Sinapic Acid Esters Research Articles

Characterization of the metabolic fate of sinapic acid in rats.

Sinapic acid (SA) is ubiquitously distributed in the plant kingdom as a free organic acid and more frequently as a biosynthetic pioneer for SA derivatives, e.g., SA esters. Broad biological and pharmacological activities have been disclosed for SA. Because of the metabolism lability property, metabolites instead of the parent compound should be the primary forms after oral treatment of SA, and those metabolites should also be rapidly observed from SA following administration of SA derivative. Hence, the metabolites might provide a primary contribution to the pharmacological properties of SA; however, the metabolite profile remains unclear. Here, our efforts were devoted to addressing this issue through deploying online energy-resolved mass spectrometry (ER-MS) to accomplish isomer identification which is the key issue hindering metabolite identification, notably those conjugated metabolites. After recording breakdown graphs of concerned fragment ions with online ER-MS, the positive correlations between optimal collision energy (OCE) and bond dissociation energy (BDE) were applied to assign candidate structures to isomeric signals. Moreover, in vitro metabolism with liver cellular subfractions, UV-triggered cis-/trans-configuration transformation, and wet-chemistry hydrogenation were carried out to justify the structures. As a result, sixteen metabolites (M1-M16) were found and confirmatively identified in rat plasma and urine following SA administration, and sulfation, glucuronidation, demethylation, reduction, and dihydroxylation served as the primary metabolic channels. Noteworthily, greater distribution occurred for sulfation and glucuronidation products while inferior distributions were observed for phase I metabolites, and the half-life (T1/2) of most metabolites was greater than that of SA. This study provides a comprehensive insight into the metabolic fate of SA. More importantly, the fortification of online ER-MS and quantum structure calculation to the conventional LC-MS program is eligible to achieve unambiguous identification of isomeric metabolites.

Changes in Quality of Cold-Pressed Rapeseed Oil with Sinapic Acid Ester-Gelatin Films during Storage.

In recent years, cold-pressed rapeseed oil (CPRO) has become an attractive health-beneficial product and a promising alternative to olive oil. However, a high level of unsaturated fatty acids renders a CPRO more susceptible to oxidative deterioration. Therefore, the effect of new gelatin strips with polyvinyl alcohol (GEL-PVA) and sinapic acid esters (ethyl sinapate-ESA; octyl sinapate-OSA, and cetyl sinapate-CSA) on the oxidative stability, antioxidant activity (AA), and total phenolic content (TPC) in CPRO samples was analyzed during accelerated storage. In addition, the antioxidant properties of the GEL-PVA films loaded with sinapic acid esters were studied. Interestingly, the CPRO stored in an amber glass marasca bottle containing GEL-PVA-ESA strips for 14 days had the highest AA, while the antioxidant potential was the lowest for oil without film strips. Furthermore, oil samples stored in bottles containing GEL-PVA-ESA and GEL-PVA-OSA strips for 14 days had higher antioxidant properties than the AA and TPC in fresh CPRO. Moreover, synchronous fluorescence (SF) spectroscopy and excitation-emission matrix (EEM) fluorescence spectroscopy were applied for the evaluation of changes in the main fluorescent components in CPRO samples during the accelerated storage. Overall, this study revealed that GEL-PVA films incorporated with sinapic acid esters enhanced the antioxidant potential of CPRO and delayed oxidative degradation by releasing amphiphilic antioxidants into the oil.

Sinapic Acid and Sinapate Esters in Brassica: Innate Accumulation, Biosynthesis, Accessibility via Chemical Synthesis or Recovery From Biomass, and Biological Activities.

Sinapic acid (SinA) and corresponding esters are secondary metabolites abundantly found in plants of Brassica family. Belonging to the family of p-hydroxycinnamic acids, SinA and its esters analogues are present in different plant parts and involved in multiple biological processes in planta. Moreover, these metabolites are also found in relatively large quantities in agro-industrial wastes. Nowadays, these metabolites are increasingly drawing attention due to their bioactivities which include antioxidant, anti-microbial, anti-cancer and UV filtering activities. As a result, these metabolites find applications in pharmaceutical, cosmetic and food industries. In this context, this article reviews innate occurrence, biosynthesis, accessibility via chemical synthesis or direct extraction from agro-industrial wastes. Biological activities of SinA and its main corresponding esters will also be discussed.

