Uses
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.
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 DT
50 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 DT
50 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 LD
50 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).
