Feruloyl Groups Research Articles

Coumaroyl and feruloyl flavonoid glycosides from the male flowers of Ginkgo biloba L. and their inhibitory activity against α-glucosidase

Four flavonoid glycosides containing coumaroyl or feruloyl groups were isolated from the male flowers of Ginkgo biloba L., and compounds 3 and 4 were identified as novel compounds. The inhibitory activities against α-glucosidase were investigated by docking studies, in vitro assays and kinetic studies. The docking results showed that all compounds mainly formed hydrogen-bond and π-π-stacking interactions with α-glucosidase. Compound 4 had the lowest binding energy and maximum number of hydrogen bonds. Subsequently, the in vitro assays showed that compound 4 exhibited the strongest inhibitory potency. Finally, the kinetic studies indicated the inhibitory mode of compounds 1–4 against α-glucosidase were mixed types of competitive and non-competitive. Together, these findings suggested that the isolated flavonoid glycosides in this study, especially compound 4, have potential as α-glucosidase inhibitors.

Steam drying markedly increases the solubility of feruloylated arabinan-rich pectic polysaccharide in sugar beet pulp

Three sugar beet pulp samples, which were dried by different methods (drum-dried, steam-dried, and shelf-dried), were prepared and hot water extractions (90 °C, 6 h) were performed to compare the pectic polysaccharide yield. The steam-dried pulp yielded 34.1 g of pectic polysaccharides per 100 g of dry matter. This represented about twice the yield of the other techniques, with a recovery of about 60% of the estimated amount contained in the raw material. The pectic polysaccharide obtained from the steam-dried pulp by hot water extraction and dialysis contained larger amount of arabinose (32.4 g/ 100 g solids) as constituent sugars than that of commercial beet pectin. The weight-average molecular mass was 175 kDa, which was lower than that of commercial beet pectin (538 kDa) and most of the extracted feruloyl group were bound to this polysaccharide. These characteristics were similar to those of pectic polysaccharides obtained previously by autoclave extraction from wet beet pulp. It was presumed that the pectic polysaccharides contained in sugar beet pulp were partially hydrolyzed and solubilized under pressurized and high temperature conditions (0.25–0.3 MPa, 150–180 °C) during steam drying, making them easier to extract. Using steam-dried pulp as a raw material, feruloylated arabinan-rich pectic polysaccharides can be efficiently obtained by hot water extraction under non-pressurized conditions without acid addition.

Feruloylated Arabinoxylan and Oligosaccharides: Chemistry, Nutritional Functions, and Options for Enzymatic Modification.

Cereal brans and grain endosperm cell walls are key dietary sources of different types of arabinoxylan. Arabinoxylan is the main group of hemicellulosic polysaccharides that are present in the cell walls of monocot grass crops and hence in cereal grains. The arabinoxylan polysaccharides consist of a backbone of β-(1→4)-linked xylopyranosyl residues, which carry arabinofuranosyl moieties, hence the term arabinoxylan. Moreover, the xylopyranosyl residues can be acetylated or substituted by 4-O-methyl-d-glucuronic acid. The arabinofuranosyls may be esterified with a feruloyl group. Feruloylated arabinoxylo-oligosaccharides exert beneficial bioactivities via prebiotic, immunomodulatory, and/or antioxidant effects. New knowledge on microbial enzymes that catalyze specific structural modifications of arabinoxylans can help us understand how these complex fibers are converted in the gut and provide a foundation for the production of feruloylated arabinoxylo-oligosaccharides from brans or other cereal grain processing sidestreams as functional food ingredients. There is a gap between the structural knowledge, bioactivity data, and enzymology insight. Our goal with this review is to present an overview of the structures and bioactivities of feruloylated arabinoxylo-oligosaccharides and review the enzyme reactions that catalyze specific changes in differentially substituted arabinoxylans.

