Amounts Of Fructans Research Articles

PECULIARITIES OF THE ACCUMULATION OF GLUCOFRUCTANS IN THE ABOVE-GROUND PART OF THE SPECIES OF THE GENUS ALLIUM (AMARYLLIDACEAE)

The specifics of the accumulation of fructose-containing carbohydrates (glucofructans) in the above-ground parts of Allium L. species were studied. High molecular weight glucofructans (polyfructans) were present in significant amounts (6.9–10.1%) during the spring regrowth period in the leaves of A. jesdianum Boiss. & Buhse and A. victorialis L. During active growth and budding, their content dropped sharply (up to 0–3.6%). In A. victorialis, at the end of the growing season, the amount of polyfructans in the leaves of the second generation increased markedly (up to 9.7–11.8%). Since the leaves of this species are preserved under the snow all winter, fructans, probably, have a protective function, increasing their resistance to low temperatures.
 In all the studied species, polyfructans were accumulated in the underground part in much greater quantities than in the leaves, except for A. victorialis, where their content in the aboveground and underground parts was similar in the same phenophases, or in the leaves they were contained in larger quantities.
 The content of low molecular weight glucofructans (oligofructans) in leaves at the beginning of the growing season varied from 2.9 to 11.7% in different species. During the period of active growth and budding their content increased significantly up to 4.6–18.9%. The leaves of A. aflatunense B. Fedtsch., A. jesdianum, A. hollandicum R.M. Fritsch, A. rosenbachianum Regel, belonging to the subgenus Melanocrommyum (Webb & Berthel.) Rouy, and A. victorialis, belonging to the subgenus Anguinum (G.Don ex W.D.J.Koch) N.Friesen, are the richest in oligofructans. In A. obliguum L. and A. saxatile M. Bieb., belonging to the subgenus Polyprason Radić, the content of oligofructans in the leaves was significantly lower than in the previous species.
 Considerable amounts of fructans were accumulated in the inflorescences of A. victorialis and A. obliquum.

Fructan (Levan) is a more pervasive polysaccharide in the sugar industry than previously thought

Fructan (levan) is a fructose polysaccharide connected by b2→6 glycosidic linkages but, compared to dextran, the amounts of fructan in factory products are much less known. By using a new enzymatic (research) method that incorporates newly available recombinant enzymes, which comes in kit form from Megazyme®, considerable amounts of fructan (>9000 mg/kg) were consistently found in final (C) molasses from Louisiana cane sugar factories. Results were verified by breaking down the fructan with inulinase and measuring resultant products with ion chromatography. Fructan was observed to be strongly related to the recovery of sucrose in upstream and downstream factory products. Results also have, at least to a partial extent, explained why total polysaccharides are often much greater than haze dextran values in Louisiana. A major source of fructan is the microbial deterioration of sugarcane either outside or inside the factory or both. Identification of the microorganisms causing the formation of fructan is urgently needed.

Side‐by‐side comparison of composition and structural properties of wheat, rye, oat, and maize bran and their impact on in vitro fermentability

AbstractBackground and objectivesCompared to wheat bran, less information on physicochemical characteristics and health‐related effects is available for bran from other cereals and results are often confounded by residual endosperm. Therefore, the objective of this study was to compare structure and composition of endosperm‐depleted bran of wheat, rye, oat, and maize, and link these characteristics to fecal fermentation characteristics.FindingsCompared to wheat, endosperm‐depleted rye bran contained twice the amount of fructan (8.0% dm) and water‐extractable arabinoxylan (1.4% dm). Oat bran had a more open structure and was rich in (1,3:1,4)‐β‐glucan (17.0% dm). For rye and oat bran, and to a lesser extent wheat bran, fermentation with fecal microbiota resulted in short chain fatty acid production, with full metabolization of fructan and β‐glucan after 2 and 24 hr of fecal fermentation, respectively. For maize bran, a less accessible structure containing over 70% of arabinoxylan and cellulose was coupled to a lower degree of fecal fermentation.ConclusionRemoval of endosperm as a confounding factor when studying bran properties allowed us to obtain more accurate estimates of the composition, structure, and some physicochemical characteristics of bran of wheat, rye, oat, and maize. Bran fecal fermentation characteristics were mainly determined by composition and to a lesser extent by accessibility of the structure.Significance and noveltyThis is the first study that compares composition, structure, and fecal fermentation characteristics of wheat, rye, oat, and maize bran, after eliminating endosperm as a confounding factor. The knowledge obtained will allow a more goal‐oriented choice of bran type for incorporation into food products, depending on targeted physiological effects and nutritional impact.

