P-coumaric Acid Content Research Articles

Biochemical Parameters as Biomarkers for the Early Recognition of Environmental Pollution in Scots Pine Trees. I. Phenolic Compounds

Abstract Pinus sylvestrish., Catechin, Ferulic Acid, p-Coumaric Acid, Picein Within a series of regular projects investigating the suitability of biochemical parameters as biomarkers for the early recognition of environmental pollution, the levels of selected phenolic compounds were determined in Scots pine needles (Pinus sylvestris L.) from young and adult trees at three field sites with different SO2 pollution (Rösa>Taura>Neuglobsow). Young trees showed no differences in the levels of soluble phenolics in case of increasing loads of SO2, whereas the concentration of the soluble phenolic component catechin in previous needles of adult trees altered significantly. In current year’ needles, differences were only found in the presence of high SO2 deposition. In contrast to catechin, picein and total phenolics remained unaffected. The concentration of catechin in the previous year’s needles of adult trees correlated positively with needle necroses. The phenolic components of the cell walls of pine needles were also analysed. The main phenolic compounds were identified as p-coumaric acid and ferulic acid. Differences in the levels of p-coumaric acid were detected in the needles of adult trees between the three sites, with the highest levels being measured at the site with the lowest pollution (Neuglobsow). However, changes in the p-coumaric acid content in young trees were low. No site-related differences were found regarding ferulic acid in adult and young pines. The findings are discussed and compared with data reported in the literature.

Thermal decomposition of α-tetralyl hydroperoxide in the presence of the phenylpropionic acids

The thermal decomposition of cinnamic, p-coumaric, ferulic and sinapic acids has been investigated by employing TG/DTG/DTA methods in the temperature range at ambient to 500°C in a self-generated atmosphere. It established high thermal stability of the investigated acids. The presence of two methoxy groups in the structure increases the thermal stability of sinapic acid. The thermal decomposition of α-tetralyl hydroperoxide (THPO) in the presence of phenylpropionic acids has been investigated under nonisothermal conditions. p-Coumaric acid inhibited THPO thermal decomposition in the system containing 0.006, 0.018 mM acid and 0.427 mM THPO. The increased content of p-coumaric acid (0.049 and 0.06 mM) in the reaction system leads to rapid reaction with tetralylperoxy radicals and the formation of THPO. Cinnamic acid interacts with THPO radicals and suppresses hydroperoxide free-radical-induced decomposition. Participation of cinnamic acid is not registered in the chain–transfer reaction leading to THPO formation (investigated systems – 0.427 mM THPO and 0.006–0.06 mM cinnamic acid). Ferulic acid inhibits THPO thermal decomposition in all the mol proportions studied (THPO: ferulic acid 1: 0.012 to 0.180). Ferulic acid is regenerated as a result of the interaction between ferulic radicals and THPO. Low concentrations of sinapic acid inhibit THPO decomposition.

Biomass of Tomato Seedlings Exposed to an Allelopathic Phenolic Acid and Enriched Atmospheric Carbon Dioxide

Increased atmospheric CO2 can affect plant growth, so competition among plants may be influenced. Allelopathy is one mechanism involved in plant competition. Experiments were conducted in a controlled-environment chamber to determine if the concentration of atmospheric CO2 altered the dose-response relationship between an allelopathic phenolic acid and tomato seedling biomass. Seeds of Lycopersicon lycopersicum were planted in quartz sand in styrofoam cups and allowed to germinate and grow for 15–17 days. During the next 14 days, seedlings were watered twice daily with nutrient solution amended with p-coumaric acid (4-hydroxycinnamic acid, HOC6H4CH = CHCO2H; ranging 0–0.85 mg mL-1; 5 concentrations in each experiment) and exposed 24 hr day-1 in continuous-stirred tank reactors (CSTRs) to ambient air (335–375 ppm CO2) or ambient air to which 350 ppm CO2 was added (i.e., approximately twice-ambient CO2; two CSTRs per CO2 concentration in each experiment). Dose-response data relating p-coumaric acid concentration and shoot, root, and total biomass were fit to a flexible decay function. In all three experiments, twice-ambient CO2 significantly increased the y-intercept for the dose-response model for the p-coumaric acid effect on shoot biomass by 25–50% but had negligible effects on other aspects of the models. Results suggest that if CO2 affects plant competition, mechanisms involving allelopathic phenolic acids may not be involved.