Effect of wheat bran feruloyl oligosaccharides on the performance, blood metabolites, antioxidant status and rumen fermentation of lambs

The objective of this experiment was to investigate the effects of wheat bran feruloyl oligosaccharides (FOs) as an antioxidant supplement on performance, blood metabolites, antioxidant status and ruminal fermentation of lambs. Fifty, two-month-old crossbred male lambs (Dorper × Small-tail Han Sheep) with an initial body weight (BW) of 20.21 ± 3.36 kg were randomly assigned into five groups of ten animals each and fed basal diet with dietary wheat bran FOs supplementation at 0, 50, 100, 200 and 400 mg/kg feed, respectively. The experimental period lasted 56 days and was preceded by an adaption period of 14 days. The absorption spectrum of FOs product used in this study revealed the presence of an esterified feruloyl group. The esterified FA concentration of this product reached 0.99 mmol/g. The feed conversion ratio improved quadratically (P < 0.05) with increasing FOs supplementation at stage from 29–56 days and over the whole experiment. During 29–56 days, the average daily gain of the lambs receiving 100 and 200 mg/kg FOs tended to be higher than lambs receiving 400 mg/kg FOs (P = 0.06). The apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP) and neutral detergent fiber (NDF) were significantly reduced when lambs were fed the 400 mg/kg FOs diet (P < 0.05). Supplementing lambs with 50, 100 and 200 mg/kg FOs significantly increased serum concentrations of total protein (P < 0.05), meanwhile, the serum albumin concentration of treatment groups showed a tendency to be higher than the control group (P = 0.05). Serum total antioxidative capacity (T-AOC) tended to increase (P = 0.07) quadratically with increasing FOs supplementation, and glutathione peroxidase (GSH-Px) activity increased (P < 0.05) quadratically with increasing doses of FOs. Compared to the control group, the serum catalase (CAT) and superoxide dismutase (SOD) activity of lambs fed with the 50 and 100 mg/kg FOs diet was significantly (P < 0.05) higher. FOs-supplementation groups had higher serum glutathione (GSH) concentrations than the control (P < 0.05). In addition, the ruminal ammonia nitrogen concentration of lambs fed with the 200 mg/kg FOs diet tended to be lower (P = 0.07) than lambs fed with the 400 mg/kg FOs diet, but the concentrations of total volatile fatty acid (VFA), individual VFA and pH were not affected. These results demonstrated that FOs supplementation can promote growth performance, decrease ruminal ammonia nitrogen concentration and improve antioxidant properties by increasing antioxidant enzyme activities and GSH concentration in lambs. Therefore, wheat bran FOs could be used as a novel antioxidant for lamb diets.

Dimeric cinnamoylamide analogues for regulation of tyrosinase activity in melanoma cells: A role of diamide-link chain length.

Dimeric cynnamoyl analogues (DCAs) with depigmenting activity have been developed. In this study, a role of diamide linkage chain length of DCAs as a tyrosinase inhibitor was investigated on tyrosinase inhibitory activity, antioxidative activity, hydrophobicity and anti-melanogenesis as well as structural characteristics and dipole moments based on density functional theory. DCAs with different diamide-link chain lengths (n = 2, 3, and 4) and various functional groups (m-coumaroyl, p-coumaroyl, isoferuloyl and feruloyl groups) were synthesized. DCAs with a diamide-link chain length of three indicated high inhibitory effect of melanin production on α-melanocyte stimulating hormone (α-MSH) stimulated B16F1 cells. Approach of p-hydroxyl group of DCAs to active site of tyrosinase, an important melanogenic enzyme, is interfered by addition of m-methoxy group. In structural modeling based on density functional theory, DCAs with a diamide-link chain length of three showed folded shapes, and they had lower dipole moment than with a diamide-link chain length of two or four. Thus, for the enhancement of the depigmenting activities of dimeric compounds, the diamide-link chain length is important. Our results provide an important index for the design of dimeric compounds with physiological activities.

Interactions, induced by heating, of whey protein isolate (WPI) with sugar beet pectin (SBP) in solution: Comparisons with a dry-state Maillard reaction

We investigate changes in the molecular structures of whey proteins (WPI) caused by heat-induced interaction and reaction with varying concentrations of sugar beet pectin (SBP) in aqueous solution at neutral pH. The resulting complexes were examined using circular dichroism (CD) and steady-state and time-resolved fluorescence spectroscopic techniques. Far-UV CD spectroscopy combined with spectral deconvolution revealed noticeable reduction (up to 5%) in the amount of antiparallel β-sheet element of WPI upon interacting with SBP. Analyses from the UV-VIS and steady-state fluorescence spectroscopies showed changes in the molecular electronic states of both WPI and the feruloyl moieties of SBP upon heat-induced interaction and conjugation. The tertiary structural contacts in WPI, studied by the intrinsic Trp fluorescence, were also disrupted in the presence of SBP in the form of FRET (Fluorescence Resonance Energy Transfer) complexes, most noticeably at a high level of SBP (3%), contrasting to the results from dry-heating. The thermal stability of WPI, at both secondary and tertiary structural levels, did not increase considerably by interacting and conjugating with SBP, especially at an equal concentration of SBP (3%). However, the stability of feruloyl groups of SBP saw moderate improvement and was less pronounced than that of the dry-state reactions.

