Cell Wall-bound Phenolic Acids Research Articles

Novel Combination of the Biophysical, Nutritional, and Nutraceutical Properties in Subtropical Pigmented Maize Hybrids.

Maize (Zea mays L.) represents the main caloric source for much of the world's population. Pigmented maize varieties are an excellent source of nutraceutical compounds: blue and yellow maize are rich in anthocyanins as well as carotenoids and phenolic acids, respectively. However, blue maize is usually grown in small quantities as a specialty crop because it lacks the qualities and adaptations of commercial white and yellow varieties. Here, a new high-yield variety of blue maize called Vitamaiz was developed from inbred lines of subtropical blue, white, and yellow maize. The aim of this study was to characterize the nutraceutical and physical properties of 30 Vitamaiz hybrids in two subtropical locations. Kernel physical traits, nutrient composition, and nutraceutical components (free phenolic acids, FPA; cell wall-bound phenolic acids, BPA; total monomeric anthocyanin content, TAC; antioxidant capacity, AOX by oxygen radical absorbance capacity assay, and total carotenoid content, TCC) were evaluated. The biophysical traits of the hybrids were suitable for nixtamalized and flour maize industries. High levels of FPA (228 mg GAE/100 g), BPA (635 mg GAE/100 g), and AOX (2.0 and 8.1 mM Trolox equivalent/100 g for FPA and BPA, respectively) were also detected with elevated TAC levels (274 mg C3G/kg dw) and AOX activity (3.1 mM Trolox equivalent/100 g). This is the first study to characterize Blue × Yellow maize hybrids that adapt to subtropical environments.

Constitutive Changes in Nutrients and Phytochemicals in Kernels of Aluminium-Tolerant Maize (Zea mays L.)

Maize (Zea mays L.) is among the three most important food crops worldwide. Maize growth is affected by high aluminium content in acid soils, which constitute nearly 50% of the world’s cultivable area. Therefore, the cultivation of aluminium-tolerant maize hybrids could be a healthier alternative and an attractive food source in these regions. In this regard, to produce hybrids kernels, 16 inbred lines aluminium-tolerant (Al-T) and aluminium-susceptible (Al-S) maize were screened for their constitutive patterns of selected nutrients and phytochemicals. Proximate analysis, free phenolic acids (FPA) and cell wall-bound phenolic acids (CPA) contents, as well as antioxidant capacity (AOX) were assayed in the anatomical kernel parts (pericarp, endosperm, and germ). Kernels of Al-T maize contained significantly higher germ protein, oil, and fibre (2.9, 3.0, and 0.5%, respectively) than Al-S kernels (1.9, 1.8, and 0.3%, respectively). Importantly, the nutraceutical contents in terms of pericarp FPA and germ CPA were significantly higher in kernels belonging to Al-T maize (92 mg and 140 mg EGA/100 g). The highest AOX was observed in germ CPA of Al-T kernels (9.0 mmol TE/100 g). The results herein indicate that Al-tolerance mechanisms induce positive changes in the nutrients and phytochemicals; this implies that the hybrids generated using Al-T maize inbred lines could emerge as an attractive source of nutrients and phytochemicals in farming regions containing acid soils.

High-amylose corn in gluten-free pasta: Strategies to deliver nutritional benefits ensuring the overall quality

High-amylose corn alone or in combination (25% and 50%) with conventional corn was used to produce gluten-free pasta. Flour pre-gelatinization in a tank (process A) or on a conveyor belt (process B) were tested. Resistant starch (RS), soluble (SPAs) and cell-wall bound phenolic acids (CWBPAs) and antioxidant capacity were significantly higher in high-amylose corn pasta. Cooked pasta from process B showed a higher SPA concentration, likely due to the lower cooking loss. The structure of pasta prepared with process B was more homogeneous, whereas it was more compact in the case of process A, as shown by a lower starch susceptibility to α-amylase hydrolysis, higher beginning of gelatinization temperature and lower water absorption. 25% HA represents a good compromise between high RS (4.2%) and good cooking behavior. At higher HA levels, process B is more suitable to obtain pasta with a better cooking quality.

