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  • 1
    ISSN: 1573-1561
    Keywords: Allelopathy ; cucumber ; Cucumis sativus ; phenolic acid mixtures ; similar joint action analysis ; leaf area expansion ; pH
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Cucumber seedlings growing in A1horizon Portsmouth soil material adjusted to pH 5.2, 6.0, or 6.9 were treated with 0, 0.25 or 0.5, μmol/ g soil ferulic acid,p-coumaric acid, vanillic acid, or an equal mixture (0.5 μmol/g total) of two acids every other day. A total of five treatments was given starting with day 7 from seeding. Absolute rates of leaf expansion were determined for seedlings. The experiment was terminated when seedlings were 17 days old. All three phenolic acids inhibited leaf expansion. The dose required for 50% inhibition of absolute rates of leaf expansion increased as pH of the soil systems increased. The order of toxicity based on 50% dose and relative potency were as follows: ferulic acid 〉 vanillic acid =p-coumaric acid. Effects of mixtures of phenolic acids on absolute rates of leaf expansion, when compared to the effects of individual phenolic acids, were found to be antagonistic for the ferulic-vanillic acid mixture and the ferulic-p-coumaric acid mixture in the pH 5.2 soil systems. Several phenolic acid treatments were required before antagonistic effects of mixtures were evident. In all other instances, when treatment effects were significant, the effects of individual phenolic acids were additive.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 17 (1991), S. 29-40 
    ISSN: 1573-1561
    Keywords: Allelopathy ; phenolic acid mixtures ; similar joint action analysis ; mean absolute rates of leaf expansion ; Cucumis sativus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Cucumber seedlings growing in a 1∶2 mixture of soil (Portsmouth B1) and sand adjusted to pH 5.2 were treated every other day five times with 0, 0.0625, 0.125, 0.25, or 0.5 μmol/g soil of ferulic, caffeic,p-coumaric,p-hydroxybenzoic, protocatechuic, sinapic, syringic, or vanillic acids. Treatments began when seedlings were 8 days old. The effects on mean absolute rates of leaf expansion were used to estimate the relative potencies of these phenolic acids to ferulic acid. Based on the results of this experiment, ferulic,p-coumaric,p-hydroxybenzoic, and vanillic acids were chosen for further study. Materials and procedures were identical in the second study, but treatments consisted of mixtures of the four phenolic acids at concentration combinations designed to achieve 40 % or 60 % inhibition of absolute rates of leaf expansion. Using joint action analysis, a model describing the action of the phenolic acid mixtures was developed. A model involving only two factor terms was sufficient to describe the observed responses of cucumber leaf area to the phenolic acid mixtures. The action ofp-hydroxybenzoic acid on absolute rates of leaf expansion was inhibited by the presence of the other three phenolic acids. No other antagonisms or synergisms existed among the four compounds.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 20 (1994), S. 1773-1782 
    ISSN: 1573-1561
    Keywords: Allelopathy ; ferulic acid ; p-coumaric acid ; phenolic acid mixtures ; Cucumis sativus ; split-root ; treatments ; leaf expansion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Experiments were conducted to determine how plant responses to mixtures of allelochemicals may change as the proportion of roots in contact with allelochemicals is modified. Thirteen-day-old cucumber seedlings were treated with ferulic and/orp-coumaric acid in a split-root nutrient culture system. Leaf areas were determined just prior to treatment and at harvest, 24 hr after treatment. Ferulic acid was more inhibitory to cucumber leaf expansion thanp-coumaric acid. The effects of ferulic andp-coumaric acids on leaf expansion were additive. For individual acids, mixtures of ferulic andp-coumaric acids in the same container and combinations of ferulic andp-coumaric acids in separate containers, the inhibition of leaf expansion was directly related to the product of the concentration of the acid(s) and the proportion of roots treated with the acid(s). Pretreatment with 0.2 or 0.4 mM ferulic acid and subsequent treatment with 0.5 mM ferulic acid failed to show evidence of acclimation by cucumber seedlings.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 16 (1990), S. 2559-2567 
    ISSN: 1573-1561
