Mixtures of phenolic acids

There are two categories of tannins condensed and hydrolyzable tannins. The polymerization of flavonoid molecules produces condensed tannins, which are commonly found in woody plants (Fig. 3.9). Hydrolyzable tannins are also polymers, but they are a more heterogeneous mixture of phenolic acids (especially gallic acid) and simple sugars. Though widely distributed, their highest concentration is in the bark and galls of oaks. 

Fig. 5 HPLC separation of standard mixtures of phenolic acids.

Luy JF, Jiang H, Wu K, Zheng X, Cai Y, Katakowski M, Chopp M (2010) Effects of mixtures of phenolic acids on phosphorus uptake by cucumber seedlings. Eur J Pharmacol 641 102... 

Effects of Seedlings, Mixtures of Phenolic Acids, and Microbes on Phenolic Acid Concentrations in Nutrient Culture... 

In summary, observed effects of individual phenolic acids or phenolic acid mixtures were similar to what had been observed in nutrient culture but the response times and the magnitude of effects (see Section 2.4.8 for direct comparison) were slower and lower, respectively. Relative potencies of phenolic acids were lower when compared to nutrient culture. Increasing the number of phenolic acids in a mixture of phenolic acids reduced the concentrations of the individual phenolic acids required for a given percent inhibition. The presence of other readily available organic compounds (inhibitory or non-inhibitory) also reduced the concentration of phenolic acids required for a given percent inhibition. The addition of nitrate or nutrient solution reduced the inhibitory activity of phenolic acids. The inhibition of methionine, an amino acid, on the other hand was enhanced by the addition of nitrate. Finally phenolic acid effects were greater under acidic than under neutral conditions. 

Lyu S-W, Blum U (1990) Effects of fendic acid, an adelopathic compound, on net P, K, and water uptake by cucumber seeddngs in a split-root system. J Chem Ecol 16 2429-2439 Lyu S-W, Blum U, Gerig TM, O Brien TE (1990) Effects of mixtures of phenolic acids on phosphorus uptake by cucumber seedlings. J Chem Ecol 16 2559-2567 MaMno T, Takahashi Y, Sakurai Y, Nanzyo M (1996) Infiuence of soil chemical properties on adsorption and oxidation of phenodc adds in sod suspension. Soil Sci Plant Nutr 42 867-879... 

Blum U, Gerig TM, Weed SB (1989) Effects of mixtures of phenolic acids on leaf area expansion of cucumber seedlings grown in different pH Portsmouth Ai soil materials. J Chem Ecol 15 2413-2423... 

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