[Cell Function Research of ß-Trefoil Lectins from Mytilidae].

Two novel ß-trefoil lectins, MytiLec-1 and SeviL were found from mussels in the coast of Yokohama and Nagasaki. MytiLec-1 was purified from gill and mantle of Mytilus galloprovincialis. It was consisted of 149 amino acid residues and there was no similarity with any other proteins when it was discovered. We advocate for this "Mytilectin" as a new protein family because of their novelty of its primary structure and homologues were also found in other mussels. Glycan array analysis revealed that MytiLec-1 specifically bound to the Gb3 and Gb4 glycan which contained the α-galactoside. MytiLec-1 caused the apoptosis against the Burkitt's lymphoma cells through the interaction of Gb3 express in their cell surface. On the other hand, SeviL obtained from gill and mantle of Mytilisepta virgata showed the specific binding against GM1b, asialo GM1 and SSEA-4 which are known as glycosphingolipid glycan including the ß-galactoside. In addition, SeviL was identified as R type lectin by confirmation of QXW motif within its primary structure. Messenger RNA of SeviL like R type lectins was also found among the musssels including Mytilus galloprovincialis. SeviL also showed the apoptosis against asialo GM1 expressing cells. To apply the anticancer lectin as a novel molecular target drug, primary structure of MytiLec-1 was analyzed to enhance the stabilization of confirmation by computational design technique. It was succeeded to produce a monomeric artificial ß-trefoil lectin, Mitsuba-1 without losing the Gb3 binding ability. Comparison of biological function between Mitsuba-1 and MytiLec-1 is also described in this study.

The human milk oligosaccharides 2'-fucosyllactose and 6'-sialyllactose protect against the development of necrotizing enterocolitis by inhibiting toll-like receptor 4 signaling.

BACKGROUND: Necrotizing enterocolitis (NEC) develops through exaggerated toll-like receptor 4 (TLR4) signaling in the intestinal epithelium. Breast milk is rich in non-digestible oligosaccharides and prevents NEC through unclear mechanisms. We now hypothesize that the human milk oligosaccharides 2'-fucosyllactose (2'-FL) and 6'-sialyllactose (6'-SL) can reduce NEC through inhibition of TLR4 signaling. METHODS: NEC was induced in newborn mice and premature piglets and infant formula was supplemented with 2'-FL, 6'-SL, or lactose. Intestinal tissue was obtained at surgical resection. HMO inhibition of TLR4 was assessed in IEC-6 enterocytes, mice, and human tissue explants and via in silico modeling. RESULTS: Supplementation of infant formula with either 2'-FL and/or 6'-SL, but not the parent sugar lactose, reduced NEC in mice and piglets via reduced apoptosis, inflammation, weight loss, and histological appearance. Mechanistically, both 2'-FL and 6'-SL, but not lactose, reduced TLR4-mediated nuclear factor kappa light-chain enhancer of activated B cells (NF-kB) inflammatory signaling in the mouse and human intestine. Strikingly, in silico modeling revealed 2'-FL and 6'-SL, but not lactose, to dock into the binding pocket of the TLR4-MD2 complex, explaining their ability to inhibit TLR4 signaling. CONCLUSIONS: 2'-FL and 6'-SL, but not lactose, prevent NEC in mice and piglet models and attenuate NEC inflammation in the human ileum, in part through TLR4 inhibition. IMPACT: Necrotizing enterocolitis (NEC) is a major cause of morbidity and mortality in premature infants that occurs in the setting of bacterial colonization of the gut and administration of formula feeds and activation by the innate immune receptor toll-like receptor 4 (TLR4). Breast milk prevents NEC through unclear mechanisms. We now show that breast milk-enriched human milk oligosaccharides (HMOs) that are derived from lactose prevent NEC through inhibition of TLR4. The human milk oligosaccharides 2'-FL and 6'-SL, but not the backbone sugar lactose, prevent NEC in mice and piglets. 2'-FL and 6'-SL but not lactose inhibited TLR4 signaling in cultured enterocytes, in enteroids derived from mouse intestine, and in human intestinal explants obtained at the time of surgical resection for patients with NEC. In seeking the mechanisms involved, 2'-FL and 6'-SL but not lactose were found to directly bind to TLR4, explaining the inhibition and protection against NEC. These findings may impact clinical practice by suggesting that administration of HMOs could serve as a preventive strategy for premature infants at risk for NEC development.