In-situ disappearance and content of p-coumaric and ferulic acid in lucerne from various vegetative stages

Content of monomeric p-coumaric (PCA) and ferulic (FA) acid was determined by HPLC either in the bud stage lucerne sample after its incubation in the rumen (0, 2, 4, 8, 16, 24, 48 h) by the in-situ method (three steers equipped with rumen cannulas, fed near the maintenance level of nutrition), or in the lucerne samples cut in ten consecutive vegetative stages. PCA and FA were analysed in four lucerne fractions based on methanol extraction: free phenolic acids (F1) extracted into ether from the methanol extract, ester-bonded phenolic acids (F2) after alkaline hydrolysis of the methanol extract, glycoside-bonded phenolic acids (F4) after acid hydrolysis of the extract, and cell wall-bonded phenolic acids (F3) after alkaline hydrolysis of the solid residue after the extraction. 95% and 98% of the total content of PCA and FA, respectively, disappeared in the rumen within the 5h interval. Total content of PCA and FA ( Y) decreased linearly with increasing maturity (vegetative stage quantified by the mean stage by weight number, MSW, X): Y = 82.3 − 9.80 X ( r 2 = 68%, P < 0.01) and Y = 97.8 − 6.53 X ( r 2 = 41%, P < 0.05), respectively. However, PCA and FA content increased significantly ( P < 0.01) to 67 and 120mg 100g −1 of dry matter, respectively, in the bud stage (MSW = 3.5). Content of the PCA fraction bound to cell wall was correlated with lucerne organic matter degradability ( r 2 = 66%, P < 0.01), this relationship was not significant in the case of FA ( r 2 = 17%, P > 0.05).

Characterisation of Lignin from CAD and OMT DeficientBm Mutants of Maize

Internodes of the maize cell line W401 and bm 1 and bm 3 mutants expressed in W401 were harvested 5 days after anthesis (A5) and at silage (S) stage. The normal maize had a higher total phenolic (TP) content (80.5-90.5 g kg -1 cell wall DM) than both bm 1 and bm 3 mutants (74.4-86.4 and 66.0-84.2 g kg -1 cell wall DM, respectively). TP were inversely related to cellulase digestibility with values of 85.4-91.5, 89.3-92. and 91.3-94.1% for normal, bm 1 and bm 3 . Marked differences in p-coumaric acid concentrations were found ranging from 20.9 to 26.3 g kg -1 cell wall DM for normal, 14.9 to 15.3 g kg -1 for bm 1 to 10.1 to 14.4 g kg -1 for bm 3 . The ferulate pattern was entirely different with the bm 1 genotype providing the lowest tota1 (9.1-10.7 g kg -1 ) and etherified (1.9-2.3 g kg -1 ) values. Although the bm 3 contained more total ferulate (11.5-13.1 vs 10.9-11.7 g kg -1 ), the normal variety had a significantly greater amount of etherified ferulate (2.8-3.4 vs 3.2-4.1 g kg -1 ) implying a greater extent of cross-linking between wall polymers. Recovery of guaiacyl and syringyl residues was greatest in the normal maize with the bm 1 occupying the middle position between the two extremes. Calculated S: G ratios from 4 M NaOH digestion and NMR were in good agreement with the normal line giving the highest ratio, bm 1 intermediate and bm 3 the lowest. Colorimetric analysis revealed a large increase in the aldehyde content of the in situ bm 1 lignin compared to normal and bm 3 genotypes although NMR failed to reveal significant numbers of aldehydic resonances.

Characterisation of Lignin from Parenchyma and Sclerenchyma Cell Walls of the Maize Internode

