The metabolism of aromatic compounds in higher plants. I. Coumarin and o-coumaric acid.
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Acids↗
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The hydroxylation of coumarin and the cyclization of o-coumaric acid in vivo.
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Acids↗
New aliphatic alcohol and (Z)-4-coumaric acid glycosides from Acanthus ilicifolius.
From the aerial parts of Acanthus ilicifolius, a new aliphatic alcohol glycoside (ilicifolioside C) and two new (Z)-4-coumaric acid glycosides, (Z)-4-coumaric acid 4-O-beta-D-glucopyranoside and (Z)-4-coumaric acid 4-O-beta-D-apiofuranosyl-(1"-->2')-O-beta-D-glucopyranoside were isolated. The structural elucidations were based on the analyses of spectroscopic data. Z-Form 4-coumaric acid glycosides were first isolated from plant.
Acanthaceae↗
Reactions of p-coumaric acid with nitrite: product isolation and mechanism studies.
p-Coumaric acid (1) is an abundant plant phenolic acid, a dietary chemoprotectant, and an antioxidant. The chemoprotective properties of 1 were demonstrated in vitro by its reaction with NaNO(2) in H(2)O over a range of pH values. The reaction pathway of 1 with nitrite is dependent on pH. 4-Hydroxybenzaldehyde (3, 16%), 1',4-dihydroxybenzeneacetaldehyde oxime (5, 59%), and 4-hydroxy-1'-oxo-benzeneacetaldehyde aldoxime (7, 26%) and 7-hydroxy-1,2(4H)-benzoxazin-4-one (11, 6%) were each formed at pH 2, whereas 4-(2-oxido-1,2,5-oxadiazol-3-yl)phenol (13) was formed at pH 3 (6%) and pH 7 and 10 (both 1%). Products were isolated and characterized by NMR and MS spectral analyses. Formation of benzoxazinone (11) requires the 4-phenolic functional group and the conjugated propenoic acid side chain of p-coumaric acid. The mechanism for nitrosation at pH 2 was examined by reacting 1 in H(2)(18)O/NaNO(2).
Antioxidants↗
The expression of catechol oxidase activity during the hydroxylation of p-coumaric acid by spinach-beet phenolase.
1. The conditions under which oxygen consumption in excess of that required for the hydroxylation of p-coumaric acid to caffeic acid, catalysed by spinach-beet phenolase, can be suppressed, have been examined. 2. With dimethyltetrahydropteridine as electron donor, oxygen uptake was exactly equivalent to the caffeic acid produced, provided that p-coumaric acid was in excess, but with excess of reductant, oxygen uptake caused by the further oxidation of caffeic acid was also observed. 3. With equal concentrations of ascorbate and p-coumaric acid, equivalent oxygen uptake and caffeic acid production was found only in the first stages of the reaction, whereas with NADH substituted for ascorbate, oxygen uptake was in excess throughout. 4. When ascorbate was used, the period of the reaction over which this equivalence was found was decreased at high reaction rates and not observed at all with aged enzyme preparations; equivalence was restored by adding bovine serum albumin to these aged preparations. 5. Equivalence between oxygen consumption and caffeic acid production was observed with NADH, if small quantities of dimethyltetrahydropteridine were also added. 6. It is concluded that hydroxylation proceeds without the concomitant production of caffeic acid only if the enzyme is stabilized for hydroxylation by p-coumaric acid and the reductant, and is protected from attack by o-quinones.