Sinapic Acid Esters: Octinoxate Substitutes Combining Suitable UV Protection and Antioxidant Activity.

In 2021, Hawaii will permanently ban the use and sale of octinoxate-based sunscreens as studies have shown serious impacts of such UV filters on the coral reef. This ban, which could be generalized to other countries, highlights the extreme need to offer alternative UV filters that are not only effective in terms of sun protection, but also healthy with regards to human health and the environment. In this context, a wide library of p-hydroxycinnamic esters deriving from naturally occurring sinapic acid has been synthesized using a Knoevenagel–Doebner condensation. The UV filtering activities as well as the antioxidant properties of these sinapic acid esters were then investigated. The results showed promising UVB protection and antioxidant efficacy. A Structure–Activity Relationship (SAR) study on the sinapic acid esters highlighted the need of a free phenol to, as expected, observe antioxidant activity, but also to obtain a higher intensity of protection. Moreover, the nature of the ester moiety also proved to be a key structural feature for the UV absorbance, as higher steric hindrance on the ester moiety leads to more active compounds. The judicious structural design of sinapic esters thus provides promising compounds combining UV protection and antioxidant activity.

Effect of sinapic acid ester derivatives on the oxidative stability of omega-3 fatty acids rich oil-in-water emulsions

Oil-in-water (O/W) emulsions are important delivery systems of omega-3 fatty acids (n-3 FA). We investigated the effect of sinapic acid esters concentration and chain length, the electrical charge of the emulsifier and emulsion pH on the oxidative stability of n-3 FA rich O/W emulsions. Echium oil was applied as n-3 FA source. A 24 factorial design was used to simultaneously evaluate these factors. Peroxide value, malondialdehyde, 2,4-heptadienal and 2,4-decadienal were measured in the emulsions. pH and the electrical charge of the emulsifier modulated the antioxidant effectiveness of sinapic acid esters, while concentration was not relevant. The combination of positively charged emulsifier with neutral pH provided the best oxidative stability for echium oil emulsions. Our results also suggested that the increase of length chain of sinapic acid, from C4 to C12, reduced the secondary products of oxidation, when echium oil emulsions were prepared using negatively charged emulsifier under acidic conditions.

Sinapic Acid and its Derivatives Increase Oxidative Stability in Different Model Lipid Systems

Sinapic acid and its derivatives syringic acid, syringaldehyde, three sinapoyl esters (ethyl, propyl, butyl sinapates), 4‐vinylsyringol, and sinapine are investigated for anti‐radical activity in relation to different free radical species, reaction environments and model systems, and with special emphasis on lipid peroxidation in different lipid systems: as an emulsion, bulk oil, oleogel and liposome suspension. Syringic acid and sinapic acid show the highest DPPH• and O2•− scavenging activities, whereas for the •OH‐scavenging the highest activities are for ethyl sinapate, propyl sinapate, and sinapine. While sinapic acid esters have the highest activities in the emulsion and liposome suspension, in bulk oil, the more polar sinapic acid, syringic acid, and syringaldehyde show the greatest inhibition of lipid peroxidation. In oleogel‐based system a noted increase in the activity of less polar compounds, especially 4‐vinylsyringol and butyl sinapate is recorded, while the level of inhibition for the more polar sinapic acid, syringic acid, and syringaldehyde remain unchanged, compared to the bulk oil. In oleogel the potential interactions of these less polar compounds with the oil structuring agent might be an additional factor that influences their inhibitory actions.Practical Applications: This study examines the potential for the application of sinapic acid and its derivatives for inhibition of lipid peroxidation, using different lipid systems as models for real food matrices. The study shows how modifications to the naturally occurring compound sinapic acid can affect its activity, and which of these modifications would be appropriate for each lipid system. It is also shown that contrary to the polar paradox, the influence of lipophilic antioxidants on the oxidative stability of oleogel‐based products might be due to their interactions with the oleogelation agents, which will thus further stabilize the oleogels. In addition to their antioxidant actions, this would open new possibilities for the application of lipophilic antioxidants to oil‐based products.While sinapic acid esters [ethyl sinapate (SE), propyl sinapate (SP), butyl sinapate (SB)] have the highest activities in the emulsion and liposome suspension, in bulk oil, the more polar sinapic acid (SA), syringic acid (SY), and syringaldehyde (SYA) show the greatest inhibition of lipid peroxidation. The increase in lipophilicity in sinapic acid by esterification and decarboxylation [4‐vinylsyringol (VS)] results in increased antioxidant activity in oleogel, compared to bulk oil, which is contradictory to polar paradox. This indicates interference in the oil structuring by the more lipophilic compounds.

