Werner Praznik

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.

Application of gel permeation chromatographic systems to the determination of the molecular weight of inulin

Abstract The application of different gel types to the separationn of inulin is discussed. A system consisting of two different columns is used for the determination of different inulins of various Compositae. The system is calibrated with glucan oligomers, by comparing the migration behaviour of the glucan series with the inulin series. The molecular weights of inulins of various plants are calculated from the different molecular distributions using the calibrated column system. The general belief that inulin has a chain length between 30 and 35 monomeric units, irrespective of the source, could not be confirmed.

Characterisation of the high-molecular weight fructan isolated from garlic (Allium sativum L.).

A high molecular weight fructan was isolated from garlic and the structure determined by enzymatic, chemical and spectroscopic (NMR) methods. It was found that the garlic fructan belongs to the neokestose family. It has a (2 --> 1)-linked beta-D-Fruf backbone with (2 --> 6)-linked beta-D-Fruf side chains. A structural model was postulated for a degree of polymerisation of about 58. This model was substantiated using an endo-inulinase purified from Aspergillus ficuum and by 1H and 13C NMR spectroscopy.

Molecular background of technological properties of selected starches

Selected starches, i.e. waxy maize, amaranth, quinoa, wheat, millet and buckwheat starches, were investigated with respect to their technological properties such as gelatinization, stability to mechanical stress, resistance to conditions and stability in continuous freeze/thaw cycles. Technological properties are correlated with molecular features such as branching characteristics in terms of iodine-complexing potential, molar mass, occupied glucan-coil volume, packing density of glucan coils and rheological properties. Waxy maize and amaranth starches were found to be amylopectin-type short-chain branched (scb) glucans with weight average molar masses M w = 17 × 10 6 g/mol and 12 × 10 6 g/mol, respectively. Waxy maize starch had a high gelatinization potential, high viscosity at 95 °C (340 mPas) low stability at acidic conditions, average stability to shearing and good freeze/thaw stability. For amaranth starch a viscosity of 122 mPas at 95°C, low resistance to acid, but high stability to applied shearing and even high freeze/thaw stability was determined. Investigated quinoa starch was classified as scb-type glucan, however, the branches are significantly longer than those of waxy maize and amaranth. With a M w = 11 × 10 6 g/mol and a viscosity of 187 mPas at 95°C, this sample is comparably resistant to acidic conditions and to shearing, but instable in freeze/thaw experiments. Wheat, millet and buckwheat starches contain significant percentages of amylose-type long-chain branched (lcb) glucans (22.1, 32.1 and 24.3%, respectively) with M w values of 5 × 10 6 g/mol, 12 × 10 6 g/mol and 15 × 10 6 g/mol, respectively. Wheat starch, with a viscosity of 107 mPas at 95°C, shows low stability under acidic conditions, but high stability to shearing. Wheat and millet starches, but not buckwheat starch, form weak gels in the course of subsequent freeze/thaw cycles. Millet starch, with a viscosity of 101 mPas at 95 °C was found to be moderately stable under acidic conditions and to shearing. Buckwheat starch with a viscosity of 230 mPas at 95 °C shows no acid resistance and is instable upon shearing but performs very well in freeze/thaw experiments.

The structure of the fructan sinistrin from Urginea maritima

The structure of sinistrin from red squill (Urginea maritima) was determined by methylation analysis and 13C NMR spectroscopy, using the fructans from Pucinella peisonis and quack-grass (Agropyron repens) as reference substances. Application of the reductive cleavage method showed that, of the beta-D-fructofuranosyl residues in sinistrin, 33% were 1-linked, 19% were 6-linked, 25% were terminal, and 19% were 1,6-linked. The average dp was 31 and, of the 3.24% of alpha-D-glucopyranosyl residues, 0.54% were terminal and 2.70% were 6-substituted. The fructan of quack grass was also highly branched with a (2-->6)-linked backbone, terminal alpha-D-glucopyranosyl residues, and a dp of approximately 45. The fructan from Pucinella peisonis was slightly branched, with a dp of approximately 10 and a (2-->6)-linked backbone.

Structural characterization of the N-linked oligosaccharides from tomato fruit

The primary structures of the N-linked oligosaccharides from tomato fruit (Lycopersicon esculentum) have been elucidated. For the isolation of the protein fraction, two procedures were employed alternatively: a low temperature acetone powder method and ammonium sulfate precipitation of the tomato extract. After peptic digestion, the glycopeptides were purified by cation-exchange chromatography; the oligosaccharides were released by N-glycosidase A and fluorescently labelled with 2-aminopyridine. Structural characterization was accomplished by means of two-dimensional HPLC in combination with exoglycosidase digestions and MALDI-TOF mass spectrometry. Two varieties as well as two stages of ripening were investigated. In all the samples, the same sixteen N-glycosidic structures were detected; the two most abundant glycans showed identical properties to those of the major N-linked oligosaccharides of horseradish peroxidase and pineapple stem bromelain, respectively and accounted for about 65-78% of the total glycan amount; oligomannosidic glycans occurred only in small quantities (3-9%). The majority of the N-glycans were beta 1,2-xylosylated and carried an alpha 1,3-fucose residue linked to the terminal N-acetylglucosamine. This structural element contributes to cross-reactions among non-related glycoproteins and has been shown to be an IgE-reactive determinant (Tretter, Altmann, Kubelka, März, & Becker, 1993). The presented study gives a possible structural explanation for reported immunological cross-reactivities between tomato and grass pollen extracts due to carbohydrate IgE epitopes (Petersen, Vieths, Aulepp, Schlaak, & Becker, 1996), thereby demonstrating the importance of the structural characterization of plant N-glycans for a more reliable interpretation of immunological data.

