Physiological activity spectra of existing graminicides and the new herbicide 2‐(2‐benzothiazolyl‐oxy)‐<i>N</i>‐methyl‐<i>N‐</i>phenylacetamide (mefenacet)

Fedtke, Carl

doi:10.1111/j.1365-3180.1987.tb00757.x

Cited by 23 publications

(16 citation statements)

References 21 publications

(26 reference statements)

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“…Mefenacet (83;Hinochloa, 1986), [103] a selective inhibitor of cell growth and cell division, was the first commercial herbicide of the Bayer-owned oxyacetamide group and is used to control barnyard grass in irrigated paddy rice (Scheme 18). The intensive search for an oxyacetamide with efficacy as a herbicide even in the absence of irrigation water that can be used on maize, soybeans, and other crops led to the development of flufenacet (84; Axiom, 1998).…”

Section: Oxyacetamidesmentioning

confidence: 99%

The Unique Role of Fluorine in the Design of Active Ingredients for Modern Crop Protection

2004

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The task of inventing and developing active ingredients with useful biological activities requires a search for novel chemical substructures. This process may trigger the discovery of whole classes of chemicals of potential commercial interest. Similar biological effects can often be achieved by completely different compounds. However, compounds within a given structural family may exhibit quite different biological activities depending on their interactions with different intracellular proteins like enzymes or receptors. By varying the functional groups and structural elements of a lead compound, its interaction with the active site of the target protein, as well as its physicochemical, pharmacokinetic, and dynamic properties can be improved. In this context, the introduction of fluorine into active ingredients has become an important concept in the quest for a modern crop protection product with optimal efficacy, environmental safety, user friendliness, and economic viability. Fluorinated organic compounds represent an important and growing family of commercial agrochemicals. A number of recently developed agrochemical candidates represent novel classes of chemical compounds with new modes of action; several of these compounds contain new fluorinated substituents. However, the complex structure-activity relationships associated with biologically active molecules mean that the introduction of fluorine can lead to either an increase or a decrease in the efficacy of a compound depending on its changed mode of action, physicochemical properties, target interaction, or metabolic susceptibility and transformation. Therefore, it is still difficult to predict the sites in a molecule at which fluorine substitution will result in optimal desired effects.

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Section: Oxyacetamidesmentioning

confidence: 99%

The Unique Role of Fluorine in the Design of Active Ingredients for Modern Crop Protection

2004

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“…Mefenacet is an oxyacetamide herbicide, a class related to chloroacelamides tha! has many characteristics in common with them (Fedtke 1987(Fedtke , 1991. Its effect on the incorporation of oleic acid into the .NLF is additional evidence that chloroacetamides and oxyacetamides may share the same primary target.…”

Section: Discussionmentioning

confidence: 97%

Inhibition of oleic acid incorporation into a non-lipid fraction by chloroacetamide herbicides

Kring¹,

Couderchet²,

Böger³

1995

Physiol Plant

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Kring, F., Couderchet, M. and Bbger, P. 1995. Inhibition of oleic acid incorporation into a non-lipid fraction by chloroacetamide herbicides. -Physioi. Plant. 95: 551-558.Oleic acid is incorporated into an insoluble fraction left over afteF lipid exfraction in Scenedesmus acutus. This incorporation is extremely sensitive to the chloroacetamide herbicide, metazachlor (I;(, = ca 20 nM). Therefore, factors influencing tlK incorporation of radioactivity from oleic acid into this non-lipid fraction were investigated. S acutus cells were cultivated under various conditions with or without inhibitors and ('*CJ-oleic acid was supplied to the algae; the lipids were extracted and the radioactivity incorporated in the remaining fraction monitored. The inhibition seemed specific for chloroacetamides and related classes since it was also observed with alachior, dimethenamid and mefenacet (an oxyacetamide). In contrast, it could not be found with diuron. oryzalin, nor could it be observed with a non-herbicidal metazachlor derivative or iodoacetamide. Incorporation of oleic acid into that fraction required metabolically active cells and was stimulated by light. Other fattjf acids (16:0, 18:2, and 18:3) were also incorporated into the non-lipid fraction but their incorporation was not inhibited by metazachior. Among other components, the fraction contains proteins. However, a possible specific effect of chloroacetamides on the binding of oleic acid to proteins or on the in vitro activity of iipid transfer proteins could not be detected. Not much is known yet about mechanism and chemistry of oleic acid incorporation but this finding opens a new path for investigations towards the primary target of these herbicides.

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“…The procedures of cultivating Chlarnydornonas reinhardtii and of testing for growth inhibition by different herbicides have been published. 2 The uptake of mefenacet into algal cells was studied by incubating with [benzothia~ole-phenyl-U-'~C]mefenacet (160 kBq pmole-') and subsequently separating the cells from the culture medium by centrifugation. The cells were then extracted by sonication.…”

Section: Experimental Methodsmentioning

confidence: 99%

Mode of action studies with mefenacet

Fedtke

1991

Pestic. Sci.

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The unicellular green alga Chlamydomonas reinhardtii was used as a model organism in studies of the mode of action of the oxyacetamide herbicide mefenacet. An algal strain with a decreased sensitivity towards mefenacet was obtained by successively increasing the herbicide concentration in the culture medium from 10 to 50 μM over 9 weeks. Similarly, a second strain was adapted to 10 μM metazachlor and a third one to 20 μM metolachlor. The resistance patterns of these three strains were studied with a selection of herbicides representing different modes of action. In the mefenacet‐ and metolachlor‐adapted strains, clear cross‐resistance was only obtained between the oxyacetamide mefenacet and the chloroacetanilides alachlor, butachlor, metazachlor and metolachlor. The resistance factors (I50 in resistant/I50 in sensitive algae) were between 4 and 50. Little or no resistance was obtained when herbicides with other modes of action were studied (resistance factors between 0.5 and 4). The situation was less clear in the metazachlor‐adapted strain, but here also strong cross‐resistance was seen with other chloroacetanilides and mefenacet (resistance factors between 25 and 40). This strain was, however, significantly cross‐resistant to some herbicides with other modes of action. Investigations of the possible resistance mechanism in the mefenacet‐adapted strain have shown that neither uptake nor metabolism can explain the observed resistance behaviour. The lipid composition and the pattern of soluble amino acids were unchanged. It is concluded that oxyacetamides and chloroacetanilides have the same site of herbicidal action.

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Physiological activity spectra of existing graminicides and the new herbicide 2‐(2‐benzothiazolyl‐oxy)‐N‐methyl‐N‐phenylacetamide (mefenacet)

Cited by 23 publications

References 21 publications

The Unique Role of Fluorine in the Design of Active Ingredients for Modern Crop Protection

The Unique Role of Fluorine in the Design of Active Ingredients for Modern Crop Protection

Inhibition of oleic acid incorporation into a non-lipid fraction by chloroacetamide herbicides

Mode of action studies with mefenacet

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