Inhibition of copper-induced lipid peroxidation by sinapic acid and its derivatives in correlation to their effect on the membrane structural properties

The efficiencies of sinapic acid and its derivatives syringic acid, syringaldehyde, three sinapoyl esters (ethyl, propyl, butyl sinapates), 4-vinylsyringol and sinapine were investigated for prevention of lipid peroxidation in correlation with their interactions with model lipid membrane systems. Significant antioxidant activities of propyl and butyl sinapates were seen by fluorimetric assay in phosphatidylcholine liposomes as model membrane using C11-BODIPY581/591 lipophilic fluorescent probe. The sinapic acid esters also had the highest impact on membrane structural properties, as observed by differential scanning calorimetry and fluorescence polarisation measurements. The greatest protection of phospholipids from peroxidation by these esters correlated well with their polarity and insertion into the lipid bilayer.

Sinapic acid or its derivatives interfere with abscisic acid homeostasis during Arabidopsis thaliana seed germination

BackgroundSinapic acid and its esters have broad functions in different stages of seed germination and plant development and are thought to play a role in protecting against ultraviolet irradiation. To better understand the interactions between sinapic acid esters and seed germination processes in response to various stresses, we analyzed the role of the plant hormone abscisic acid (ABA) in the regulation of sinapic acid esters involved in seed germination and early seedling growth.ResultsWe found that exogenous sinapic acid promotes seed germination in a dose-dependent manner in Arabidopsis thaliana. High-performance liquid chromatography mass spectrometry analysis showed that exogenous sinapic acid increased the sinapoylcholine content of imbibed seeds. Furthermore, sinapic acid affected ABA catabolism, resulting in reduced ABA levels and increased levels of the ABA-glucose ester. Using mutants deficient in the synthesis of sinapate esters, we showed that the germination of mutant sinapoylglucose accumulator 2 (sng2) and bright trichomes 1 (brt1) seeds was more sensitive to ABA than the wild-type. Moreover, Arabidopsis mutants deficient in either abscisic acid deficient 2 (ABA2) or abscisic acid insensitive 3 (ABI3) displayed increased expression of the sinapoylglucose:choline sinapoyltransferase (SCT) and sinapoylcholine esterase (SCE) genes with sinapic acid treatment. This treatment also affected the accumulation of sinapoylcholine and free choline during seed germination.ConclusionsWe demonstrated that sinapoylcholine, which constitutes the major phenolic component in seeds among various minor sinapate esters, affected ABA homeostasis during seed germination and early seedling growth in Arabidopsis. Our findings provide insights into the role of sinapic acid and its esters in regulating ABA-mediated inhibition of Arabidopsis seed germination in response to drought stress.

