P-Coumarate esters

Norton, R. A. Quantitation of steryl ferulate and p-coumarate esters from corn and rice. Lipids 1995 30(3) 269-274. 

Norton, R.A. (1995) Quantitation of steryl ferulate and p-coumaric esters from com and rice. lipids, 30,... 

Hoffmann, L., Besseau, S., Geoffroy, R, Ritzenthaler, C., Meyer, D., Lapierre, G., Pollet, B. and Legrand, M. (2005) Acyltransferase-catalysed p-coumarate ester formation is a committed step of lignin biosynthesis. Plant Biosys., 139, 50-3. 

In some lignins, 5-10% of the units are esterihed examples includep-hydroxybenzoate esters in lignins from Salix species (56) [69,108] and p-coumarate esters in grass lignins (57) [109-111]. The y-positions in lignin are the ones that primarily are esterified [110]. 

Vajs, V., D. Jeremic, M. Stefanovic, and S. Milosavuevic p-Coumaric esters and fatty alcohols from Artemisia campestris. Phytochemistry 14, 1659—1660 (1975). 

Leptospermum scoparium Wax esters (C26, C28, C24 acid, 25, C24 alcohol), p-coumarate esters (C24, C22 alcohol) 84... 

Recent biosynthetic studies on the Lythraceae alkaloids have concentrated on the macrolide alkaloids. Of interest is a demonstration that the cis- and /rany-fused quinolizidinones 913 and 914 were effective and specific precursors for biaryl macrolide alkaloids such as vertine (915) and lythrine (916) in H. salicifolia, respectively, whereas the four possible monomethyl ethers of 913 and 914 were not incorporated effectively 597). Another in vitro incorporation study on H. salicifolia with labeled lysine, phenylalanine, and p-coumaric acid showed that 4-arylquinolizidinols, their p-coumarate esters, and biaryl macrolide alkaloids are formed from different precursor pools, but cis- and /ra 5-fiised alkaloids within each class originate from a common metabolic pool 598). 

Wheat, maize and rye Secale cereale) contain ferulic and p-coumaric esters of sterols and stanols. Oats ( Avena sativd) contain a series of 24 caifeic and ferulic esters of glycerol, long chain alkanols, alkandiols (n = 22, 23, 24) and m-hydroxy acids (n = 26, 28). In addition, there is a large series of compounds (>25) that are esters of anthranihc acid or 5-hydroxyanthranilic acid with either p-coumaric, cafifeic or ferulic acids (avenanthramides) (Figure 7.51) or with their ethylenic analogues (avenulamides). Oat meal has been reported to contain some 200-300 mg/kg of esterified ferulic acid. 

The pure enzyme was tested for activity against several methylated phenolic and cinnamic acids (Table 2). The enzyme was active on methyl esters of cinnamic acids caffeio p-coumaric> ferulic, and is therefore termed a cinnamoyl esterase (CinnAE). 

The most common hydroxycinnamic acid derivatives are p-coumaric (4-hydroxy-cinnamic), caffeic (3,4-dyhydroxycinnamic), ferulic (4-hydroxy-3-methoxycinnamic), and sinapic (4-hydroxy-3,5-dimethoxycinnamic) acids, which frequently occur in foods as simple esters with quinic acid or glucose (Mattila and Kumpulainen 2002). 

Several workers have suggested that some, and possibly most, of the p-coumaric acid in graminaceous cell walls is ester-linked to lignin (16-19). Others have provided evidence that a small proportion of the ferulic acid units of cell walls are ether-linked via their phenolic groups to lignin (20). 

Depending on the identity, number and position of the acyl residues, these acids may be divided into the following groups mono-esters of caffeic, p-coumaric and ferulic acid di-, tri- and tetra-esters of caffeic acid [14,15] mixed di-esters of caffeic and ferulic acid or caffeic and sinapic acid [16] mixed esters of caffeic acid with dibasic aliphatic acids (e.g., oxalic, succinic) [17]. 

Broccoli florets and leafy cruciferous vegetables will be the major source of sugar esters and of conjugated sinapic acid (10 mg/100 g). Tomato and tomato products are likely to be the major source of glucosides at up to 13 mg/100 g in total, and possibly the second richest source of conjugate p-coumaric acid (3 mg/100 g). 

Some of the pathways of animal and bacterial metabolism of aromatic amino acids also are used in plants. However, quantitatively more important are the reactions of the phenylpropanoid pathway,173-1743 which is initiated by phenylalanine ammonia-lyase (Eq. 14-45).175 As is shown at the top of Fig. 25-8, the initial product from phenylalanine is trails-cinnam-ate. After hydroxylation to 4-hydroxycinnamate (p-coumarate) and conversion to a coenzyme A ester,1753 the resulting p-coumaryl-CoA is converted into mono-, di-, and trihydroxy derivatives including anthocyanins (Box 21-E) and other flavonoid compounds.176 The dihydroxy and trihydroxy methylated products are the starting materials for formation of lignins and for a large series of other plant products, many of which impart characteristic fragrances. Some of these are illustrated in Fig. 25-8. 

Polyphenolic phytochemicals are classified into three major groups phenolic acids, fla-vonoids, and tannins. Phenolic acids include hydroxybenzoic, hydroxyphenylacetic, and hydroxycinnamic acids (Figure 11.3.3). Hy-droxycinnamic acids are the most widely distributed of the phenolic acids in plant tissues. The important hydroxycinnamic acids are p-coumaric, caffeic, ferulic, and sinapic acids. Most hydroxycinnamic acids are rarely encountered in the free state in nature. They occur as glucose esters and, more frequently, as quinic acid esters (Herrmann, 1989). Phenolic acids are usually detected at wavelengths between 210 and 320 nm. In general, the polarity of phenolic acids is increased mainly by the hy-... 

Also, the phenolic compounds in olives have a strong influence on the flavor of the oil and seem to be responsible for the high oxidation resistance of olive oil. The phenolic content in the flesh of olive fruits ranges between 1% and 3%, w/w, (66) oleuropein, vanillic, caffeic, p-coumaric acid, rutin, luteolin-7-glucoside, heterosidic ester of caffeic acid, and hydroxytyrosol (verbascoside) have been identified in olive fruits. 

For white wines (85), a similar HPLC condition to that of Betes-Saura et al. (79) was employed with a Nucleosil C)8 column (250 X 4.0-mm ID, 5 /zm) with binary gradient using eluent (A) acidified water (pH 2.65) and eluent (B) 20% A with 80% acetonitrile applied for hydroxy-cinnamate derivatives esters (caffeoyl tartaric, p-coumaroyl tartaric, and feruloyl tartaric acid esters) and free hydroxycinnamic acids (caffeic, ferulic, and p-coumaric acids). 

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. 

Nakamura Y, Higuchi T (1976) Ester linkage of p-coumaric acid in bamboo lignin Holzforschung 30 187-191... 

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