Anticomplement triterpenoids from the roots of Ilex asprella

Five new (1–5) and twenty-eight known (6–33) triterpenoids were isolated from the roots of Ilex asprella. The structures of the new compounds were elucidated by the detailed spectral analysis. The ursane and oleanane triterpenoids were found to show anticomplement activity with some structure-activity relationships. Several triterpenoids (1–3, 6–7) exhibited potent anticomplement activity with the CH50 and AP50 values of 0.058–0.131mg/mL and 0.080–0.444mg/mL, respectively. It was found that caffeoyl group could enhance activity remarkably, followed by coumaroyl and feruloyl group. The 28-carboxyl group was also important to anticomplement activity for the triterpenoids. However, the triterpenoids with lactone ring (4, 9–14) exhibited weak activity and triterpenoid glycosides (5, 23–33) showed no inhibition. The targets of several bioactive triterpenoids in complement activation cascade were identified as well.

Stabilization of whey protein isolate (WPI) through interactions with sugar beet pectin (SBP) induced by controlled dry-heating

It has been shown previously that reacting whey protein isolate (WPI) with sugar beet pectin (SBP) through a Maillard type reaction in a dry-state led to noticeable improvement in the physical, chemical and functional properties of the end products. Studies on the changes in the molecular structure of whey protein as a result of the reaction were carried out in this work to provide a molecular understanding of these observed improvements. The effect of interacting and conjugating with SBP on the apparent secondary structure of WPI was examined by far-UV circular dichroism (CD) spectroscopy and followed by spectral deconvolution. Results showed that the structure of WPI, especially the antiparallel β-sheet element, was preserved by reacting with SBP at the weight ratios of WPI:SBP = 3:1, 2:1, and 1:1. The analysis of difference UV-VIS spectra indicated significant changes occurred in the molecular electronic states of both WPI and the feruloyl moieties of SBP. Initial Maillard reaction products were detected in the form of the FRET complexes with WPI as the donor, and SBP, the acceptor by the studies of the steady-state fluorescence and the lifetime of the excited states. The tertiary structural contacts in WPI, probed by the intrinsic Trp fluorescence, were disrupted significantly upon reacting with SBP at an equal ratio (1:1). The thermal stability of WPI, however, at both secondary and tertiary structural levels, was greatly improved by the dry-heating induced reaction with SBP at all levels. The thermal stability of the feruloyl groups of SBP was also enhanced by reacting with WPI. Furthermore, the fluorescence lifetime studies definitively identified the distinctive advanced Maillard reaction end products (AMREPs) formed between WPI and SBP at varying ratios.

Synthesis and characterization of enzymatically cross-linked feruloyl amylopectin for curcumin encapsulation

Feruloyl amylopectin (FAP) was synthesized by the N,N′-carbonyldiimidazole (CDI) activation method, and the enzymatically cross-linked feruloyl amylopectin (CL-FAP) was prepared via catalysis of horseradish peroxidase (HRP) with the presence of hydrogen peroxide (H2O2). RP-HPLC-DAD/ESI-TOF-MS measured ferulic acid and its derivatives in FAP and CL-FAP. FAP was primarily composed of two ferulate monomers, while CL-FAP was composed of two ferulate monomers and two ferulate dehydrodimers. The ester formation in the feruloyl group was confirmed by the presence of carbonyl and aromatic CC signal near 1725 (1723) and 1510cm−1 in the FT-IR spectra. X-ray diffraction studies showed that the two modified amylopectins lost the ordered A-type crystalline structure, characteristic of maize amylopectin. The encapsulation capacity of curcumin (ECC) in 1mg/mL CL-FAP microemulsion was measured at 88.13μg/mg by HPLC.

Effects of enzymatic removal of plant cell wall acylation (acetylation, p-coumaroylation, and feruloylation) on accessibility of cellulose and xylan in natural (non-pretreated) sugar cane fractions.

