Effects of Isoxazole Herbicides on Protoporphyrinogen Oxidase and Porphyrin Physiology

Abstract

The biochemical and physiological effects of 10 isoxazoles were investigated. The amount of protoporphyrin IX caused to accumulate by the compounds correlated well with their herbicidal activity. Protoporphyrinogen oxidase (Protox) was inhibited competitively in the proximity of the catalytic site. However, the Protox I 50 values of the methyl esters and acid chloride derivatives were lower than expected on the basis of their in vivo herbicidal activity. The results suggest that some tolerance mechanism, other than differential absorption and translocation, may protect the plants against these compounds. The molecular properties of 9 isoxazoles and 2 other well-known inhibitors of different herbicide groups were compared to those of protoporphyrinogen (Protogen). The most active compounds have similar bulk, electronic, and energy properties that approximate half of the Protogen molecule. Furthermore, these compounds have atoms/groups on the ring that generate distinct negative electrostatic potential fields that may mimic the reactive part of the Protogen molecule.

Behavior of Bradyrhizobium japonicum strains under different herbicide concentrations

“…Clomazone applied to susceptible plants inhibits the biosynthesis of the isoprenoids compounds precursors of the photosynthetic Behavior of Bradyrhizobium japonicum strains under different herbicide concentrations The sulfentrazone inhibits the protoporphyrinogen oxidase (protox) enzyme in susceptible plants (Dayan et al, 1997), with oxidation of tissues, causing the death of the plants. In microorganisms, the sulfentrazone mechanism of action is still unknown.…”

Crystal structure of 2-hydroxybenzylidene-5-methylisoxazole-4- carbohydrazide monohydrate, C12H13N3O4

“…Similarly, Singh et al [5] synthesized the cobalt(II) complexes with somea cylhydrazones, which showed afair antifungal and antibacterial activity against anumber of fungi and bacteria. Otherwise, photoluminescence, photoabsorption and photoemission studies of hydrazone thin filmsused as hole transporting material in organic light emitting diodes (OLEDs) were reported [6].Onthe other hand, isoxazole compounds have arich history with both pharmaceutical and agricultural applications due to their apoptotic activity [7], plantgrowth regulating activity [8] and antibacterial activity [9]. In the title compound, C 12 H 11 N 3 O 3 ,the molecule is almost planar, the dihedral angle formed by the benzene and isoxazole rings is 2.03 (8) …”

3D-QSARs of Herbicidal 2-N-Phenylisoindolin-1-one Analogues as a New Class of Potent Inhibitors of Protox

“…9,10 Recently, the study of herbicidal activity and biochemistry, and also the physiological studies about N-(4-chloro-2-fluoro-5-propagyloxy) phenyl-3,4,5,6-tetrahydrophthalimide analogues have been reported. 11,12 As part of other trials we reported 13,14 molecular similarity about not only inhibition activity of N-substitutionphenyl-3,4,5,6-tetrahydrophthalimide and N-substituted-phenyl-3,4-dimethylmaleimide analogues but also CoMFA analysis. Especially, it is possible to understand the results of CoMFA, CoMSIA and HQSAR, [15][16][17] about protox inhibition activity of 1-(5-methyl-3-phenylisoxazolin-5-yl)-methoxy-2-chloro-4-fluorobenzene analogues.…”