Distribution of bioactive compounds in pearled fractions of tritordeum

Hexaploid tritordeum is the amphidiploid cereal derived from the cross between wild barley and durum wheat. The present study compares two cultivars of tritordeum with other cereals grown in the same experimental area to weigh up its potential use as ingredient for health-valued foods. Tritordeum shows 2.5-fold higher concentration of lutein than common wheat and barley, and 1.2-fold higher than durum wheat, while the concentration of β-glucans is 5 folds lower than the one observed for barley. Based on the distribution of bioactive compounds in pearled fractions, the use of whole-grain flours seems the best way to exploit the antioxidant potential of tritordeum. Nevertheless, the internal layers of the kernel of this cereal are characterized on average by high concentrations of antioxidants (32.0 mg/kg and 518 mg/kg soluble and cell wall-bound phenolic acids, respectively), making tritordeum interesting also for the production of refined flours rich in bioactive compounds.

Changes in phenolic acid abundance involved in low temperature and Microdochium nivale (Samuels and Hallett) cross-tolerance in winter triticale (x Triticosecale Wittmack)

Tolerance to the pink snow mould resulting from Microdochium nivale infection is an essential trait of triticale (x Triticosecale) for winter survival. In the present study, we aimed to verify whether the presence and concentration of free and cell wall-bound phenolic acids are important factors in triticale responses to M. nivale infection. Based on 3 years’ testing of triticale tolerance, 2 out of 92 doubled haploid triticale lines derived from ‘Hewo’ × ‘Magnat’ F1 hybrid were selected, which are the most tolerant and the most sensitive to M. nivale infection. Plants were grown along with their parents under controlled conditions, pre-hardened and cold-hardened, while non-hardened plants served as the control. Hardened plants were covered with the artificial snow-imitating covers and inoculated with M. nivale mycelium, while the control plants were treated the same way except the infection. The aim of the study was to identify differences in the initial content and composition of phenolics under the influence of applied stresses. Conducted HPLC analysis showed that the most abundant were ferulic, rosmarinic, chlorogenic, sinapic, and trans-cinnamic acids. The contents of most of phenolics depended on genotype and growth conditions. Two cell wall-bound sinapic and trans-cinnamic acids, could be indicated as potentially related to the increased snow mould tolerance of winter triticale seedlings. A correlation between the total phenolic levels with the tolerance was not found; however, the proportion between the total levels of cell wall-bound and free phenolic compounds under low temperature could play a role prior to M. nivale infection.

Suppression of Hydroxycinnamate Network Formation in Cell Walls of Rice Shoots Grown under Microgravity Conditions in Space.

Network structures created by hydroxycinnamate cross-links within the cell wall architecture of gramineous plants make the cell wall resistant to the gravitational force of the earth. In this study, the effects of microgravity on the formation of cell wall-bound hydroxycinnamates were examined using etiolated rice shoots simultaneously grown under artificial 1 g and microgravity conditions in the Cell Biology Experiment Facility on the International Space Station. Measurement of the mechanical properties of cell walls showed that shoot cell walls became stiff during the growth period and that microgravity suppressed this stiffening. Amounts of cell wall polysaccharides, cell wall-bound phenolic acids, and lignin in rice shoots increased as the shoot grew. Microgravity did not influence changes in the amounts of cell wall polysaccharides or phenolic acid monomers such as ferulic acid (FA) and p-coumaric acid, but it suppressed increases in diferulic acid (DFA) isomers and lignin. Activities of the enzymes phenylalanine ammonia-lyase (PAL) and cell wall-bound peroxidase (CW-PRX) in shoots also increased as the shoot grew. PAL activity in microgravity-grown shoots was almost comparable to that in artificial 1 g-grown shoots, while CW-PRX activity increased less in microgravity-grown shoots than in artificial 1 g-grown shoots. Furthermore, the increases in expression levels of some class III peroxidase genes were reduced under microgravity conditions. These results suggest that a microgravity environment modifies the expression levels of certain class III peroxidase genes in rice shoots, that the resultant reduction of CW-PRX activity may be involved in suppressing DFA formation and lignin polymerization, and that this suppression may cause a decrease in cross-linkages within the cell wall architecture. The reduction in intra-network structures may contribute to keeping the cell wall loose under microgravity conditions.

