Chemical modification avermectin family

The avermectins are a family of broad-spectrum antiparasitic compounds with avermectin A (Figure 8.10) being an example. These compounds were originally sold by Merck (with a slight chemical modification) as veterinary agents... 

This chapter deals with recent progress in the chemical modification and structure-activity relationships of 14- and 15-membered macrolides (mainly erythromycin derivatives), 16-membered macrolides (mainly the leucomycin and tylosin families), and the avermectin family of macrolides, showing nematocidal, insecticidal, and arachnidicidal activities. Previous reviews of these macrolides were given by Sakakibara and Omura in the first edition of this book in 1984 [1]. 

In the middle of the 20th century, the synthetic development of DDT and other chlorinated hydrocarbons (C.H.), increased insecticidal activity well beyond that of most natural products. Problems arose with bioaccumulation of C.H. residues in the food chain, human fat tissue, mother s milk, as well as the development of insecticide resistance. It became obvious there were limitations to synthetic technology as well. The modification of a natural product, for example, from chrysanthemum flowers and their pyrethrum extracts (7) to pyrethroids such as allethrin, resmethrin, permethrin (2), and deltamethrin created a model in which insecticides are created from the skeleton of insecticidally active natural molecules. Thus, the avermectin, abamectin, ivermectin family of pesticides originated from compounds produced by the soil bacterium, Streptomyces avermitilis (5), and the commercially successful chloronicotinyl insecticides, though not derived from nicotine, are chemically related 4). Both pyrethroids and chloronicotinyls are currently used commercially as termiticides. We have previously provided a detailed review of natural products as pesticidal agents for control of the Formosan subterranean termites, Coptotermes formosanus Shiraki (5). 

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