Physical and chemical properties and uses of abamectin drugs

Avermectin (avermectins, AVMs) by Streptomyces a class of macrolide antibiotics produced sixteen yuan (Streptomyces avermitilis noncyanogenus and S.
Cyanneogrisens)
.

AVMs has strong anthelmintic and insecticidal activity, and has a unique anti-parasitic mechanism, and has no cross-resistance with other anti-parasitic drugs

21.
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1 Physical and chemical properties and uses

21.
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1 Physical and chemical properties

In 1976, researchers from Merck in the United States isolated Streptomyces avermitilis from a soil sample from Japan, which can produce avermectin (avermectin, AVM), which is a group of sixteen-membered ring lactones and A glycoside produced by a disaccharide olean fructose has a spiroketal system containing two six-membered rings and a hexahydrobenzofuran ring system around the sixteen-membered ring lactone
.

There are usually 8 components in the fermentation broth of wild bacteria: Ala, A2a, Bla, B2a, Alb, A2b, B1b, B2b

In order to obtain AVMs with more stable structure, stronger insecticidal activity, and safer action, researchers have conducted a lot of research on the modification of AVM structure, and some structural modifications have made it have new properties
.

Among them, the most successful example is the selective reduction of the double bond at the C-22 and C-23 positions of the B1 component to form ivermectin (IVM); doramectin (DOR) is used in AVM C-25 is connected with a six-membered ring to synthesize; eprinomectin (EPR) introduces an acetylamino group through the 4" end of AVM, which can be accomplished by glycosylation or direct synthesis

Moxidectin (MOX) is a semi-synthetic single-component macrolide antibiotic produced by fermentation of S.
Cyanneogrisens noncyanogenus
.

It introduces =N-OCH ₃ group in C-23 , C-13 has one less disaccharide group, so it has higher fat solubility, and its water solubility is 4.

The physical and chemical structure of AVMs is shown in Table 21-1
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Although AVMs is inactive against bacteria and molds, it has strong anthelmintic and insecticidal activity, and has a unique anti-parasitic mechanism, and has no cross-resistance with other anti-parasitic drugs
.

One of the explanations for its mechanism of action is that by interfering with the neurophysiological activities of nematodes and arthropods, stimulating the body to produce y-aminobutyric acid (GABA), thereby blocking the central nervous system and nerve-muscle transmission, so that the central nervous system of the pests The signal cannot be received by the motor neuron, which cuts off the connection between the motor nerve and the muscle, causing the pest to quickly paralyze, refuse to eat, move slowly or immobile within a few hours, and die after 24 days; the other reason is that the drug causes glutamate control The opening of the CI ^- channel leads to an increase in the permeability of the membrane to CI ^- .

Table 21-1 The physical and chemical properties of common abamectins

 

AVMs are widely used in the treatment of a variety of internal and external parasitic diseases in domestic animals, mainly for the treatment of gastrointestinal nematodes, bovine myiasis, rhinoidosis, itchy mites and scabies of pigs and sheep
.

AVM has good insecticidal effects on gastrointestinal nematodes, lung nematodes and ectoparasites of cattle, sheep, pigs and horses, but has no effect on tapeworms and flukes