Changes in phenolic acids and stilbenes induced in embryogenic cell cultures of Norway spruce by two fractions of Sirococcus strobilinus mycelian

We examined defence responses in embryogenic cell suspension cultures of Norway spruce (Picea abies [L.] Karst) elicited by intracellular protein and cell wall fractions (PF and WF, respectively) prepared from mycelia of the fungus Sirococcus strobilinus Preuss focusing on changes in (soluble and cell wall-bound) phenolic and stilbene concentrations. Treatment with both preparations induced an increase in the total contents of phenolic acids in Norway spruce cells and variations in the levels of stilbene glycosides. More rapid and intense induction of defence response was observed in cells after WF application. The contents of soluble phenolic acids (especially benzoic acid derivatives) and cell wall-bound phenolic acids (especially ferulic acid) started to increase (relative to controls) within 4 h after the addition of the WF preparation and remained high in elicited cells for 8–12 h. A moderate increase in phenolic acids in cells exposed to the PF preparation was observed within 8 h after application. However, after 24 h of WF treatment a decline of total phenolics was observed, while in PF elicited Norway spruce cells the phenolic content continued to increase. Significantly decreased concentrations of stilbene glycosides, isorhapontin, astringin and piceid, were determined in PF and WF treated Norway spruce cell cultures. The total content of stilbene glycosides decreased within 8 h after WF application to 68% of the amount determined in the control and within 12 h to 73% of the control in PF-treated cells. These results demonstrate that both PF and WF prepared from the Sirococcus strobilinus mycelium elicit changes in the metabolism of phenylpropanoids, which are involved in the defence responses of plants to pathogens.

Involvement of cell wall-bound phenolic acids in decrease in cell wall susceptibility to expansins during the cessation of rapid growth in internodes of floating rice

The cell walls in the elongating zone of submerged floating rice internodes show high susceptibility to expansins. When internode sections corresponding to such an elongation zone were incubated for 24 h under osmotic stress conditions produced by treatment with 100 mM polyethylene glycol 4000 (PEG), the cell wall susceptibility to expansins remained at its initial level, while the susceptibility of internode sections incubated under unstressed conditions decreased considerably during the same period. The contents of polysaccharides and phenolic acids as ferulic, diferulic and p-coumaric acids in the cell walls of internode sections increased substantially under unstressed conditions, but the increases were almost completely prevented by osmotic stress. Ferulic acid applied to internode sections under osmotic stress reduced the susceptibility of the cell walls to expansins and increased the levels of ferulic and diferulic acids in the cell walls, with little effect on the accumulation of polysaccharides. In contrast, applied p-coumaric acid increased the level of p-coumaric acid in the cell walls without a change in the levels of ferulic and diferulic acids but did not reduce the susceptibility to expansins. These results suggest that the deposition of ferulic and diferulic acids is a primary determinant in regulating the reduction of the susceptibility of cell walls to expansins in floating rice internodes.

Cadmium and Nickel Uptake Are Differentially Modulated by Salicylic Acid inMatricaria chamomillaPlants

Chamomile (Matricaria chamomilla) is a widely used medicinal plant which also accumulates heavy metals in its above-ground organs. We investigated the effect of the important plant signaling molecule, salicylic acid (SA), on the accumulation of Ni or Cd, by exposing plants over 7 days to 60 microM solutions of individual heavy metals with or without 50 microM SA. Special emphasis was focused on phenolic metabolism-related parameters, not only because of their importance for growth and stress tolerance but also because phenolics are potent antioxidants in human diet. In combined treatments, SA stimulated an increase in soluble proteins of roots and reduced their water content. SA reduced total Cd in the shoot and increased Ni. Total and "intraroot" Ni decreased in Ni + SA treatment, while in the case of Cd, only "intraroot" content decreased in Cd + SA treatment, being correlated with cell wall-bound phenolic acids and lignin. SA was strongly accumulated in roots from the Ni + SA treatment, being correlated with an increase in hydrogen peroxide. In both Cd + SA and Ni + SA treatments, SA enhanced phenylalanine ammonia-lyase activity and accumulation of total soluble phenols, particularly in the roots. Here, we report for the first time that soluble phenols may be involved in Cd shoot-to-root translocation. In the case of Ni, it seems that phenols serve as a root barrier in order to prevent Ni from reaching the above-ground organs. The effects of SA on phenolic metabolism, and the signaling role of ROS in the accumulation of phenols, are discussed.

Induced changes in phenolic acids and stilbenes in embryogenic cell cultures of Norway spruce by culture filtrate of Ascocalyx abietina

