The mode of toxic action of the pesticide Gliftor: The metabolism of 1,3-difluoroacetone to (-)-erythro-fluorocitrate
Menon, K.I., Feldwick, M.G., Noakes, P.S. and Mead, R.J. (2001) The mode of toxic action of the pesticide Gliftor: The metabolism of 1,3-difluoroacetone to (-)-erythro-fluorocitrate. Journal of Biochemical and Molecular Toxicology, 15 (1). pp. 47-54.
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The biochemical toxicology of 1,3-difluoroacetone, a known metabolite of the major ingredient of the pesticide Gliftor (1,3-difluoro-2-propanol), was investigated in vivo and in vitro. Rat kidney homogenates supplemented with coenzyme A, ATP, oxaloacetate, and Mg2+ converted 1,3-difluoroacetone to (-)-erythro-fluorocitrate in vitro. Administration of 1,3-difluoroacetone (100 mg kg-1 body weight) to rats in vivo resulted in (-)-erythro-fluorocitrate synthesis in the kidney, which was preceded by an elevation in fluoride levels and followed by citrate accumulation. Animals dosed with 1,3-difluoroacetone did not display the 2-3 hour lag phase in either (-)-erythro-fluorocitrate synthesis or in citrate and fluoride accumulation characteristic of animals dosed with 1,3-difluoro-2-propanol. We demonstrate that the conversion of 1,3-difluoro-2-propanol to 1,3-difluoroacetone by an NAD+-dependent oxidation is the rate-limiting step in the synthesis of the toxic product, (-)-erythro-fluorocitrate from 1,3-difluoro-2-propanol. Prior administration of 4-methylpyrazole (90 mg kg-1 body weight) was shown to prevent the conversion of 1,3-difluoro-2-propanol (100 mg kg-1 body weight) to (-)-erythro-fluorocitrate in vivo and to eliminate the fluoride and citrate elevations seen in 1,3-difluoro-2-propanol-intoxicated animals. However, administration of 4-methylpyrazole (90 mg kg-1 body weight) to rats 2 hours prior to 1,3-difluoroacetone (100 mg kg-1 body weight) was ineffective in preventing (-)-erythro-fluorocitrate synthesis and did not diminish fluoride or citrate accumulation in vivo. We conclude that the prophylactic and antidotal properties of 4-methylpyrazole seen in animals treated with 1,3-difluoro-2-propanol derive from its capacity to inhibit the NAD+-dependent oxidation responsible for converting 1,3-difluoro-2-propanol to 1,3-difluoroacetone in the committed step of the toxic pathway.
|Publication Type:||Journal Article|
|Murdoch Affiliation:||School of Biological Sciences and Biotechnology|
|Publisher:||John Wiley and Sons Inc.|
|Copyright:||© 2001 John Wiley & Sons, Inc.|
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