Carbohydrate esters of ferulic acid as components of cell-walls of Lolium multiflorum

Carbohydrate esters of ferulic acid were released from grass cell-walls by cellulase action as a mixture of at least four H₂O-soluble compounds in which the carboxylic group of the acid was bound to carbohydrate by ester bonds. The MW of these esters varied from a few hundred to over 50 000. Hydrolysis of one of the carbohydrate moieties showed that it contained xylose, arabinose and glucose units. The linkage of the carbohydrate esters of ferulic acid to other cell-wall constituents is discussed.     

Comparison of cell-walls of Lolium multiflorum with cotton cellulose in relation to their digestion with enzymes associated with cellulolysis

Activities of several enzymes associated with cellulolysis were compared using as substrates cell-walls of Lolium multiflorum and cotton cellulose. Purified enzymes C₁ (see Ref. 1 for definition), C._x (CM-cellulase) and β-glucosidase were employed as well as culture filtrates containing C_x. Activities were determined by ability to digest the substrates and to release H₂O-soluble phenolic compounds from the grass cell-walls. The culture filtrates most active on cotton cellulose were obtained using the fungi Trichoderma viride and Fusarium solani; with grass cell-walls the most active were from T. viride, Gliocladium roseum, a species of Basidiomycetes, and one strain of Myrothecium verrucaria (IMI Strain 25 291). For the crude enzyme preparations tested, there were highly significant correlations between the digestibility of grass cell-walls and the UV-absorption of the filtrate at λ_max 290 nm and at λ_max 324 nm but there was no significant correlation between the digestibility of grass cell-walls and that of cotton cellulose. Partially purified C₁ and C_x from two different fungal sources showed activity on both substrates. Differences in MW of the H₂O-soluble phenolic compounds obtained by treatment of grass cell-walls with C₁ and C_x components suggest that these enzymes could have different modes of action. Synergism between C₁ and C_x from T. koningii occurred with both substrates but with C₁ and C_x from F. solani synergism only occurred with cotton cellulose.     

Isolation and analysis of lignin-carbohydrate complexes from Lolium multiflorum

Lignin-carbohydrate complexes were extracted from grass cell walls by a variety of solvents. The yield of complexes was greatly enhanced if the sample was finely milled in a ball mill; dimethyl sulphoxide and N alkali extractions gave the highest yields. Hydrolysis showed that the carbohydrate fraction of the alkali-extracted complex contained mainly xylose (ca. 70%) and arabinose (ca. 20 %) whereas the dimethyl sulphoxide extracted complex contained glucose (ca. 50 %), xylose (ca. 30%), arabinose (ca. 12 %) and galactose (ca. 5 %). The UV spectrum of the dimethyl sulphoxide extracted complex showed lignin absorbance at 280 nm, but, in addition, ester bonding was also observed by the presence of a secondary absorbing region near 325 nm. This secondary absorbing region was absent from the spectrum of the alkali-extracted complexes. Fractionation of the complexes by ethanol precipitation gave a major component which appeared homogeneous by molecular sieve chromatography and had a MW of ? 150,000.     

Lignin-carbohydrate complexes from Lolium perenne

Lignin-carbohydrate and lignin-hemicellulose complexes were extracted sequentially from four varieties of Lolium perenne which had previously been     

Diferulic acid as a component of cell walls of Lolium multiflorum

Trans,trans-, cis,trans- and cis,cis-diferulic acids were released from cell walls of Lolium multiflorum by treatment with sodium hydroxide. The isomers were apparently bound via ester links to the structural carbohydrates of the cell walls. Sodium hydroxide treatment gave, per g of wall, 0.18 mg trans,trans-diferulic, 0.02 mg cis,trans-diferulic and a trace of cis,cis-diferulic acids compared with 5.3 mg trans-ferulic, 1.2 mg cis-ferulic, 0.78 mg trans-p-coumaric and 0.12 mg cis-p-coumaric acids. The significance of these acids in lignin biosynthesis is discussed. The effect of UV light on the trans,trans isomer and its fully silylated trimethylsilyl either derivative was also investigated.     

Distribution and roles of p-hydroxycinnamate: CoA ligase in lignin biosynthesis

p-Hydroxycinnamate:CoA ligases were extracted from the xylems of angiosperms and gymnosperms, and the substrate specificities toward ferulate and sinapate were examined. Most of angiosperm and gymnosperm CoA ligases examined were active with ferulate but not with sinapate; however, the enzymes of Erythrina crista-galli, Robinia pseudoacacia and bamboo showed considerable activity with sinapate. The other enzymes, although inactive with sinapate, showed no inhibitory effect on the Erythrina CoA ligase reaction with sinapate. The K_ms for sinapate and ferulate of the Erythrina enzyme were 1.0 and 2.1 μM, respectively, and p-hydroxycinnamate was the best substrate among cinnamates examined. The MW of the CoA ligase was 40 000 and the pH optimum was between 7.2 and 7.6. The possible roles of p-hydroxycinnamate:CoA ligase in lignin biosynthesis are discussed.     

Oxidative dimerization of ferulic acid by extracts from Sorghum

Extracts from leaves and first internodes of Sorghum bicolor catalyze the conversion of ferulic acid to a β-β-coupled dimer, the dilactone dimer of ferulic acid. The dilactone is then hydrolyzed, probably non-enzymatically, to a blue fluorescing compound, tentatively identified as a β-β-coupled dimer with at least one lactone ring opened to form a carboxylic acid. Both the initial enzymatic and the subsequent non-enzymatic steps are greater at pH 8 than pH 6. The most active preparation is a crude particulate fraction from leaves obtained by centrifugation at 37000 g; white light increases the amount of dimer formed.     

