; 1988), angiotension converting enzyme inhibition (Ueno, et al; 1988), lipid lowering activity (Khanna, et al; 2002), anti HIV activity (Qian cutron, et al; 1996) and anti cancer activity (Giridharan, et al; 2002).1.2 Aim and objectivesThis study is aimed at showing which of the plants above is more effective in the treatment of diseases caused by micro-organisms based in the natural products present in them.The specific objectives include;a. Determination of antibacterial effect of P. amarus and P. niruri.b. Determination of anti fungal effect of P. amarus and P. niruri.