BackgroundSugar cane internodes can be divided diagonally into four fractions, of which the two innermost ones are the least recalcitrant pith and the moderately accessible pith-rind interface. These fractions differ in enzymatic hydrolyzability due to structural differences. In general, cellulose hydrolysis in plants is hindered by its physical interaction with hemicellulose and lignin. Lignin is believed to be linked covalently to hemicellulose through hydroxycinnamic acids, forming a compact matrix around the polysaccharides. Acetyl xylan esterase and three feruloyl esterases were evaluated for their potential to fragment the lignocellulosic network in sugar cane and to indirectly increase the accessibility of cellulose.ResultsThe hydrolyzability of the pith and pith-rind interface fractions of a low-lignin-containing sugar cane clone (H58) was compared to that of a reference cultivar (RC). Acetyl xylan esterase enhanced the rate and overall yield of cellulose and xylan hydrolysis in all four substrates. Of the three feruloyl esterases tested, only TsFaeC was capable of releasing p-coumaric acid, while AnFaeA and NcFaeD released ferulic acid from both the pith and interface fractions. Ferulic acid release was higher from the less recalcitrant clone (H58)/fraction (pith), whereas more p-coumaric acid was released from the clone (RC)/fraction (interface) with a higher lignin content. In addition, a compositional analysis of the four fractions revealed that p-coumaroyl content correlated with lignin, while feruloyl content correlated with arabinose content, suggesting different esterification patterns of these two hydroxycinnamic acids. Despite the extensive release of phenolic acids, feruloyl esterases only moderately promoted enzyme access to cellulose or xylan.ConclusionsAcetyl xylan esterase TrAXE was more efficient in enhancing the overall saccharification of sugar cane, compared to the feruloyl esterases AnFaeA, TsFaeC, and NcFaeD. The hydroxycinnamic acid composition of sugar cane fractions and the hydrolysis data together suggest that feruloyl groups are more likely to decorate xylan, while p-coumaroyl groups are rather linked to lignin. The three different feruloyl esterases had distinct product profiles on non-pretreated sugar cane substrate, indicating that sugar cane pith could function as a possible natural substrate for feruloyl esterase activity measurements. Hydrolysis data suggest that TsFaeC was able to release p-coumaroyl groups esterifying lignin.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-014-0153-3) contains supplementary material, which is available to authorized users.

Investigation of molecular interactions between β-lactoglobulin and sugar beet pectin by multi-detection HPSEC

Molecular interactions between β-lactoglobulin (β-LG) and sugar beet pectin (SBP) were studied using online multi-detection high performance size exclusion chromatography (HPSEC) at neutral pH and 50mM ionic strength. The hydrodynamic properties of various interacting polymer fractions were characterized in detail and compared with those of β-LG and SBP. Results showed that ∼6.5% (w/w) of native dimeric β-LG molecules formed complexes with over 35% SBP molecules of varying sizes, 800, 110 and 75kDa. Although the β-LG molecules bind to SBP molecules of all sizes and shapes, they tend to favor the intermediate (110kDa) and small sized (75kDa) SBP molecules. All resulting complexes possess altered shapes and hydrodynamic properties when compared to unbound SBP and β-LG. About half of the interacting β-LG (∼3.5%) molecules were thought to bind to a small amount of non-covalently bound feruloyl groups, possibly present in SBP. When pre-heat treated β-LG and SBP were combined, more than 16% of β-LG formed complexes with at least 45% of SBP molecules of varying sizes, Mw∼750–800, 110, and 55–80kDa. The complexes formed between β-LG aggregates and/or oligomers and the large SBP molecules (750–800kDa) adopt the shape of β-LG aggregates, random coil. Both groups of complexes formed between β-LG intermediate (110kDa) and small sized (55–80kDa) SBP take on the shape of rigid rod. It was speculated that half of the interacting heat-treated β-LG molecules (∼8%) are complexed with non-covalently bound feruloyl groups in SBP.