Nutrients and natural toxic substances in commonly consumed Jerusalem artichoke (Helianthus tuberosus L.) tuber

This study determined nutrients, chemical contaminants, (insecticide residues and heavy metals), and natural toxic substances (nitrate, nitrite, cyanide, oxalate, phytate, and trypsin inhibitor) in tubers of Jerusalem artichokes—Kaentawan in the Thai language—grown in four major provinces in Thailand. They were purchased, prepared, homogenized, and freeze-dried for further analysis using standard methods. All Kaentawan samples contained considerable amounts of fructans and dietary fiber (15.4±0.2gand3.2±0.8g/100gfresh weight [FW], respectively), as well as potassium and iron (339±61and0.32±0.05mg/100gFW, respectively). All samples had very low amounts of insecticide residues (37 compounds), cyanide, and trypsin inhibitor, as well as Pb, Cd, nitrate, and nitrite (0.82±0.09, 0.10±0.02, 1.9–17.5, and 0.01–0.24mgkg−1FW, respectively), in addition to oxalate and phytate (14±9and0.17±0.02mg/100gFW, respectively). This study’s data can be used for food composition databases and for safety consumption.

Structural Modifications of Fructans in Aloe barbadensis Miller (Aloe Vera) Grown under Water Stress.

Aloe barbadensis Miller (Aloe vera) has a Crassulaceae acid metabolism which grants the plant great tolerance to water restrictions. Carbohydrates such as acemannans and fructans are among the molecules responsible for tolerating water deficit in other plant species. Nevertheless, fructans, which are prebiotic compounds, have not been described nor studied in Aloe vera, whose leaf gel is known to possess beneficial pharmaceutical, nutritional and cosmetic properties. As Aloe vera is frequently cultivated in semi-arid conditions, like those found in northern Chile, we investigated the effect of water deficit on fructan composition and structure. For this, plants were subjected to different irrigation regimes of 100%, 75%, 50% and 25% field capacity (FC). There was a significant increase in the total sugars, soluble sugars and oligo and polyfructans in plants subjected to water deficit, compared to the control condition (100% FC) in both leaf tips and bases. The amounts of fructans were also greater in the bases compared to the leaf tips in all water treatments. Fructans also increase in degree of polymerization with increasing water deficit. Glycosidic linkage analyses by GC-MS, led to the conclusion that there are structural differences between the fructans present in the leaves of control plants with respect to plants irrigated with 50% and 25% FC. Therefore, in non-stressed plants, the inulin, neo-inulin and neo-levan type of fructans predominate, while in the most stressful conditions for the plant, Aloe vera also synthesizes fructans with a more branched structure, the neofructans. To our knowledge, the synthesis and the protective role of neo-fructans under extreme water deficit has not been previously reported.

Isolation, structural elucidation and immunomodulatory activity of fructans from aged garlic extract

Traditionally, garlic ( Allium sativum) is known to be a significant immune booster. Aged garlic extract (AGE) possesses superior immunomodulatory effects than raw garlic; these effects are attributed to the transformed organosulfur compounds. AGE is also known to contain fructans; the amount of fructans in AGE represents a small fraction (0.22%) of the total fructans in raw garlic. In order to evaluate the biological activity of fructans present in AGE, both high molecular weight (>3.5 kDa; HF) and low molecular weight (<3 kDa; LF) fructans were isolated. The structures of purified HF and LF from AGE determined by 1H NMR and 13C NMR spectroscopy revealed that both have (2 → 1) β- d-fructofuranosyl bonds linked to a terminal glucose at the non-reducing end and β- d-fructofuranosyl branching on its backbone. Biological activity of fructans was assessed by immunostimulatory activity using murine lymphocytes and peritoneal exudate cells (source of macrophages). Both HF and LF displayed mitogenic activity and activation of macrophages including phagocytosis. These activities were comparable to that of known polysaccharide immunomodulators such as zymosan and mannan. This study clearly demonstrates that garlic fructans also contribute to the immunomodulatory properties of AGE, and is the first such study on the biological effects of garlic fructans.

