SPINOSAD

Description

Spinosyn A, along with its almost identical isomer, spinosyn D, is a component of spinosad, a US Environmental Protection Agency–registered insecticide and Food and Drug Administration–registered topical treatment for head lice. The active ingredients are produced by the bacterium?Saccharopolyspora spinosa. An enzyme in genes extracted from in this bacterium is the?first natural product shown to catalyze the Diels–Alder reaction, a step in spinosyn biosynthesis.

The Uses of SPINOSAD

Spinosyn A is the major component of a complex of unusual, hydrophobic macrocyclic lactones isolated from Saccharopolyspora spinosa in 1991. The 12-membered macrocyclic lactone is fused to form a rare 12-5-6-5 tetracyclic ring system, with the macrocycle and the terminal cyclopentane bearing glycosides. Spinosyn A is a potent insecticide for crop pathogens and ectoparasite control on animals. The spinosyns have a unique mechanism of action involving disruption of nicotinic acetylcholine receptors.

What are the applications of Application

Spinosyn A is a potent insecticide for pathogens of crops and disruptor of nicotinic acetylcholine receptor

Definition

ChEBI: A spinosyn in which the sugar amino and hydroxy groups are globally methylated. One of the two active ingredients of spinosad.

Biological Activity

spinosyn a is an insect nicotinic acetylcholinesterase receptors (nachrs) agonist and potent insecticide.the spinosyns are a family of macrolide natural products produced by the soil microorganism saccharopolyspora spinosa. spinosyn a is identified as a naturally-occurring macrocyclic lactone that is a potent insecticide.

Veterinary Drugs and Treatments

For the prevention and treatment of fleas for one month on dogs 14 weeks of age and older.
Spinosad is a group 5 nicotinic acetylcholine receptor agonist, that causes involuntary muscle contractions and tremors secondary to motor neuron activation. Prolonged exposure causes paralysis and flea death. Flea death begins within 30 minutes of dosing and in 4 hours is complete. Spinosad does not interact with bindings sites of other insecticidal agents (GABA-ergic or nicotinic).

in vitro

the mixture of spinosyns a and d, a commercial insecticide tracertm (dowagrosciences), is useful against various crop pests such as tobacco budworm. it was found that the deoxy analogs of spinosyns a were more potent insecticides than their respective parent factor. moreover, the 2’-desmethoxy analogs of spinosyns a showed insecticidal potency against h. virescens greater than that of spinosyns a and d, suggesting that polarity was not well tolerated. furthermore, the activity of 3'-deoxy spinosyn j was about the same as spinosyn a, and the activity of 2'-deoxy spinosyn h was found to be slightly greater than that of spinosyn a [1].

Metabolic pathway

Spinosad consists of two major components, namely psinosyns A (ca 85%) and D (ca 15%). When either 14C-spinosyn A or -spinosyn D is applied in the soil under aerobic conditions, the major degradation product of spinosyn A is spinosyn B, resulting from demethylation on the forosamine sugar. Other degradation products are hydroxylation products of psinosyns A and B, probably on the aglycone portion of the molecule.

Degradation

Spinosad is relatively stable in water with no observed decomposition between pH 5 and 7. Measured DT₅₀ values at pH 9 were 200 and 259 days, respectively, for spinosyns A and D (Saunders and Bret, 1997). Aqueous photolysis was very rapid with a DT₅₀ of < 1 day in pH 7 buffered water at 25 °C (DowElanco, 1996). Spinosad was rapidly dissipated and degraded in an outdoor mesocosm study and on plant surfaces (Saunders and Bret, 1997).

Toxicity evaluation

Acute oral LD₅₀ for rats: 2,000-5,000 mg/kg

References

[1] l. c. creemer, h. a. kirst, j. w. paschal, et al. synthesis and insecticidal activity of spinosyn analogs functionally altered at the 2'-,3'- and 4'-positions of the rhamnose moiety. j.antibiot.(tokyo) 53(2), 171-178 (2000).