Lead compounds systematic screening

Natural sources are still important sources of lead compounds and new drugs. However, the large diversity of potential natural sources in the world makes the technique of random screening a rather hit or miss process. The screening of local folk remedies (ethnopharmacology) offers the basis of a more systematic approach. In the past this has led to the discovery of many important therapeutic agents, for example, the antimalarial quinine from cinchona bark, the... 

A frequent problem facing one interested in ligand design is that in which the structure of the receptor is unknown and must be deduced from systematic variation of the structure of some lead compound, often found by randomly screening compounds from a large database in biological or biochemical test... 

Most, if not all, of the compounds mentioned in this volume have arisen through the systematic screening of novel chemicals and the identification of active lead compounds. The subsequent development of more active analogues and suitable formulation/delivery systems illustrates the ingenuity and expertise of the R D chemists/biologists involved in the launch of a new herbicide. While this approach has been eminently successful, there is a view that, ideally, novel compounds should be tailored to fit specific enzyme receptor sites. This aim will be achieved only with improved understanding of the molecular architecture of the site(s) and the molecular requirements for transport into and within the plant. The approach taken in this book should serve to illuminate the problems and possible solutions. 

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