Cloning and functional characterization of a fructan 1-exohydrolase (1-FEH) in the cold tolerant Patagonian species Bromus pictus

Fructans are fructose polymers synthesized in a wide range of species such as bacteria, fungi and plants. Fructans are synthesized by fructosyltransferases (FTs) and depolymerized by fructan exohydrolases (FEHs). Bromus pictus is a graminean decaploid species from the Patagonian region of Argentina, which accumulates large amounts of fructans even at temperate temperatures. The first gene isolated from B. pictus fructan metabolism was a putative sucrose:fructan 6-fructosyltransferase (6-SFT). Here, a complete cDNA of the first fructan exohydrolase (FEH) from B. pictus (Bp1-FEHa) was isolated using RT-PCR strategies. The Bp1-FEHa encoding gene is present as a single copy in B. pictus genome. Functional characterization in Pichia pastoris confirmed Bp1-FEHa is a fructan exohydrolase with predominant activity towards beta-(2-1) linkages. Its expression was analyzed in different leaf sections, showing the highest expression levels in the second section of the sheath and the tip of the blade. Bp1-FEHa expression was studied along with FEH and FT activities and fructan accumulation profile in response to chilling conditions during a 7-day time course experiment. Bp1-FEHa expression and FEH activity followed a similar pattern in response to low temperatures, especially in basal sections of the sheaths. In these sections the FEH and FT activities were particularly high and they were significantly correlated to fructan accumulation profile, along with cold treatment.

Soluble dietary fibres in Jerusalem artichoke powders: composition and application in bread.

Powders of tubers from Jerusalem artichoke (Helianthus tuberosus, L.), cultivar Gigant, of different harvesting times (autumn and spring) were applied in bakery products, particularly in wheat/rye bread. The quality of this bread was compared to bread with cereal flours substituted with commercial products as Raftilin ST and Raftilose P95. Compared to standard and substituted bread, Jerusalem artichoke bread shows a high quality in organoleptic evaluation (grade I with 36.5 and 37.5 scores). In utilised Jerusalem artichoke powders (JAPs) the amount of fructan (inulin) hydrolysis to fructose during the baking process depends on its initial degree of polymerisation (dp). With JAP of autumn harvest (fructan: dpn = 9.9, dpw = 21.8) less fructose (24.6%) is formed than with those of spring harvest (fructan: dpn = 4.9, dpw = 7.1) (40.7%). Compared to this bread, substitution with commercial products Raftilin ST (inulin: dpn = 8.4, dpw = 17.4) and Raftilose P95 (fructo-oligosaccharides: dpn = 2.7, dpw = 3.0) yields 11.9% and 45.8% of fructose upon total hydrolysis, respectively. The loss of fructan content by the bakery process is 38% in bread with JAP of autumn and 43% in bread with JAP of spring harvest; Raftilin ST- and Raftilose P95-bread come up with loss of fructan content of 35% and 47%, respectively.

Storage and Remobilization of Soluble Carbohydrates after Heading in Different Plant Parts of a Winter Wheat Cultivar

Several types of water soluble carbohydrates (WSG) were traced into plant parts of a winter wheat (Triticum aestivum L.) cultivar from heading to physiological maturity. Field grown plants were harvested at intervals of a few days and divided into grain, chaff, leaf blades, leaf sheaths, rachis + peduncle and culm internodes. Leaf blades and sheath showed the peak of WSC contents at about anthesis. Culm internodes accumulated fructan and sucrose during the early grain-filling phase, from a week after anthesis until the milk-ripe stage, then remobilized them during late and final grain filling phases, from the milk-ripe stage until maturity. The amount of sucrose known as short-term storage WSC was higher than fructan known as long-term storage WSC in each internode throughout the grain-filling phase. Chaff showed a large amount of fructan and fructose before anthesis, although it did very little sucrose. A pattern of sucrose accumulation in chaff was very different from that of fructan, unlike the other parts. These patterns of changes in WSC contents in plant organs roughly corresponded with four grain-filling phases, the initial, early, late and final phases.