Pollen Genotype Effects on Seed Quality Traits in Winter Oilseed Rape

ABSTRACTThe genetics of seed compounds is complex because seed quality traits might be exclusively determined by the genotype of the female parent or, depending on the genotype of the embryo, may also be affected by the genotype of the pollen parent. For many quality traits of oilseed rape (Brassica napus L.), the influence of the pollen parent is not well known. In this study, two male sterile lines (female parent) were pollinated by 10 genotypes (pollen parent) differing largely in seed quality. Field experiments were conducted at three locations in Northern Germany, with two replications in 1 yr. Pollen parents were sown in plots and 10 male sterile plants from each female parent were hand planted into the center of each plot. Seeds were harvested from pollen parents and from the interplanted female parents. Seeds were analyzed for oil, protein, and sinapic acid esters by near‐infrared reflectance spectroscopy; for glucosinolate and tocopherol content by high‐performance liquid chromatography; and for fatty acid content by gas liquid chromatography. Earlier results were confirmed in that fatty acid composition is dependent on the embryo genotype and is therefore largely influenced by the pollen parent. Significant pollen parent effects were also observed for oil content, indole glucosinolate, sinapoylglucose, total sinapic acid ester, and γ‐tocopherol contents. The F1 seed quality was positively correlated with the pollen parent seed quality. In conclusion, not only the fatty acid composition but also other seed quality traits such as oil content are influenced by the genotype of the pollen parent. This should be considered when analyzing open pollinated plants.

Nitrate Reductase- and Nitric Oxide-Dependent Activation of Sinapoylglucose:malate sinapoyltransferase in Leaves of Arabidopsis thaliana

Nitrate reductase (NR) activity is necessary for the synthesis of nitric oxide (NO), a key signaling molecule in plants. Here, we investigated the effect of NR deficiency on NO production and phenylpropanoid metabolism of Arabidopsis thaliana leaves. HPLC-mass spectrometry analysis showed that the NR double mutant (nia1 nia2) is deficient in the synthesis of sinapoylmalate (SM), the main phenylpropanoid end-product in wild-type leaves, resulting in accumulation of its precursor sinapoylglucose (SG). While real-time PCR analysis revealed no significant difference at the transcript level, sinapoylglucose:malate sinapoyltransferase (SMT) activity in leaf extracts was reduced in the mutant compared with the wild type. The low levels of SM in nia1 nia2 leaves do not result from the deficient nitrogen incorporation into amino acids, since the recovery of the amino acid content of nia1 nia2 by irrigating the plants with glutamine did not change the metabolic profile of this mutant. In contrast, an increased supply of nitrate stimulated NR activity and NO production, and enhanced SM and decreased SG levels in both genotypes. Nevertheless, sinapic acid esters in nia1 nia2 were not recovered when compared with those detected in the leaves of the wild-type plant. Mutant plants grown in medium supplemented with malate and an NO donor recovered SM to the levels of wild-type leaves. Overall, the results suggest that SMT activity is dependent on the NR-dependent steady-state levels of NO during plant development.

Sinapic acid derivatives in defatted Oriental mustard (Brassica juncea L.) seed meal extracts using UHPLC-DAD-ESI-MS n and identification of compounds with antibacterial activity

This study identified phenolic compounds from mustard seed meal and characterized their antibacterial activity. Phenolic compounds were extracted from defatted Oriental mustard (Brassica juncea L.) seed meal and characterized using ultra-high-performance liquid chromatography with diode array and electrospray ionization-mass spectrometric detection (UHPLC-DAD-ESI-MS n ). Sinapic acid and several sinapoyl conjugates were identified based on retention time, UV spectra, MS fragmentation pattern, and by comparison with the authentic sinapic acid reference substance. The crude extract and a purified phenolic fraction exhibited selective antibacterial effects against Gram-negative and Gram-positive spoilage bacteria including Staphylococcus aureus and Listeria monocytogenes; Lactobacillus plantarum was resistant. After alkaline hydrolysis, only sinapic acid could be detected, enabling quantification with the authentic reference substance. Alkaline hydrolysis released 2.66 ± 0.00 mg sinapic acid g−1 dry matter defatted mustard seed meal. Minimum inhibitory concentrations of the hydrolyzed extract against Bacillus subtilis, Escherichia coli, L. monocytogenes, Pseudomonas fluorescens, and S. aureus were 0.1 g L−1 or less. Growth of L. plantarum remained unaffected. Sinapic acid and sinapoyl esters are generally found in members of the Brassicaceae family. Methods for their fast identification will be useful in chemotaxonomic studies. The release of sinapic acid after alkaline hydrolysis not only allows for the quantification using the reference substances but also facilitates the standardization of the antibacterial activity of plant extracts for use as food preservative.