A trisaccharide phenylethanoid glycoside from Scrophularia flava Grau with potential anti-type 2 diabetic properties by inhibiting α-glucosidase enzyme and decreasing oxidative stress.

The Scrophularia genus is a rich source of phenylethanoid glycosides, with diverse biological activities including anti-diabetic properties. This study investigated anti-type 2 diabetic potential and active component of Scrophularia flava Grau. A new phenylethanoid glycoside was isolated from aerial parts of the plant and identified as 2-(4-hydroxy-3-methoxyphenyl) ethyl 6-deoxy-3-O-[(2E)-3-(3 hydroxy-4-methoxyphenyl) prop-2-enoyl]-α-rhamnopyranosyl-(1 â†’ 3)-[α-rhamnopyranosyl-(1 â†’ 6)]-4-O-[(2E)-3-(4-hydroxy-3-methoxyphenyl) prop-2-enoyl]-ß-glucopyranoside. It was named flavaioside. The structure of flavaioside was identified based on 1H NMR, 13C NMR, DEPT-HSQC, COSY, HMBC, NOESY and LC-ESI-MS-MS. Total methanol extract, fractions (A-F) and specific main phenylethanoid glycoside (flavaioside), were assessed for inhibitory effects against the α-glucosidase enzyme (in vitro anti-type 2 diabetic assay). The antioxidant activities of methanol extracts, all fractions and isolated flavaioside were identified based on 2, 2'-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging activity, 2, 2'-azino-bis (3-ethylbenzothiazoline)-6-sulphonic acid radical cation (ABTS+) scavenging activity, phosphomolybdenum method, and metal chelating activity. In comparison to the other fractions, the best antioxidant result was observed in fraction E and its main compound, flavaioside, in DPPH (IC50 = 4.26, 2.57 µg/mL) and ABTS+ (EC50 = 55.45, 6.34 µg/mL) scavenging activities. Flavaioside showed significantly stronger activities than α-tocopherol and ascorbic acid in DPPH and ABTS+ assays. Furthermore, flavaioside showed a potent inhibitory activity on the α-glucosidase enzyme which was comparable with the known anti-type 2 diabetic drug, acarbose (91.85%, and 92.87%, respectively). Fraction E and flavaioside showed α-glucosidase inhibitory activities with IC50 values, 65.05 and 6.50 µg/mL. The plant and its isolated flavaioside can possess acceptable anti-type 2 diabetic potential and anti-oxidant activity.

Efficient production of isomelezitose by a glucosyltransferase activity in Metschnikowia reukaufii cell extracts.

Metschnikowia reukaufii is a widespread yeast able to grow in the plants' floral nectaries, an environment of extreme conditions with sucrose concentrations exceeding 400 g l-1 , which led us into the search for enzymatic activities involved in this sugar use/transformation. New oligosaccharides were produced by transglucosylation processes employing M. reukaufii cell extracts in overload-sucrose reactions. These products were purified and structurally characterized by MS-ESI and NMR techniques. The reaction mixture included new sugars showing a great variety of glycosidic bonds including α-(1→1), α-(1→3) and α-(1→6) linkages. The main product synthesized was the trisaccharide isomelezitose, whose maximum concentration reached 81 g l-1 , the highest amount reported for any unmodified enzyme or microbial extract. In addition, 51 g l-1 of the disaccharide trehalulose was also produced. Both sugars show potential nutraceutical and prebiotic properties. Interestingly, the sugar mixture obtained in the biosynthetic reactions also contained oligosaccharides such as esculose, a rare trisaccharide with no previous NMR structure elucidation, as well as erlose, melezitose and theanderose. All the sugars produced are naturally found in honey. These compounds are of biotechnological interest due to their potential food, cosmeceutical and pharmaceutical applications.

Synthesis, antiasthmatic, and insecticidal/antifungal activities of allosamidins.

Allosamidins come from the secondary metabolites of Streptomyces species, and they have the pseudotrisaccharide structures. Allosamidins are chitinase inhibitors that can be used to study the physiological effects of chitinases in a variety of organisms. They have the novel antiasthmatic activity and insecticidal/antifungal activities. Herein, the synthesis and activities of allosamidins were summarized and analyzed.

