Evaluation of the mechanism of action of the bleaching herbicide SC-0051 by HPLC analysis

Mayonado, David J.; Hatzios, Kriton K.; Orcutt, D. M.; Wilson, H. R.

doi:10.1016/0048-3575(89)90111-9

Cited by 34 publications

(24 citation statements)

References 13 publications

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“…Based On pigment patterns in treated radish (Raphanus satiws L.) plants, and Uchida (1987) concluded that the triketones were affecting p i p e n t biosynthetic steps but in a manner unlike that of other bleaching herbicides such as norflurazon. In contrast, Mayonado et al (1989) showed that SUlCOtriOne caused the Same pattern Of p i p e n t changes in soybean (Gly " L.) treated with norflurazon. Kawakubo et al (1979) concluded that 1 3 -dimethy1-4-(2~4-dichorobe~oY1)-5-h~~o~~azo1e synthesis of Pchlide.…”

Section: Chemicals and Reagentsmentioning

confidence: 95%

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Inhibition of Barnyardgrass 4-Hydroxyphenylpyruvate Dioxygenase by Sulcotrione

Secor¹

1994

Plant Physiol.

105

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Section: Chemicals and Reagentsmentioning

confidence: 95%

“…One striking difference is that the triketones affect new growth, whereas other bleaching herbicides affect older growth (Mayonado et al, 1989). Also, unlike the other…”

Section: Materials and M E T H O D Smentioning

confidence: 98%

Inhibition of Barnyardgrass 4-Hydroxyphenylpyruvate Dioxygenase by Sulcotrione

Secor¹

1994

Plant Physiol.

105

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“…The herbicidal mode of action of triketones is known to be due to inhibition of HPPD in the target plants resulting in effects on the biosynthesis of plastoquinones and tocopherols. These effects result in a decrease in phytoene desaturase activity and lead to bleaching of the plants [2]. During evaluation of the triketones in laboratory animals, it was discovered that this class of compounds also inhibit mammalian HPPD [3].…”

Section: Introductionmentioning

confidence: 99%

Pharmacokinetics and pharmacodynamics of NTBC (2‐(2‐nitro‐4‐fluoromethylbenzoyl)‐1,3‐cyclohexanedione) and mesotrione, inhibitors of 4‐hydroxyphenyl pyruvate dioxygenase (HPPD) following a single dose to healthy male volunteers

Hall

Wilks

Provan

et al. 2001

Brit J Clinical Pharma

103

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Aims NTBC (2-(2-nitro-4-¯uoromethylbenzoyl)-1,3-cyclohexanedione) and mesotrione (2-(4-methylsulphonyl-2-nitrobenzoyl)-1,3-cyclohexanedione) are inhibitors of 4-hydroxyphenyl pyruvate dioxygenase (HPPD). NTBC has been successfully used as a treatment for hereditary tyrosinaemia type 1 (HT-1), while mesotrione has been developed as an herbicide. The pharmacokinetics of the two compounds were investigated in healthy male volunteers following single oral administration. The aim of the NTBC study was to assess the bioequivalence of two different formulations and to determine the extent of the induced tyrosinaemia. The mesotrione study was performed to determine the magnitude and duration of the effect on tyrosine catabolism. Additionally, the urinary excretion of unchanged mesotrione was measured to assess the importance of this route of clearance and to help develop a strategy for monitoring occupational exposure. Methods A total of 28 volunteers participated in two separate studies with the compounds. In the ®rst study, the relative bioavailability of NTBC from liquid and capsule formulations was compared and the effect on plasma tyrosine concentrations measured. In the second study the pharmacokinetics of mesotrione were determined at three doses. Plasma tyrosine concentrations were monitored and the urinary excretion of mesotrione and tyrosine metabolites was measured. Results Both compounds were well tolerated at the dose levels studied. Peak plasma concentrations of NTBC were rapidly attained following a single oral dose of 1 mg kg x1 body weight of either formulation and the half-life in plasma was approximately 54 h. There were no statistical differences in mean (t s.d.) AUC(0,?) (capsule 602t154 vs solution 602t146 mg ml x1 h) or t 1/2 (capsule 55t13 vs solution 54t8 h) and these parameters supported the bioequivalence of the two formulations. Mesotrione was also rapidly absorbed, with a signi®cant proportion of the dose eliminated unchanged in urine. The plasma half-life was approximately 1 h and was independent of dose and AUC(0,?) and C max increased linearly with dose. Following administration of 1 mg NTBC kg x1 in either formulation, the concentrations of tyrosine in plasma increased to approximately 1100 nmol ml x1 . Concentrations were still approximately 8 times those of background at 14 days after dosing, but had returned to background levels within 2 months of the second dose. Administration of mesotrione resulted in an increase in tyrosine concentrations which reached a maximum of approximately 300 nmol ml x1 following a dose of 4 mg kg x1 body weight. Concentrations returned to those of background within 2 days of dosing. Urinary excretion of tyrosine metabolites was increased during the 24 h immediately following a dose of 4 mg mesotrione kg x1 , but returned to background levels during the following 24 h period. Conclusions NTBC and mesotrione are both inhibitors of HPPD, although the magnitude and duration of their effect on tyrosine concentrations are very different. When normalized for dose...

