INTRODUCTION AND LITERATURE REVIEW
1.1 INTRODUCTION Vernonia amygdalina, a member of the Asteraceae family, is a widely used local vegetable inNigeria, Uganda and other African countries. It grows in a range of ecological zones in Africa and the Arabian Peninsula (Bonsi et al., 1995). The leaf is commonly called “bitter leaf” in English, “Olubu or Onugbo” in Igbo, “Ityuna” in Tiv , “Oriwo” in Edo, “Ewuro” in Yoruba, “Chusar-doki” in Hausa, “Etidot” in Efik, “Omubiriz i” or “Omululuza” in West and Central Uganda; “Olusia” in Luo, Kenya. It is used in vario us food preparations and in ethnomedicine for the treatment of malaria and gastrointestinal infections. It is a shrub of 2-5 m tall with petiolate leaves of about 6.0mm wide (Ojiako and Nwanjo, 2006). It is up to 20 cm long and its bark is rough. The bitter taste of the leaf has been attributed to the presence of anti-nutritive principles like saponins, alkaloids, tannins and glycosides (Buttler and Bailey, 1973). There have been several reports on its antimicrobial, antiplasmodial, antitumor, antioxidant and antihelminthic properties (Jisaka et al., 1993; Izevbigie, 2003; Farombi, 2003; Ehiagbonare, 2007). Aqueous leaf extracts of V. amygdalina have been previously reported to have prebiotic properties (Ukwah and Ezeonu, 2008; Ezeonu and Ukwah, 2009; Ezeonu et al., 2012). For many years, medicine depended exclusively on leaves, flowers and barks of plants, until the 1970s when synthetic drugs came into use (Conway, 1973). In orthodox medicine, a plant may be subjected to several chemical processes before its active ingredients are extracted, while in traditional medicine, a plant is simply eaten raw, cooked or infused in water or native wine or even prepared as food (Sofowora, 1992; Jones, 1996; Reynolds, 1996).