Structure Versus Activity of Substituted Pyridazinones as Related to Mechanism of Action

Weed Science ◽  
1976 ◽  
Vol 24 (6) ◽  
pp. 579-582 ◽  
Author(s):  
J. B. St. John ◽  
J. L. Hilton
Keyword(s):  
Fatty Acids ◽  
Phenyl Ring ◽  
Membrane Lipids ◽  
Carotenoid Biosynthesis ◽  
Polar Lipids ◽  
Maximum Effect ◽  
Hill Reaction ◽  
Methyl Substitution ◽  
Chloroplast Membrane ◽  
The Hill

In at least three metabolic processes in wheat (Triticum aestivumL. var. ‘Arthur’) shoots inhibitory activity can be related to the chemical structure of substituted pyridazinones. Inhibitory activities include: inhibition of the Hill reaction and photosynthetic CO2fixation; inhibition of carotenoid biosynthesis accompanied by photodestruction of chlorophyll; and interference with the formation of chloroplast membrane polar lipids. The parent compound, pyrazon [5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone], inhibits the Hill reaction and photosynthetic CO2fixation. Trifluoromethyl substitution of the phenyl ring of pyrazon, mono-methyl substitution of the amine, or substitutions at both positions result in inhibition of carotenoid biosynthesis. However, both substitutions are required for maximum effect. Substitutions onto the molecular structure of pyrazon are also related to alterations in the formation of membrane polar lipids. Dimethyl substitution of the amine of pyrazon is related to a decrease in linolenic acid accompanied by an increase in linoleic acid without a shift in the relative proportion of saturated to unsaturated fatty acids of the membrane lipids. The trifluoromethyl substitution of the phenyl ring and mono-methyl substitution of the amine are related to a shift toward a higher proportion of saturated fatty acids of chloroplast membrane lipids. Results obtained with diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] and with dark-grown wheat tissue indicated that activity of the pyridazinones on the formation of membrane lipids was probably not related to inhibition of the Hill reaction.

scholarly journals Galactolipase and chilling sensitivity of plants.

1997 ◽  
Vol 44 (1) ◽  
pp. 21-35 ◽  
Author(s):  
Z Kaniuga
Keyword(s):  
Fatty Acids ◽  
Membrane Lipids ◽  
Ph Dependence ◽  
Hill Reaction ◽  
High Melting Point ◽  
Lipid Acyl Hydrolase ◽  
Chilling Sensitivity ◽  
Acyl Lipids ◽  
The Hill

Galactolipase is a lipid acyl hydrolase (EC 3.1.1.26) acting predominantly on galactolipids which constitute up to 80% of total acyl lipids in chloroplast membrane. Evidence is presented on the involvement of this enzyme in plant response to chilling via degradation of membrane lipids and the increase of free fatty acids, associated with reduced oxygen evolution in the Hill reaction. The occurrence of two pools of fatty acids has been hypothesized. Analysis of numerous plant species showed higher galactolipase activity in the chilling-sensitive than in the chilling-resistant plants. Differences in the pH-dependence curve and in the response to detergents of galactolipases from these two groups of plants suggest heterogeneity of the enzyme. Referring to the hypothesis concerning the role of high melting-point fatty acids of phosphatidylglicerol molecular species in chilling sensitivity the data are presented against generalization of this hypothesis.

Cyanoacrylate Inhibitors of the Hill Reaction V. The Effect of Chirality on Inhibitor Binding

1987 ◽  
Vol 42 (6) ◽  
pp. 684-689 ◽  
Author(s):  
John L. Huppatz ◽  
John N. Phillips
Keyword(s):  
Phenyl Ring ◽  
Alkyl Substituent ◽  
Receptor Site ◽  
Optically Active ◽  
Hill Reaction ◽  
Inhibitor Binding ◽  
Level Of Activity ◽  
The Difference ◽  
The Hill