Effect of sowing time on grain yield, oil content, and fatty acids in rapeseed (Brassica napus subsp. oleifera)

Sowing time is an important factor affecting crop yield and quality, especially in arid and semi-arid regions. The aim of this research was to investigate the effects of sowing time on the growth, yield, and quality of rapeseed genotypes and to determine genotype × sowing time interactions for grain yield and its related traits. The study was carried out using 8 winter rapeseed genotypes (H604049, H604038, H604041, Viking, Elan, Titan, Lorenz, and Trabant) and 4 sowing times (10 October, 20 October, 30 October and 10 November) during the 2005-2006 and 2006-2007 growing seasons. An NIRS system was used to determine oil, protein, glucosinolate and sinapic acid esters. Fatty acid analyses were done by the capillary gas chromatography method. Significant differences were found between sowing times for most of the traits measured. The lowest average seed yield (1027.40 kg ha^{-1}) was obtained from the latest sowing time, whereas the highest average seed yield (2437.50 kg ha^{-1}) was obtained from the earliest sowing time. The genotype H604038 produced the highest seed yield (1988.4 kg ha^{-1}), and it was followed by Trabant (1980.8 kg ha^{-1}) and Titan (1963.8 kg ha^{-1}). The highest oil content, at 42.0%, was obtained from genotype Lorenz at the first sowing time and from genotype Trabant at the second sowing time. No interaction was found between genotype and sowing time for oil content, but significant interactions were found for seed yield and glucosinolates. Seed yield significantly decreased as sowing time was delayed. The effects of sowing time on fatty acid composition were also significant. As a result, it was found that sowing time is an important factor for seed yield and quality in rapeseed.

Analysis of the metabolome and transcriptome of Brassica carinata seedlings after lithium chloride exposure

Exposure of B. carinata seedlings to increasing concentrations of a non-physiological ion, lithium, showed significant effects on the germination rate, root length, chlorophyll content and fresh weight in brown-seeded and yellow-seeded near-isogenic lines. Metal content analysis and phytochemical profiling indicated that lithium hyper-accumulated and the lipid and phenolic composition dramatically changed in brown-seeded seedlings. Here, sinapic acid esters and chloroplast lipid were replaced by benzoate derivatives, resveratrol and oxylipins after lithium exposure. In contrast, the yellow-seeded plants maintained the same phenolic and lipid composition before and after exposure to lithium and did not tolerate the high metal concentrations tolerated by the brown-seeded line. Microarray analysis using a Brassica napus 15,000 expressed sequence tag (EST) array indicated a total of 89 genes in the brown-seeded line and 95 genes in the yellow-seeded line were differentially expressed more than 20-fold after treatment of B. carinata seedlings with lithium chloride and more than 1083 genes with expression changes greater than 2-fold. The putative functions of the differentially expressed genes included proteins involved in defense, primary metabolism, transcription, transportation, secondary metabolism, cytochrome P450, as well as proteins with unknown functions. Transcriptome changes between yellow-seeded and brown-seeded B. carinata seedlings after lithium chloride exposure indicated that the two lines responded differently to lithium treatment. The expression patterns generally supported the phytochemical data. From the results of this study, B. carinata brown-seeded germplasm showed an ability to survive under moderately high concentrations of lithium chloride (>150 mM). The ability to accumulate this metal ion suggests brown-seeded B. carinata has some potential in phytoremediation of lithium-contaminated water and soil.