Effect of Chlorophytum Borivilianum Santapau and Fernandes on sexual dysfunction in hyperglycemic male rats

ObjectiveTo investigate the effects of Chlorophytum borivilianum (CB) on sexual dysfunction, loss of body weight, and lack of libido in hyperglycemic rats induced with streptozotocin or alloxan.MethodsWistar strain male albino rats were divided into five groups of six animals each: the control group (2% polyvinylpyrollidone solution), the streptozotocin control group (50 mg/kg), the alloxan control group (100 mg/kg), the streptozotocin + CB treated group (200 mg/kg), and the alloxan + CB treated group (200 mg/kg). Only after confirming the induction of diabetes, the animals of test groups were treated with CB. The sexual behavior of male rats of in presence of female rat in a special cage was recorded. The effects of induced diabetes in control groups and on simultaneous extract treatment in CB treated groups were tested for sexual parameters. The parameters evaluated included mount, ejaculation, and intromission latencies/frequencies, hesitation time, and penile erection index. Parallel to this, using a separate set of similarly treated animals, the influence of diabetes and CB treatment on anabolism and weight of secondary sexual organs were determined on day 0 and day 28 of the treatment.ResultsCB extract treatment ameliorated the diabetes-induced dysfunction at 200 mg/kg dose. There was very low weight loss (P<0.05) in CB-treated animals as compared to the diabetic control. There was a very high latency time (P<0.05) in the diabetic animals, whereas the latency time was very low in CB-treated animals. Mount, intromission, and ejaculation frequencies were very high (P<0.01) in CB-treated animals, while streptozotocin and alloxan groups animals had a very significantly lower sexual behavior (P<0.05) compared to the normo-glycemic control group animals.ConclusionCB can significantly ameliorate diabetes-induced sexual dysfunction. Polysaccharide and saponin-rich aqueous extract appears to have the most suitable effects on diabetes and its associated effects on sexual functionality.

Characterisation of the (1→4)-α-d-glucan-branching 6-glycosyltransferase by in vitro synthesis of branched starch polysaccharides

Abstract Starch branching enzyme (Q-enzyme; EC 2.4.1.18), isolated from young, mature potato tubers (Solanum tuberosum L.) and purified by ammonium sulfate precipitations, hydrophobic-interaction chromatography, and size-exclusion chromatography, was completely free of phosphorylase (EC 2.4.1.1) and alpha-amylase (EC 3.2.1.1) activity, had a molecular mass of 64 kDa, was homogeneous in SDS-PAGE, was inhibited by 4 × 10−5 m oxidised glutathione, and could be stored at −80° in the presence of SH-reducing agents. The actions of Q-enzyme alone and in combination with potato phosphorylase on amylose, pea starch, potato amylose, potato amylopectin, and waxy maize was investigated. The combination gave high molecular weight polysaccharides, debranching of which yielded patterns of short and long chains similar to those of debranched amylopectin. Treatment of amylose with Q-enzyme reseulted in a decrease in the molecular weight averages and broadening of the molecular weight distribution, and debranching of the product yielded a short-chain distribution pattern.

Structure of fructo-oligosaccharides from leaves and stem of Agave tequilana Weber, var. azul

Fructo-oligosaccharides (FOSs) of a six year old agave plant variety, Agave tequilana, were isolated and fractionated by 2D preparative chromatography (SEC and rpHPLC). Structural analyses of different FOS-fractions were performed by reductive methylation analysis connected to GC/FID identification and NMR-analysis. FOSs from leaves (d.p. 3-8) contain single α-d-Glcp residues as well in terminal as internal position, however (2→1)-linked β-d-Fruf residues only. FOSs from stem, however, contain as well (2→1)- and (2→6)-linked β-d-Fruf residues with branched oligomeric repeating units. These characteristics indicate an enzymatically catalyzed metabolic regulation for the biosynthesis and transformation of fructans in A. tequilana which strongly depends on location and transport activities.

Fructo-oligosaccharides from Urginea maritima☆

Fructo-oligosaccharides from red squill (Urginea maritima) were isolated by precipitation with methanol, GPC on Biogel P2/P4, and reversed-phase HPLC. Structures of the tri- and tetra-saccharides were verified by the reductive cleavage method. A tetrasaccharide that contained both (2-->1)- and (2-->6)-linked beta-D-Fru f residues was isolated. The higher fractions from GPC were analysed by the reductive cleavage method without prior purification by reversed-phase HPLC. The mode of biosynthesis of sinistrin is discussed.