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“…In plants, triketones such as sulcotrione (2-[4-chloro-2-nitrobenzoyl]-5,5-dimethylcyclohexane-1,3-dione) are effective bleaching herbicides. Their mode of action arises from a direct inhibition of plastoquinone and tocopherol synthesis and an indirect inhibition of carotenoid desatu-ration (Mayonado et al, 1989;Schultz et al, 1993;Secor, 1994). The latter results in accumulation of the carotenoid biosynthetic intermediate phytoene and photooxidation of the plastid.…”

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confidence: 99%

Complementation of the Arabidopsispds1Mutation with the Gene Encodingp-Hydroxyphenylpyruvate Dioxygenase

1998

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Plastoquinone and tocopherols are the two major quinone compounds in higher plant chloroplasts and are synthesized by a common pathway. In previous studies we characterized two loci in Arabidopsis defining key steps of this biosynthetic pathway. Mutation of the PDS1 locus disrupts the activity of p-hydroxyphenylpyruvate dioxygenase (HPPDase), the first committed step in the synthesis of both plastoquinone and tocopherols in plants. Although plants homozygous for the pds1 mutation could be rescued by growth in the presence of homogentisic acid, the product of HPPDase, we were unable to determine if the mutation directly or indirectly disrupted HPPDase activity. This paper reports the isolation of a cDNA, pHPPD, encoding Arabidopsis HPPDase and its functional characterization by expression in both plants and Escherichia coli. pHPPD encodes a 50-kD polypeptide with homology to previously identified HPPDases, including 37 highly conserved amino acid residues clustered in the carboxyl region of the protein. Expression of pHPPD in E. coli catalyzes the accumulation of homogentisic acid, indicating that it encodes a functional HPPDase enzyme. Mapping of pHPPD and co-segregation analysis of the pds1 mutation and the HPPD gene indicate tight linkage. Constitutive expression of pHPPD in a pds1 mutant background complements this mutation. Finally, comparison of the HPPD genomic sequences from wild type and pds1 identified a 17-bp deletion in the pds1 allele that results in deletion of the carboxyterminal 26 amino acids of the HPPDase protein. Together, these data conclusively demonstrate that pds1 is a mutation in the HPPDase structural gene.

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Evaluation of the mechanism of action of the bleaching herbicide SC-0051 by HPLC analysis

Cited by 34 publications

References 13 publications

Inhibition of Barnyardgrass 4-Hydroxyphenylpyruvate Dioxygenase by Sulcotrione

Inhibition of Barnyardgrass 4-Hydroxyphenylpyruvate Dioxygenase by Sulcotrione

Pharmacokinetics and pharmacodynamics of NTBC (2‐(2‐nitro‐4‐fluoromethylbenzoyl)‐1,3‐cyclohexanedione) and mesotrione, inhibitors of 4‐hydroxyphenyl pyruvate dioxygenase (HPPD) following a single dose to healthy male volunteers

Complementation of the Arabidopsispds1Mutation with the Gene Encodingp-Hydroxyphenylpyruvate Dioxygenase

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