Differential expression of four Arabidopsis PAL genes; PAL1 and PAL2 have functional specialization in abiotic environmental-triggered flavonoid synthesis

Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) catalyzes the first step in the phenylpropanoid pathway, and is considered an important regulation point between primary and secondary metabolism. In the present work we analyzed expression of the PAL genes in leaves of Arabidopsis thaliana rosette-stage plants in response to nitrogen depletion at temperatures ranging from 5 to 30 degrees C. Only PAL1 and PAL2 responded strongly to both environmental factors, nitrogen and temperature. Regardless of nitrogen treatments, PAL1 and 2 transcript levels increased at 5 and 10 degrees C. Averaged across all temperatures, nitrogen depletion led to a two-fold increase in PAL1 and PAL2 transcripts. PAL activity was correlated with PAL transcript levels (R=0.94). Accumulation of major soluble phenylpropanoids, sinapic acid esters and flavonoids, increased in response to lowering temperature. The flavonoids, kaempferols, quercetins and anthocyanins, showed significantly increased levels as a result of nitrogen depletion (two-, five- and six-fold increases, respectively) when averaged across all temperatures. PAL1, PAL2 and PAL4 have previously been shown to be related with tissue-specific lignin synthesis, and the present work shows that PAL1 and PAL2 also have functional specialization in abiotic environmental-triggered flavonoid synthesis.

Nitrogen and fungicide applications against Erysiphe cruciferarum affect quality components of oilseed rape

Oilseed rape (Brassica napus L.) is one of the most important oilseed crops in temperate climates. Erysiphe cruciferarum is an important disease of oilseed rape and causes crop loss in warmer areas of Europe. The research investigated the effect of nitrogen fertilizer and fungicidal treatment against powdery mildew infection caused by E. cruciferarum of oilseed rape on seed components, including protein, oil, oleic acid, linolenic acid and undesirable substances such as sinapic acid esters (SAE) and glucosinolates (GSL), using near infrared spectroscopy (NIRS). Five susceptible oilseed rape varieties were employed in this research using four treatment groups: no nitrogen fertilization and no fungicidal treatment (N(0)-F(0)); no nitrogen fertilization but fungicidal treatment (N(0)-F(1)); and nitrogen fertilization but no fungicidal treatment (N(1)-F(0)); nitrogen fertilization and fungicidal treatment (N(1)-F(1)). Nitrogen fertilization increased the protein, but lowered the oil content, of the seeds. Fungicidal treatments significantly increased oil contents in all varieties tested, however reduced protein levels in fertilized and non-fertilized plots. The level of linolenic acid did not change significantly in any plots of any treatment combinations; a similar result was observed in the level of oleic acid in most of the genotypes. Nitrogen fertilization increased GSL and SAE levels, whereas fungicidal treatment had no effect. Our findings demonstrated that nitrogen fertilization can markedly influence some quality parameters in oilseed rape; however, the application of fungicides reduced side effects of nitrogen fertilizer and resulted a reduction on GSL, SAE and protein contents but an increase on total oil and oleic acid contents.

Chemical structure of flavonoid compounds in wheat ( Triticum aestivum L.) flour that contribute to the yellow colour of Asian alkaline noodles

Colour is an important criterion of quality in Asian noodles prepared from bread-wheat flour and ranges from white to cream for white salted noodles to a bright yellow for alkaline noodles. A high-performance liquid chromatographic protocol for the analysis of naturally occurring flavonoids and related phenolic compounds in wheat was developed to identify the compounds responsible for the yellow colour of alkaline noodles. The separation system consisted of a C18 reversed-phase column and a gradient system of water/formic acid (99:1,v/v) (A) and methanol/acetonitrile/formic acid (95:4:1,v/v/v) (B). A post column derivatisation technique was employed to identify the compounds that turned yellow at alkaline pH. A comparison of the HPLC profiles of water, alkaline water and hydroxylamine soluble fractions revealed that the level of compounds contributing to yellow alkaline noodle colour was highest in the hydroxylamine extract. Two flavonoid apigenin- C-diglycosides and their Wessely–Moser isomers, together with their sinapic acid esters, were isolated and identified by absorbance spectroscopy, ES-MS spectrometry and 13C NMR. These flavone- C-diglycosides were found to be the major components responsible for the alkali-induced change in noodle colour and are relatively stable at ambient temperature. Furthermore the compounds are located only in the germ (embryo+scutellum tissue) of wheat grains and hence their presence in flour must represent a redistribution during the milling process.

