Studies on natural products have become more and more important with the realization that plants are sources of secondary metabolites with high chemical diversity. Plant cells produce secondary metabolites either due to the response to adverse environmental conditions or as a result of potential defence approach against predators. These secondary metabolites may be used directly or as starting material for the synthesis of drugs useful for defence or protection against various diseases. They are also useful as nutraceuticals and health foods or supplements to promote good health and growth.