    Keywords: Joint action analysis ; phenolic acid mixtures ; phosphorus uptake ; phenolic acid uptake ; ferulic acid ; vanillic acid ; p-coumaric acid ; Cucumis sativus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract To determine how individual phenolic acids in a mixture might affect phosphorus (P) uptake, 15-day-old cucumber seedlings grown in solution culture were treated with ferulic, vanillic,p-coumaric, or equimolar mixtures of these phenolic acids. Phenolic acid and P uptake were determined by solution depletion. The joint action of the mixtures of these phenolic acids on P uptake was primarily additive. Thus, as the number of phenolic acids increased in the mixture, the concentrations of the individual phenolic acids in the mixture required to bring about a given response declined. Seedling uptake of individual phenolic acids from solution mixtures of phenolic acids was reduced when compared to the uptake of phenolic acids from single phenolic acid solutions. The magnitude of the reduction varied with phenolic acid and concentration. The dose required for 50% inhibition of P uptake was approximately two to three times higher for vanillic acid (6.73 mM) than for ferulic (2.27 mM) andp-coumaric acids (3.00 mM) when dose was based on the initial treatment concentrations. The dose required for 50% inhibition of P uptake was not significantly different for the three phenolic acids (42 ± 5 μmol/g root fresh weight) when dose was based on phenolic acid uptake. Potential reasons for these differences are discussed.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 5 (1992), S. 529-532 
    ISSN: 0894-3230
    Keywords: Organic Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Spectroscopic and potentiometric studies of Ag(I) binding by tris-bipyridine strands indicate that the formation of trinuclear silver trihelicates is a process displaying positive cooperativity.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of a series of polyguanidinium salts of potential interest as anion complexones is described. Among the various synthetic methods investigated, the polyguanidinium salts were found to be most conveniently prepared from polyamines via polynitroguanidine intermediates. The complexation of phosphate and carboxylate anions by these complexones and by related polyammonium salts were studied by analysis of pH-metric titration data. The ligands studied from relatively stable complexes (log Ks = 2.0-4.0 for PO43- in water) which also present good selectivities in some cases. Both the stability and the selectivity of complexation are primarily governed by electrostatic forces and thus depend on charge accumulation in the interacting species; structural effects are also observed. Since the binding is primarily electrostatic, polyammonium salts from more stable complexes (at a given charge) than do polyguanidinium salts. However, whereas the complexation properties of the latter are independent of pH, the complexes of the former are observed only in the limited ranges of pH where both the protonated polyamine and the anion of interest can coexist. The polycationic ligands may, in principle, form chelate type anion complexes. Comparison with the corresponding single binding sites reveals an increase in complexation constant of about two or three orders of magnitude; this may be considered as a thermodynamic indication of a chelate effect for the polydentate ligands (by analogy with the well known effects displayed by cation complexones); however, structural data on the formation of chelate ‘rings’ are not yet available. The nature of the complexes and the prospects of anion complexones in various fields are discussed.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The NMR. chemical shift (δH) of the acidic proton in the systems HCl/H2O and HCl/H2O/HOAc was correlated with the acidity function (Ho)I determined by the indicator method. By using three indicators it could be shown that, except for solutions with very low concentrations of hydrochloric acid, the acidity function (Ho)I correlates with δH in a way which can be rationalized. Addition of 7,5% (W) formaldehyde to these systems changes (Ho)I and δH very significantly, particularly in systems with low water content. Logarithmic rate constants of cellulose formal formation in HCl/H2O/HOAc systems which do not show a linear relationship with (Ho)I, measured without presence of formaldehyde, do so if (Ho)I is measured with formaldehyde present. For these systems, however, δH is not a suitable acidity parameter.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 177 (1875), S. 304-311 
    ISSN: 0075-4617
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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