Pool sizes of fructans in roots and leaves of mycorrhizal and non‐mycorrhizal barley

The effect of arbuscular mycorrhizas on fructan accumulation was studied in barley (Hordeum vulgare) infected with Glomus mosseae. Treatments with and without fertilizer were included in order to distinguish between mere fertilizer effects and the effects of the symbiosis, and plants were harvested at two different time points, 35 and 50 d after planting. Fructan was the major storage carboyhdrate in both leaves and roots. The amounts of fructan were markedly altered in the mycorrhizal plants. In roots of non‐fertilized mycorrhizal plants, fructan pools were significantly greater than in the corresponding non‐mycorrhizal plants. By contrast, fertilization caused a general decrease in amounts of fructan in roots. The increase of fructan in mycorrhizal roots was correlated with a decrease of invertase activity. In leaves, fructan pools decreased or remained unchanged upon mycorrhizal infection; fertilization had a similar effect. However, when individual leaves of a plant were compared, intriguing effects of the mycorrhizal symbiosis could be observed. Whereas in non‐mycorrhizal plants, the youngest leaves had the highest fructan contents and the oldest leaves the lowest (as previously reported), this gradient was markedly altered in mycorrhizal plants, indicating systemic effects of mycorrhiza on assimilate partitioning in shoots.

Changes of enzyme activities associated with the mobilization of carbohydrate reserves (fructans) from the stem of wheat during kernel filling

Wheat plants were grown at a day/night temperature of 18/13°C under glasshouse conditions. Twenty‐two d after anthesis, one set of plants was shaded to 50% of the normal photon fluence rate, another was ‘degrained’ by selective spikelet removal which left only the grains in the five central spikelets; a further set was left as control. Individual plants were harvested at days 22, 30 or 42 after anthesis. Extracts from the peduncle and the penultimate internode were prepared to determine the activities of sucrose phosphate synthase, sucrose synthase, fructan exohydrolase and acid invertase, and to assess the concentration of hexose sugars, sucrose and fructans. Measurements were also made of ear and individual grain weights, and stem f. wt and d. wt. There was a decline in the amount of fructans with time, more pronounced in ‘shaded’ (source‐limited) than in control plants. By contrast, in ‘degrained’ (sink‐limited) plants, the amount of fructans in the stem initially rose, then decreased, with a concomitant increase in the amount of fructose. The shifts in sugar content of the wheat culm reflected both the sink demand of the ear and source activity. The activity of fructan exohydrolase correlated with the carbohydrate changes. Under limited photosynthate assimilation, the mobilization of fructans from the internodes towards the ear was related to an increase in this enzyme, whereas the other enzymes played a less direct role in the mobilization of fructan reserves from the wheat stem.

Seasonal fluctuations in fructan content and related enzyme activities in yacon (Polymnia sonchifolia)

The content of fructan and the activities of sucrose: sucrose fructan fructosyltransferase (EC 2.4.1.99), fructan: fructan fructosyltransferase (EC 2.4.1.100), and fructan hydrolase in each part of yacon (Polymnia sonchifolia) were determined during the growth period. During summer, the amount of fructan (g plant−1) accumulated in each part was minimal despite the existence of relatively high specific activities (units mg−1 protein) of sucrose: sucrose fructosyltransferase and fructan: fructan fructosyltransferase in the stems, roots, tuberous roots, and rhizo-mataceous stem. On the other hand, from October to December, the amount of fructan in the tuberous roots and rhizomataceous stem remarkably increased along with an increase of the total activities (units plant−1) of sucrose: sucrose fructosyltransferase and fructan: fructan fructosyltransferase. The specific and total activity of fructan hydrolase in each part markedly increased in September when the rapid regrowth of aerial parts after physical damage caused by strong typhoon winds was observed. In this month, the amount of fructan in the tuberous roots and rhizomataceous stem decreased. The specific and total activity of fructan hydrolase in the tuberous roots increased again in December while at the same time there was a decrease in the content of fructan and an increase in the content of fructose.

