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Characterization of recombinant plant cinnamate 4-hydroxylase produced in yeast. Kinetic and spectral properties of the major plant P450 of the phenylpropanoid pathway.

Helianthus tuberosus cinnamate 4-hydroxylase (CYP73 or CA4H), a member of the P450 superfamily which catalyses the first oxidative step of the phenylpropanoid pathway in higher plants by transforming cinnamate into p-coumarate, was expressed in the yeast Saccharomyces cerevisiae. The PCR-amplified CA4H open reading frame was inserted into pYeDP60 under the transcriptional control of a galactose-inducible artificial promoter. Engineered S. cerevisiae strains producing human P450 reductase or normal or overproduced amounts of yeast P450 reductase were transformed to express recombinant CA4H. When grown on galactose, yeast cells produced CA4H holoprotein bound to the endoplasmic reticulum membrane as judged from the reduced iron/carbon monoxide difference spectrum centered at 452 nm and from typical cinnamate 4-hydroxylase activity upon coupling with the different P450 reductases and NADPH. Some CA4H protein was found also addressed to the yeast mitochondria but as a low-activity form. The spectral and kinetic characterizations of the yeast-produced CA4H in different redox protein environments are presented using both assays on yeast microsomal fractions and bioconversions on living cells. Results indicate that the microsomal system constituted by the overexpressed yeast P450 reductase and CA4H is characterized by a 1:1 coupling between NADPH oxidation and cinnamate hydroxylation and by one of the highest turnover numbers reported for an NADPH-dependent P450 reaction. Based on spectral perturbation and inhibition studies, coumarate appeared to have no detectable affinity for the enzyme. A possible geometry of the substrate recognition pocket is discussed in the light of these data.

Base Sequence↗

Lipase-catalyzed synthesis of arbutin cinnamate in an organic solvent and application of transesterification to stabilize plant pigments.

Arbutin cinnamate was synthesized from arbutin (4-hydroxyphenyl beta-D-glucopyranoside) and vinyl cinnamate by regioselective transesterification with a bacterial lipase in acetonitrile. The product was identified by NMR and FAB-MS analyses. These spectra showed that one ester bond was formed between the primary alcohol moiety of the D-glucose of arbutin and the carboxyl residue of cinnamic acid. Furthermore, plant pigments such as isoquercitrin (quercetin 3-O-beta-D-glucopyranoside) and callistephin (pelargonidin 3-O-beta-D-glucopyranoside) were also converted to their corresponding cinnamate esters in the same manner.

Acetonitriles↗

[Effects of cinnamic acid on physiological characteristics of Cucumis sativus seedling].

With substrate culture, this paper studied the effects of different concentrations of cinnamic acid on the physiological characteristics of Cucumis sativus seedling. The results showed that 25 micromol.L(-1) of cinnamic acid had an inhibition effect on carotenoids, but a promotion effect on chlorophyll a and b. 50 micromol.L(-1) of this compound could significantly inhibit the photosynthetic rate, transpiration rate and root activity (P < 0.05), and this effect was getting stronger when the concentration was higher. 150 micromol cinnamic acid.L(-1) had a significant inhibition effect on chlorophyll a and b (P < 0.05). Cinnamic acid had a weak inhibition effect on root activity when its concentration was low (25-50 micromol.L(-1)), but the effect was significant when the concentration was high (100-150 micromol.L(-1)), which became stronger with the longer handling time (P < 0.05).

Carotenoids↗

[High performance liquid chromatographic determination of cinnamic acid in rabbit plasma and application in study of pharmacokinetics].

A high performance liquid chromatographic method was developed to determine the content of cinnamic acid in rabbit plasma and the method was utilized for the study of pharmacokinetics. Cinnamic acid was separated by employing a column of Kromasil C18 (250 mm x 4.6 mm i.d., 5 microm) and a mobile phase of methanol-acetonitrile-water-glacial acetic acid (10:22:55:0.5, v/v) at a flow rate of 0.8 mL/min and room temperature with UV detection at 270 nm and phenylpropionic acid as internal standard. The extraction recoveries of the spiked samples at low, middle and high levels were 84.9%, 84.4% and 87.7%, respectively, while the method recoveries were 98.4% with relative standard deviation (RSD) of 5.5%, 99.2% with RSD of 3.6%, 100.1% with RSD of 3.7% in turn. The RSDs of intra-day and inter-day were both lower than 6%. Finally, the metabolism of cinnamic acid in rabbit plasma after medication of Guanxin Suhe Wan and Guanxin Suhe Capsule fitted in a first order absorption of two-compartment model. The method was found to be sensitive, accurate and precise, and is appropriate for the determination of cinnamic acid.

