Hydroxybenzoic occurrence

The occurrence of 4-hydroxybenzoate decarboxylase was also found in facultative anaerobic bacteria, E. cloacae P240, and the enzyme was purified and characterized. The activity of the cell-free extract of E. cloacae P240 was determined to be 13.7 ijumol min (mg protein) at 30°C, which was much higher than... 

The occurrence of 3,4-dihydroxybenzoate decarboxylase was also found widely in facultative anaerobes. Among them, Enterobacter cloacae P241 showed the highest activity of 3,4-hydroxybenzoate decarboxylase, and the activity of the cell-free extract of E. cloacae P241 was determined to be 0.629 p.mol min (mg protein) at 30°C, which was more than that of C. hydroxybenzoicum, 0.11 (xmol min mg protein)" at 25°C. The E. cloacae P241 enzyme has a molecular mass of 334 kDa and consists of six identical 50 kDa subunits. The value for 3,4-dihydroxybenzoate was 177 p.M. The enzyme is also characteristic of its narrow substrate specificity and does not act on 4-hydroxybenzoate and other benzoate derivatives. The properties of E. cloacae P241 3,4-hydroxybenzoate decarboxylase were similar to those of C. hydroxybenzoicum in optimum temperature and pH, oxygen sensitivity, and substrate specificity. 

Herrmann, K. (1989). Occurrence and content of hydroxycinnamic and hydroxybenzoic acid compounds in foods. Crit. Rev. Food Sci. 28, 315-347. 

Tomas-Barberan, F.A. and Clifford, M.N., Dietary hydroxybenzoic acid derivatives — nature, occurrence and dietary burden, J. Sci. Food Agric., 80, 1024, 2000. 

Schultz, J.M. and Herrmann, K. (1980) Occurrence of hydroxybenzoic acid and hydroxycinnamic acid in spices. IV. Phenolics of spices. Zeitschrift fur Lebensmittel-Untersuchung und -Forschung 171,1 93-1 99. 

Benzaldehydes (Ig, 2g, 3g) are liberated in the same way but originate in part from other sources (cf. Fig. 6.1.2). The presence of benzoic acids (Ih, 2h, 3h) and ferulic acid (Ij) can be explained by hydrolysis of ether or ester linkages. p-Hydroxybenzoic and p-coumaric acids (3h and 3j, respectively) are attached to certain types of lignins by ester linkages and their occurrence in the acidolysis mixtures is, in these cases, at least primarily due to the hydrolysis of these linkages. 

Davis concluded that shikimic acid was a common precursor of phenylalanine, tyrosine, tryptophan, p-aminobenzoic acid, p-hydroxybenzoic acid, and an unknown sixth factor, and he next set out to determine other substances lying on the biosynthetic pathway. The various mutants were therefore tested for syntrophism, i.e., for the ability of one mutant to produce a substance necessary for the growth of another mutant. There was thus found a thermolabile substance, X, which was a true precursor of shikimic acid (184). X was isolated from culture filtrates and identified as 5-dehydroshikimic acid (744). Similar experiments revealed a substance, W, which was a true precursor of substance X (187, 193). This also was isolated and shown to be 5-dehydroquinic acid (906). The enzyme, named 5-dehydroquinase, converting dehydroquinic acid to dehydroshikimic acid has been partially purified (606). It is fairly stable, has a high specificity, appears to have no cofactors, and is of wide occurrence in bacteria, algae, yeasts, and plants but, as expected, could not be found in mammalian liver. 

Source Based on Sarkanen, K.V. and Ludwig, C.H., lignins Occurrence, Formation, Structure and Reactions. New York Wiley-Interscience, 1971 Adler, E., Wood Sci Technol, 11, 169-218, 1977. Most hardwood lignins are composed of about equal amounts of 1 and 2, but quite a few exceptions are known. Some hardwood lignins are esterifled with p-hydroxybenzoic acid. 

The occurrence of Reactions 12 and 13 may also explain the present observation that G(hydroxybenzoic acids) was higher in 02 than in presence of H202, although the number of OH radicals interacting with benzoic acid in the latter experiment was increased by a factor of two. 

Other 4-substituted phenols also reacted with HOCl to give ipso cyclohex-adienones, either as stable compounds or as intermediates in the displacement of side chains by chlorine (Dence and Sarkanen, 1960 Larson and Rockwell, 1979). For example, /7-hydroxybenzoic acid reacted rapidly with HOCl at environmentally realistic concentrations to give a mixture of substitution and decarboxylation products (Larson and Rockwell, 1979). It is plausible that such decarboxylation and side-chain cleavage products are at least partially responsible for the occurrence of chlorinated phenol derivatives in drinking water and in paper pulp bleaching effluents. 

In the ICDRG standard series, the parabens are tested as a mixture of 3% of methyl-, ethyl-, propyl-, butyl- and benzyl-p-hydroxybenzoic acid, a total of 15% in petrolatum which may be irritating and enhance the occurrence of multiple false positive patch tests (angry back) (Mitchell 1977). 

Phenolic compounds of low molecular weight, particularly P hydroxybenzoic, vanillic, p-coumaric and ferulic acids, are of widespread occurrence in soils and occur mainly but not entirely in chemically-bound forms. They are believed to be important intermediates in the formation of humic substances and, at certain concentrations, they may influence the growth of plants and the activities of soil micro-organisms (see chapter 6). There is evidence that the phenolic acids and related compounds in soils originate in part from the decomposition of plant residues and in part from synthesis by soil micro-organi sms. 

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