ABSTRACT
Natural products, as the term implies, are those chemical compounds derived from living organisms, plants, animals, insects, and the study of natural products is the investigation of their structure, formation, use and purpose in the organism. Drugs derived from natural products are usually secondary metabolites and their derivatives, and those must be pure and highly characterized compounds. A plant cell produces two types of metabolites: primary metabolites involved directly in growth and metabolism, viz., carbohydrates, lipids and proteins, and secondary metabolites considered as end products of primary metabolism and are in general not involved in metabolic activity, viz., alkaloids, phenolics, essential oils, steroids, lignins, tannins, etc. Primary metabolites are produced as a result of photosynthesis and these products are further involved in the cell component synthesis.