Maintenance of the plant genome under natural light

Solar UV interacts with and alters a number of cellular components. Among these, DNA is perhaps the most critical and irreplaceable target. The majority of UV-induced damage takes the form of pyrimidine dimers. These lesions act both as blocks to the progression of both replicative DNA polymerases and the RNA polymerase holoenzyme. Expression of dimer bypass DNA polymerases may also lead to permanent changes (mutations) in DNA sequence, by inserting potentially incorrect bases opposite the lesion. Thus the excision or reversal of UV-induced damage is important both in the soma, as it is required for the maintenance of gene expression, and in the germline, where error-free repair pathways maintain genomic integrity. The basic mechanisms of photoreactivation and excision repair of UV-induced dimers are well understood in plants, although we would like to learn more about the tissue-specificity and environmental regulation of these important UV-protective mechanisms. Field experiments suggest that repair of UV-induced dimers is not essential to the survival of Arabidopsis plants, nor is the expression of the sinapic acid esters that act as natural sunscreens. However, plants that are defective in both repair and sunscreen production die within hours of exposure to natural light. Progression through the cell cycle in the presence of unrepaired DNA damage products leads to a progressive deterioration of the genome. During S phase, persisting lesions are either miscopied or produce daughter strand gaps opposite dimers, which are difficult to repair in an error-free manner. For this reason, cells respond to persisting DNA damage by arresting the cell cycle in order to provide time prior to the initiation of S phase (G1/S arrest), the continuation of S phase (intra-S arrest) or progression into M (G2/M arrest). These DNA damage-induced cell cycle checkpoints are now being characterized in plants. Given the homologies between plant and mammalian damage checkpoint genes, it is likely that many aspects of cell cycle regulation by UV-induced damage are shared between plants and animals. One UV-induced mammalian response to persisting DNA damage is the induction of programmed cell death. This actively induced apoptosis and necrosis of damaged cells leads to the inflammation observed in sunburn. The induction of cell death has two beneficial effects: the resulting bursts of radicals are thought to further stimulate the repair response of neighboring cells, and the suicide of damaged cells precludes their possible progression into cancer. Plant cells can also be killed by very high doses of UV light, in what might be a programmed response (as the genomic laddering characteristic of programmed cell death occurs), but it is not clear that such a response occurs under natural light. Given plants natural resistance to the lethal effects of cancer, it is possible that plants differ from mammals in this aspect of UV-response, and lack a sensitive apoptotic response to DNA damage.

Production of a Laccase and Decrease of the Phenolic Content in Canola Meal during the Growth of the Fungus Pleurotus ostreatus in Solid State Fermentation Processes

