The Design of New Pesticides

Other mnch more toxic componnds operating throngh specific biochemical mechanisms (e.g., OP anticholinesterases) cannot be modeled in this way. If 

Organic Pollutants An Ecotoxicological Perspective, Second Edition 

In general, it is easier to use models such as these to predict the distribution of chemicals (i.e., relationship between exposure and tissue concentration) than it is to predict their toxic action. The relationship between tissue concentration and toxicity is not straightforward for a diverse group of compounds, and depends on their mode of action. Even with distribution models, however, the picture can be complicated by species differences in metabolism, as in the case of models for bioconcentration and bioaccumulation (see Chapter 4). Rapid metabolism can lead to lower tissue concentrations than would be predicted from a simple model based on values. Thus, such models need to be used with caution when dealing with different species. 

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Clavicepspurpurea. Indeed, these natural toxins have given many useful leads in the design of new pesticides, biocides, or drugs. 

In contrast to "pro" compounds of the type described above, a large number of propesticides have also been developed in recent years which were designed on the basis of their anticipated activation in biological systems. In these cases, active compounds were modified by derivatization into products which reverted back to the original compound within the target organism. This kind of approach to the design of new pesticides has many virtues and the most important of these are described briefly as follows. 

Derivatization, therefore, has been widely applied to improve the toxicological properties of known insecticides and this paper will attempt to review accomplishments and discuss possibilities for future strategy for the design of new compounds with this group of pesticides. 

In the course of our attempts dedicated to the search of new pesticides, we were interested in the design of proinsecticides, especially procarbamates which are less toxic to mammalians than the parent carbamates. N-Acyl-N-methyl or N-sulfenyl-N-methyl carbamates derived from Carbofuran or Aldicarbe are quite effective insecticides and are often equal to superior to their parent compound against insects. 

Kovach J, Petzoldt C, Degni J, Tette J (1992) A method to measure the environmental impact of pesticides. New York Food Life Sci Bull 192 2-8 Kropff MJ, Bouma J, Jones JW (2001) System approaches for the design of sustainable agroecosystems. Agric Sys 70 369-393... 

These developments indicate potential new modes of selective insecticidal action. Through a better understanding of the physiological processes, the basis of screening can be broadened and the increased knowledge of the diverse biochemical pathways suggests new approaches to the design of pesticides. 

This paper will discuss our views on the critical components needed for the successful design of new herbicides using biochemical approaches. This topic has been the subject of a number of recent reports (i-5). ile there have been no commercial successes to date using target-site based approaches, there liaig been a number of near misses, some of which will be describe here, and there is tremendous potential for success in this approach. At Du Pont, we are firmly committed to biochemical approaches to the discovery of novel pesticides and believe that it will ultimately be successful from a commercial standpoint. 

Not all carbon compounds are derived from living organisms, of course, and chemists over the years have developed a remarkably sophisticated ability to design and synthesize new organic compounds. Medicines, dyes, polymers, food additives, pesticides, and a host of other substances are now prepared in the laboratory. Organic chemistry touches the lives of everyone. Its study is a fascinating undertaking. 

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