CHAPTER ONE
INTRODUCTION
Background of the study
Phytochemicals are a large group of plant derived compound hypothesized to be responsible for much of the disease protection conferred from diets high in fruits, vegetables, beans, cereals and plant-based beverages such as tea and wine (Hollman, 2005). They are biologically naturally occurring chemical compounds found in plants . They protect plants from disease and damage and contribute to the plants colour, aroma and flavor. They also protect plants from environmental hazards such as pollution, stress, drought, uv exposure and pathogenic attack. These Phytochemicals are known as secondary metabolities .
Recently it is clearly known that phytochemicals have roles in the protection of human health when their dietary intake is significant.
A wide range of dietary Phytochemicals are found in fruits, vegetables, legumes, whole grains, nuts, seeds, fungi, herbs and spices (Mathai, 2000). It is well known that plants produce these chemicals to protect themselves, but recent research demonstrate that many phytochemicals can also protect humans against diseases (Narasinga, 2003). The most important of these bioactive constituents of plants are alkaloids, tannins, steroids, terpenoids and phenolic compounds. In recent years secondary plant metabolites previously with unknown pharmacological activities have been extensively investigated as a source of medicinal agents. Thus it is anticipated that phyto-antimicrobial efficacy will be used for the treatment of bacterial infection (Balandrin et al., 2005).
Perseaamericana is one of the 150 varieties of avocado pear. The seeds of Perseaamericana has a diverse application in ethnomedicine, ranging from treatment for diarrhea, dysentery, toothache, intestinal parasites to the area of skin treatment and beautification (Pamplona and Roger, 1999). P. americana leaves have been reported to posses anti-inflammatory and analgesic activities (Adeyemi et al., 2002). The seeds are rich in tannins and carotenoids and tocopherols from the fruit were shown to inhibit the in-vitro growth of prostate cancer cell lines (lu et al, 2005) and “persin” from avocado leaves was shown to have antifungal properties and to be toxic to silkworms (oelrichs et al., 1995). The effect of P.americana extract was evaluated on in-vitro rat lymphocyte proliferation (Gomezflores et al., 2008). Antioxidant activity and phenolic content of seeds of avocado pear was found to be greater than 70% (Soong and Barlow 2004).