Ascorbic Acid↗
Microbial transformations of p-coumaric acid by Bacillus megaterium and Curvularia lunata.
p-Coumaric acid (1) is an abundant phenolic natural product that exhibits both chemoprotectant and antioxidant properties. Microbial transformation screening studies showed that 1 was converted to 4-vinylphenol (4), 4-hydroxybenzoic acid (2), caffeic acid (5), protocatechuic acid (6), and other unidentified metabolites over 144 h. 4-Vinylphenol (4) and its dimer, (2R,2S)-4-(2,3-dihydro-5-hyroxy-2-benzofuranyl) phenol (11), were produced by Bacillus megaterium, and 5-[(E)-2-carboxyethenyl]-2,3-dihydro-2-(4-hydroxyphenyl)-3-benzofurancarboxylic acid (15) and 4-hydroxybenzoic acid (2) were produced by Curvularia lunata. On the basis of deuterium-labeling experiments, B. megaterium catalyzes the nonoxidative enzymatic tautomerization of 1 to a vinylogous beta-keto acid intermediate that decarboxylates to 4. The presence of peroxidase and laccase activities in C. lunata extracts suggests that these enzymes may be involved in one-electron, p-coumaric acid dimerization in this organism.
Bacillus megaterium↗
Evidence of a new biotransformation pathway of p-coumaric acid into p-hydroxybenzaldehyde in Pycnoporus cinnabarinus.
Pycnoporus cinnabarinus MUCL39533 was shown to be able to convert p-coumaric acid into p-hydroxybenzaldehyde, a component of high organoleptic note present in natural vanilla aroma. Use of phospholipid-enriched medium led to high-density cultures of P. cinnabarinus, since dry mycelial biomass was increased three-fold as compared to glucose medium. In the presence of phospholipids, 155 mg l(-1) p-hydroxybenzaldehyde was produced as the major compound on culture day 13 with a molar yield of 26%. The degradation pathways of p-coumaric acid were investigated. Based on the different metabolites identified, an oxidative side-chain degradation pathway of p-coumaric acid conversion to p-hydroxybenzoic acid was suggested. This acid was further reduced to p-hydroxybenzaldehyde and p-hydroxybenzyl alcohol, or hydroxylated and reduced to protocatechyl derivatives. Additionally, a reductive pathway of p-coumaric acid with 3-(4-hydroxyphenyl)-propanol as the terminal product occurred.
Agaricales↗
Transepithelial transport of p-coumaric acid and gallic acid in Caco-2 cell monolayers.
The transepithelial transport of such common dietary phenolic acids as p-coumaric acid (CA) and gallic acid (GA) across Caco-2 cell monolayers was examined. CA transport was dependent on pH, and in a vectorial manner in the apical-basolateral direction. The permeation was concentration-dependent and saturable, the Michaelis constant and maximum velocity being 17.5 mM and 82.7 nmol min(-1) (mg of protein)(-1), respectively. Benzoic acid and acetic acid inhibited the permeation of CA. These results indicate that the transepithelial transport of CA was via the monocarboxylic acid transporter (MCT). On the other hand, the permeation of GA was not in a polarized manner, was independent of pH and linearly increased with increasing concentration of GA. The transport rate of GA was about 100 times lower than that of CA, suggesting the transepithelial transport of GA to be via the paracellular pathway. Dietary phenolic acids thus showed diversified characteristics in their intestinal absorption.
Adenocarcinoma↗
Protection against ultraviolet B-induced oxidative DNA damage in rabbit corneal-derived cells (SIRC) by 4-coumaric acid.
The exposure of cells to ultraviolet B radiation (UV-B) can induce the production of reactive oxygen species (ROS) which damage cellular components. Free radical scavengers and antioxidants can interfere with the production of ROS. We measured 8-hydroxy-2'-deoxyguanosine (8-OHdG) levels, a marker of oxidative DNA damage in rabbit corneal-derived cells (SIRC) exposed to UV-B in the presence of 4-coumaric acid, a natural polyphenol. The levels of 8-OHdG were increased significantly (P<0.01) following irradiation (from 12+/-1.2x10(-6) to 29+/-6.2x10(-6) dG, means+/-SE). When 10 microM 4-coumaric acid was added to the medium, 8-OHdG levels were similar to those of unexposed cells (16.8+/-0.8x10(-6) dG). UV-B irradiation decreased superoxide dismutase (SOD) activity in SIRC cells from 0.29+/-0.6 to 0.15+/-0.04 mU/mg (means+/-SE). The presence of 10 microM 4-coumaric acid prevented the decrease in SOD activity (0.20+/-0.05 mU/mg, P<0.05). On the contrary, SIRC cells exposed to UV-B had higher levels of xanthine oxidase (XO) activity compared with control ones (0.40+/-0.07 and 0.24+/-0.08 mU/mg, means+/-SE, respectively). In the presence of 10 microM 4-coumaric acid, the increase in XO activity was prevented (0.16+/-0.03 mU/mg; mean+/-SE). In conclusion, UV-B-induced oxidative DNA damage in SIRC cells is inhibited by 4-coumaric acid, which, probably through its free radical scavenging activity, stabilizes SOD activity and blocks the increase of XO activity following UV-B irradiation. Thus, the topical use of 4-coumaric acid may prevent free radical damage in the cornea.