A silica gel orthogonal high-performance liquid chromatography method for the analyses of steviol glycosides: novel tetra-glucopyranosyl steviol.

A silica gel orthogonal method using acetonitrile: water was developed for the analyses of fractions rich in very polar steviol glycosides and resolve regions of co-elution of these compounds in reversed-phase. Additionally, we also used this normal phase analytical method to scale up the purification process of steviol glycosides. Using these approaches, one novel minor tetra-glucopyranosyl diterpene glycosides together with three known compounds were purified from a commercial Stevia rebaudiana leaf extract. Compound 1 was unambiguously elucidated as 13-[(2-O-ß-D-glucopyranosyl-ß-D-glucopyranosyl)oxy]ent-kaur-16-en-19-oic acid-(6-O-ß-D-glucopyranosyl-ß-D-glucopyranosyl) ester (rebaudioside Y) based on high-performance liquid chromatography retention times, tandem mass spectrometry dissociation pattern and 1D and 2D NMR experiments. Known compounds were isolated in gram quantities and identified as rebaudioside D, E and M.

High-level expression of soluble recombinant proteins in Escherichia coli using an HE-maltotriose-binding protein fusion tag.

Recombinant proteins are commonly expressed in prokaryotic expression systems for large-scale production. The use of genetically engineered affinity and solubility enhancing fusion proteins has increased greatly in recent years, and there now exists a considerable repertoire of these that can be used to enhance the expression, stability, solubility, folding, and purification of their fusion partner. Here, a modified histidine tag (HE) used as an affinity tag was employed together with a truncated maltotriose-binding protein (MBP; consisting of residues 59-433) from Pyrococcus furiosus as a solubility enhancing tag accompanying a tobacco etch virus protease-recognition site for protein expression and purification in Escherichia coli. Various proteins tagged at the N-terminus with HE-MBP(Pyr) were expressed in E. coli BL21(DE3) cells to determine expression and solubility relative to those tagged with His6-MBP or His6-MBP(Pyr). Furthermore, four HE-MBP(Pyr)-fused proteins were purified by immobilized metal affinity chromatography to assess the affinity of HE with immobilized Ni2+. Our results showed that HE-MBP(Pyr) represents an attractive fusion protein allowing high levels of soluble expression and purification of recombinant protein in E. coli.

Structure of the LPS O-chain from Fusobacterium nucleatum strain 10953, containing sialic acid.

Fusobacterium nucleatum is an anaerobic bacterium found in the human mouth where it causes periodontitis. Recently, it has been gaining attention as a potential causative agent for colorectal cancer and is strongly linked with pregnancy complications including pre-term and still births. Little is known about virulence factors of this organism and thus we have initiated studies to examine the bacterial surface glycochemistry. Consistent with a recent paper suggesting that F. nucleatum strain 10593 can synthesize sialic acid, a staining technique identified sialic acid on the bacterial surface. We isolated lipopolysaccharide from this F. nucleatum strain and performed structural analysis on the O-antigen. Our studies identified a trisaccharide repeating unit of the O-antigen with the following structure: -[→4)-α-Neup5Ac-(2 â†’ 4)-ß-d-Galp-(1 â†’ 3)-α-d-FucpNAc4NAc-(1-]- where Ac indicates 4-N-acetylation of ∼30% FucNAc4N residues. The presence of sialic acid as a constituent of the O-antigen is consistent with recent data identifying de novo sialic acid synthesis in this strain.

Mode of Action of the Natural Insecticide, Decaleside Involves Sodium Pump Inhibition.