Internodes of maize (Zea mays L, Co125), harvested 5 days after anthesis, were sectioned into five equal parts and samples of sclerenchyma and parenchyma cells mechanically isolated from each section. Phenolic acids and syringyl and guaiacyl degradation products of lignin were released from the walls of the two cell types by microwave digestion with 4 M NaOH. Aryl ether bonded units were selectively released by thioacidolysis. Total phenolic content of cell walls from the youngest (basal) sections were approximately two-thirds of those of the oldest, topmost sections (parenchyma 70·8–99·0 and sclerenchyma 72·5–114·1 mg g-1) indicating that the process of lignification was already well advanced amongst most of the cell walls of the youngest section. The total phenolic content was marginally, but significantly, greater (P<0·05) in sclerenchyma walls than in parenchyma walls at all stages of maturity. There was no significant difference in phenolic acid concentrations between cell types from the same section but p-coumaric acid concentration increased with maturity (P<0·001) in walls from both cell types. The increase in p-coumarate with age was matched by an increased recovery of syringyl units resulting in a constant coumaroyl: syringyl molar ratio. Recovery of acetosyringone was significantly greater (P<0·001) from sclerenchyma than parenchyma walls and, in sclerenchyma, acetosyringone as a proportion of total syringyl recovery, increased significantly with age (P=0·015). Digestion with NaOH and thioacidolysis released comparable amounts of guaiacyl residues but NaOH digestion released approximately twice the amount of syringyl residues. This difference may be explained by the retention of the ester-bond between p-coumaric acid and syringyl units during thioacidolysis but not during digestion with 4 M alkali. The similarity in phenolic composition suggested that both cell types, despite their considerable anatomical differences, were exposed to a common flux of lignin precursors during the later stages of lignification as illustrated by the internode sections. Differences between cell walls arose because of differences in the regiochemistry of precursor incorporation. © 1997 SCI.

Tiller Development Influences Seasonal Change in Cell Wall Digestibility of Big Bluestem(Andropogon gerardii)

The productivity of cool-season forage grasses declines during mid-summer in the southern corn belt of the USA. Warm-season grasses are productive during this time, but their digestibility decreases from spring to summer. The objective of this study was to investigate cell wall factors contributing to the decline in in vitro dry matter digestibility (IVDMD) of big bluestem (Andropogon gerardii Vitman) leaf blades from late spring (May) to mid-summer (July) under three harvest regimens. Under frequent defoliation, decrease in cell wall digestibility accounted for much of the change in IVDMD. Among cell wall constituents, only xylose and alkali-labile phenolic acids increased significantly from spring to summer. Change in p-coumaric acid content and the ratio of p-coumaric acid to ferulic acid were both negatively correlated with the decrease in cell wall digestibility. While glucose and uronic acid digestibility decreased from spring to summer, xylose was consistently the least digestible of the cell wall monomers. In warm-season grasses grown under constant environments, tiller development causes an increase in leaf structural tissue, and the data suggest that the seasonal decline in leaf blade cell wall digestibility was partially due to tiller development.

Mechanism by which noninhibitory concentrations of glucose increase inhibitory activity ofp-coumaric acid on morning-glory seedling biomass accumulation

Noninhibitory levels of glucose-C [≤ 72 µg carbon (C)/g soil] increased the inhibitory activity ofp-coumaric acid on morning-glory seedling biomass accumulation in Cecil Bt-horizon soil. The amount ofp-coumaric acid required for a given level of inhibition of shoot and seedling biomass accumulation decreased as the concentration of glucose increased. Soil extractions with neutral EDTA (0.25 M, pH 7) after addition of combinations ofp-coumaric acid and glucose (concentrations ranging from 0 to 1.25 µmol/g soil) to the soil showed that utilization ofp-coumaric acid by microbes decreased linearly as the concentration of glucose increased. The increased inhibitory activity of a given concentration ofp-coumaric acid in the presence of glucose was not due to a reduction in soil sorption ofp-coumaric acid or effects of nitrogen-limited microbial growth. Noninhibitory levels of phenylalanine andp-hydroxybenzoic acid slowed the utilization ofp-coumaric acid by microbes in a similar manner as glucose. The presence of methionine, however, did not affect the rate ofp-coumaric acid utilization by microbes. These observations suggest that differential utilization of individual molecules in organic mixtures by soil microbes can modify, and in this case increase, the effectiveness of a given concentration of an inhibitor such asp-coumaric acid on the inhibition of seedling growth such as morning-glory.

