Thesis Abstract

Abstract
The use of plants in the treatment of diseases caused by microorganisms has been a common practice throughout human history. Natural products derived from plants have been utilized for their antimicrobial properties and have played a significant role in traditional medicine systems. This review aims to provide an overview of the role of plants in the treatment of diseases caused by microorganisms, focusing on the natural products they contain. Plants produce a diverse array of bioactive compounds, such as alkaloids, terpenoids, phenolics, and essential oils, which possess antimicrobial properties against a wide range of pathogens, including bacteria, fungi, viruses, and parasites. These natural products act through various mechanisms, such as disrupting cell membranes, inhibiting cell wall synthesis, interfering with nucleic acid synthesis, and inhibiting enzyme activity. The complex chemical composition of plant extracts allows for a multi-targeted approach in combating microbial infections, reducing the likelihood of resistance development. Numerous studies have demonstrated the efficacy of plant-derived compounds in inhibiting the growth and proliferation of pathogenic microorganisms. Furthermore, some plant extracts have been shown to enhance the effectiveness of conventional antimicrobial agents, suggesting the potential for synergistic interactions. Plants such as garlic, turmeric, neem, tea tree, and ginger have been extensively studied for their antimicrobial properties and have been incorporated into various medicinal formulations. In addition to their direct antimicrobial effects, plant-derived compounds exhibit anti-inflammatory, immunomodulatory, and antioxidant activities, which can contribute to the overall management of infectious diseases. The synergy between these pharmacological effects enhances the therapeutic potential of plant-based treatments, making them valuable alternatives or adjuncts to conventional antimicrobial therapies. The utilization of plant-based treatments for microbial infections aligns with the increasing global interest in natural products and traditional medicine practices. With the growing concern over antibiotic resistance and the limited availability of effective antimicrobial agents, exploring the potential of plant-derived compounds offers a promising avenue for the development of novel therapies. Further research is warranted to elucidate the mechanisms of action, optimize formulations, and evaluate the safety and efficacy of plant-based treatments in clinical settings.

Thesis Overview

1.1 BACKGROUND OF STUDY1.1.1 PhyllanthusThis 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, windbreaker, 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 Phyllanthus is one of the genus that falls under this enormous family. Phyllanthus 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 Phyllanthus 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 worldwide recognition (Sri Divya 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 antiviral 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 2000 mg/kg 1 day (Krithika and Verma, 2009).1.1.3 Phyllanthus 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 Hepatitis B (Paranjape, 2001).P. niruri is an annual plant, its stem is angular with numerous distichous, elliptic oblong 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, alexipharmic and useful in thirst, bronchitis, leprosy, anemia, urinary discharge, anuria, biliousness, asthma, for hiccups, and as a diuretic. According to Unani system of medicine, it is stomachic and good for sores and useful in Chronic dysentery. Fruits useful for tubercular ulcers, wounds, sores, scabies and ringworm (Agharkar 1991, Krishnamurti 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 hypophyllanthin, 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, gonorrhea, fever and malaria. It has also been reported to possess hypoglycemic activity (Hukuri, et al; 1988), angiotensin 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 microorganisms 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 antifungal effect of P. amarus and P. niruri.