1.1 Medicinal Plant
Medicinal plants are various plants which can have medicinal properties. Plants in most developing countries, as a basis for promoting and maintenance of good health, has been widely recognized (UNESCO, 1996). Historically, plants have provided a source of inspiration for novel drug compounds, as plant derived medicines have made l arge contributions to human health and well being (Igbinosa et al., 2009). Different plant parts have also been used for various forms of diseases and infections. Traditional medicine is the oldest method of curing diseases and infections and various plants have been used in different parts of the world to treat human diseases and infections (Nweze et al., 2004; Vineela and Elizabeth, 2005; Ekpo and Etim, 2009).
According to the World Health Organization (WHO, 2002), traditional medicine using plant extracts continues to provide health coverage for over 80% of the world’s population, especially in the developing world and, in African countries; this rate is much higher. In recent years, however, medicinal plants have represented a primary health source for the pharmaceutical industry (Ajose, 2007). No less than 400 compounds derived from plants are currently used in the preparation of drugs, such as vincristine and vinblastine used in the treatment of cancer (Ajose, 2007).
Recently, some higher plant products have attracted the attention of microbiologists to search for some phytochemicals for their exploitation as antimicrobials, such plant products would be biodegradable and safe to human health (Kumar et al., 2008; Sugar et al., 2008; Krishnamurthy et al., 2008; Wang et al., 2010).
Furthermore, the increasing awareness on the use of medicinal plants in industrialized countries has been traced to the development of several drugs and
chemotherapeutics from the traditionally used herbs (UNESCO, 1998). Nigerians still depend largely on crude herbal remedies or traditional medicine. They also use wild plants for cosmetics and perfumery. Some of these herbal remedies have been observed to be effective in certain skin diseases (Ajose, 2007). Medicinal plants are known to owe their curative potentials to certain biological active substances, which exist in parts of the plants. The chemicals which are referred to as active principles or phytochemical substances include terpenses, flavonoids, bioflavonoids, benzophonones, xanthenes as well as some metabolites such as tannins, saponins, cyanates, oxalate and anthrax-quinones (Ekpo and Etim, 2009).
1.2 The disease Malaria and Statement of The Problem
Malaria is a disease caused by a parasite that lives part of its life in humans and part in mosquitoes. Malaria remains one of the major killers of humans worldwide, threatening the lives of more than one-third of the world’s population. It thrives in the tropical areas of Asia, Africa, and Central and South America, where it strikes millions of people (Branen, 1975). Each year 350 to 500 million cases of malaria occur worldwide. Sadly, more than 1 million of its victims, mostly young children, die yearly.
Although malaria has been virtually eradicated in the United States and other regions with temperate climates, it continues to affect hundreds of people in this country every year. The Centers for Disease Control and Prevention (CDC) estimates 1,200 cases of malaria are diagnosed each year in the United States. People who live in the United States typically get malaria during trips to malaria-endemic areas of the world.
Round the world, the malaria situation is serious and getting worse. Malaria threatens the lives of 40% of the world’s population – over 2 200 million people. Each year, there are an estimated 300-500 million clinical cases. Malaria is estimated to kill more than 1 million people annually, the majority of whom are young children. Ninety per cent of malaria cases in the world occur in Africa south of the Sahara. Children under 5 years of age and pregnant women are the worst affected by malaria. It is one of the leading causes of death among young children. Together with pneumonia, diarrhoea, measles and malnutrition, malaria is responsible for over 70% of deaths in young children especially in developing countries. Malaria pregnancy causes severe maternal illness and anaemia, and is also associated with low birth weight among newborn infants, a leading risk factor for infant mortality.
1.3 Justification of the Study
Several findings has accumulated and proven the potentials of medicinal plants use in traditional medicine in the treatment of several human diseases. Medicinal plants usage as therapeutics in the management of different ailment locally differs from society to society. Several studies have however identified compounds within herbal plants that are effective as antibiotics (Basile et al., 2000). Traditional healing systems around the world that utilize herbal remedies are an important source for the discovery of new antibiotics (Okpekon et al., 2004), some traditional remedies have successfully been used against antibiotic-resistant strains of bacteria (Kone et al., 2004). The demands for traditional herbal medicines is increasing globally, because it is cheap, safe and able to compete with most commercial antibiotics that bacterial pathogens are now even becoming resistant to. Herbal medicine has become more popular to cure many diseases due to its ease of availability, safety and less side effects. In view of its medicinal value, the present study is aimed to screen the anti malaria activity of Phyllantus amarus and Solanum nigrum extracts so as to contribute to their ethnomedicinal properties.
1.4 Aim and Objectives
The overall aim of the study is to evaluate the anti-malaria activity of crude leaf extract of Phyllantus amarus and Solanum nigrum on Plasmodium berghei infected mice.
i. To determine the anti-plasmodial activity of Phyllanthus amarus, using suppressive, curative and prophylaxis techniques.
ii. To determine the anti malarial activity of Solanum nigrum using suppressive test.
iii. To assay for the differences in the body weight and survival time of the infected mice.