Phenolic acid and condensed tannin concentrations of six cotton genotypes

Phenolic acids and condensed tannins have been implicated in plant resistance to insects and diseases. The objective of this study was to determine phenolic acid and condensed tannin concentrations in six cotton ( Gossypium hirsutum L.) genotypes that display varying degrees of spider mite [ Tetranychus urticae (Koch)] resistance. Since phenolic acids are precursors for condensed tannins in the shikimate pathway, the levels of these compounds should be positively correlated. Leaf blades from whole cotton plants grown in a controlled environment were analyzed using HPLC techniques at two growth stages (pinhead-square and first-bloom) for concentrations of 13 tentatively identified phenolic acids, while condensed tannin concentrations were determined spectrophotometrically from extracts of the topmost unfolded leaf and the fourth mainstem leaf from the terminal. Caffeic, p-coumaric and salicylic acids occurred at high concentrations relative to the other phenolic acids. Gallic, gentisic, protocatechuic, benzoic and ferulic acids occurred at intermediate concentrations; p-hydroxybenzoic, vanillic, syringic, sinapic and cinnamic acids occurred at low concentrations. Genotypes that exhibited higher levels of condensed tannins also had significantly higher levels of total phenolic acids, syringic acid and p-coumaric acid concentrations. Additionally caffeic, p-hydroxybenzoic, syringic, p-coumaric and benzoic acids and total phenolic acids were highly correlated with condensed tannin concentrations. Phenolic acid concentrations decreased, while condensed tannin concentrations increased, from pinhead-square to first-bloom growth stages in all genotypes. While genotypes displaying some degree of resistance to the spider mite may have been selected for elevated condensed tannin levels, these genotypes also may have been inadvertently selected for high phenolic acid levels. Therefore, the observed resistance in these genotypes may be attributed to high levels of not only condensed tannins, but also phenolic acids.

Digestion Kinetics and Composition of Normal and Brown Midrib Sorghum Morphological Components

The brown midrib (bmr) mutation has shown the potential to improve the nutritive quality of forage sorghum [Sorghum bicolor (L.) Moench]; however, no study has been conducted to directly compare the effect of the bmr gene in a sudangrass (sorghum × drummondii (Steudel) Millsp. &amp; Chase) and its hybrid with a grain sorghum. Research was conducted to evaluate the relationship between cell wall composition and digestibility within the morphological components of normal and bmr sorghum cultivars. Cell wall constituents, structural carbohydrates, alkali‐labile phenolic monomers, and in vitro digestion kinetics were determined for ‘Piper’ (normal sudangrass), ‘S407’ (Piper. bmr‐6 sudangrass), and ‘F1006‐8 × S407’ (male sterile grain type bmr‐6 sorghum × Piper bmr‐6 sudangrass). Whole plants were harvested at the boot and hard dough growth stages and separated in to leaf blade, leaf sheath, inflorescence, and stem components. Significant differences were found between cultivars in concentrations of cell wall constituents. Neutral detergent fiber (NDF) concentration was lower (P &lt; 0.05) in the bmr cultivars than in Piper due to lower concentrations of cellulose and acid detergent lignin (ADL). Concentrations of ADL averaged g kg−1 dry matter for Piper, 28 g kg−1 for S407, and 25 g kg−1 for F1006‐8 × S407. The bmr cultivars had lower (P&lt;0.05) concentrations of p‐coumaric acid and higher (P &lt; 0.05) concentrations of vanillin than Piper. There were no differences (P &gt; 0.05) among cultivars ferulic acid concentration. p‐Coumaric acid concentrations averaged 25 g kg−1 of NDF for Piper, 16 g kg−1 NDF for S407, and 14 g kg−1 NDF for F1006‐8 − S407. Rate constants for in vitro digestion of NDF were similar (P &gt; 0.05) among cultivars. The bmr sudangrass (S407) had a greater (P &lt; 0.05) extent of NDF digestion than either Piper of F1006‐8 × S407. Extent of NDF digestion averaged 0.596 for Piper, 0.623 for S407, and 0.597 for F1006‐8 × S407. Results of this study indicate that the bmr mutation can effectively be expressed in both sudangrass and sorghum × sudangrass hybrid backgrounds

Degradability of parenchyma and sclerenchyma cell walls isolated at different developmental stages from a newly extended maize internode