Animals↗

A thiocholine ester of cinnamic acid inhibits crosslinking of fibrin without specific binding to donor lysines.

In the presence of activated factor XIII, 2-diethylbenzyl-aminoethylthiol-14C-transcinnamate bromide completely inhibited the crosslinking of fibrin. However, all three fibrin chains bound the cinnamic acid, and, in the alpha- and gamma-chains, the binding of label was not restricted to the crosslinking donor sites as might be expected. Furthermore, even in the absence of activated factor XIII, fibrinogen and fibrin incorporated cinnamic acid. Thus, as well as reacting with the functional thiol group of factor XIII, the thiocholine ester of cinnamic acid is incorporated non-specifically throughout the fibrinogen and fibrin subunit chains. The thiocholine ester used differs in this respect from dansyl cadaverine which is incorporated enzymatically and exclusively to the (acceptor) sites involved in crosslinking. Thiocholine ester of cinnamic acid cannot be used as a label for localization of specific crosslinking donor sites.

Chemical Phenomena↗

Kinetic and mechanistic studies on the oxidation of the melilotate hydroxylase . 2-OH-cinnamate complex by molecular oxygen.

The reaction mechanism of melilotate hydroxylase in the presence of 2-OH-cinnamate has been investigated by equilibrium titration, steady state kinetic and rapid reaction kinetic techniques. Analysis of the rapid reaction results for the reoxidation of reduced enzyme . 2-OH-cinnamate complex by molecular oxygen revealed the presence of an intermediate with visible absorption spectrum very similar to that of a C4a-flavin adduct. Repetition of this reoxidation experiment in the presence of 32 mM potassium iodide indicated the sequential appearance of two C4a-flavin adducts. Further analysis of these spectra indicated that hydroxylation of the substrate occurred during the conversion of the first intermediate into the second. Reaction of the oxidized enzyme . 2-OH-cinnamate complex with NADH was saturable in NADH. Oxidized enzyme was converted, in an apparent first order fashion, to a reduced enzyme . NAD charge-transfer-type species which subsequently decayed to reduced enzyme. The turnover number calculated from rapid reaction data was in good agreement with that determined from steady state analyses. Titration and rapid reaction results indicated that at no point in the reaction was there an observable intermediate which contained 2-OH-cinnamate in its phenolate form.

Cinnamates↗

Protein binding and metabolism influence the relative skin sensitization potential of cinnamic compounds.

Skin protein modification (haptenation) is thought to be a key step in the manifestation of sensitization to low molecular mass chemicals (<500 g/mol). For sensitizing chemicals that are not protein reactive, it is hypothesised that metabolic activation can convert such chemicals into protein reactive toxins within the skin. trans-Cinnamaldehyde, alpha-amyl cinnamaldehyde, and trans-cinnamic alcohol are known sensitizers with differing potencies in man, where the former two are protein reactive and the latter is not. Here, we have used immunochemical methods to investigate the extent of protein-cinnamaldehyde binding in rat and human skin homogenates that have been incubated (for either 5, 15, 30, or 60 min) at 37 degrees C with cinnamaldehyde, alpha-amyl cinnamaldehyde (at concentrations of between 1 and 40 mM), and cinnamic alcohol (at higher concentrations of 200 or 400 mM). Cinnamaldehyde specific antiserum was raised specially. A broad range (in terms of molecular mass) of protein-cinnamaldehyde adducts was detected (as formed in a time- and concentration-dependent manner) in skin treated with cinnamaldehyde and cinnamic alcohol but not with alpha-amyl cinnamaldehyde. Mechanistic observations have been related to relative skin sensitization potential, as determined using the local lymph node assay (LLNA) as a biological read-out. The work presented here suggests that there is a common hapten involved in cinnamaldehyde and cinnamic alcohol sensitization and that metabolic activation (to cinnamaldehyde) is involved in the latter. Conversely, there does not appear to be a common hapten for cinnamaldehyde and alpha-amyl cinnamaldehyde. Such mechanistic work on protein modification is important in understanding the early mechanisms of skin sensitization. Such knowledge can then be used in order that effective and appropriate in vitro/in silico tools for predicting sensitization potential, with a high confidence, can be developed.

