Pharmaceutical development from plant-derived natural products

Discovering new drugs has never been a simple matter. From ancient times to the beginning of the last century, treatment for illness or disease was based mainly on folklore and traditional curative methods derived from plants and other natural sources. The isolation and chemical characterization of the principal components of some of these traditional medicines, mainly alkaloids and the like, spawned the development of the modem pharmaceutical industry and the production of drugs in mass quantities. Within the last century, however, the changes the industry has undergone have been profound. As the companion chapters of this volume describe, the emphasis has changed from isolation of active constituents to creation of new, potent chemical entities. This evolution from folklore to science is responsible for the thousands of pharmaceuticals available worldwide at present (1). 

Higher plants have evolved an extraordinary variety of secondary metabolic pathways, the resulting products of which have been put to use by man providing pharmaceuticals for drug use, insecticides and various allelochemicals for pest control, and extracts for the flavor and fragrances industries. In spite of advances in synthetic organic chemistry, plants remain a major source of natural products, particularly in the specialty chemicals industry. Compounds, such as the insecticide derived from Azadiraohta indioa or the antitumor alkaloids vinblastine and vincristine found in periwinkle (Catharanthus roseus) (1 ), have complicated structures which preclude at the present time the development of an economical chemical synthesis (Figure 1). In the case of... 

Natural products have been used as therapeutic agents or medicinal products for millennia in one form or another and a huge number of these, especially prior to the last 50 years, are derived from plants [2]. Today, natural products derived from plant sources continue to play a vital role in the treatment of diseases. There are many examples where the active compound in plant-derived traditional medicines has been used as a pharmaceutical agent. A particularly important example is the discoveiy and development of anti-malarial drugs such as quinine and artemisinin (Fig. 1.3). Quinine was isolated as early as 1820 and was used extensively until the... 

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