Decalesides are a new class of natural insecticides which are toxic to insects by contact via the tarsal gustatory chemosensilla. The symptoms of their toxicity to insects and the rapid knockdown effect suggest neurotoxic action, but the precise mode of action and the molecular targets for decaleside action are not known. We have presented experimental evidence for the involvement of sodium pump inhibition in the insecticidal action of decaleside in the cockroach and housefly. The knockdown effect of decaleside is concomitant with the in vivo inhibition of Na+, K+ -ATPase in the head and thorax. The lack of insecticidal action by experimental ablation of tarsi or blocking the tarsal sites with paraffin correlated with lack of inhibition of Na+- K+ ATPase in vivo. Maltotriose, a trisaccharide, partially rescued the toxic action of decaleside as well as inhibition of the enzyme, suggesting the possible involvement of gustatory sugar receptors. In vitro studies with crude insect enzyme preparation and purified porcine Na+, K+ -ATPase showed that decaleside competitively inhibited the enzyme involving the ATP binding site. Our study shows that the insecticidal action of decaleside via the tarsal gustatory sites is causally linked to the inhibition of sodium pump which represents a unique mode of action. The precise target(s) for decaleside in the tarsal chemosensilla and the pathway linked to inhibition of sodium pump and the insecticidal action remain to be understood.

Recognition of human milk oligosaccharides by bacterial exotoxins.

The affinities of the most abundant oligosaccharides found in human milk for four bacterial exotoxins (from Vibrio cholerae and pathogenic Escherichia coli) were quantified for the first time. Association constants (Ka) for a library of 20 human milk oligosaccharides (HMOs) binding to Shiga toxin type 2 holotoxin (Stx2) and the B subunit homopentamers of cholera toxin, heat-labile toxin and Shiga toxin type 1 (CTB5, HLTB5 and Stx1B5) were measured at 25°C and pH 7 using the direct electrospray ionization mass spectrometry assay. Notably, all four bacterial toxins bind to a majority of the HMOs tested and five of the HMOs (2'-fucosyllactose, lacto-N-tetraose, lacto-N-fucopentaose I, lacto-N-fucopentaose II and lacto-N-fucopentaose III) are ligands for all four toxins. These five HMOs are also reported to bind to other bacterial toxins (e.g. toxin A and toxin B of Clostridium difficile). In all cases, the HMO affinities (apparent Ka) are relatively modest (≤15,000 M(-1)). However, at the high concentrations of HMOs typically ingested by infants, a significant fraction of these toxins, if present, is expected to be bound to HMOs. Binding measurements carried out with 2'-fucosyllactose or lacto-N-fucopentaose I, together with a high-affinity ligand based on the native carbohydrate receptor, revealed that all four toxins possess HMO-binding sites that are distinct from those of the native receptors, although evidence of competitive binding was found for lacto-N-fucopentaose I with Stx2 and 2'-fucosyllactose and lacto-N-fucopentaose I with HLTB5. Taken together, the results of this study suggest that, while HMOs are expected to bind extensively to these bacterial toxins, it is unlikely that HMO binding will effectively inhibit their interactions with their cellular receptors.

Open tubular capillary electrochromatography with an N-phenylacrylamide-styrene copolymer-based stationary phase for the separation of anomers of glucose and structural isomers of maltotriose.

A ligand with a terminal halogen (4-chloromethylphenyl isocyanate) was chemically bound on the inner surface of pretreated silica capillary with 50 µm internal diameter and 58 cm total and 50 cm effective length in the presence of dibutyl tin dichloride as a catalyst through isocyanate-hydroxyl reaction. Attachment of initiator (sodium diethyl dithiocarbamate) to the bound ligand was carried out and followed by in situ polymerization. Reversible addition-fragmentation chain transfer polymerization was used for the immobilization of N-phenylacrylamide-styrene copolymer on the inner surface of capillary column. The resultant open tubular column showed excellent separation performance for derivatized saccharide isomers in capillary electrochromatography. D-Glucose was separated into α- and ß-anomers while five structural isomers were separated for derivatized maltotriose with separation efficiency above one million theoretical plates per meter. The effects of pH and acetonitrile composition on the electrochromatographic performance of the derivatized saccharides were studied and the optimized elution condition was found to be 90:10 v/v% acetonitrile/30 mM sodium acetate at pH 6.6. UV absorption at 214 nm was used as detection mode in open tubular capillary electrochromatography separations.

Triglyceride accumulation inhibitory effects of new chromone glycosides from Drynaria fortunei.

Two new chromone glycosides, drynachromosides C (1) and D (2), along with five known chromones (3-7), were isolated from the rhizomes of Drynaria fortunei. The structures of the two new compounds were elucidated on the basis of physico-chemical property and spectroscopic data. Triglyceride (TG) accumulation inhibitory effects of the obtained chromones on 3T3-L1 cells were investigated. The results showed that 1, 2 and 5 exhibited inhibitory activity on TG accumulation. Effects of compounds 1 and 2 on mRNA expression of PPARγ, C/EBPα and aP2 in 3T3-L1 cells were also investigated.