Effects of nitrogen deficiency on accumulation of fructan and fructan metabolizing enzyme activities in sink and source leaves of barley (Hordeum vulgare)

Seedlings of barley (Hordeum vulgare L. cv. Agneta) were grown hydroponically under continuous light, constant temperature and relative humidity. During the first two weeks, the relative growth rate (RGR) was kept at 25% by limiting only the supply of nitrogen. The cultures were then transferred to nitrogen‐free media and the amounts of fructan, starch, sucrose, glucose and fructose in sink and source leaves were measured at 0, 12, 24, 48, 72, 120 and 156 h. The activities of two key enzymes in fructan metabolism, sucrose:sucrose fructosyltransferase (SST), fructan exohydrolase (FEH), as well as acid invertase were also measured in the two types of leaves.The fructan and starch levels in both sink and source leaves increased during nitrogen deficiency. The highest increase in starch was 200% of the control while for fmctans a 700% increase was recorded. The activity of SST increased parallel to fructan accumulation in sink leaves. However the FEH activity was constant and not affected by nitrogen deficiency. The invertase activity both in sink and source leaves was reduced by nitrogen deficiency. More fructans as well as sucrose and fructose accumulated in source leaves compared to sink leaves both before and after nitrogen starvation. The results show that fructan is the major carbohydrate reserve accumulating under nitrogen deficiency both in sink and source leaves in barley plants. The induction of fructan accumulation in sink leaves caused by nitrogen deficiency is intimately connected with the regulation of SST

Effect of nitrate concentration during growth on carbon partitioning and sink strength in chicory

Abstract Chicory plants (Cichorium intybus), which produce a tuberized root containing high concentrations of fructans, were grown with nitrate at either optimal (4 mol m−3) or suboptimal (0.6 mol m−3) concentration. At 120 DAS (days after sowing), shoot/root dry mass ratio in the plants grown at low N was less than one-third of that of plants grown at the higher concentration. This reflected differences in shoot dry mass, as root dry mass was similar in the two treatments. Pulse-chase experiments with 14CO2 showed increased allocation of carbon to the root and decreased partitioning to the growing shoot in the plants grown at low N. Root activities of three enzymes involved in sucrose and fructan metabolism were measured, in an attempt to identify the factors which determine sink strength. Whereas invertase activity showed little difference between the treatments, sucrose synthase and particularly sucrose-sucrose fructosyl transferase were higher in the roots of plants grown at low N. Activity of SST was also much greater in roots of young plants synthesizing large amounts of fructan than in mature roots no longer producing fructan. It is, therefore, suggested that SST plays a role in determining the sink strength. Possible interactions between N status and SST activity/sink strength are discussed.

Differences in fructan accumulated in induced and field‐grown wheat plants: an elongation‐trimming pathway for their synthesis

summaryMature blades of wheat seedlings were induced to form fructan by excision and continuous illumination, and their sugars were analyzed either 24 or 60 h after induction by both gel permeation and high performance liquid chromatography. The earliest accumulated fructan consisted mainly of 1‐kestose, nystose, bifurcose, and short oligomers rich in (2→1)‐linkages and branch point residues. After several days, fructan included more than fifty compounds, among which one‐half of the total were heptamers or larger. Oligomers accumulated during long‐term incubation contained a higher proportion of (2→6)‐linkages than those accumulated early after induction. Stems of field‐grown wheat contained about the same amount of fructan as blades of induced seedlings, but with larger proportions of phlein oligomers initiating with 6‐kestose, phlein‐like oligomers initiating with bifurcose, and other branched oligomers enriched in (2→6)‐linkages. An ‘elongation‐trimming’ pathway is proposed in which a (2→1)‐specific fructan fructosyl transferase and O‐6 branching activity produce branched oligomers rich in (2→1)‐linkages, and in which a fructan exo‐hydrolase cleaves 1‐linked terminal‐fructosyl units selectively to have phlein‐like oligomers resistant to further hydrolysis.

