CHAPTER ONE
INTRODUCTION AND LITERATURE REVIEW
1.1 INTRODUCTION
Knowledge of the chemical constituents of plants is desirable, not only for the discovery of therapeutic agents, but also because such information could be valuable in disclosing new sources of economic and important materials as tannins, oils, gums, and precursors for the synthesis of complex chemical substances. Furthermore, the knowledge of the chemical constituents of plants is valuable in discovering the actual value of folkloric remedies (Mojab et al., 2003). Plants have a limitless ability to synthesize substances mainly secondary metabolites, of which at least 12,000 are known, This figure is estimated to be less than10% of the total (Mallikharjuna et al., 2007). The natural substances are used by plants as defensive molecules against micro-organisms, insects and herbivores. However, some of these product are involved in determination of plant odour (terpenoids), pigmentation (tannins and quinines), and flavour (Capsacin) (Mallikharjuna et al., 2007). However, these defensive molecules give plants their medicinal value which is exploited by human beings because of their great importance in health care of individuals and communities. These natural compounds formed the basis of modern drugs development today
(Edeoga et al., 2005).