Effect of storage xyloglucans on peritoneal macrophages.

Xyloglucans from seeds of Copaifera langsdorffii (XGC), Hymenaea courbaril (XGJ) and Mucuna sloanei (XGM) were obtained from milled and defatted cotyledons by aqueous extraction at 25 degrees C. The resulting fractions contained Glc, Xyl and Gal in molar ratios of 2.5: 1.5: 1.0 (XGC), 3.8: 2.6: 1.0 (XGJ) and 2.5: 1.6: 1.0 (XGM). HPSEC-MALLS/RI analysis showed that each polysaccharide fraction was homogeneous; M(w) values were 1.6 x 10(5), 2.0 x 10(5) and 1.5 x 10(5)g/mol, respectively. The effect of the xyloglucans on the production of O(2)*(-) and NO* and on the recruitment of macrophages to the mouse peritoneum was evaluated. All polysaccharides promoted an increase in the number of peritoneal macrophages in a dose-dependent manner. The largest increase, of 576% in comparison to the control group, was elicited by XGJ at 200 mg/kg. The effect of XGC, XGJ and XGM on O(2)*(-) production, in the presence or absence of phorbol 12-myristate 13-acetate (PMA), was not statistically significant. For NO(.) production, the lowest concentration of XGC (10 microg/ml) gave rise to an increase of 262% when compared to the control group; the effect was dose-dependent, reaching 307% at 50 microg/ml. On the other hand, XGJ at a concentration of 50 microg/ml enhanced NO* production by 92%. XGM did not affect NO* production significantly. The results indicate that xyloglucans from C. langsdorffii, H. courbaril and M. sloanei have immunomodulatory activity.

New 4-O-substituted xylosyl units in the xyloglucan from leaves of Hymenaea courbaril.

A homogeneous fucogalactoxyloglucan, isolated from the leaves of Hymenaea courbaril, was analysed by methylation-GC-MS. These procedures involved derived partially O-methylated alditol acetates and acetylated aldononitriles, which demonstrated the presence of both 2-O- and 4-O-substituted Xylp units in the side-chains. The presence of the unusual, latter structure was confirmed by 2D NMR spectroscopy with a correlated HMQC C-4/H-4 signal at delta 77.8/3.73. A similar 4-O-substituted xylosyl structure was present in a decasaccharide Glc4Xyl3Gal2Fuc obtained via endo-glucanase treatment of the polysaccharide, which gave rise to a molecular ion with m/z 1555 (ESI-MS, Na+ form).

Structural and rheological properties of polysaccharides from mango (Mangifera indica L.) pulp.

The structure and rheological properties of water-soluble polysaccharides from industrialized mango pulp were investigated. Soluble fraction (SF) 2 was heterogeneous on high performance size exclusion chromatography, giving two peaks as determined by multi-angle laser light scattering and refractive index detectors. The presence of starch in SF2 was demonstrated by a positive iodine reaction and by 13C nuclear magnetic resonance (NMR) spectroscopy. The presence of pectic polysaccharides was shown by a calorimetric method, 13C-NMR spectroscopy and carboxyl reduction. The main pectic polysaccharide was polygalacturonic acid; type I rhamnogalacturonan was also detected. Analysis of the rheological properties of SF2 showed a pseudoplastic behavior up to 3 g x l(-1). 'Creep and recovery' tests and analysis performed under a dynamic state revealed a weak gel character for solutions at concentrations of 15, 20 and 30 g x l(-1).

Xyloglucan from the leaves of Hymenaea courbaril.

A fucosylated xyloglucan was isolated from the leaves of Hymenaea courbaril by alkaline extraction, followed by ethanol precipitation and ion-exchange chromatography. The isolated polysaccharide showed Glc:Xyl:Gal:Fuc in molar ratio of 8:5:2.5:1 and (D)(25) +40.5 degrees. Composition and linkage analyses, supported by NMR spectroscopic measurements, showed that the polysaccharide has a glucan backbone which is highly substituted at O-6 with D-xylopyranose residues, about a half of which are substituted at O-2 by D-galactopyranosyl units. Some of the galactose residues are further substituted by L-fucopyranose at O-2. The M(r), as determined by HPSEC, was 49,500.

