Chiral effects of (R)‐/(S)‐1‐(α‐methylbenzyl)‐3‐(p‐tolyl)urea on the free amino acid levels in the root tips of rice and wheat

Imai, Kazuhiro; Kojima, Hisahiro; Numata, Takako; Omokawa, Hiroyoshi; Tanaka, Hideyuki

doi:10.1111/j.1445-6664.2008.00323.x

Cited by 8 publications

(3 citation statements)

References 19 publications

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“…Because of the vital importance of the chirality, the enantioselective ecological fate and effects of chiral herbicides have gradually received much attention. The present studies show enantioselectivities in the toxicity and environmental fate of chiral herbicides (4)(5)(6)(7)(8)(9)(10)(11)(12). The behavior of the active enantiomer, instead of just the racemate, may have more relevance to the herbicidal effects and ecological safety.…”

Section: Introductionmentioning

confidence: 63%

Molecular Mechanism of Enantioselective Inhibition of Acetolactate Synthase by Imazethapyr Enantiomers

Zhou

Zhang

et al. 2010

J. Agric. Food Chem.

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Chiral compounds usually behave enantioselectively in phyto-biochemical processes. Imidazolinones are a class of chiral herbicides that are widely used. They inhibit branched-chain amino acid biosynthesis in plants by targeting acetolactate synthase (ALS). It has been reported that the imidazolinone enantiomers show different inhibiting activities to maize (Zea mays L.) seedlings and ALS. However, to date, the mechanism of enantioselective inhibition of imazethapyr (IM) on ALS activity has not been well studied. In this study, pure enantiomers of IM were used for characterizing their differences in activity to ALS. Computational molecular docking was performed to discover the molecular interaction between IM enantiomers and ALS at the first time. Results showed that the IM enantiomers enantioselectively suppressed the in vitro and in vivo ALS activity of maize leaves. R-(-)-IM was more active than S-(+)-IM. The in vivo ALS activity study showed only a 2-fold difference between R-(-)-IM and S-(+)-IM. Quite different from the in vivo study, the in vitro study showed that the difference in inhibition between the enantiomers fell sharply as concentration increased. At the lowest concentration of 40 microg L(-1), R-(-)-IM appeared 25 times more active than S-(+)-IM, but only 7 times at 200 microg L(-1). At the highest concentration of 25 mg L(-1), in vitro ALS activity was almost completely inhibited by S-(+)-, R-(-)-IM and (+/-)-IM, there was only 1.1 times differences between S-(+)- and R-(-)-IM. Molecular modeling results provide the rational structural basis to understand the mechanism of enantioselective inhibition of IM on ALS activity.

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Section: Introductionmentioning

confidence: 63%

Molecular Mechanism of Enantioselective Inhibition of Acetolactate Synthase by Imazethapyr Enantiomers

Zhou

Zhang

et al. 2010

J. Agric. Food Chem.

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“…In the previous study, we investigated changes in the free amino acids in the root tips of rice and wheat in order to clarify the mode of action of R-/S-MBTU (Imai et al 2009). Several amino acids changed their content between rice and wheat, enantioselctively.…”

Section: Discussionmentioning

confidence: 99%

Root growth profiles of Aveneae and Poeae plants in optically active α‐methylbenzyl‐3‐p‐tolylurea media

Kojima

Ohnuma

Omokawa

2009

Weed Biology and Management

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Using a root growth inhibition assay, we studied the diverse chiral responses of plants in the tribes, Aveneae and Poeae, to the optically active compounds, R-and S-1-a-methylbenzyl-3-p-tolylurea (MBTU).We specifically examined the responses of grasses belonging to the Poeae tribe (Lolium, Briza, Poa, Dactylis, and Festuca) and the Aveneae tribe (Avena, Holcus, Agrostis, Alopecurus, Beckmannia, and Phleum). These plants include companion weeds of wheat and barley, and turf grass. The companion weeds of cereal crops, such as Poa annua, Poa pratensis, Dactylis glomerata, Avena fatua, Avena sativa, Holcus lanatus, Agrostis stolonifera, Alopecurus myosuroides, Al. aequalis, and Beckmannia syzigachne, showed significantly inhibited root growth in response to 20 mmol L -1 R-MBTU, whereas the root growth of Triticum aestivum was not inhibited at this concentration. Like Oryza sativa, almost all the Poeae and Aveneae plants tested here preferentially responded to R-MBTU, but the four grasses, Lolium multiflorum, D. glomerata, Alopecurus species, and Phleum pratense, preferentially responded to S-MBTU.Among them, the Agrostis species were highly sensitive to R-MBTU and the Alopecurus species were highly sensitive to S-MBTU. All the plants among the genera, Poa, Avena, and Alopecurus, showed a homogeneous chiral preference.

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“…In contrast, the root growth of Echinochloa and wheat was more sensitive to S-MBTU than to the antipodal R-MBTU ( Omokawa et al, 2004;Kazuhiro et al, 2009). Imai et al thought that the decrease in free amino levels in the root tips was the reason that R-/S-MBTU inhibited the growth of the plants (Imai, Kojima & Numata, 2009). The activity of α-methylbenzyl-p-tolylureas (4-Me) mainly depends on the substituents of benzene.…”

Section: Ureasmentioning

confidence: 99%

Enantioselective Activity and Toxicity of Chiral Herbicides

Liu¹,

Tang²

2011

Herbicides - Mechanisms and Mode of Action

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Chiral effects of (R)‐/(S)‐1‐(α‐methylbenzyl)‐3‐(p‐tolyl)urea on the free amino acid levels in the root tips of rice and wheat

Cited by 8 publications

References 19 publications

Molecular Mechanism of Enantioselective Inhibition of Acetolactate Synthase by Imazethapyr Enantiomers

Molecular Mechanism of Enantioselective Inhibition of Acetolactate Synthase by Imazethapyr Enantiomers

Root growth profiles of Aveneae and Poeae plants in optically active α‐methylbenzyl‐3‐p‐tolylurea media

Enantioselective Activity and Toxicity of Chiral Herbicides

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