Acrolein↗

Piperonylic acid, a selective, mechanism-based inactivator of the trans-cinnamate 4-hydroxylase: A new tool to control the flux of metabolites in the phenylpropanoid pathway

Piperonylic acid (PA) is a natural molecule bearing a methylenedioxy function that closely mimics the structure of trans-cinnamic acid. The CYP73A subfamily of plant P450s catalyzes trans-cinnamic acid 4-hydroxylation, the second step of the general phenylpropanoid pathway. We show that when incubated in vitro with yeast-expressed CYP73A1, PA behaves as a potent mechanism-based and quasi-irreversible inactivator of trans-cinnamate 4-hydroxylase. Inactivation requires NADPH, is time dependent and saturable (KI = 17 &mgr;M, kinact = 0.064 min-1), and results from the formation of a stable metabolite-P450 complex absorbing at 427 nm. The formation of this complex is reversible with substrate or other strong ligands of the enzyme. In plant microsomes PA seems to selectively inactivate the CYP73A P450 subpopulation. It does not form detectable complexes with other recombinant plant P450 enzymes. In vivo PA induces a sharp decrease in 4-coumaric acid concomitant to cinnamic acid accumulation in an elicited tobacco (Nicotiana tabacum) cell suspension. It also strongly decreases the formation of scopoletin in tobacco leaves infected with tobacco mosaic virus.

Journal Article↗

Effects of Culture Conditions on Production of trans-Cinnamic Acid from Alkylbenzenes by Soil Microorganisms.

The production of trans-cinnamic acid from various alkylbenzenes by soil microorganisms was studied intensively by use of a co-oxidation technique. The microorganisms were grown on n-paraffins, and they did not use aromatic compounds as a carbon source when the preferred substrate was present in the medium. The effects of cell population, co-oxidation time, and type and mode of addition of the alkylbenzenes on the yield of trans-cinnamic acid were investigated. Yields (5 g/liter) of a product consisting of trans-cinnamic acid (88 to 100%) and 5-phenylvaleric acid (0 to 12%) were obtained when the proper conditions were chosen. Of a variety of microorganisms studied, a soil isolate closely related to Cellulomonas galba was found to be best for the production of trans-cinnamic acid.

Journal Article↗

Contact urticaria from cinnamic aldehyde.

Lip swelling developed following the use of a cinnamic aldehyde-containing mouthwash in a woman with allergic rhinitis and asthma. Open application of the mouthwash on the antecubital fossae of the patient and control subjects produced immediate erythematous or urticarial responses in all tested individuals. Subsequent investigation established cinnamic aldehyde as the responsible ingredient. The incidence of positive reactions was shown to depend on site of application, vehicle, concentration, and time of reading. Of several related cinnamates, only cinnamic acid produced easily detectable responses at similar concentrations.

Acrolein↗

Perioral leukoderma simulating vitiligo from use of a toothpaste containing cinnamic aldehyde.

Perioral leukoderma simulating vitiligo developed in a 25-year-old woman. A patch test to cinnamic aldehyde was positive; depigmentation was observed at the patch test site three months after initial application. No changes in pigmentation occurred from a concomitant allergic patch test reaction to neomycin sulfate; only hyperpigmentation occurred at the site of an irritant patch test reaction to nonanoic acid. A toothpaste containing cinnamic aldehyde was implicated; perioral hypopigmentation resolved when a toothpaste without cinnamic aldehyde was substituted. A repeated patch test to cinnamic aldehyde again showed depigmentation at the patch test site three months after application.

Acrolein↗

The occurrence, metabolism and toxicity of cinnamic acid and related compounds.

