History and functioning of Plinazolin (isocycloseram)

The molecule commercially named by Syngenta as Plinazolin is gaining prominence this year in Brazil due to the start of sales of several products that contain it. In technical terms, it is isocicloseram (isocycloseram, CAS 2061933-85-3, Irac 30), a compound belonging to the group of isoxazolines (isoxazoline).

Isocycloseram has several theoretical functions. In one of its patents, Syngenta scientists described it as capable of "combating and controlling [...] insects, mites, molluscs and nematodes". Obviously, this is a definition for scientific and legal purposes. Use for each of the functions requires appropriate vehicles and registrations with the competent administrative spheres.

At this moment, the molecule is only registered in Brazil for use as an insecticide, under the trade names Atexzo ANT-F, Joiner, Sponta and Verdavis.

Mode of action of isocicloseram

In many cases, there are disagreements about the mode of action of chemicals. They are known to work. But not always how. In the case of insecticides from the isoxazoline group, scientists express some consensus. They act as modulators of GABA (gamma-aminobutyric acid) receptors in the central nervous system of insects. After binding to the receptor, the influx of ions is inhibited, resulting in hyperexcitation of the nervous system. This situation is paralyzing.

Specifically, isocycloseram rises, Syngenta scientists explain that, when larvae of Drosophila melanogaster were treated with the product, the symptoms induced were comparable to dieldrin (Irac group 2A). Larvae became hypercontracted and immobile, which is consistent with the disruption of nerve/muscle physiology expected from GABA receptor inhibition.

Furthermore, the researchers point out, isocicloseram interacts in a different location from insecticides belonging to Irac group 2. In a similar way, they add, isocicloseram interacts in a location distinct from that of group 6 insecticides.

For this reason, isocicloseram was classified in the new allosteric modulators of GABA-controlled chloride channels in Irac group 30, together with fluxametamide (fluxametamide) and broflanilide (broflanilide), as it acts as a non-competitive antagonist of the GABA receptor in invertebrates. in a location distinct from that of fiproles and cyclodienes.

A little about the history of isoxazolines (isoxazolines)

The literature attributes the discovery of the isoxazoline (isoxazoline) class of insecticides to researchers at Nissan Chemical Industries. There are those who maintain that the origin of 2-trifluoromethylated 5-isoxazolines as insecticides and parasiticides begins with a fortuitous discovery during investigations into the classes of phthalic and anthranilic diamide insecticides. Obviously, in the patent registration WO/2005/085216 there is nothing about this curiosity.

The discovery generated interest from major agrochemical companies. In 2019, more than 170 active ingredient patent applications were published in the isoxazoline chemical class. At least 19 companies and institutions were represented there.

In the case of Syngenta, researchers also reported a fortuitous encounter based on research with 1,2-diamide. In their experiment, thietan-3-amine was prepared and coupled to chlorantraniliprole anthranilic acid. By introducing the same 4-membered ring amine as a new amide side chain into the isoxazoline class, its first new compounds were discovered. Some of the main patents generated from there are WO/2007/080131 and WO/2009/080250.

What about Plinazolin?

Registration of the Plinazolin trademark was first requested in Switzerland, on May 30, 2018. It received number 716936. In Brazil, the application took place on July 13, 2018.

See also: Isocycloseram