1.0 Introduction
1.1 Background of Study
Natural products can either be of pre-biotic origin or originate from microbes, plants, or animal sources (Nakanishi, 1999). As chemicals, natural products include such classes of compounds as terpenoids, polyketides, amino acids, peptides, proteins, carbohydrates, lipids, nucleic acids, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and so forth. Natural products do not just occur by accident or products of convenience of nature, but more than likely are a natural expression of the increase in complexity of organisms (Jarvis, 2000).
Interest in natural sources to provide treatments for pain palliatives, or curatives for a variety of maladies or recreational use reaches back to the earliest points of history. Nature has provided many things for humankind over the years, including the tools for the first attempts at therapeutic intervention (Nakanishi, 1999). The Nei Ching is one of the earliest health science anthologies ever produced and dates back to the thirtieth century B.C. (Nakanishi, 1999). Some of the first records on the use of natural products in medicine were written in cuneiform in Mesopotamia on clay tablets and date to approximately 2600 B.C. (Cragg and Newman, 2001; Nakanishi, 1999).
Indeed, many of these agents continue to exist in one form or the other to this day and are used for the treatment of inflammation, influenza, cough, and parasitic infestation among others. Chinese herb guides document the use of herbaceous plants as far back in time as 2000 B.C (Holt and Chandra, 2002). For a variety of different reasons, the interest in natural products continues to this very day (Barron and Vanscoy, 1993; Bhattaram et al., 2002; Chan, 1995; Holt and Chandra, 2002; Koh and Woo, 2000; Marriott, 2001). The first commercial pure natural product introduced for therapeutic use is generally considered to be the narcotic morphine, marketed by Merck in 1826 (Newman et al., 2000). The first semi-synthetic pure drug based on a natural product, aspirin, was introduced by Bayer in 1899.
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