Parenchyma and sclerenchyma cell walls were mechanically isolated from sections of a newly extended maize internode containing cells at different stages of maturity. Internodes were divided into four equal segments (A[top]-D[bottom]) and preparations of both cell types obtained from each segment. The lignin content of sclerenchyma (57.5–108.3 g kg−1) was greater than that of parenchyma (48.0–86.8 g kg−1) at all stages of development. The extent of lignification increased with age in both cell types but was similar in cells taken from segments A and B. The ratio of the saponifiable phenolic acids differed with age with levels of (E+Z)-ferulic acid remaining essentially constant while the (E+Z)-p-coumaric acid content increased in parallel with lignification. The extent to which commercial ‘cellulase’ was able to degrade both cell types decreased with age and extent of lignification. Sclerenchyma walls were less degradable than parenchyma walls isolated from the same segment. The fitted rate constant calculated for the period 2–72 h, however, was independent of both age and cell type. The mean thickness of sclerenchyma walls increased with age because of secondary wall formation (confirmed by image analysis of sections prepared for microscopy) while parenchyma remained thin walled. The consequences of lignification appeared to be essentially the same for both cell types and, by implication, for both primary and secondary wall layers.

Modification of in-vitro digestibility and cell-wall composition of cocksfoot, ryegrass and timothy by imazethapyr

Recent studies have shown that the compound imazethapyr (5-ethyl-2-(4-isopropyl-4-methyl-5-oxo-2-imidazolin-2-yl)nicotinic acid) possesses growth regulatory activity and can be used to enhance nutritive value of grasses. However, little is known about possible effects of this material on fibre composition or potential fibre utilisation by ruminants. The objective of this research was to examine imazethapyr-treated cocksfoot (Dactylis glomerata L), ryegrass (Lolium perenne L × L multiflorum Lam), and timothy (Phleum pratense L) for possible treatment-induced changes in in-vitro digestibility and in concentrations of selected fibre constituents. Replicated field plots treated with imazethapyr at 0 (control) or 100 g ai ha−1 during the vegetative (pre-elongation) stage of growth were harvested when controls were in the early stage of inflorescence emergence. Samples taken from treated plots 4 weeks post-treatment had higher in-vitro dry matter disappearance (IVDMD), lower neutral detergent fibre (NDF), lower acid detergent fibre (ADF), lower cellulose, lignin, and higher hemicellulose concentrations compared with controls. Imazethapyr treatment also reduced the concentration of p-coumaric acid in NDF, but had no effect on ferulic acid. The treatment effect on in-vitro NDF disappearance, however, was inconsistent among the grass species and was statistically non-significant (P = 0·10), implying that, under the conditions of this study, imazethapyr-related enhancements in IVDMD can be attributed primarily to a reduction in the amount of NDF and its associated constituents, as opposed to qualitative differences in NDF composition.

Chemical composition, digestibility in vitro and biodegradability of grass hays oven-treated with different amounts of ammonia

This study examined the effects of thermo-ammoniation (0, 15, 25 or 35 g ammonia kg −1 dry matter (DM) on the chemical composition, organic matter digestibility in vitro (OMD [vt]) and cell wall degradability by cellulase (CWD) of cocksfoot, ryegrass and timothy hays, each prepared at three stages of plant maturity. For each variety, absolute increases in total nitrogen, ammonia nitrogen and soluble non-ammonia nitrogen in response to ammoniation were large, and of similar magnitude between varieties and between cuts. However, incremental effects were small for applications above 15 g kg −1 DM. In contrast, concentrations of 4-methylimidazole were, with one exception, more than doubled when treatment was raised from 15 to 35 g ammonia kg −1 DM, and related to the amount of water soluble carbohydrate (WSC) in the untreated hays. Each increment of ammonia stimulated the release of aromatic compounds (principally phenolic acids) from cell walls. OMD [vt] was most strongly influenced by CWD and the proportions of cellulase undegradable cell walls, cell walls and total nitrogen (percentage of variance accounted for (VAR) = 74, 79, 59 and 62 respectively). Of the cell wall constituents, CWD was most closely related to the concentrations of p-coumaric acid and total phenolic acids (VAR=69 and 68% respectively). The validity of using gravimetric methods to determine OMD [vt] and CWD in ammoniated hays can however be questioned. To limit the production of potential toxins, it is suggested that ammoniation should be restricted to crops with a low content of WSC, and that ammonia should be applied in minimal amounts, commensurate with requirements for preservation or upgrading under relatively low temperature conditions.

