The herbicidally active compound N-2-(5-chloro-pyridyl) aminomethylene bisphosphonic acid acts by inhibiting both glutamine and aromatic amino acid biosynthesis

Abstract

Abstract. The effect of the herbicidally active compound N-2-(5-chloro-pyridyl)aminomethylene bisphosphonic acid (Cl-pyr-AMBPA), previously found in vitro to inhibit the activity of the first enzyme in the shikimate pathway 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase, was investigated in vivo on suspension cultured cells of Nicotiana plumbaginifolia Viviani. Amino acid pool measurement showed an actual reduction of tyrosine, tryptophan and phenylalanine level following the addition of the compound to the growth medium. However, an even stronger effect was noticed for other amino acids, mainly glutamine. When the activity of the enzymes involved in the glutamate cycle was measured in the presence of Cl-pyr-AMBPA, glutamate synthase was unaffected, while glutamine synthetase was significantly inhibited. Contrary to the herbicide phosphinothricin, the inhibitor bound reversibly to the enzyme. Kinetic analysis accounted for an inhibition of uncompetitive type with respect to ammonium, glutamate and ATP, with K i values of 113, 97 and 39 µM, respectively. Only the exogenous supply of a mixture of glutamine and aromatic amino acids relieved cell growth inhibition, suggesting that the phytotoxic properties of Cl-pyr-AMBPA are due to inhibition of key enzymes in both the corresponding pathways.

Computer-Aided Analysis and Design of Phosphonic and Phosphinic Enzyme Inhibitors as Potential Drugs and Agrochemicals

“…Detailed investigation of their molecular mode of action revealed that they are able to inhibit at least three enzymes: FPP synthase [137], 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase [159] and glutamine synthetase (GS) [160]. Docking performed using Insight 2000 program package showed that two herbicidally active compounds 116 and 124 readily fit the active sites of all three enzymes with comparable potency [154].…”

The role of hydrogen bonding in conformational stabilization of 3,5,6- and 3,5-substituted (pyridin-2-yl)aminomethane-1,1-diphosphonic acids and related (pyrimidin-2-yl) derivative

“…The only exception is to now the zwitterion of the parent acid 1-a (Scheme 1), which despite almost equal populations of the E and Z in solution crystallizes as the E isomer [11]. Herein we present the solid state and solution behavior of three new members of this family, namely, (3,5-dibromo-6-methylpyridin-2-yl)aminomethane-1,1-diphosphonic acid (2), (3-chloro-5-trifluoromethylpyridin-2-yl)aminomethane-1,1-diphosphonic acid (3) and (pyrimidin-2-yl)aminomethane-1,1-diphosphonic acid (4). The latter compound may be considered as the derivative of 1-a, in which atom C-3 is replaced by a nitrogen atom (Scheme 2).…”

“…Although first developed at the end-seventies of the twentieth century [1], they are examined intensely to date. At first, they have been probed as potential inhibitors of 3-deoxy-D-arabino-heptulosonate-7-phosphate (DAHP) synthase [2] and glutamine synthetase [3,4]. The most recent studies have indicated that compounds of this class rank among very potent inhibitors of the FPP synthase, an enzyme of the mevalonate pathway now considered as a major target of nitrogen-containing bisphosphonates in human, parasitic protozoa, and plant cells [5][6][7][8].…”

Herbicidally active aminomethylenebisphosphonic acids

“…In order to ascertain that 3-deoxy-D-arabino-heptulosonate-7-phosphate synthase could represent the main target of compound 15 in vivo, studies of the effect of sublethal concentrations of this compound on the pool of free amino acids in cultured Nicotiana plumaginifolia cells were undertaken [20]. The results obtained with compound 15 showed a strikingly different pattern than that found for glyphosate.…”

“…Unlike phosphinithricin, which inactivates glutamine synthetase irreversibly, compound 15 binds reversibly to the enzyme, and this could account in part for the noteworthy effectiveness of the compound in vivo, as compared to that of the former. Thus, inhibition of both aromatic amino acids and glutamine biosynthesis might be an unusual mode of action of herbicidal compound 15 [20].…”