8-Hydroxy-2'-Deoxyguanosine↗
Degradation of trans-ferulic and p-coumaric acid by Acinetobacter calcoaceticus DSM 586.
Cell suspensions of Acinetobacter calcoaceticus strain DSM 586 and DSM 590 were able to grow on benzoic, p-hydroxybenzoic and vanillic acid as sole carbon source. Testing the utilization of trans-ferulic and p-coumaric acid, we found that the sole A. calcoaceticus DSM 586 efficiently degraded the lignocellulose related monomers. Cells induced with trans-ferulic acid were able to oxidize trans-ferulic, p-coumaric, vanillic, p-hydroxybenzoic and protocatechuic acid at rates higher than the uninduced culture. The same activity was found in the p-coumaric acid induced culture. Two aromatic compounds, vanillic and p-hydroxybenzoic acid, were isolated from culture filtrates of trans-ferulic and p-coumaric acid grown cells, respectively, and further characterized by high performance liquid chromatography. 1H- and 13C-nuclear magnetic resonance and ultraviolet spectrophotometry. Cell extracts of trans-ferulic or p-coumaric acid induced cultures were shown to rapidly convert protocatechuic acid to beta-carboxymuconic acid. Moreover, A. calcoaceticus DSM 586 produced high levels of protocatechuic 3,4-dioxygenase compared to cathecol 1,2-dioxygenase and gentisate 1,2-dioxygenase in the degradation of trans-ferulic or p-coumaric acid. Based upon these results, a reaction sequence for the complete degradation of trans-ferulic and p-coumaric acid in A. calcoaceticus DSM 586 is proposed.
Acinetobacter calcoaceticus↗
Goitrogenic activity of p-coumaric acid in rats.
The effects of three natural phenolic acids (caffeic, ferulic, and p-coumaric) on the rat thyroid gland were examined in a 3-week oral-treatment study. Forty male Wistar albino rats, divided into groups of 10 rats each and fed iodine-rich diet, were administered by gastrointestinal tube saline (control), caffeic acid, ferulic acid, or p-coumaric acid at a dose level of 0.25 micromol/kg/day for 3 weeks. The mean absolute and relative thyroid weights in caffeic, ferulic, or p-coumaric acid groups were significantly increased to 127 and 132%, 146 and 153%, or 189 and 201% compared to control value, respectively. Histological examination of the thyroids of p-coumaric acid group revealed marked hypertrophy and/or hyperplasia of the follicles. Caffeic or ferulic groups showed slight to moderate thyroid gland enlargement. Thyroid lesions in p-coumaric acid group were associated with significant increases in cellular proliferation as indicated by [(3)H]thymidine incorporation. In addition, the goitrogenic effect of p-coumaric acid was further confirmed by significant decreases (50%) in serum tri-iodothyronine (T(3)) and thyroxine (T(4)), and a parallel increase (90%) in serum thyroid stimulating hormone (TSH) compared to control group. These results indicate that administration of p-coumaric acid at relatively high doses induces goiter in rats.
Administration, Oral↗
Pharmacokinetic study of p-coumaric acid in mouse after oral administration of extract of Ananas comosus L. leaves.