Cinnamic acid is a compound of low toxicity, but its molecular structure and the known toxicity of similar molecules, such as styrene, have brought it to the toxicologist's attention. Commercially, its use is permitted as flavouring and it is ubiquitous in products containing cinnamon oil and to a lesser extent in all plants. The related aldehyde, alcohol and esters are all more toxic than cinnamic acid. Certain substituted cinnamates containing cyano and fluoro moieties are of particular interest because they inhibit mitochondrial pyruvate transport. The literature about this whole group of commercially important compounds is diverse and many key studies are in languages other than English. This review looks at the history and legal constraints, as well as the results of metabolism and toxicology studies.

Acrolein↗

The solvent-tolerant Pseudomonas putida S12 as host for the production of cinnamic acid from glucose.

A Pseudomonas putida S12 strain was constructed that efficiently produced the fine chemical cinnamic acid from glucose or glycerol via the central metabolite phenylalanine. The gene encoding phenylalanine ammonia lyase from the yeast Rhodosporidium toruloides was introduced. Phenylalanine availability was the main bottleneck in cinnamic acid production, which could not be overcome by the overexpressing enzymes of the phenylalanine biosynthesis pathway. A successful approach in abolishing this limitation was the generation of a bank of random mutants and selection on the toxic phenylalanine anti-metabolite m-fluoro-phenylalanine. Following high-throughput screening, a mutant strain was obtained that, under optimised culture conditions, accumulated over 5 mM of cinnamic acid with a yield (Cmol%) of 6.7%.

3-Deoxy-7-Phosphoheptulonate Synthase↗

Enzymatic synthesis of cinnamic acid derivatives.

Using Novozym 435 as catalyst, the syntheses of ethyl ferulate (EF) from ferulic acid (4-hydroxy 3-methoxy cinnamic acid) and ethanol, and octyl methoxycinnamate (OMC) from p-methoxycinnamic acid and 2-ethyl hexanol were successfully carried out in this study. A conversion of 87% was obtained within 2 days at 75 degrees C for the synthesis of EF. For the synthesis of OMC at 80 degrees C, 90% conversion can be obtained within 1 day. The use of solvent and high reaction temperature resulted in better conversion for the synthesis of cinnamic acid derivatives. Some cinnamic acid esters could also be obtained with higher conversion and shorter reaction times in comparison to other methods reported in the literature. The enzyme can be reused several times before significant activity loss was observed.

Acrylic Resins↗

Plant growth inhibition by cis-cinnamoyl glucosides and cis-cinnamic acid.

Spiraea thunbergii Sieb. contains 1-O-cis-cinnamoyl-beta-D-glucopyranose (CG) and 6-O-(4'-hydroxy-2'-methylene-butyroyl)-1-O-cis-cinnamoyl-beta-D-glucopyranose (BCG) as major plant growth inhibiting constituents. In the present study, we determined the inhibitory activity of CG and BCG on root elongation of germinated seedlings of lettuce (Lactuca sativa), pigweed (Amaranthus retroflexus), red clover (Trifolium pratense), timothy (Phleum pratense), and bok choy (Brassica rapa var chinensis) in comparison with that of two well-known growth inhibitors, 2,4-dichlorophenoxyacetic acid (2,4-D) and (+)-2-cis-4-trans-abscisic acid (cis-ABA), as well as two related chemicals of CG and BCG, cis-cinnamic acid (cis-CA) and trans-cinnamic acid (trans-CA). The EC50 values for CG and BCG on lettuce were roughly one-half to one-quarter of the value for cis-ABA. cis-Cinnamic acid, which is a component of CG and BCG, possessed almost the same inhibitory activity of CG and BCG, suggesting that the essential chemical structure responsible for the inhibitory activity of CG and BCG is cis-CA. The cis-stereochemistry of the methylene moiety is apparently needed for high inhibitory activity, as trans-CA had an EC50 value roughly 100 times that of CG, BCG, and cis-CA. Growth inhibition by CG, BCG, and cis-CA was influenced by the nature of the soil in the growing medium: alluvial soil preserved the bioactivity, whereas volcanic ash and calcareous soils inhibited bioactivity. These findings indicate a potential role of cis-CA and its glucosides as allelochemicals for use as plant growth regulators in agricultural fields.