Tumoral cytotoxic and antioxidative phenylpropanoid glycosides in Smilax riparia A. DC

Ethnopharmacological relevanceSmilax riparia A. DC., known as “Niu-Wei-Cai” in China, is distributed through the south and middle of China. The roots and rhizomes of Smilax riparia have been used not only as traditional Chinese medicines (TCMs) for the treatment of bronchitis, lumbago of renal asthenia, traumatic injury, asthenia edema, and cancer but also as edible wild herbs in some areas of China. Aim of the studyTo identify the phytochemicals in the roots and rhizomes of Smilax riparia and to investigate their antioxidant activities and cytotoxicities toward several tumor cell lines. Materials and methodsFour fractions and five phenylpropanoid glycosides were obtained from roots and rhizomes of Smilax riparia under bioassay-guided screenings. The structures of five compounds were elucidated by spectroscopic methods and compared with published data. We evaluated their antioxidant activities and their cytotoxicities on five cancer cell lines: human promyelocytic leukemia (HL-60), human hepatocellular carcinoma (SMMC-7721), human lung cancer (A-549), human breast cancer (MCF-7), and human colon cancer (SW480). ResultsOf the five glycosides, one new compound (3, smilaside P) was isolated from an EtOAc fraction. Compound 1 was cytotoxic toward HL-60, SMMC-7721, A-549, MCF-7, and SW480 (IC50 2.70, 3.80, 11.91, 3.79, and 3.93μM, respectively). Moreover, compounds 1–3 showed moderate scavenging activities against the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical (IC50 339.58, 330.66, 314.49μM, respectively). ConclusionsFive phenylpropanoid glycosides were reported for the first time from this TCM. Each was studied, as observed here for the first time, in the cytotoxic experiments toward HL-60, SMMC-7721, and SW480 cell lines. Compound 1, bearing three feruloyl groups and three acetyl groups, had the greatest cytotoxicity toward the five tumor cell lines. Compounds 1–3 showed moderate antioxidant activities. All results reflect that compounds 1–3 are cytotoxic for a wide variety of cancer cell lines of differing tissue origins and that the cytotoxicities of these compounds may be related to their antioxidant activities.

Arabidopsis and Brachypodium distachyon Transgenic Plants Expressing Aspergillus nidulans Acetylesterases Have Decreased Degree of Polysaccharide Acetylation and Increased Resistance to Pathogens

The plant cell wall has many significant structural and physiological roles, but the contributions of the various components to these roles remain unclear. Modification of cell wall properties can affect key agronomic traits such as disease resistance and plant growth. The plant cell wall is composed of diverse polysaccharides often decorated with methyl, acetyl, and feruloyl groups linked to the sugar subunits. In this study, we examined the effect of perturbing cell wall acetylation by making transgenic Arabidopsis (Arabidopsis thaliana) and Brachypodium (Brachypodium distachyon) plants expressing hemicellulose- and pectin-specific fungal acetylesterases. All transgenic plants carried highly expressed active Aspergillus nidulans acetylesterases localized to the apoplast and had significant reduction of cell wall acetylation compared with wild-type plants. Partial deacetylation of polysaccharides caused compensatory up-regulation of three known acetyltransferases and increased polysaccharide accessibility to glycosyl hydrolases. Transgenic plants showed increased resistance to the fungal pathogens Botrytis cinerea and Bipolaris sorokiniana but not to the bacterial pathogens Pseudomonas syringae and Xanthomonas oryzae. These results demonstrate a role, in both monocot and dicot plants, of hemicellulose and pectin acetylation in plant defense against fungal pathogens.

Stabilization of oil-in-water emulsions by enzyme catalyzed oxidative gelation of sugar beet pectin

Enzyme catalyzed oxidative cross-linking of feruloyl groups can promote gelation of sugar beet pectin (SBP). It is uncertain how the enzyme kinetics of this cross-linking reaction are affected in emulsion systems and whether the gelation affects emulsion stability. In this study, SBP (2.5% w/v) was mixed into an oil-in-water emulsion system (4.4% w/w oil, 0.22% w/w whey protein, pH 4.5). Two separate, identically composed, emulsion systems were prepared by different methods of preparation. The emulsions prepared separately and subsequently mixed with SBP (referred as Mix A) produced significantly larger average particle sizes than the emulsions in which the SBP was homogenized into the emulsion system during emulsion preparation (referred as Mix B). Mix B type emulsions were stable. Enzyme catalyzed oxidative gelation of SBP helped stabilize the emulsions in Mix A. The kinetics of the enzyme catalyzed oxidative gelation of SBP was evaluated by small angle oscillatory measurements for horseradish peroxidase (HRP) (EC 1.11.1.7) and laccase (EC 1.10.3.2) catalysis, respectively. HRP catalyzed gelation rates, determined from the slopes of the increase of elastic modulus (G′) with time, were higher (P < 0.05) than the corresponding laccase catalyzed rates, but the final G′ values were higher for laccase catalyzed gels, regardless of the presence of emulsions or type of emulsion preparation (Mix A or Mix B). For both enzymes, rates of gelation in Mix A were higher (P < 0.05) than in Mix B, and higher stress was needed to break the gels in Mix A than in Mix B at similar enzyme dosage levels. These differences may be related to a lower availability of the feruloyl groups for cross-linking when the SBP was homogenized into the emulsion system during preparation.