Quantification of p-coumaric acid in mouse plasma following oral administration of Ananas comosus L. leaves was achieved by reversed-phase high-performance liquid chromatography using a mobile phase of water-acetonitrile (82:18, v/v) and UV detection at 310 nm. The method was linear (determination coefficient, r2 = 0.9997) within the tested range (0.04-1.28 microg/mL). Intra- and inter-day precision coefficients of variation and accuracy bias were acceptable (maximal CV value was 4.06% for intra-day and 4.19% for inter-day) over the entire range. The recoveries were 90.63, 97.98 and 100.01% for concentrations of 0.04, 0.32 and 1.28 microg/mL, respectively. This is a very rapid, sensitive and economical way to determine p-coumaric acid concentration in mouse plasma after oral administration of A. comosus leaves. The concentration-time curve was fitted to the one-compartment model. This is the first time that p-coumaric acid extracted from A. comosus leaves was detected by HPLC-UV method and its pharmacokinetic characteristic was comprehensively studied.
Administration, Oral↗
Cholesteryl ester hydroperoxide formation in myoglobin-catalyzed low density lipoprotein oxidation: concerted antioxidant activity of caffeic and p-coumaric acids with ascorbate.
Two diet-derived phenolic acids, caffeic and p-coumaric acids, interplayed with ascorbate in the protection of low density lipoproteins (LDL) from oxidation promoted by ferrylmyoglobin. Ferrylmyoglobin, a two-electron oxidation product from the reaction of metmyoglobin and H2O2, was able to oxidize LDL, degrading free cholesterol and cholesteryl esters. Upon exposure to ferrylmyoglobin, LDL became rapidly depleted of cholesteryl arachidonate and linoleate, which turn into the corresponding hydroperoxides. Cholesteryl oleate and cholesterol were, comparatively, more resistant to oxidation. Caffeic (2 microM) and p-coumaric (12 microM) acids efficiently delayed oxidations, as reflected by an increase in the lag times required for linoleate hydroperoxide and 7-ketocholesterol formation as well as for cholesteryl linoleate consumption. At the same concentration, ascorbate, a standard water-soluble antioxidant, was less efficient than the phenolic acids. Additionally, phenolic acids afforded a protection to LDL that, conversely to ascorbate, extends along the time, as inferred from the high levels of cholesteryl linoleate and cholesteryl arachidonate left after 22 hr of oxidation challenging. Significantly, the coincubation of LDL with ascorbate and each of the phenolic acids resulted in a synergistic protection from oxidation. This was inferred from the lag phases of cholesteryl linoleate hydroperoxide (the major peroxide found in LDL) formation in the presence of mixtures of ascorbate with phenolic acids longer than the sum of individual lag phases of ascorbate and the phenolic acids. A similar description could be drawn for the accumulation of a late product of oxidation, 7-ketocholesterol. It is concluded that ferrylmyoglobin induces a typical pattern of LDL lipid peroxidation, the oxidation rate of cholesteryl esters being a function of unsaturation; furthermore, there is a synergistic antioxidant activity of diet-derived phenolic acids with ascorbate in the protection of LDL from oxidation, a finding of putative physiological relevance.
Animals↗
Molecular characterization of an inducible p-coumaric acid decarboxylase from Lactobacillus plantarum: gene cloning, transcriptional analysis, overexpression in Escherichia coli, purification, and characterization.
By using degenerate primers designed from the first 19 N-terminal amino acids of Lactobacillus plantarum p-coumaric acid decarboxylase (PDC), a 56-bp fragment was amplified from L. plantarum in PCRs and used as a probe for screening an L. plantarum genomic bank. Of the 2,880 clones in the genomic bank, one was isolated by colony hybridization and contained a 519-bp open reading frame (pdc gene) followed by a putative terminator structure. The pdc gene is expressed on a monocistronic transcriptional unit, which is transcribed from promoter sequences homologous to Lactococcus promoter sequences. No mRNA from pdc and no PDC activity were detected in uninduced cell extracts, indicating that the expression is transcriptionally regulated by p-coumaric acid, which corresponds to an activation factor up to 6,000. The pdc gene was overexpressed constitutively in Escherichia coli, and the recombinant enzyme was purified and characterized.