The aim of this work was to identify whether the Ascocalyx abietina culture filtrate has the ability to induce changes in the contents of phenolic substances that might be indicative for the disease response of Norway spruce (Picea abies). We focused on the accumulation of soluble and cell wall-bound phenolics, stilbenes as well as extracellular peroxidase activities elicited in the embryogenic cell cultures of Norway spruce by A. abietina culture filtrate. Treatment of spruce cells with fungal culture filtrate (5 and 20% v/v concentrations) evoked an increase in the total contents of phenolic acids (represented by the sum of free, methanol soluble ester- and glycoside-bound phenolics and methanol insoluble cell-wall bound phenolic esters). The challenge with filtrate was in particular manifested in the increase (compared with the control) in the contents of cell wall-bound phenolic acids (by about 100 and 130% in 5 and 20% filtrate, respectively) and soluble phenolic glycosides (by 37 and 65% in 5 and 20% filtrate, respectively) already 6 h after filtrate addition. Significantly decreased concentrations of stilbene glycosides, isorhapontin, astringin and piceid, were determined in filtrate-treated spruce cell cultures 6 and12 h after filtrate addition. The culture filtrate did not influence significantly the extracellular peroxidase activity 12 h after filtrate addition. Reduced extracellular peroxidase activity at 24 and 48 h in treated cells and decline in the amounts of soluble phenolics coincided with the rate of browning of filtrate-treated cells.

GENETIC VARIATION OF PHENOLIC COMPOUNDS CONTENT, ESSENTIAL OIL COMPOSITION AND ANTI OXIDATIVE ACTIVITY IN ISRAEL-GROWN MENTHA LONGIFOLIA L.

Phenolic acids, in free soluble form and cell wall-bound, were extracted from leaves and stems from 40 genetic variants from 25 populations of Mentha longifolia native to Israel. Rosmarinic and caffeic acid were the most abundant freely soluble acids whereas caffeic acid was most abundant among cell wall-bound phenolic acids. Assessment of the total antioxidant efficacy, based on the reduction of 1,1-diphenyl-2-picryldrazyl (DPPH), revealed high antioxidant activity by tissues of many M. longifolia variants, stemming in part, from antioxidant activity of rosmarinic acid. Although phenolic acids in free extractable form comprise a major portion of total phenolic acids, cell wall-bound acids were found in significant amounts and may also contribute to the antioxidant efficacy of the plants.

Soluble and cell wall-bound phenolics and lignin in Ascocalyx abietina infected Norway spruces

This study was conducted to identify the defence-related alterations in phenylpropanoid pathway in Norway spruce trees naturally infected with Ascocalyx abietina (Lagerberg). The results show differences in accumulation of soluble and cell wall-bound phenolics, contents of lignin and total peroxidase activities in the bark collected from three distinct regions of infected branches. The sites of the A. abietina infection, the browning reaction zones, were characterised by significantly higher levels of free and cell wall-bound phenolic acids, higher amount of lignin and lower peroxidase activities when compared with zones localised 20–30 mm from the margin of browning area and regions of infected branches that were not in contact with the pathogen. On the rise of phenolic contents in the reaction zones participated predominately derivatives of cinnamic acid, in particular p-coumaric acid, content of which increased by about 2.3- and 3.0-fold compared to the controls grown on two different stands in Karlův vrch and Velká Deštná. Pronounced accumulation of ester- and glycoside-bound benzoic acid derivatives (namely p-hydroxybenzoic and protocatechuic acids) was observed in regions of infected branches that were not in contact with the pathogen. The induction of biochemical response in these healthy looking zones of branches from infected trees might represent a systemic induction of phenylpropanoid accumulation in A. abietina infected Norway spruces.

Changes in Cell Wall-Bound Phenolic Acids in the Internodes of Submerged Floating Rice

Submergence induces rapid elongation of internodes in floating rice (Oryza sativa L.). We examined the distributions of p-coumaric, ferulic and 5-5-coupled diferulic acids ester-linked to cell walls along the axis of highest internodes of submerged and air-grown floating rice stem segments. The amounts of ferulic and 5-5-diferulic acids per cell wall weight were lowest around the intercalary meristem, and increased as the distance from the meristematic zone increased toward the upper part of the internode in both air-grown and submerged stem segments. The ratio of 5-5-diferulic acid to ferulic acid also increased toward the upper, old parts of internodes in both air-grown and submerged stem segments. These observations suggest that the feruloylation of cell wall polysaccharides and the formation of diferulic acids contribute to the cessation of internodal cell elongation and that the formation of diferulic acids in cell walls is controlled by the coupling reaction in addition to the feruloylation. The amounts of p-coumaric acid per unit length and per cell-wall weight were markedly low in the newly elongated region of submerged internodes, and closely correlated with cell-wall dry mass in both air-grown and submerged internodes, suggesting that the deposition of p-coumaric acid in cell walls is related to the formation of secondary cell walls in floating rice internodes.