Antioxidant properties of feruloyl glycerol derivatives

The natural plant components, 1-feruloyl-sn-glycerol (FG) and 1,3-diferuloyl-sn-glycerol (F2G), were synthesized by the enzymatic esterification of glycerol and soybean oil mono- and diacylglycerols, respectively, with ethyl ferulate. The isolated FG and F2G were examined for their antioxidant activities as free radical scavengers (DPPH assay) and peroxyl lipid oxidation inhibitors (TBARS assay). The H atom transfer kinetics, as monitored by DPPH free radical bleaching, of FG showed that the mono-feruloyl glycerol acted as a rapid antioxidant (50% reduction of DPPH radical<5min) in ethanol solutions while F2G and ferulic acid activity rates were in the range of intermediate antioxidants (50% reduction of DPPH radical in 5–30min). FG and F2G showed similar activity as the control agent, ethyl ferulate, towards the inhibition of the AAPH-induced peroxyl radical oxidation of surfactant emulsified γ-linolenic acid. A slight excess of feruloyl groups was sufficient to completely suppress the formation of secondary lipid oxidation products.

In situ gellable sugar beet pectin via enzyme-catalyzed coupling reaction of feruloyl groups for biomedical applications

In situ gellable hydrogels are more attractive in many biomedical and biopharmaceutical applications than pre-formed hydrogels because they can be implanted simply by injection and allow homogeneous incorporation of bioactive materials. In this study, the potential suitability of in situ gellable sugar beet pectin (SBP) for biomedical and biopharmaceutical applications was investigated. SBP aqueous solution gelled within 1 min after addition of appropriate amounts of horseradish peroxidase (HRP) and H₂O₂ via HRP-catalyzed oxidative coupling reaction of feruloyl groups on SBP molecules. The resultant gels gradually degraded under simulated physiological condition. L929 fibroblast cells encapsulated in the gels were scarcely damaged during the gelation process. A subcutaneously injected mixture of SBP, HRP and H₂O₂ solutions successfully gelled, and the gel did not induce necrosis in the surrounding tissue 1 week after implantation. These results demonstrate that the in situ gellable SBP gels are useful for biomedical and biopharmaceutical applications.

Effect of glucose addition and N sources in defined media on fibrolytic activity profiles of Neocallimastix sp. YQ1 grown on corn stover

Cleavage of plant cell wall arabinoxylans occurs by the action of ferulic acid esterase (FAE) and acetyl esterase (AE), which cleave feruloyl groups substituted at the 5'-OH group of arabinosyl residues and acetyl groups substituted at O-2/O-3 of the xylan backbone, respectively. In this study, we examined the enzyme profiles of the anaerobic rumen fungus Neocallimastix sp. YQ1 for FAE, AE and polysaccharide hydrolases when grown on corn stover, a lignin-rich waste biomaterial. A 2 × 4 factorial experiment in 10-days pure cultures was used to test glucose addition (G(+) : glucose at 1.0 g/l, G(-) : no glucose) and four N sources (N1: 1.0 g/l yeast extract, 1.0 g/l tryptone and 0.5 g/l (NH(4))(2) SO(4); N2: 2.8 g/l yeast extract and 0.5 g/l (NH(4))(2) SO(4) ; N3: 1.6 g/l tryptone and 0.5 g/l (NH(4))(2) SO(4); N4: 1.4 g/l tryptone and 1.7 g/l yeast extract) in defined media. The optimal combinations of glucose and N sources to promote FAE and AE activity were G(+) N2 and G(+) N4, respectively. The peak activities of FAE and AE occurred on days 9 and 10, respectively. Addition of glucose and an increase in yeast extract and/or tryptone to a Hungate's medium favoured fungal production of volatile fatty acids, which could be just a consequence of more organic matter available to digest. This suggests that enzymatic release of ferulic acid by a synergistic action of lignin hydrolytic esterase and polysaccharide hydrolases may be essential for plant cell wall biodegradation in the rumen.