Optically active α-methylbenzylamino 2-cyanoacrylic esters were synthesized and assayed as inhibitors of the Hill reaction in isolated pea chloroplast fragments. The 5-isomers were more potent inhibitors than the S-isomers with discriminations of from ten to greater than 100-fold being observed. A β-alkyl substituent in the cyanoacrylate molecule affected both the level of activity and the difference in activity between the isomers. An α,α-dimethylbenzylamino derivative was also active at about the same level as the corresponding α-methylbenzylamino racemate. This result could be explained in terms of the orientation of the phenyl ring in the receptor site. Replacement of the α-methylbenzylamino group by other α-alkyl and α-phenyl substituents had little effect on activity. However, an α-benzyl group was beneficial.

scholarly journals Lipid composition of the isolated rat intestinal microvillus membrane

1968 ◽  
Vol 109 (1) ◽  
pp. 51-59 ◽  
Author(s):  
G. G. Forstner ◽  
K. Tanaka ◽  
K. J. Isselbacher
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Neutral Lipid ◽  
Lipid Composition ◽  
Plasma Membranes ◽  
Membrane Lipids ◽  
Saturated Fatty Acids ◽  
Polar Lipids ◽  
Published Data ◽  
Microvillus Membrane

1. Rat intestinal microvillus plasma membranes were prepared from previously isolated brush borders and the lipid composition was analysed. 2. The molar ratio of cholesterol to phospholipid was greatest in the membranes and closely resembled that reported for myelin. 3. Unesterified cholesterol was the major neutral lipid. However, 30% of the neutral lipid fraction was accounted for by glycerides and fatty acid. 4. Five phospholipid components were identified and measured, including phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, sphingomyelin and lysophosphatidylcholine. Though phosphatidylethanolamine was the chief phospholipid, no plasmalogen was detected. 5. In contrast with other plasma membranes in the rat, the polar lipids of the microvillus membrane were rich in glycolipid. The cholesterol:polar lipid (phospholipid+glycolipid) ratio was about 1:3 for the microvillus membrane. Published data suggest that this ratio resembles that of the liver plasma membrane more closely than myelin or the erythrocyte membrane. 6. The fatty acid composition of membrane lipids was altered markedly by a single feeding of safflower oil. Membrane polar lipids did not contain significantly more saturated fatty acids than cellular polar lipids. Differences in the proportion of some fatty acids in membrane and cellular glycerides were noted. These differences may reflect the presence of specific membrane glycerides.

scholarly journals 13,16-Dimethyl Octacosanedioic Acid (iso-Diabolic Acid), a Common Membrane-Spanning Lipid of Acidobacteria Subdivisions 1 and 3

2011 ◽  
Vol 77 (12) ◽  
pp. 4147-4154 ◽  
Author(s):  
Jaap S. Sinninghe Damsté ◽  
W. Irene C. Rijpstra ◽  
Ellen C. Hopmans ◽  
Johan W. H. Weijers ◽  
Bärbel U. Foesel ◽  
...  
Keyword(s):  
Fatty Acids ◽  
High Performance ◽  
Membrane Lipids ◽  
Direct Analysis ◽  
Polar Lipids ◽  
Gas Chromatography Mass Spectrometry ◽  
Content Type ◽  
Alkyl Chains ◽  
Intact Polar Lipids ◽  
Membrane Spanning

ABSTRACTThe distribution of membrane lipids of 17 different strains representing 13 species of subdivisions 1 and 3 of the phylumAcidobacteria, a highly diverse phylum of theBacteria, were examined by hydrolysis and gas chromatography-mass spectrometry (MS) and by high-performance liquid chromatography-MS of intact polar lipids. Upon both acid and base hydrolyses of total cell material, the uncommon membrane-spanning lipid 13,16-dimethyl octacosanedioic acid (iso-diabolic acid) was released in substantial amounts (22 to 43% of the total fatty acids) from all of the acidobacteria studied. This lipid has previously been encountered only in thermophilicThermoanaerobacterspecies but bears a structural resemblance to the alkyl chains of bacterial glycerol dialkyl glycerol tetraethers (GDGTs) that occur ubiquitously in peat and soil and are suspected to be produced by acidobacteria. As reported previously, most species also containediso-C15and C16:1ω7Cas major fatty acids but the presence ofiso-diabolic acid was unnoticed in previous studies, most probably because the complex lipid that contained this moiety was not extractable from the cells; it could only be released by hydrolysis. Direct analysis of intact polar lipids in the Bligh-Dyer extract of three acidobacterial strains, indeed, did not reveal any membrane-spanning lipids containingiso-diabolic acid. In 3 of the 17 strains, ether-boundiso-diabolic acid was detected after hydrolysis of the cells, including one branched GDGT containingiso-diabolic acid-derived alkyl chains. Since the GDGT distribution in soils is much more complex, branched GDGTs in soil likely also originate from other (acido)bacteria capable of biosynthesizing these components.