Colchicine precursors and the formation of alkaloids in suspension-cultured Colchicum autumnale

Various precursors of colchicine were added to cell suspension cultures of Colchicum autumnale and the formation of colchicine alkaloids was examined. Phenylalanine, tyrosine and methionine had no effect on the formation of colchicine, but p-coumaric acid, tyramine and demecolcine increased alkaloid formation. Production of colchicine occurred at maximum level when both p-coumaric acid and tyramine were provided together, suggesting a synergistic formation. However, concentrations of p-coumaric acid and tyramine were very low in the cultured cells in spite of high levels of phenylalanine and tyrosine. Activities of trans-cinnamic acid 4-hydroxylase and tyrosine decarboxylase, involved in the biosynthesis of both p-coumaric acid and tyramine, respectively, were very low in the callus tissues during growth, although light increased activity of phenylalanine ammonia-lyase. We conclude that p-coumaric acid and tyramine are triggers for the formation of colchicine alkaloids in Colchicum callus tissues.

Effects of ammoniation of tall fescue on phenolic composition, feed intake, site and extent of nutrient digestion and ruminal dilution rates of steers.

Tall fescue hay (H) supplemented with corn and urea (HU) or corn gluten meal (HCGM) and ammoniated tall fescue hay supplemented with corn (AH) or corn gluten meal (AHCGM) were fed to steers in two 4 X 4 Latin-square trials. Diets were fed to four Angus-Hereford steers (550 kg) at equal intakes in trial 1 and to four Hereford steers (350 kg) at ad libitum intakes in trial 2. Ammoniation reduced cell wall concentrations of p-coumaric acid and ferulic acid by 48 and 67%, respectively. Concentrations of other phenolics were also reduced. Apparent total tract digestibilities of vanillin, p-coumaric acid and ferulic acid were lower (P less than .05, .001 and .01, respectively) when nontreated hay was fed in trial 1, but were not different between hay types in trial 2. In trial 1, greater negative intestinal digestibilities of p-coumaric acid (P less than .001) and vanillin (P less than .05) occurred for steers fed HU and HCGM vs AH and AHCGM diets. Digestibilities of neutral detergent fiber (NDF) and acid detergent fiber (ADF) were greater (P less than .001) for steers fed ammoniated hay diets in both trials and greater (P less than .05) for HCGM vs HU in trial 1. More than 96% of the NDF and ADF digested by steers in trial 1 was digested in the stomach. Intakes of digestible NDF and ADF, but not indigestible NDF or ADF, were higher (P less than .001) for steers fed AH and AHCGM in trial 2. In situ dry matter disappearance rate of ammoniated hay was greater (P less than .05) than that of nontreated hay, but rate of cotton thread disappearance from bags suspended in the rumen of steers fed the various diets was similar among treatments. In both trials, feeding ammoniated hay resulted in higher (P less than .05) ruminal concentrations of acetate and higher (P less than 0.05) acetate:propionate ratios. Ruminal liquid dilution rates were lower (P less than .05) for steers fed AH and AHCGM in trial 1, but were not different in trial 2. Ruminal dry matter concentration and solids dilution rate were not affected by diet in either trial. The results are interpreted to indicate that increased intake of ammoniated hay is a result of increased rate and extent of fiber digestion.

The nutritive value of normal and brown midrib-3 maize

SummaryNormal and brown midrib-3 (bm3) maize plants of three genotypes (Inra 188, Inra 240 and Inra 258) were sampled at three stages of maturity. Whole crop and plant components were analysed for in vitro digestible organic matter in the dry matter (DOMD) and the concentration of neutral detergent fibre, cellulose, hemicellulose, xylose, soluble sugars, starch and total nitrogen in the dry matter.The concentrations of total nitrogen, neutral detergent fibre, cellulose, hemicellulose and xylose were similar in both normal and bm3 plants. Xylose was the main constituent sugar of hemicellulose forming 70–75% of the total hemicellulose. The higher concentration of soluble sugars and lower concentration of starch in the bm3 plants was attributed to the later maturity of the bm3 plants.The bm3 gene significantly reduced lignin synthesis in the whole plant and plant components at all harvests. The mean concentration of lignin in the normal and bm3 plants were 2·2 and 1·4%, respectively. The ferulic and p-coumaric acid concentrations in the bm3 plants were 1·31 and 0·93 mg/g D.M. compared with 1·59 and 1·16 mg/g D.M. for the normal plants, respectively.The in vitro DOMD values for the bm3 plants were significantly higher (P &lt; 0.05) than their normal counterparts.