Changes in levels of cell wall constituents in wheat seedlings grown under continuous hypergravity conditions

Effects of continuous hypergravity stimuli on the amounts and composition of cell wall constituents were investigated in wheat shoots. Hypergravity (300 g) treatment for three days after germination increased the net amount of cell wall polysaccharides such as hemicellulose and cellulose, but reduced the shoot elongation. As a result, the amount of cell wall polysaccharides per unit length of shoot increased under hypergravity. The hemicellulose fraction contained polysaccharides in the middle and low molecular mass range (5 kDa-1 MDa) and increased in response to hypergravity. Also, the amounts of arabinose (Ara) and xylose (Xyl), the major sugar components of the hemicellulose fraction, increased under hypergravity conditions. In addition to wall polysaccharides, hypergravity increased the amounts of cell wall-bound phenolic acids, such as ferulic acid (FA) and diferulic acid (DFA). Furthermore, the activity of phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) was enhanced under hypergravity conditions. These results suggest that continuous hypergravity stimulates the synthesis of cell wall constituents, especially hemicellulosic arabinoxylans and cell wall-bound FA and DFA in wheat shoots. The increased PAL activity may promote the formation of FA and DFA. These changes in cell wall architecture may be involved in making rigid and tough cell walls under hypergravity conditions and thereby contribute to the ability of plant to sustain their structures against gravitational stimuli.

Biodegradability of Free Monomeric and Cell-Wall-Bound Phenolic Acids in Maize Stover by Two Strains of White-Rot Fungi

Development of fungal bioconversion technology to upgrade feeding value of fibrous crop residues into animal feed requires the understanding of the impact of fungal treatments on cell wall phenolic acids. This study investigated the capacity of two strains of white-rot fungi, Phanerochaete chrysosporiumandPhlebia brevispora, in degrading cell wall-bound phenolic acids in maize (Zea maizeL) stover and the free phenolic monomers in a liquid culture medium. In the study, 150 mg litre−1 ofp-coumaric acid (PCA), ferulic acid (FA), syringic acid (SYA),p-hydroxybenzoic acid (PHBA), vanillic acid (VA), and 200 mg litre−1 of caffeic acid (CA) were added to a liquid nutrient medium and incubated with each of the fungi for 28 days. The results indicated that within 21 days the fungal treatments completely removed the added PCA and FA from the medium, and over 94% of SYA was degraded after 28 days. During the incubation periods, VA and PHBA were also extensively removed byP chrysosporium, but resistant to degradation byP brevispora. Disappearance of caffeic acid from the medium was related to both fungal degradation and abiotic hydrolysis. In the culture media,P chrysosporiumwas superior toP brevisporain removing the phenolic acids. Solid incubation of maize stover with the selected fungi for 28 days resulted in extensive degradation of cell-wall-bound FA and PCA. However, complete degradation of cell wall FA and PCA did not occur in maize stover. In contrast to results in pure liquid medium,P chrysosporiumdegraded only 20% of the initial concentration of cell wall PCA, and was less effective in degrading cell wall FA compared toP brevispora. These results indicate that the white-rot fungi were able to degrade phenolic acids both in pure culture medium and in cell wall matrix of maize stover. Furthermore,P brevisporaexhibited stronger ability to degrade cell-wall-bound phenolic acids. Thus, this fungus can be more effective for the enhancement of fibre digestibility.

Changes in Pattern of Phenolic Acids Induced by Culture Filtrate of Fusarium oxysporum in Alfalfa Plants Differing in Susceptibility to the Pathogen

Plants of alfalfa ( Medicago sativa L.) differing in their susceptibility to Fusarium oxysporum Schlecht were cultivated in hydroponic solution with crude culture filtrate of this pathogen. Susceptibility of plant seedlings to the pathogen positively correlated with the sensitivity of seedlings to culture filtrate treatment. The 6-week old susceptible control seedlings accumulated higher amounts of free and bound phenolic acids than was determined in resistant control seedlings (122.54 and 98.37 μg g −2 fresh mass, respectively). In spite of the higher content of total phenolics, salicylic and caffeic acids were not detected in the susceptible genotype. Culture filtrate treatment caused significant changes in the total content and fraction composition of phenolic acids in both studied plants. In susceptible seedlings the increase in the level of free and cell wall-bound phenolic acids was compensated for by a decrease in the content of phenolic glycosides. In resistant seedlings all the determined fractions (free, ester-, glycoside- and cell wall-bound phenolic acids) participated in the rise of total content of phenolics. The level of cinnamic acid derivatives increased earlier and more significantly in resistant seedlings. A relatively high level of salicylic acid was detected in seedlings of both genotypes challenged for 72 h.