Cinnamates↗

A specific and reversible macromolecular inhibitor of phenylalanine ammonia-lyase and cinnamic acid-4-hydroxylase in gherkins.

A non-dialysable inhibitor of phenylalanine ammonia-lyase (L-phenylalanine ammonia-lyase, EC 4.3.1.5) has been partially purified from dark-grown gherkin hypocotyls. On extraction of tissue it is found both in the soluble (106 000 X g supernatant) and microsomal (106 000 X g pellet) fractions and can be extracted from the microsomal membranes with 10 mM sodium cholate and 1 M KCl. The soluble and microsomal fractions have similar properties, suggesting the presence of the same active component. The inhibitor is small (Mr less than 20 000), thermolabile, sensitive to proteolytic digestion, and apparently hydrophobic. Purification of the inhibitor was achieved by chromatography on DEAE-cellulose by gel filtration on Sephadex G-50. The inhibitor preparations inhibit phenylalanine ammonia-lyase isolated from a number of plant tissues and also cinnamic acid-4-hydroxylase (trans-cinnamate, NADPH:oxygen oxidoreductase (4-hydroxylating), EC 1.14.13.11) from gherkins and peas, but not a wide range of other enzymes. The evidence suggests that inhibition of the two enzymes is due to the same substance, but this has not yet been confirmed. Kinetic experiments show that the inhibitor is competitive with phenylalanine for the lyase and that its association with the lyase is reversible. Further, a mixture of inhibitor and lyase can be separated on non-denaturing polyacrylamide gels without loss of lyase activity. The activities of phenylalanine ammonia-lyase and cinnamic acid 4-hydroxylase are often concurrently regulated and both have regulatory roles in phenol metabolism; it is suggested that the inhibitor may be specifically involved in controlling their activities in vivo.

Ammonia-Lyases↗

Methyl cinnamate derivatives enhance UV-induced mutagenesis due to the inhibition of DNA excision repair in Escherichia coli B/r.

UV-induced mutagenesis in Escherichia coli B/r WP2 was enhanced by certain derivatives of methyl cinnamate which themselves were not mutagenic. Methyl ferulate, methyl isoferulate and methyl sinapate showed this effect markedly. Such an enhancement effect was absent with the derivatives of cinnamic acid and ethyl cinnamate and was not observed in Escherichia coli WP2s uvrA. Methyl sinapate also enhanced 4NQO-induced mutation and suppressed liquid-holding recovery in the above repair-proficient strain. The presence of methyl sinapate in plating agar medium decreased the survival of UV-irradiated cells of a recombination-repair-deficient strain, CM571 recA. However, the effect was not observed with those of WP2s uvrA. In an in vitro experiment in which the removal rate of thymine dimers was measured, methyl sinapate clearly inhibited this repair event. From these results, we conclude that methyl sinapate inhibits DNA excision repair, thus enhancing UV mutagenicity.

Cinnamates↗

Metabolism of trans-cinnamic acid in the rat and the mouse and its variation with dose.

The metabolism of [3-14C/phenyl-2H5] cinnamic acid was investigated in rats and mice at a dose level of 2.5 mmol/kg body weight. Recoveries of the 14C dose were between 92 and 98% with most (82-90%) present in the 0-24 hr urine samples. Urinary metabolites were identified by their chromatographic properties and mass spectra. In both species the major metabolite was hippuric acid, which is also an endogenous urinary component. Several minor metabolites, 3-hydroxy-3-phenylpropionic acid, benzoic acid and benzoyl glucuronide, were found in both species. Two, acetophenone and cinnamoylglycine, the glycine conjugate of cinnamic acid, could be positively identified only in mouse urine. The effect of dose size on the urinary excretion of 14C-cinnamic acid metabolites was studied over the dose range 0.0005 to 2.5 mmol/kg. In the rat the pattern of metabolite excretion was very similar over the whole dose range with slight increases in the proportion of the dose excreted as minor metabolites as dose size increased. In the mouse the excretion of cinnamoylglycine was more important at the lowest dose level and decreased in relative importance as dose size increased. Changes in the other metabolites were similar to those seen in the rat.

Acetophenones↗