scholarly journals Evaluation of microalgae polysaccharides as biostimulants of tomato plant defense using metabolomics and biochemical approaches

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Farid Rachidi ◽  
Redouane Benhima ◽  
Yassine Kasmi ◽  
Laila Sbabou ◽  
Hicham El Arroussi
Keyword(s):  
Fatty Acids ◽  
Plant Defense ◽  
Systemic Acquired Resistance ◽  
Membrane Lipids ◽  
Acquired Resistance ◽  
Metabolite Profile ◽  
Gas Chromatography Mass Spectrometry ◽  
Maximum Effect ◽  
Tomato Plants ◽  
Biotic Stresses

AbstractMicroalgal polysaccharides (PSs) may be an effective elicitor agent that can efficiently protect plants against biotic stresses. In this study, wee investigates, the effect of PS obtained from microalgae and cyanobacteria (D. salina MS002, P. tricorontum MS023, Porphyridium sp. MS081, Desmodesmus sp., D. salina MS067 and A. platensis MS001) on the biochemical and metabolomics markers linked to defense pathways in tomato plants. The phenylalanine ammonia lyase (PAL), chitinase, 1,3-beta-glucanase and peroxidase (POX) activities have been improved in tomato plants leaves treated by polysaccharides extracted from P. triocnutum (238.26%); Desmodesmus sp. (19.95%); P. triocnutum (137.50%) and Porphyridium sp. (47.28%) respectively. For proteins, polyphenols and H2O2, the maximum effect was induced by D. salina 067 (55.01%), Porphyridium sp. (3.97%) and A. platensis (35.08%) respectively. On the other hand, Gas Chromatography-mass spectrometry (GC–MS) metabolomics analysis showed that PSs induced the modification of metabolite profile involved in the wax construction of tomato leaves, such as fatty acids, alkanes, alkenes and phytosterol. PS treatments improved the accumulation of fatty acids C16:3, C18:2 and C18:3 released from the membrane lipids as precursors of oxylipin biosynthesis which are signaling molecules of plant defense. In addition, PS treatment induced the accumulation of C18:0 and Azelaic acid which is a regulator of salicylic acid-dependent systemic acquired resistance. However, molecular and metabolic studies can determine more precisely the mode of action of microalgal polysaccharides as biostimulants/elicitors plant defense.

PYRIDAZINONES, Their Influence on the Biosynthesis of Carotenoids and the Metabolism of Lipids in Plants (Survey of Literature)

1979 ◽  
Vol 34 (11) ◽  
pp. 1052-1054 ◽  
Author(s):  
F. A. Eder
Keyword(s):  
Fatty Acids ◽  
Unsaturated Fatty Acids ◽  
Primary Effect ◽  
Hill Reaction ◽  
Pigment Formation ◽  
The Hill

Abstract The pyridazinone herbicides influence to several degrees, the Hill reaction, the pigment formation, the ratio of saturated to unsaturated fatty acids and the chloroplast ribosomes. Which is the primary effect is not yet known.