Covalently attached ferulic acid in a proteoglycan from rice bran

A water-soluble proteoglycan, precipitated with ammonium sulfate from the hot-water extract of rice bran, contained ferulic acid, which was liberated by alkaline treatment. Evidence for the linkage between the carboxyl group of ferulic acid and the proteoglycan was obtained by the characterization of ferulic acid hydroxamate after treatment of the proteoglycan with hydroxylamine.     

Phenolic acids and their carbohydrate esters in rice endosperm cell walls

Ferulic acid, p-coumaric acid and diferulic acid were detected in the alkaline extract of rice endosperm cell walls. The amount of each component was estimated as 9.1, 2.5 and 0.56 mg/g cell wall, respectively. Several phenolic-carbohydrate esters were isolated from the enzymatic digest of this cell wall, which included a series of ferulic acid esters of arabinoxylan fragments and also some fractions containing a high proportion of diferulic acid.     

Molecular Genetic Analysis of QTLs for Ferulic Acid Content in Dried Straw of Rice (Oryza sativa L.)

Phenolic acids are secondary metabolic organic compounds produced by plants and often are mentioned as allelochemicals. This study was conducted to determine the genetic basis controlling the ferulic acid content of rice straw in a recombinant inbred (RI) population derived from a cross between a japonica variety, Asominori, with a higher content of ferulic acid, and an indica variety, IR24, with a lower content, using 289 RFLP markers. Continuous distributions and transgressive segregations of ferulic acid content were observed in the RI population, which showed that ferulic acid content in rice straw was quantitatively inherited. Single marker analysis and composite interval mapping identified three quantitative trait loci (QTLs) for ferulic acid content with LOD values of 2.03 (chromosome 3), 3.16 (chromosome 6), and 3.06 (chromosome 7); all three had increased additive effects (13.5, 18.3, and 18.1 g g ^–1) from the Asominori parent and accounted for 5.5, 16.9, and 12.8% of total phenotypic variation, respectively. This is the first report on the identification of QTLs associated with ferulic acid and their chromosomal localization on the molecular map of rice. The tightly linked molecular markers that flank the QTLs might be useful in breeding and selection of varieties with higher phenolic acid content.     

Phenolic components and degradability of cell walls of grass and legume species

Cell walls separated from the aerial parts of Lolium multiflorum, Lolium perenne and Phleum pratense contained bound cis and trans ferulic and p-coumaric acids and diferulic acid which were released from the walls by treatment with sodium hydroxide. The total content of these acids in L. multiflorum ranged from 5 to 16.8 mg/g of wall, the trans-ferulic acid content varying between 2.8 and 8.9 mg/g of wall. In addition, small amounts of p-hydroxybenzoic acid were released from senescent leaf blade plus sheath parts. Cell walls from legume species gave much smaller amounts of the acids, the total content of aerial parts of Trifolium pratense being <0.8 mg/g of wall. The degra dability of the cell walls with a commercial cellulase preparation was determined and the water-soluble phenolic compounds released were estimated by UV absorption spectroscopy.     

Regulation of o-diphenolase activity by auxin and abscisic acid in germinating wheat embryos

During germination o-diphenolase activity increased several fold ( x 13) in wheat embryos. The enzyme activity and the number of multiple forms wer     

阿魏酸酯酶和纤维素酶在水解汽爆稻草中的协同作用

利用阿魏酸酯酶, 水解天然木质纤维素原料中半纤维素与木质素之间的阿魏酸酯键, 从破坏两者共价键连接的角度, 探索阿魏酸酯酶促进纤维素酶水解汽爆稻草中纤维素的可行性。结果显示, 当阿魏酸酯酶加入量为240 mu/g底物、水解72 h时, 汽爆稻草纤维素的酶解率、不溶性底物失重率较不加阿魏酸酯酶分别增加了32.00%、32.77%; 阿魏酸酯酶(300 mu/g底物)作用120 min后, 纤维素酶对汽爆稻草纤维素的酶解率、不溶性底物失重率分别增加了29.85%、32.48%。通过比较不同酶法处理后的汽爆稻草的可及度和红外光谱图发现, 阿魏酸酯酶能有效地水解原料中的酯键, 提高原料可及度50%以上。由此表明, 阿魏酸酯酶和纤维素酶之间存在较大的协同作用, 添加阿魏酸酯酶能够提高纤维素酶对天然木质纤维素的酶解效率。     

Volatile compounds from triticum aestivum

Volatile compounds were isolated from aerial parts (foliage and culms) of wheat plants by reduced pressure steam distillation-extraction and identified by gas chromatography-mass spectrometry and co-chromatography with authentic compounds. Infrared spectra were also obtained on some constituents. Compounds identified included nonanal and related unsaturated C₉ aldehydes and alcohols as major components and some additional aldehydes, alcohols and a ketone.     

禾本科植物细胞壁的木质化和阿魏酰化

介绍了禾本科植物细胞壁木质化和阿魏酰化的过程及其生理意义,并阐述了木质化和阿魏酰化在细胞壁分子网络形成过程中的作用。     

Diferulic acid as a possible crosslink in hemicelluloses from wheat germ.

Bound diferulic acid has been identified in small amounts in the water-insoluble pentosans of wheat endosperm. Evidence is presented suggesting that diferulic acid crosslinks adjacent polysaccharide molecules and reduces their solubility.     

Separation of macromolecular components of plant cell walls: electrophoretic methods

Qualitative quantitative and preparative electrophoretic methods of separating polymeric substances derived from plant cell walls are described. Analyt     

Gibberellin-phenol interactions in plant extracts

Radioactive materials, with low mobilities on PC, occurred in extracts of barley that had been dosed with gibberellic acid ([¹⁴C]GA₃) before ge