Structural aspects of the exudate from the fruit of Chorisia speciosa St. Hil.

Mature fruit of Chorisia speciosa yield an exudate (E-I) following mechanical injury. The polysaccharide contains rhamnose, arabinose, xylose, mannose, glucose, galactose and glucuronic acid in molar ratios of 20:11:1:3:2:40:23. The main chain of the structure is composed by beta-galactopyranosyl units linked (1 --> 3) and (1 --> 6) as indicated by NMR spectra and methylation data. Arabinosef and rhamnose are terminal residues. In order to compare E-I with the polysaccharides from the fruit mesocarp, the latter was submitted to different extractions. The water fraction contains rhamnose, arabinose, xylose, mannose, glucose, galactose and uronic acid in molar ratios of 18:4:1:2:3:44:28. It was treated with CTAB yielding a precipitate which was decomplexed with NaCl, giving four fractions. The fraction obtained using 0.15 M NaCl had a quantitative composition similar that of E-I.

Role of galactomannan composition on the binary gel formation with xanthan.

The influence of the galactomannan characteristic ratios (M/G) on the temperature of gelation (Tg) and the gel strength of mixtures of galactomannan with xanthan is reported. Two galactomannans were investigated: one highly substituted from the seeds of Mimosa scabrella (M/G = 11), and the other, less substituted, from the endosperm of Schizolobium parahybae, with (M/G = 30) [Ganter JLMS, Zawadzki-Baggio SF, Leitner SC, Sierakowski MR, Reicher F. J Carbohydr Chem 1993;12:753]. The xanthan:galactomannan systems (4:2 g l(-1), in 5 mM NaCl) showed a temperature of gel formation (Tg) of 24 degrees C for that of S. parahybae [Bresolin TMB, Milas M, Rinaudo M and Ganter JLMS. Int J Biol Macromol 1998;23:263] and 20 degrees C for the galactomannan of M. scabrella, determined by viscoelastic measurements and microcalorimetry. A Tg of 40-50 degrees C was found by Shatwell et al. [Shatwell KP, Sutherland IW, Ross-Murphy SB, Dea ICM. Carbohydr Polym 1991;14:29] for locust bean gum-LBG (M/G = 43). Lundin and Hermansson [Lundin L, Hermansson AM. Carbohydr Polym 1995;26:129] reported a difference of 13 degrees C for Tg of two LBG samples with M/G = 3 (40 degrees C) and 5 (53 degrees C), in mixtures with xanthan. It appears that the more substituted galactomannans have lower temperatures of gelation in the presence of xanthan. The mechanism of gelation depends also on the M/G ratio. For the lower values it involves only disordered xanthan chains in contrast to M/G ratios higher than 3. In addition, the presence of the galactomannan from M. scabrella increased slightly the temperature of the conformational change (Tm) of xanthan probably due to the ionic strength contribution of proteins (3.9%) present in the galactomannan. On the other hand, the galactomannans from S. parahybae, with 1.5% of proteins and M. scabrella, with 2.4% of protein, did not show this effect, the Tm of xanthan alone or in a mixture being practically unchanged.

Xyloglucan octasaccharide XXLGol derived from the seeds of hymenaea courbaril acts as a signaling molecule

Treatment of the xyloglucan isolated from the seeds of Hymenaea courbaril with Humicola insolens endo-1,4-beta-d-glucanase I produced xyloglucan oligosaccharides, which were then isolated and characterized. The two most abundant compounds were the heptasaccharide (XXXG) and the octasaccharide (XXLG), which were examined by reference to the biological activity of other structurally related xyloglucan compounds. The reduced oligomer (XXLGol) was shown to promote growth of wheat (Triticum aestivum) coleoptiles independently of the presence of 2, 4-dichlorophenoxyacetic acid (2,4-D). In the presence of 2,4-D, XXLGol at nanomolar concentrations increased the auxin-induced response. It was found that XXLGol is a signaling molecule, since it has the ability to induce, at nanomolar concentrations, a rapid increase in an alpha-l-fucosidase response in suspended cells or protoplasts of Rubus fruticosus L. and to modulate 2,4-D or gibberellic acid-induced alpha-l-fucosidase.

Galactomannan from the seeds of Mimosa scabrella: a scale-up process.

