3- Hydroxycinnamic acid

Hydroxycinnamic acid (p-coumaric acid) [501-98-4] M 164.2, m 210-213 , 214-215 , 215 pK 4.64, pKj 9.45. Crystd from H2O (charcoal). Needles from cone aqueous solutions as the anhydrous acid, but from hot dilute solutions the monohydrate acid separates on slow cooling. The acid (33g) has been recrystd from 2.5L of H2O (1.5g charcoal) yielding 28.4g of recrystd acid, m 207°. It is insol in CgH6 or pet ether. The UV in 95% EtOH has 223 and 286nm (e 14,450 and 19000 M cm ). [UV Wheeler and Covarrubias J Org Chem 28 2015 7965 Corti Helv Chim Acta 32 681 1949.]... 

Coumarin, the lactone of o-hydroxycinnamic acid, and some of its derivatives have been isolated from many plant species 31). Thimann and Bonner 141) attributed the growth-inhibiting effects of coumarin to its action on enzyme sulfhydryl groups. Inhibitory effects of coumarin on Avena coleoptiles and pea stem sections could be overcome by 2,3-dimercaptopropanol (BAL). Coumarin has also been reported to disrupt mitosis 29,30). 

The course of the reaction has not been fully clarified. Hydrolytic and aromatization processes are probably responsible for the formation of colored or fluorescent deriva4 tives (cf. Potassium Hydroxide Reagent). For instance, sevin is converted to a-naphthalkali metal salt of the o-hydroxycinnamic acid pro- duced by hydrolytic cleavage of the pyrone ring is converted from the non-fluorescent cis- to the fluorescent trans-form by the action of long-wavelength UV light (X = 365 nm) [2]. 

Figure 6.6. Three hydroxycinnamic acids common in plants and of interest as potential sporopollenin components.

Advances in analytical procedures resulted in several reports on anthocyanins acy-lated with hydroxycinnamic acids (p-coumaric, caffeic, ferulic, sinapic, and 3,5-dihydroxycinnamic acids), hydroxybenzoic acids (p-hydroxybenzoic and gallic acids), and aliphatic acids (malonic, acetic, malic, oxalic, succinic and tartaric acids). However, not all of them were found in anthocyanins isolated from foods. Among the 44 fruits listed in Table 4.3.1, 15 presented acylated anthocyanins as did 12 of 13 vegetables shown in Table 4.3.3 and 2 of the 9 grains cited in Table 4.3.4. On the other hand, acylated anthocyanins were found in all grapes from Vitis species, although at different abundance levels, as can be seen in Table 4.3.2. A higher... 

Among the hydroxycinnamic acids, anthocyanins acylated with sinapic acid are not widespread in foods they have been isolated only in black carrots " and red cabbages." Anthocyanins that are acylated with p-hydroxybenzoic acid were only found in black carrots " and sweet potatoes. This acyl group was located within the 6 position of a glucoside moiety. 

The decarboxylation of 4-hydroxycinnamic acid to 4-hydroxystyrene, and of fernlic acid (3-methoxy-4-hydroxycinnamic acid) to 4-vinylgnaiacol by several strains of Haf-nia alvei and H. protea, and by single strains of Enterobacter cloacae and K. aerogenes (Fignre 2.7d) (Findsay and Priest 1975). The decarboxylase has been pnrihed from Bacillus pumilis (Degrassi et al. 1995). 

The metabolism of ferulic acid (3-methoxy-4-hydroxycinnamic acid) by Ent. cloacae to a nnmber of products including phenylpropionate and benzoate (Fignre 2.8) (Grbic-Galic 1986). 

Decarboxylation of aromatic carboxylic acids has been encountered extensively in facultatively anaerobic Enterobacteriaceae. For example, 4-hydroxycinnamic acid is... 

FIGURE 8.32 Decarboxylation of ferulic acid (3-methoxy-4-hydroxycinnamic acid). 

Gasson Ml, Y Kitamura, WR McLaughlan, A Narbad, AJ Parr, ELH Parsons, J Payne, MJC Rhodes, NK Walton (1998) Metabolism of ferulic acid to vanillin. A bacterial gene of the enoyl-SCoA hydratase/ isomerase superfamily encodes an enzyme for the hydration and cleavage of a hydroxycinnamic acid SCoA thioester. J Biol Chem 273 4163-4170. 

Various hydroxybenzoic and hydroxycinnamic acids are present in plants (Gross, 1981 Herrmann, 1979, 1989). Steeg and Montag (1988)... 

Quideau, S. Incorporation of p-hydroxycinnamic acids into lignins via oxidative coupling. Ph.D. Thesis, University of Wisconsin—Madison, USA, University Microfilms International 9428350, 1994. 1994. 

Takahama, U. Oniki T. Shimokawa H. A possible mechanism for the oxidation of sinapyl alcohol hy peroxidase-dependent reactions in the apoplast enhancement of the oxidation hy hydroxycinnamic acids and components of the apoplast. Plant Cell Physiol. 1996, 37, 499-504. 

Takahama, U. Oxidation of hydroxycinnamic acid and hydroxycinnamyl alcohol derivatives by laccase and peroxidase—interactions among p-hydroxyphenyl, guaiacyl and syringyl groups during the oxidation reactions. Physiol. Plantarum 1995, 93, 61-68. 

Takahama, U. Oniki, T. Effects of ascorbate on the oxidation of derivatives of hydroxycinnamic acid and the mechanism of oxidation of sinapic acid by cell wall-bound peroxidases. Plant Cell Physiol. 1994, 35, 593-600. 

Figure 2. Linear regression plot of root growth inhibition of tomato and radish seedlings by o and -hydroxyphenyl) acids. o-Hydroxycinnamic acid, (o-hydroxyphenyl) acetic acid ( ) melilotic acid, 2-(o-hydroxyphenyl) butanoic acid ( ) o-hydroxy-benzoic acid, ( -hydroxypheny 1 )acetic acid (0) -hydroxycinnamic acid, =hydroxybenzoic acid, 3-( -hydroxyphenyl) propanoic acid (X) o-coumaryl glucoside, water control (----) (1 ). ...

Murata, M., Okada, H., Homma, S., Hydroxycinnamic acid derivatives and p coumaryl-(L)-tryptophan, a novel hydroxycinnamic acid derivative from coffee beans, Biosci. Biotechnol. Biochem., 59(10), 1887, 1995. (CA124 54202q)... 

Despite the large number whole-cell MALDI protocols that have been tested a single approach has not yet been widely adopted. There remain different and sometimes conflicting reports in the literature regarding optimum methodologies.3 In addition to the ferulic acid matrix mentioned above sinapinic acid, a-yano-4-hydroxycinnamic acid, 2,4-hydroxyphenyl benzoic... 

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