Ferulic acid, occurrence

Smith MM, Hartley RD. 1983. Occurrence and nature of ferulic acid substitution of cell wall polysaccharides in gramineous plants. Carbohydrate Research 118 65-80. 

Benzaldehydes (lg, 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 (lh, 2h, 3h) and ferulic acid (1 j) can be explained by hydrolysis of ether or ester linkages. p-Flydroxybenzoic 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. 

Spermidines substituted with cinnamic acid derivatives seem to be widely distributed in the plant kingdom. Cinnamic acid (alkaloid maytenine), caffeic acid (caffeoylspermidine, dicaffeoylspermidine), 4-coumaric acid (coumaroylspermidine, dicoumaroylspermidine, tricoumaroylspermidine), ferulic acid (feruloylspermidine, diferuloylspermidine), and sinapic acid (sinapoylspermidine, disinapoylspermidine) are known as aromatic amide substituents of spermidine. Occurrence, structure elucidation, and syntheses are summarized in Section V. 

Dalton BR (1989) Physicochemical and biological processes tiffect the recovery of exogenously applied ferulic acid from tropical soils. Plant Soil 115 13-22 Dalton BR (1999) The occurrence and behavior of plant phenolic acids in soil environments and their potential involvement in aUelochemical interference interactions methodological limitations in establishing conclusive proof of allelopathy. In Indeqit, Daskshini KMM, Foy CL (eds) Principles and practices in plant ecology aUelochemical interactions. CRC Press, Boca Raton, FL, pp 57-74... 

Rowe, J. W., C. L. Bower, and E. R. Wagner Extractives of jack pine bark Occurrence of cis- and /ran -pinosylvin dimethyl ether and ferulic acid esters. Phytochemistry 8, 235—241 (1969). 

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. 

Naturally occurring phenolic compounds such as catechol, resorcinol, pyro-gallol, salicylic, gallic, ferulic, caffeic, and coumaric acids all serve as germination inhibitors. Indeed, some of the selective herbicides such as the substituted phenols and cresols also serve as germination inhibitors. Because of the widespread occurrence of coumarin in plants and its demonstrated inhibitory effects at levels found in fruits and some seeds, it is considered to be a natural germination inhibitor (Lerner et al. 1959). In time, of course, coumarin is metabolized in resting seeds to a level below inhibition. 

Occurrence in the Solanaceae. p-Coumaric acid, caffeic acid, methyl caffeate, and methyl ferulate as well as certain of their 2,3-dihydro derivatives have been identified as constituents of the leaves of Cestrum parqui L Herit. with good phytotoxic activity against different species (D Abrosca et al. 2004). Family-specific phenylpropanoid acids like tropic acid or 2-hydroxytropic acid as acyl moieties of tropane alkaloids are synthesized via phenylalanine -> phenylpyruvic acid (l )-3-phenyllactic acid (Fig. 3.14 Table 3.1 (T5-T7-B)]. Tropic acid may occur as a metabolite of, e.g., hyoscyamine, but the free acid is not synthesized as such (for details see Sect. 3.4). 

Research on maize fiber (Moreau et al. 1996) has shown that oil associated with the fiber fraction is different in composition compared to regular oil obtained from the germ. The fiber oil contains important amounts of ferulate phytosterol esters, free phytosterols, and fatty acid phytosterol esters, which lower serum cholesterol in laboratory animals. The most common class is ferulate phytosterol esters dominated by sitostanol, which is considered more efficient in lowering cholesterol. Phytosterols, such as ergosterol, campesterol, P-sitosterol, and stigmasterol, compete for cholesterol absorption, and therefore are considered hypocholesterolemic and preventive against CVD. According to Raicht et al. (1980) and Fiala et al. (1985) the supplementation of 0.2% P-sitosterol decreases the occurrence of chemically induced colon tumors. 

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