Über eine p-Hydroxylierung in isolierten Chloroplasten

1963 ◽  
Vol 18 (2) ◽  
pp. 105-109 ◽  
Author(s):  
Achim Trebst ◽  
Herbert Eck
Keyword(s):  
Electron Transport ◽  
Transport System ◽  
Phenyl Ring ◽  
Functional Role ◽  
Electron Transport System ◽  
Hill Reaction ◽  
The Hill ◽  
Isolated Chloroplasts ◽  
Carbonyl Function

Salicylaldoxime at a concentration of 10-2-m. is an inhibitor of the Hill - reaction and therefore also of aerobic photophosphorylation in isolated chloroplasts. This might indicate a functional role for copper in the electron transport system of photosynthesis.At a concentration of 10-3-m. and lower, salicylaldoxime is not an inhibitor, but a cofactor of aerobic photophosphorylation. This is due to its hydroxylation to the p-hydroquinone, which is the actual cofactor. This p-hydroxylation, which is probably catalyzed by a peroxidase, takes place only with salicylaldehyde and its oxime, but not with other phenols, whether they have a carbonyl function attached to the phenyl ring or not. A number of o- and p-hydroquinones with a carbonyl function at the phenyl ring and two naphthohydroquinones, of which the corresponding quinone cannot be prepared by chemical means, are reversibly oxidized and reduced in photosynthetic phosphorylation in chloroplasts. A possible explanation is that these hydroquinones are oxidized only to the semiquinone level and rapidly reduced again.

Modes of Action of Pyridazinone Herbicides

Weed Science ◽  
1969 ◽  
Vol 17 (4) ◽  
pp. 541-547 ◽  
Author(s):  
J. L. Hilton ◽  
A. L. Scharen ◽  
J. B. St. John ◽  
D. E. Moreland ◽  
K. H. Norris
Keyword(s):  
Molecular Structure ◽  
Hordeum Vulgare ◽  
Phenyl Ring ◽  
Chloroplast Development ◽  
Biological Properties ◽  
Hill Reaction ◽  
Action Mechanism ◽  
Physiological Properties ◽  
Second Mode ◽  
The Hill

Four substituted pyridazinone compounds inhibited the Hill reaction and photosynthesis in barley (Hordeum vulgareL., var. Dayton C.I. 9517). These inhibitions appeared to account for the phytotoxicity of 5-amino-4-chloro-2-phenyl-3(2H)-pyridazinone (pyrazon). The pyridazinone chemicals were weaker inhibitors than 2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine (atrazine). Two substitutions onto the molecular structure of pyrazon result in a new experimental herbicide, 4-chloro-5-(dimethylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone (hereinafter referred to as 6706), which retains the action mechanism of pyrazon but also has two additional biological properties. It is resistant to metabolic detoxication in plants, and it possesses a second mode of action involving interference with chloroplast development. The second action is like that expressed by 3-amino-s-triazole (amitrole) and by 3,4-dichlorobenzyl methylcarbamate (dichlormate). However, the new chemical is 100 to 1000 times more effective. The trifluoromethyl substitution on the phenyl ring and the dimethyl substitution on the amine are both required to give either of the two additional physiological properties. Analogs with only one of the two substitutions behave like pyrazon rather than like 6706.

Stereospecific Inhibitor Probes of the PS II Herbicide Binding Site

1987 ◽  
Vol 42 (6) ◽  
pp. 674-678 ◽  
Author(s):  
John L. Huppatz ◽  
John N. Phillips
Keyword(s):  
Phenyl Ring ◽  
Receptor Site ◽  
Spatial Arrangement ◽  
Hill Reaction ◽  
Hydrophobic Region ◽  
Inhibitor Molecule ◽  
Ps Ii ◽  
Hydrophobic Domain ◽  
The Difference ◽  
The Hill

The influence of steric factors on the activity of 2-cyanoacrylic esters as inhibitors of the Hill reaction was examined. The spatial arrangement of the different groups in the inhibitor molecule was found to be an important factor in determining potency. The positioning of the phenyl ring in aralkylamino derivatives and the steric properties of the β-substituent are particularly significant in the interaction of molecules with the) hydrophobic domain of the receptor site. The difference in activity observed with optically active α-methylbenzylamino derivatives confirmed the importance of the orientation of the phenyl ring and indicated an interaction with a specific hydrophobic region.

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