Fipronil

Figure 12.1 The in silico prediction of the site of metabolism for Gefitinib and Fipronil, and the in silico prediction of MBI for 4-ipomelanol, showing the problematic molecular moiety.

Bobe, A., Coste, C.M., and Cooper. J.-F. Factors influencing the adsorption of fipronil on soils, J. Agric. Food Chem., 45(12) 4861-4865, 1997. 

Ngim, K.K. and Crosby. D.G. Abiotic processes in influencing fipronil and desthiofipronil dissipation in California, USA. rice fields. Environ. Toxicol. Chem., 20(5) 972-977, 2001. 

Ramesh, A. and Balasubramanian, M. Kinetics and hydrolysis of fenamiphos, fipronil, and trifluralin in aqueous buffer solutions, J. Agric. Food Chem., 47(8) 3367-3371, 1999. 

Stehr CM, Linbo TL, Incardona JP, Scholz NL (2006) The developmental neurotoxicity of fipronil notochord degeneration and locomotor defects in zebrafish embryos and larvae. Toxicol Sci 92 270-278... 

More recently, the new insecticide, fipronil (Figure 3.11), has been shown to act as a potent blocker of the GABA-regulated chloride channel. It is being used to control both foliar and soil insects9 whilst the avermectins and milbemycins can only be used against foliar pests. 

F. Colliot, K.A. Kukorowski, D. Hawkins and D.A. Roberts, Fipronil a new soil and foliar broad spectrum insecticide , in Brighton Crop Protection Conference - Pests and Diseases, 1992 , British Crop Protection Council, Farnham, UK, 1992, Vol. 1, pp. 29-34. 

One approach to the introduction of the trifluoromethylsulfinyl group in fipronil involves the reaction of 5-amino-3-cyano-1-(2,6-dichloro-4-trifluoromethylphe-nyl)pyrazole and trifluoromethylsulfinyl chloride in toluene (Fig. 8) [43], Exposure of fipronil to sunlight results in the extrusion of sulfur oxide, to give a 4-trifluoromethylpyrazole photoproduct derivative [44],... 

Note of the Editor A recent article by A. Lattes and B. Sillion on the effects of Fipronil appeared in Actualite Chimique" 294, pp. 6-10, 2006. ... 

Fig. 8. Trifluoromethylsulfinylation of pyrazole to prepare fipronil, and elimination of sulfur oxide from under sunlight conditions.

The A/-phenylpyrazole insecticide fipronil, already discussed in Section 2.1.1.2, contains the unusual trifluoromethylsulfinyl substituent, not often seen in agrochemical chemistry. Following the introduction of fipronil, several chemistries related to fipronil were launched, including acetoprole [105], an insecticide with acaricidal and nematicidal activity, and ethiprole [106], a systemic insecticide for the control of a broad spectrum of insects, both from Bayer CropScience. 

Cyflumetofen [198] is an experimental acaricide/miticide for use in vegetables and fruits. Pyriprole and pyrafluprole are two experimental insecticides introduced by Nihon Nohyaku and related, both in chemistry and mode of action to the highly successful insecticide fipronil. Fipronil acts at the GABA receptor to block the chloride channel. 

K.K. Ngim, S.A. Mabury, D.G. Crosby, Elucidation of fipronil photodegradation pathways, J. Agric. Food Chem. 48 (2000) 4661-4665. 

Chloro 6 nitro toluene bifenox, fomesafen, lactofen, perfluidone m-Chloro perbenzoic acid fipronil, rimsulfuron m-Chlorophenol cloprop, 3 CPA, oxyfluorfen... 

Dichloro 4 trifluoro methyl aniline fipronil, nipyraclofen... 

Dicyano propionic acid ethyl ester fipronil Dicycloheptadiene aldrin... 

Sulfonyl (trifluoro methyl fluoride) fipronil, mefluidide... 

In plants, animals and the environment, fipronil is metabolized via reduction to the sulfide, oxidation to the sulfone, and hydrolysis to the amide... 

Animals. Distribution is rapid. Elimination is mainly via the feces as fipronil and its sulfone. 

Plants. Uptake of fipronil into plants was low (c. 5%). At crop maturity, the major residue components were fipronil, the sulfone, and the amide. Following foliar application to cotton, cabbage, rice and potatoes, at crop maturity, fipronil and the photodegradate were the major residue components... 

The inhibition by other organophosphate compounds of the carboxylesterase which hydrolyzes malathion is a further example of xenobiotic interaction resulting from irreversible inhibition because, in this case, the enzyme is phosphorylated by the inhibitor. A second type of inhibition involving organophosphorus insecticides involves those containing the P=S moiety. During CYP activation to the esterase-inhibiting oxon, reactive sulfur is released that inhibits CYP isoforms by an irreversible interaction with the heme iron. As a result, these chemicals are inhibitors of the metabolism of other xenobiotics, such as carbaryl and fipronil, and are potent inhibitors of the metabolism of steroid hormones such as testosterone and estradiol. 

Konwick, B.J. Garrison, A.W. Black, M.C. Avants, J.K. Eisk, A.T, Bioaccumulation, biotransformation, and metabolite formation of fipronil and chiral legacy pesticides in rainbow trout Environ Sci. Technol. 2006, 40, 2930-2936. 

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