Roy D. Hartley

Occurrence and nature of ferulic acid substitution of cell-wall polysaccharides in graminaceous plants

Abstract Cell walls of wheat bran were treated with Oxyporus “cellulase” (a mixture of polysaccharide hydrolases) in order to release compounds containing ferulic acid bound to carbohydrate. The major feruloyl compound released has been identified as 2- O -[5- O -( trans -feruloyl)-β- l -arabinofuranosyl]- d -xylopyranose. Similar treatment of the cell walls of other graminaceous plants also released this compound.

Linkage of p-coumaroyl and feruloyl groups to cell-wall polysaccharides of barley straw

Abstract Treatment of cell walls of barley straw with Oxyporus “cellulase” (a mixture of polysaccharide hydrolases) released compounds containing p-coumaroyl and feruloyl groups bound to carbohydrates, two of which were identified as O-[5-O-(trans-p-coumaroyl)-α- l -arabinofuranosyl]-(1→3)-O-β- d -xylopyranosyl-(1→4)- d -xylopyranose (PAXX) and O-[5-O-(trans-feruloyl)-α- l -arabinofuranosyl]-(1→3)-O-β- d -xylopyranosyl-(1→4)- d -xylopyranose (FAXX).

Phenolic constituents of the cell walls of monocotyledons.

Abstract Monocotyledons of 104 species in 52 families were divided into two groups depending on the UV fluorescence behaviour of their cell walls. The unlignified cell walls of the first group, fluoresced blue, which changed to green with increased intensity after treatment with NH 3 due to the presence of bound ferulic acid. The isolated cell walls of members of the first group were shown to contain bound ferulic, p -coumaric and diferulic acids. These acids were absent from cell walls of the second group. The first group contained families of the Commelinidae of Cronquist, the Palmae (part of the Arecidae), and the Philydraceae, Pontederiaceae, and Haemodoraceae (all part of Liliidae). The other families of the latter two subclasses and those of the Alismatidae belonged to the second group.

Feruloyl and p-coumaroyl esterase from anaerobic fungi in relation to plant cell wall degradation

SummaryTrans-feruloyl and trans-p-coumaroyl esterases were found in the culture filtrates of two monocentric (Piromyces MC-1, Neocallimastix MC-2) and three polycentric (Orpinomyces PC-2, Orpinomyces PC-3, and PC-1, an unnamed genus with uniflagellated zoospores) isolates of anaerobic rumen fungi. Treatment of cell walls of Coastal bermudagrass shoots with the filtrates released the trans isomers of ferulic and p-coumaric acids; results of microscopic observations indicated that fungal isolates degraded primarily unlignified cell walls in leaf blades and stems. A greater proportion of ferulic than p-coumaric acid was released by this treatment when compared with the amounts of the acids released by saponification of the walls with 1 M NaOH. The filtrates also showed esterase activities against the trans isomers of methyl ferulate and methyl p-coumarate, with ferulic acid being released at a faster rate than p-coumaric acid. Assays for other cell-wall-degrading enzymes (xylanase, β-xylosidase, α-l-arabinosidase, cellulase, β-glucosidase) indicated that only β-xylosidase correlated with ferulate and p-coumarate esterase activities. The monocentric isolate MC-2 had the highest esterase activity against both the plant cell wall and methyl ester substrates and the highest specific activities of acetyl esterase, β-xylosidase, α-l-arabinosidase, cellulase and β-glucosidase. Isolate MC-2 produced substantially greater amounts of feruloyl and p-coumaroyl esterase when the growth substrate contained higher levels of saponifiable ferulic and p-coumaric acids.

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

Abstract 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

Assay for trans-p-coumaroyl esterase using a specific substrate from plant cell walls☆

Cell walls of Coastal Bermuda grass (Cynodon dactylon) were treated with polysaccharide hydrolases to release O-[5-O-(trans-p-coumaroyl)-alpha-L-arabinofuranosyl]-(1----3)-O-be ta-D- xylopyranosyl-(1----4)-D-xylopyranose (PAXX) which was isolated by liquid chromatography. The isolated PAXX was greater than 95% pure as determined by 1H NMR and was used as substrate for a sensitive assay of trans-p-coumaroyl esterase. PAXX was hydrolyzed by culture filtrates from the anaerobic fungus Neocallimastix MC-2. The trans-p-coumaric acid released by enzymatic hydrolysis was assayed by reverse-phase HPLC, and as little as 100 ng of acid could be determined. Steady-state velocities for the release of the acid obeyed Michaelis-Menten kinetics. Vmax was determined to be 1.17 mumol min-1 mg-1 and Km 13.2 microM at pH 7.5 and 30 degrees C.

4,4′-Dihydroxytruxillic acid as a component of cell walls of Lolium multiflorum

Abstract 4,4′-Dihydroxytruxillic acid was released from the cell walls of Lolium multiflorum by treatment with sodium hydroxide. Combined gas chromatography-mass spectrometry indicated that other similar dimers, probably resulting from the photodimerization of p-coumaric acid or ferulic acid, were also released from the cell walls. The possible role of the dimers in cross-linking cell wall heteroxylans is discussed.

Substituted truxillic and truxinic acids in cell walls of Cynodon dactylon.

Abstract Twelve substituted truxillic and truxinic acids were separated by GC-MS from the compounds released from the cell walls of Cynodon dactylon by treatment with sodium hydroxide. These acids are probably formed in cell walls from two ester-linked molecules of p -coumaric acid, two ester-linked molecules of ferulic acid, or from one ester-linked molecule of each of the two acids. The three major dimers found were 4, 4′-dihydroxy-α-truxillic acid, 4, 4′-dihydroxy-3,3′-dimethoxy-α-truxillic acid, and 4,4′-dihydroxy-3-methoxy-α-truxillic acid; tentative structures are proposed for the other dimers, some of which have not been described previously. The same three major dimers were obtained by treatment with sodium hydroxide of the water-soluble compounds released from the cell walls with wall degrading carbohydrases suggesting that the dimers are ester-linked to cell wall polysaccharides. Dimer formation within cell walls could involve cross-linking of wall polysaccharides, thus affecting cell wall properties including biodegradability.

Carbohydrates and carbohydrate esters of ferulic acid released from cell walls of Lolium multiflorum by treatment with cellulolytic enzymes

Abstract 41% of the cell walls from mature leaf blades of Lolium multiflorum were digested by treatment during 14 days with C 1 enzyme (cellulase) which had been purified by gel filtration and ion-exchange chromatography. Cellobiose was the main sugar released from the walls, together with some glucose and higher oligosaccharides. Considerable amounts of carbohydrate esters of ferulic and p -coumaric acids were also released. When the C 1 enzyme was further purified by isoelectric focusing, only 8% of the cell walls were digested. Purified C x (CM-cellulase) containing β-glucosidase digested 51% of the cell walls in 16 hours: the major component detected in the soluble products was glucose together with some β (1 → 4)-xylobiose, xylose and arabinose. Higher oligosaccharides and carbohydrate esters of ferulic and p -coumaric acids were also present. It was shown that these acids were present in the cell walls mainly in the trans -configuration.

Aromatic aldehyde constituents of graminaceous cell walls

Abstract p -Hydroxybenzaldehyde, vanillin and syringaldehyde were released as their sodium salts from graminaceous cell walls by treatment with sodium hydroxide. Treatment of the walls with ‘cellulase’ having both cellulase and hemicellulase activity released the aldehydes in bound form apparently linked at their phenolic groups to the wall polysaccharides. These findings are discussed in relation to tests for lignin using phloroglucinol-HC1 and alkaline nitrobenzene reagents.