Correlations of Phenolic Acids and Xylose Content of Cell Wall with In Vitro Dry Matter Digestibility of Three Maturing Grasses

Maturing reed canarygrass, Russian wildrye, and smooth bromegrass cell walls were analyzed for lignin, phenolic acids, and neutral sugars. Linear correlation between in vitro dry matter digestibility and the p-coumaric acid content was −.86. The correlation between in vitro dry matter digestibility and ratio of p-coumaric to ferulic acid was −.84. Samples with high percentages of lignin also contained high ratios of p-coumaric to ferulic acid. Thus, p-coumaric acid may be more important than ferulic acid in crosslinking lignin to structural carbohydrates. Percent xylose and in vitro dry matter digestibility also were correlated significantly in all three species. A Russian wildrye regrowth sample contained a relatively high percentage of lignin despite its immature appearance. The lower digestibility of that regrowth sample may have resulted both from its high lignin content as well as branched xylans in the hemicellulosic fraction.

The influence of nitrogen and phosphorus levels on the phytotoxicity of phenolic compounds

The interaction between the phytotoxicity of certain phenolic compounds and deprivation of certain nutrients was investigated by means of a factorial experiment. Two concentrations of p-coumaric acid and two of vanillic acid were added to nutrient solutions containing various quantities of nitrogen and phosphorus, and these solutions were tested on barley plants in sand culture. Phenolic toxicity appears to depend intimately on nutrient concentrations; the phenolic acids were uniformly and significantly inhibitory only at low nutrient concentrations. Allelopathy with phenolics as chemical inhibitors seems most likely to occur in nutrient-poor soils.

Behavior of phenolic substances in the decaying process of plants

Abstract Phenolic compounds in the soils collected from 6 paddy fields and 9 forests were surveyed quantitatively by gas chromatography. The results are as follows: 1) p-Coumaric, ferulic, vanillic, p-hydroxybenzoic, syringic, salicylic, and protocatechuic acids were detected in all soils. Among these acids, p-coumaric acid was present in the largest quantity in most of the soils. Gallic, caffeic, and sinapic acids, resorcinol, and phloroglucinol were not detected. 2) The total amounts of individual phenolic acids in the forest soils (34-632 ppm) were markedly higher than those in the paddy soils (10-26 ppm). p-Coumaric acid content went up to 188 ppm in the forest soils and up to 7 ppm in the paddy soils. The average concentration of total phenolic acids per weight of organic matter in the forest soils was about 2 times as high as that in the paddy soils. 3) In the paddy soils, the concentrations of p-hydroxybenzoic, vanillik, syringic, p-coumarie, and ferulic acids, which have no chelating ability, were considerably related to the pH and the carbon content of the soil, but the concentrations of protocatechuic and salicylic acids, which are chelating agents, were not related to those of the soil. Also in A horizons of forest soils, the concentrations of many phenolic acids were related to carbon content, but not to pH. 4) In a forest soil surveyed, the concentrations of individual phenolics decreased with increasing depth. However, the ratios of the amounts of individual phenolics to the carbon content increased with depth.

Behavior of phenolic substances in the decaying process of plants

Abstract Phenolic compounds in the soils collected from 6 paddy fields and 9 forests were surveyed quantitatively by gas chromatography. The results are as follows: 1) p-Coumaric, ferulic, vanillic, p-hydroxybenzoic, syringic, salicylic, and protocatechuic acids were detected in all soils. Among these acids, p-coumaric acid was present in the largest quantity in most of the soils. Gallic, caffeic, and sinapic acids, resorcinol, and phloroglucinol were not detected. 2) The total amounts of individual phenolic acids in the forest soils (34-632 ppm) were markedly higher than those in the paddy soils (10-26 ppm). p-Coumaric acid content went up to 188 ppm in the forest soils and up to 7 ppm in the paddy soils. The average concentration of total phenolic acids per weight of organic matter in the forest soils was about 2 times as high as that in the paddy soils. 3) In the paddy soils, the concentrations of p-hydroxybenzoic, vanillik, syringic, p-coumarie, and ferulic acids, which have no chelating ability, were...