Phenolic acid production effects

The effects of glyphosate on phenolic compound production are two-fold 1) accumulation of phenolic compounds that are derivatives of aromatic amino acids is reduced and 2) pools of phenolic compounds derived from constituents of the shikimate pathway prior to 5-enolpyruvylshikimate-3-phosphate become larger. Assays that do not distinguish between effects on these two groups, such as that for hydroxyphenolics of Singleton and Rossi (18), can lead to equivocal and difficult to interpret results (e.g. 3-5). 

There are numerous reports describing the allelopathic (phytotmicrobial products on crop growth, particularly in conjunction with heavy residues from the previous crop (1-5). The cause of the reduced crop growth has been attributed to the production of a variety of toxic compounds such as phenolic acids, short-chain fatty acids, patulin, and many others (6-9). These compounds may be produced directly or indirectly during the microbial decomposition of organic residues under varying environmental conditions, such as when the soil remains wet over an extended period of time. 

Formylation of the less reactive phenol and anisole with CO in HF-BF3 was found to require at least stoichiometric amount of the acid for effective transformation (50 equiv. of HF, 2 equiv. of BF3, 50 bar CO, 45°C).445 Conversion increases with increasing reaction time but results in decreasing paralortho ratios suggesting a change from kinetic control to thermodynamic control and the reversibility of formylation. Furthermore, the amount of byproducts (mainly diphenylmethane derivatives) originating from reactions between substrates and products also increases. Additional studies in ionic liquids showed that imidazolium cations with increased chain lengths—for example, l-octyl-3-methylimidazolium salts—are effective in the formylation process. This was attributed to the enhanced solubility of CO in the ionic liquid medium. Tris(dichloromethyl)amine, triformamide, and tris (diformylamino)methane have recently been applied in the formylation of activated aromatic compounds in the presence of triflic acid at low temperature (— 10 to 20°C) albeit yields are moderate.446... 

It was reported independently by three research groups that MFI-type zeolites selectively catalyze the reaction of N20 with benzene to give phenol C6H6 + N20 —> C6H5OH + N2 [93-96]. Fe/ZSM-5 shows remarkable performance in benzene hydroxylation to phenol with N20 as oxidant, which is the first example of a successful gas phase direct phenol synthesis from benzene [97]. No other catalysts show similar high performances to the Fe/ZSM-5 catalyst. At present, iron is the sole element capable of catalyzing the benzene-to-phenol reaction [98]. Direct oxidation of benzene to phenol by N20 has been commercialized in the so-called AlphOx process in Solutia Inc., US A, where N20 is obtained as a by-product in adipic acid production with nitric acid [97, 99, 100] a selectivity >95% to phenol is achieved at >40% conversion at around 4000 C. But the process is cost-effective only if N20 can be obtained cheaply as a by-product in adipic acid production. 

Blum, U. Effects of microbial utilization of phenolic acids and their phenolic acid breakdown products on allelopathic interactions. J Chem Ecol 1998 24 685-708. 

Incidental reactions that have been reported include the preparation of derivatives of 5-(hydroxymethyl)-2-furaldehyde by reaction of D-fructose in acetic or propionic acid in the presence of the respective anhydride.158 The condensation of D-glucose with phenol has been effected in acetic acid in the presence of dry hydrogen chloride, prior to resinification,157 and the reaction of sucrose with thionyl chloride in acetic acid-acetic anhydride produced partially acetylated chlorodeoxysucroses.158 Sucrose has been condensed with maleic anhydride in acetic anhydride mixed with acetic acid or formic acid, to give solid products having an undetermined structure.159... 

The impact of plant products on the metabolism of synthetic dmgs results from the inhibition or activation of cytochrome P-450 (CYP) enzymes. Evaluation of the potential activation of CYP by administration of natural plant products or dietary supplements is important for prediction of interactions between their components and dmgs. Therefore, attention is directed to research on the impact of products available on the food market known as natural non-nutritive substances on dmg absorption. Non-nutritive dietary components are mainly secondary plant metabolites, which include, among others, phenolic compounds such as phenolic acids and flavonoids. The health effects of non-nutritive substances are not yet known. So far, there is no answer on the extent to which they are absorbed and metabolized by the body, and there is no information on the permitted daily intake for these compounds. This information is particularly important because certain non-nutritive natural substances are simultaneously considered to be anti-nutritional factors, mainly because they inhibit digestion and reduce the bioavailability of nutrients or dmgs. It is also possible that they form undesirable interactions with dmgs. The positive health effects of non-nutritive natural substances are not only attributed to their antioxidant properties. These substances are involved in various metabolic... 

Use of some oilseed proteins in foods is limited by flavor, color, and flatus effects. Raw soybeans, for example, taste grassy, beany, and bitter. Even after processing, residues of these flavors may limit the amounts of soybean proteins that can be added to a given food (87). The use of cottonseed and sunflower seed flours is restricted by the color imparted by gossypol and phenolic acids, respectively. Flatus production by defatted soy flours has been attributed to raffinose and stachyose, which are removed by processing the flours into concentrates and isolates (88). 

The depolymerization reaction was modified by Ouchi, Imuta, and Yamashita (3), who substituted p-toluenesulfonic acid (PTSA) for BF3 as the catalyst and increased the reaction temperature to 180° to 185°C. A very high degree of depolymerization was achieved under these conditions, with pyridine-soluble product yields over 90%. Darlage and Bailey (4) investigated the effects of reaction temperature, various solvents, and coal preoxidation on depolymerization product yields using a number of acid catalysts. They found that meta-substituted phenols were more effective aromatic substrates for the depolymerization reaction than phenol. The preoxidation of coal, particularly of some sulfur-rich bituminous coals, with dilute aqueous nitric acid considerably increased the yield of depolymerization products (5),... 

Increased imderstanding of the trace chemistry of SMPO allows process modifications to be introduced to reduce by-product formation, or, at least, to allow the effect of such changes to be predicted. For example, "oxygen starvation" has been shown in bench scale EB oxidation experiments to lead to higher selectiv-ities for MPC, MPK, benzaldehyde, benzoic acid, and phenol by-products. Higher by-product formation reflects the anaerobic decomposition of EBHP, which reacts with EB solvent to give up to two equivalents of MPC. Higher levels of... 

Tanaka, T., Kojima, T., Suzui, M., and Mori, H., Chemoprevention of colon carcinogenesis by the natural product of a simple phenolic compound protocatechuic acid suppressing effects on tumor development and biomarkers expression of colon tumorigenesis. Cancer Res., 53, 3908-... 

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