Amino Acid Sequence↗
Reconstitution photoactive yellow protein from apoprotein and p-coumaric acid derivatives.
We report reconstitution of photoactive yellow protein (PYP) from apoPYP and p-coumaric acid derivatives. The addition of p-coumaric acid to the apoPYP sample did not result in the recovery of PYP. In contrast, yellow products were obtained by the addition of p-coumaryl thiophenyl ester or p-coumaric anhydride to the apoPYP sample, the absorption spectra of which were indistinguishable from the spectrum of intact PYP. Our findings provide strong evidence that PYP has the p-coumaryl chromophore. This reconstitution technique opens the way for further biophysical studies of PYP using artificial chromophore analogs.
Apoproteins↗
[Determination of p-coumaric acid in Hedyotis diffusa Willd. from different sources by reversed-phase high performance liquid chromatography].
A method for the determination of p-coumaric acid in Hedyotis diffusa Willd. from different sources by reversed-phase high performance liquid chromatography (RP-HPLC) has been developed. p-Coumaric acid was successfully separated on a Diamonsil ODS column (4.6 mm i.d. x 250 mm, 5 microm) at ambient temperature, using a mixture of CH3CN-20 mmol/L NH4Ac (pH 4.0) (15:85, v/v) as mobile phase and detection at 308 nm. The flow rate was 1.0 mL/min. There was good linear relationship (r = 0.9996) between the mass concentration and the peak area of p-coumaric acid in the range of 4.04 - 202 mg/L. The recoveries were found to be in the range of 97.4% - 102.2%. The results of the experiments have demonstrated that the established method is rapid and simple with good accuracy and reproducibility. The method is suitable for use in quality control of Hedyotis diffusa Willd. from different sources.
Antioxidants↗
Reversal of Abscisic Acid-Induced Stomatal Closure by trans-Cinnamic and p-Coumaric Acid.
Abscisic acid (ABA)-induced increase in stomatal diffusive resistance (SDR) in excised leaves of bean (Phaseolus vulgaris L. cv Pencil Pod) and maize (Zea mays L. cv Golden Bantam) is inhibited by low concentrations of trans-cinnamic acid (TCA) (1 micromolar) and p-coumaric acid (PCA) (10 micromolar) when given together with ABA (10 micromolar) in the transpiration stream through the cut end of the petiole or leaf blade. A concentration effect is observed both in the ABA action and its reversal by phenolic acids. Leaves having attained a high diffusive resistance in ABA solution recover rapidly when transferred to water. ABA (10 micromolar) induced closure of the stomata in onion, Allium cepa L. and Vicia faba epidermal peels. This is associated with loss of K(+) from guard cells. In the presence of TCA (10 micromolar) and PCA (10 micromolar) K(+) is retained in the guard cells with open stomata. The dark closure of stomata is also inhibited by TCA and PCA. It is suggested that these phenolic acids may inhibit the ABA effect by competing with or acting on some ABA-specific site, probably located on the plasma membrane, regulating flux of K(+) ions. A weak association of ABA with the plasma membrane is envisaged because of the rapid recovery obtained upon transferral of the leaves to water.
Journal Article↗
Modulation of luteinizing hormone receptors: effect of an inhibitor of prolactin secretion, p-coumaric acid.
Daily oral administration of p-coumaric acid (PCA) at a dose of 50 mg/kg body wt for 21 days to adult male mice caused a dramatic reduction in serum prolactin concentrations. A significant fall in testicular LH binding was also observed after PCA treatment. Complete recovery of testicular LH binding was obtained by daily administration of prolactin (500 micrograms/mouse) when given simultaneously from day 9 of PCA treatment. A lower daily dose of prolactin (250 micrograms) was found to be ineffective. Scatchard analysis of binding data suggested a decrease in the number of testicular LH binding sites after PCA treatment whereas the affinity constant was unchanged. These results provide direct evidence for an inhibitory effect of PCA on prolactin secretion and also provide additional evidence in favour of a role of prolactin in the modulation of LH receptors.
Animals↗