AbstractSolid state fermentation of canola meal was carried out with the fungus Pleurotus ostreatus DAOM 197961, which is a producer of laccase. The aim of this study was to examine the effects of moisture content, inoculum size, homogenisation of inoculum and particle size of canola meal on the growth of the fungus, the production of a laccase and the decrease of the content of sinapic acid esters (SAE) in a solid state process. The results showed that the optimum moisture content, which was varied in the media between 50% and 75%, for the growth and enzyme production was 60%. The initial rate of SAE content decrease was faster in the media with 70% and 75% moisture than in those with lower moisture levels. In the study of the effects of inoculum concentration in the range of 1.1 mg to 5.5 mg/g of the medium, it was found that larger amounts of biomass and enzyme were produced in the media with inoculum concentrations from 1.1 mg to 3.3 mg/g of the medium than in the media with a higher inoculum concentration. The final and approximately the same concentrations of SAE were reached at the same time regardless of the inoculum concentration. Considering that the fungus formed pellets under the conditions at which it was grown during the inoculum preparation, it was necessary to break them by homogenisation prior to their utilisation as an inoculum. The homogenisation was carried out during a period between 15s and 200s. Although higher biomass concentrations and enzyme activities were obtained in the media which were inoculated with the inoculum homogenised for 15s and 30s, the maximum enzyme activities and biomass concentrations were reached in the media inoculated with the inoculum, which was homogenised for 120s and 200s. The time of inoculum homogenisation did not influence the kinetics of the SAE decrease. When the effects of the particle size of canola meal on the process were studied, it was found that larger particles of the meal in the solid media were more favourable for the production of the biomass and enzyme, and for a faster decrease of the SAE content than those of smaller sizes. From the obtained results it can be concluded that the tested variables have a significant influence on the growth of the fungus Pleurotus ostreatus DAOM 197961, the production of laccase and the decrease of the SAE content in canola meal. The data could be useful for the development of a solid state process for the production of laccase and for the decrease of the phenolics content in canola meal.

Nucleotide Sequence Variation at Two Genes of the Phenylpropanoid Pathway, the FAH1 and F3H Genes, in Arabidopsis thaliana

The FAH1 and F3H genes encode ferulate-5-hydroxylase and flavanone-3-hydroxylase, which are enzymes in the pathways leading to the synthesis of sinapic acid esters and flavonoids, respectively. Nucleotide variation at these genes was surveyed by sequencing a sample of 20 worldwide Arabidopsis thaliana ecotypes and one Arabidopsis lyrata spp. petraea stock. In contrast with most previously studied genes, the percentage of singletons was rather low in both the FAH1 and the F3H gene regions. There was, therefore, no footprint of a recent species expansion in the pattern of nucleotide variation in these regions. In both FAH1 and F3H, nucleotide variation was structured into two major highly differentiated haplotypes. In both genes, there was a peak of silent polymorphism in the 5' part of the coding region without a parallel increase in silent divergence. In FAH1, the peak was centered at the beginning of the second exon. In F3H, nucleotide diversity was highest at the beginning of the gene. The observed pattern of variation in both FAH1 and F3H, although suggestive of balancing selection, was compatible with a neutral model with no recombination.

A method for the decrease of phenolic content in commercial canola meal using an enzyme preparation secreted by the white-rot fungus Trametes versicolor.

An enzymatic process for upgrading the quality of canola meal (CM) by decreasing its phenolic content was investigated. The new method was based on the addition of the enzyme preparation from white-rot fungus Trametes versicolor to the meal-buffer slurry. A 98% decrease in the concentration of SAE was observed after 1 h of the treatment. The following process variables were considered for optimizing the process: pH, temperature, enzyme, meal, and oxygen concentrations. It was found that: (1) the natural buffering capacity of CM resulted in a negligible effect of the pH of the buffer, which was used as the continuous phase in the process, on the extent of decrease in sinapic acid esters (SAE); (2) the system was saturated with the enzyme when its concentration was 4 nkat/mL of the continuous phase; and (3) the optimum temperature was 50 degrees C. The process could be carried out even at higher temperatures due to the protective action of CM, which resulted in an increase in the thermal stability of the enzyme. The particle size influenced the extraction of the SAE from the meal, indicating that, at lower SAE concentrations, the process became diffusion limited. This result, together with those showing no effect of the intensity of agitation, indicated that the enzymatic process can be characterized by high Biot numbers. During the enzymatic process, the molar concentration of available oxygen can become a limiting factor when it is more than four times lower than the molar concentration of phenolics in the treated meal. The new enzymatic method was compared with other methods reported in the literature for the decrease in the phenolic content of rapeseed meals. It was found that, among the methods tested, the enzymatic treatment was the most effective, followed by the lime treatment. The enzymatic process did not reduce the quality of the protein isolates prepared from the CM. After the addition of a simple acetone-washing step, the isolate from the enzymatically treated meal had even better properties. Copyright 1999 John Wiley & Sons, Inc.