Feruloylated and Nonferuloylated Arabino-oligosaccharides from Sugar Beet Pectin Selectively Stimulate the Growth of Bifidobacterium spp. in Human Fecal in Vitro Fermentations

The side chains of the rhamnogalacturonan I fraction in sugar beet pectin are particularly rich in arabinan moieties, which may be substituted with feruloyl groups. In this work the arabinan-rich fraction resulting from sugar beet pulp based pectin production was separated by Amberlite XAD hydrophobic interaction and membrane separation into four fractions based on feruloyl substitution and arabino-oligosaccharide chain length: short-chain (DP 2-10) and long-chain (DP 7-14) feruloylated and nonferuloylated arabino-oligosaccharides, respectively. HPAEC, SEC, and MALDI-TOF/TOF analyses of the fractions confirmed the presence of singly and doubly substituted feruloylated arabino-oligosaccharides in the feruloyl-substituted fractions. In vitro microbial fermentation by human fecal samples (n = 6 healthy human volunteers) showed a selective stimulation of bifidobacteria by both the feruloylated and the nonferuloylated long-chain arabino-oligosaccharides to the same extent as the prebiotic fructo-oligosaccharides control. None of the fractions stimulated the growth of the potential pathogen Clostridium difficile in monocultures. This work provides a first report on the separation of potentially bioactive feruloylated arabino-oligosaccharides from sugar beet pulp and an initial indication of the potentially larger bifidogenic effect of relatively long-chain arabino-oligosaccharides as opposed to short-chain arabino-oligosaccharides.

Effect of Glucose Levels and N Sources in Defined Media on Fibrolytic Activity Profiles of Neocallimastix sp. YQ1 Grown on Chinese Wildrye Grass Hay or Alfalfa Hay

Ferulic acid esterase (FAE) and acetyl esterase (AE) cleave feruloyl groups substituted at the 5'-OH group of arabinosyl residues and acetyl groups substituted at O-2/O-3 of the xylan backbone, respectively, of arabinoxylans in the cell wall of grasses. In this study, the enzyme profiles of FAE, AE and polysaccharide hydrolases of the anaerobic rumen fungus Neocallimastix sp. YQ1 grown on Chinese wildrye grass hay (CW) or alfalfa hay (AH) were investigated by two factorial experiments, each in 10-day pure cultures. The treatments consisted of two glucose levels (: glucose at 1.0 g/L, : no glucose) and four N sources (N1: 1.0 g/L yeast extract, 1.0 g/L tryptone and 0.5 g/L ; N2: 2.8 g/L yeast extract and 0.5 g/L ; N3: 1.6 g/L tryptone and 0.5 g/L ; N4: 1.4 g/L tryptone and 1.7 g/L yeast extract) in defined media. The optimal combinations of glucose level and N source for the fungus on CW, instead of AH, were and for maximum production of FAE and AE, respectively. Xylanase activity peaked on day 4 and day 6 for the fungus grown on CW and AH, respectively. The activities of esterases were positively correlated with those of xylanase and carboxymethyl cellulase. The fungus grown on CW exhibited a greater volatile fatty acid production than on AH with a greater release of ferulic acid from plant cell wall.

Characterization of Oligomeric Xylan Structures from Corn Fiber Resistant to Pretreatment and Simultaneous Saccharification and Fermentation

Corn fiber, a byproduct from the corn industry, would be a good source for bioethanol production if the hemicellulose, consisting of polymeric glucoronoarabinoxylans, can be degraded into fermentable sugars. Structural knowledge of the hemicellulose is needed to improve the enzymatic hydrolyses of corn fiber. Oligosaccharides that resisted a mild acid pretreatment and subsequent enzymatic hydrolysis, representing 50% of the starting material, were fractionated on reversed phase and size exclusion material and characterized. The oligosaccharides within each fraction were highly substituted by various compounds. Oligosaccharides containing uronic acid were accumulated in two polar fractions unless also a feruloyl group was present. Feruloylated oligosaccharides, containing mono- and/or diferulic acid, were accumulated within four more apolar fractions. All fractions contained high amounts of acetyl substituents. The data show that complex xylan oligomers are present in which ferulic acid, diferulates, acetic acid, galactose, arabinose, and uronic acids were combined within an oligomer. Hypothetical structures are discussed, demonstrating which enzyme activities are lacking to fully degrade corn glucuronoarabinoxylans.