In view of the wide industrial applications of galactomannans as a thickening agent, those of Mimosa scabrella (bracatinga), a leguminous tree abundant in Southern Brazil, are under investigation. Seeds of bracatinga were processed on a pilot plant scale in order to obtain its galactomannan. The process consisted of successive milling, enzyme inactivation, aqueous extraction, precipitation of polysaccharide, and drying and milling. The product was obtained in 20% yield, with characteristics similar to those obtained on the laboratory scale, namely mannose:galactose ratio (M:G) 1.1:1.0 and intrinsic viscosity. Considering the seed availability in the metropolitan regions of Curitiba, it should be possible to obtain 3000 ton/year of this polysaccharide.

Polysaccharides from the seeds of Senna multijuga.

The seeds of Senna multijuga were extracted with water or 1% acetic acid and treated with ethanol, resulting in two insoluble fractions. After purification, the major one (FIA, 23%) was shown to be a galactomannan (Man:Gal 2.3:1; [alpha] = +54.6; [eta] = 1340 ml g-1). It consists of a main chain of (1-->4)-linked beta-D-mannopyranosyl residues substituted at O6 by single-unit alpha-D-galactopyranosyl side chains. The second fraction (FIB, 2.5%) was an O-acetyl-glucuronoarabinoxylan from the seed coats (O-acetyl 8.3 mol%; glucuronic acid 11.7%, Xyl:Ara ratio 20:1), which showed a predominance of 4-O-substituted Xylp units (84.4%), branched at O3 with non-reducing end units of Xylp, Araf and glucuronic acid. The O-acetyl positions in D-xylosyl units are at O2 (4.8%), O3 (4.4%) and O2,3 (0.9%). The ratio between O3 and O2 determined by 13C-nuclear magnetic resonance spectroscopy is 1.5:1.

Oligosaccharides derived from the xyloglucan isolated from the seeds of Hymenaea courbaril var. stilbocarpa.

On aqueous extraction, Hymenaea courbaril var. stilbocarpa, known in Brazil as jatobá, furnishes a high yield of viscous xyloglucan (45%) from its seeds. The crude polysaccharide (B1) was hydrolysed and the products, analysed as alditol acetates, were glucose, xylose, galactose and arabinose in the ratio 50:35:13:2. After further fractionation on DEAE-cellulose column (chloride form), the main fraction (70% yield, B2) was obtained. The basic structure of the xyloglucan was determined as a cellulose-type (1-->4)-linked beta-D-glucan backbone partially substituted with side chains at O6 of alpha-D-xylopyranose, some of which were themselves substituted at O2 by the units of beta-D-galactopyranose. Treatment of the xyloglucan (B2) with commercial cellulase from Trichoderma sp. yielded six oligosaccharides. These oligosaccharides were isolated by preparative paper chromatography, and their structures were determined by gas-liquid chromatography-mass spectroscopy of the derived partially O-methylated alditol acetates. These results confirm the structure proposed for jatobá seed xyloglucan.

Galactomannans from Brazilian seeds: characterization of the oligosaccharides produced by mild acid hydrolysis.

Galactomannans with Man:Gal ratios ranging from 1.1:1 to 3:1, obtained from the seeds of Mimosa scabrella, Stryphnodendron barbatiman, Schizolobium parahybum and Schizolobium amazonicum, were submitted to mild acid hydrolysis. The products were fractionated by gel permeation chromatography on BioGel P2 yielding fractions with degrees of polymerization (DP) of 1 to 6. Those with DP 2 to 6 from each species were analysed by ion-exchange high-performance liquid chromatography and characterized by 13C- and 1H-nuclear magnetic resonance (NMR) spectroscopy. The distribution of the oligosaccharides of each degree of polymerization was very similar for the products from S. parahybum and S. amazonicum, indicating the same D-galactosyl distribution on the D-mannan backbone, in agreement with the 13C-NMR splitting in the C4 region of the D-mannosyl units in the original polymers. The hydrolytic conditions adopted allowed characterization of compounds that are not generally produced by enzymatic treatments. The results show that the structures of the oligosaccharides, even if there is a preferential hydrolysis of Gal-Man linkages, reflect the composition of the parent polymer.