Ivermectin from Streptomyces avermitilis

Ivermectin, a semisynthetic macrocyclic lactone, is a mixture of avermectin Bia and Bib- is derived from the soil actinomycete Streptomyces avermitilis. 

Ivermectins B1 are derived from the avermectines Bl, the natural fermentation products of Streptomyces avermitilis. The avermectins Bl have double bonds between carbon atoms at 22 and 23, whereas the ivermectins Bl have single bonds in these positions (Fig. 2a). They have an intermediate polarity. The ivermectins Bl are a mixture of two major homologs, ivermectins Bla (>80%) and ivermectins Bib (<20%), but a crude ivermectin complex also contains various minor components. Ivermectins Bl are broad-spectrum antiparasitic agents used against Onchocerca volvulus in human medicine and for food production animals such as cattle, swine, and horses. 

Ivermectin is a macrolide compound derived from abamectin, a metabolite produced by Streptomyces avermitilis. More precisely, it is a mixture of two compounds, 22,23-dihydroavermectin (80%) and 22,23-dihydroavermectin (20%) (12). It is widely... 

Extracted from the soil actinomycete Streptomyces avermitilis, the natural avermectins are 16-membered macrocyclic lactones that, on reduction of the C22-23 double bond, give rise to ivermectin (IVM), which is an 80 20 mixture of dihydroavermectin Bia and Bip, respectively. The natural avermectins have minimal biological activity, but IVM has proven to be quite beneficial in the treatment of various nematode infections. 

Ivermectins B1 are broad-spectrum antiparasitic agents widely used for food-producing animals such as cattle, swine, and horse.They are derived from avermectins Bl, the natural fermentation products of Streptomyces avermitilis. 

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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