Traditional Plant Sources

Currently the primary commercial plant-derived sources for inulin are Jerusalem artichoke and chicory. The former is grown more so in Eastern Europe and the latter in Northwestern Europe. There is increasing interest in the commercial production of Jerusalem artichoke in China and several other countries. At present, neither crop is grown to any extent in the U.S., although there is some fresh-market production of Jerusalem artichoke. 

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The most well known and most widely used compounds mentioned in the chapter are the doubly protected monosaccharide derivatives (cf. Schemes 16-18 and 27-29), which serve as building blocks for the regio- and stereospecific synthesis of a host of more complex carbohydrates. A number of newly discovered alkaloids contain fused 5 6 6-triheterocyclic systems these compounds may come from not only traditional (plant) sources, for example, compounds 96, 292-294, 446, and 447, but also insects (compounds 531-533), marine animals of various kinds, for example, sponges (compounds 58 R = H or OH) and ascidians (compound 289), and amphibians (compound 535). Although the majority of these alkaloids are known to be toxic in sufficient quantity, any possible therapeutic applications have apparently not yet been disclosed. 

The underlying assumption driving marine natural products chemistry research is that secondary metabolites produced by marine plants, animals, and microorganisms will be substantially different from those found in traditional terrestrial sources simply because marine life forms are very different from terrestrial life forms and the habitats which they occupy present very different physiological and ecological challenges. The expectation is that marine organisms will utilize completely unique biosynthetic pathways or exploit unique variations on well established pathways. The marine natural products chemistry research conducted to date has provided many examples that support these expectations. 

Traditionally, plants are a rich source of AChE inhibitors. People from the Caucasus used bulbs of snowdrops Galanthus sp.) to treat forgetfulness [25]. The active compound in this plant has been isolated and called galanthamine. Other plant-derived AChE inhibitors used for treatment of Alzheimer s disease include Huperzine A from Huperzia serrata and Rivastigmine (Excelon). The latter is a derivative from physostigmine isolated from the calabar bean, Physos-tigma vmmosum. 

Some of the traditionally used industrial enzymes (e.g., rennet and papain) are prepared from animal and plant sources. Recent developments in industrial enzyme production have emphasized the microbial enzymes (Frost 1986). Microbial enzymes are very heat stable and have a broader pH optimum. Most of these enzymes are made by submerged cultivation of highly developed strains of microorganisms. Developments in... 

A few thiophene natural products have either been synthesized or recently isolated from plant sources. A short synthesis of the Otanthus Maritima amide 217 was recently disclosed . A group of known dithiophenes including 218 were isolated from Rhaponticum uniflorum . Finally, a novel tetrahydrothiophene, 6-hydroxythiobinupharidine (219), was isolated from a traditional Chinese medicinal plant, Nuphar pumilum . 

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... 

Curare is a muscle relaxant drug, originally used as an arrow poison by Amazonian Indians. The traditional curare is prepared by a secret recipe thought to involve a number of plant species (Plotkin 1993). Plant sources of curare include Strychnos castelnaei and species in the Loganaceae family and Chondodendron tomentosum in the Menispermaceae family. Tubocurarine, a benzylisoquinoline dimer, is the major alkaloid in the curare plants. It exhibits paralysing effects on skeletal muscles, and is used as a muscle relaxant in surgical procedures. It controls convulsions caused by the toxic alkaloid strychnine. 

Like other alkaloids, supply of colchicine from traditional sources is limited either due to the gradual decreasing condition of plant sources or due to trace amounts of compounds present in the plants. Therefore, several alternative strategies have been adapted to increase the production of colchicine and colchicine derivatives. 

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