The influence of phytohormones on growth, organ differentiation and fructan production in callus of Symphytum officinale L.

Callus derived from Symphytum officinale L. regenerants was cultured in the presence of various phytohormones. The growth rate of callus was stimulated by all phytohormones at various concentrations. With 1-naphthaleneacetic acid no organ differentiation could be observed. With indole-3-butyric acid at low concentrations only roots were formed, whereas 6-benzylaminopurine, kinetin and zeatin at various concentrations induced either root or shoot formation or the simultaneous regeneration of both. Minor amounts of fructans were formed at high 6-benzylaminopurine-, zeatin- and at all indole-3-acetic acid-concentrations. The concentration of 1-naphthaleneacetic acid had no influence on the fructan content. Highest rates of fructan synthesis occurred at low zeatin-concentrations up to 1.5 mg/l. Only zeatin at all concentrations induced the synthesis of polyfructans, whereas appreciable amounts of oligofructans were formed under the influence of all other phytohormones.

Fructan Synthesis in Tissue Cultures ofSymphytum officinale;L. Initiation, Differentiation, and Metabolic Activity

Tissue cultures originating from different organs i.e. leaves, leaf-stalks, ovaries, anthers, and roots of SYMPHYTUM OFFICINALE were initiated under various growth conditions and subcultured several times to give the first callus generation. From all these calli, whole plants could be regenerated which again were used for the preparation of tissue cultures resulting in the formation of the second callus generation. The different calli and the regenerated plants were analyzed with respect to the fructan-synthesizing capacity. Only calli derived from the leaves of the original plant synthesized fructan whereas calli derived from ovaries, anthers, and roots, which are known to contain large amounts of fructan, were not capable of synthesizing fructan. The regenerated plants obtained from the first callus generation showed ability for fructan synthesis only if the originating callus synthesized fructan. The calli of the second generation, which were prepared from fructan-containing leaves and roots of regenerated plants, showed the capacity for fructan formation. The calli of the second generation obtained from leaves and roots of regenerated, fructan-free plants were not able to synthesize this specific reserve polysaccharide. From these data it can be concluded that the calli of the first generation prepared from roots, ovaries, and anthers have lost their ability for fructan synthesis. Calli initiated from leaves and leaf-stalks preserved the capacity for fructan formation even after many calli generations and regeneration to entire plants. Different phytohormones used in the tissue cultures had only a slight effect upon the fructan formation. An influence of light on fructan synthesis could not be detected.

Fructan-Synthesis in Cell Cultures of Symphytum officinale

Tissue cultures originating from different organs i.e. leaves, leaf-stalks, ovaries, anthers, and roots of Symphytum officinale were initiated under various growth conditions and subcultured several times to give the first callus generation. From all these calli, whole plants could be regenerated which again were used for the preparation of tissue cultures resulting in the formation of the second callus generation. The different calli and the regenerated plants were analyzed with respect to the fructan-synthesizing capacity. Only calli derived from the leaves of the original plant synthesized fructan whereas calli derived from ovaries, anthers, and roots, which are known to contain large amounts of fructan, were not capable of synthesizing fructan. The regenerated plants obtained from the first callus generation showed ability for fructan synthesis only if the originating callus synthesized fructan. The calli of the second generation, which were prepared from fructan-containing leaves and roots of regenerated plants, showed the capacity for fructan formation. The calli of the second generation obtained from leaves and roots of regenerated, fructan-free plants were not able to synthesize this specific reserve polysaccharide. From these data it can be concluded that the calli of the first generation prepared from roots, ovaries, and anthers have lost their ability for fructan synthesis. Calli initiated from leaves and leaf-stalks preserved the capacity for fructan formation even after many calli generations and regeneration to entire plants. Different phytohormones used in the tissue cultures had only a slight effect upon the fructan formation. An influence of light on fructan synthesis could not be detected.