Influence of processing procedure on the quality of Radix Scrophulariae: a quantitative evaluation of the main compounds obtained by accelerated solvent extraction and high-performance liquid chromatography.

An improved high-performance liquid chromatography with diode array detection combined with accelerated solvent extraction method was used to simultaneously determine six compounds in crude and processed Radix Scrophulariae samples. Accelerated solvent extraction parameters such as extraction solvent, temperature, number of cycles, and analysis procedure were systematically optimized. The results indicated that compared with crude Radix Scrophulariae samples, the processed samples had lower contents of harpagide and harpagoside but higher contents of catalpol, acteoside, angoroside C, and cinnamic acid. The established method was sufficiently rapid and reliable for the global quality evaluation of crude and processed herbal medicines.

Two New Flavonoids and Biological Activity of Astragalus abyssinicus (Hochst.) Steud. ex A. Rich. Aerial Parts.

2 new flavonoid glycosides, kaempferol 3-O-(4",6"-di-O-α-L-rhamnopyranosyl)-ß-D-glucopyranoside (1) and quercetin 3-O-(4",6"-di-O-α-L-rhamnopyranosyl)-ß-D-glucopyranoside (2), were isolated from the n-butanol soluble fraction of the methanol extract (BF) of Astragalus abyssinicus aerial parts, together with 3 known compounds, rutin (3), kaempferol 3-O-ß-D-rutinoside (4) and 5,7,4'-trihydroxy-3'-methoxyisoflavone (5). The structures of the isolated compounds were characterized on the basis of UV, NMR and negative ESI-MS analyses. The BF fraction showed in vitro weak antibacterial activity against Staphylococcus aureus, while 2 and 3 exhibited in vitro antioxidant activity higher than ascorbic acid using DPPH free radical scavenging activity method.

Isolation and characterization of a novel rebaudioside M isomer from a bioconversion reaction of rebaudioside A and NMR comparison studies of rebaudioside M isolated from Stevia rebaudiana Bertoni and Stevia rebaudiana Morita.

A minor product, rebaudioside M2 (2), from the bioconversion reaction of rebaudioside A (4) to rebaudioside D (3), was isolated and the complete structure of the novel steviol glycoside was determined. Rebaudioside M2 (2) is considered an isomer of rebaudioside M (1) and contains a relatively rare 1→6 sugar linkage. It was isolated and characterized with NMR (1H, 13C, COSY, HSQC-DEPT, HMBC, 1D-TOCSY, and NOESY) and mass spectral data. Additionally, we emphasize the importance of 1D and 2D NMR techniques when identifying complex steviol glycosides. Numerous NMR spectroscopy studies of rebaudioside M (1), rebaudioside D (3), and mixture of 1 and 3 led to the discovery that SG17 which was previously reported in literature, is a mixture of rebaudioside D (3), rebaudioside M (1), and possibly other related steviol glycosides.

A one-pot approach to bio-synthesize globotriose and its derivatives from simpler substrates.

Globotriose is involved in numerous pathogenic processes and drug development strategies. Recent studies have demonstrated that globotriosylceramide could be used in colon cancer therapy and as a crucial indicator for susceptibility to HIV-1 infection. Therefore, the cost-effective and facile approaches for large-scale production of globotiose as potential drugs are highly required. Here, a multi-enzyme one-pot system containing a galactokinase (SpGalK, E.C.2.7.1.6), a UDP-glucose pyrophosphorylase (SpGalU, E.C.2.7.7.9), a α-1,4-galactosyltransferase (LgtC, E.C. 2.4.1.44) and a commercial inorganic pyrophosphatase (PPase, EC 3.6.1.1) was designed to achieve globotriose on preparative scales. This method exploits a cheaper initial substrate, galactose, for donor UDP-galactose production. More importantly, the substrate specificity of SpGalK and SpGalU is highly promiscuous and various UDP-galactose derivatives obtained could be used as the donor substrates for LgtC. This pointcut of rapid preparation of globotriose derivatives is proposed for the first time. Finally, three globotriose analogs were achieved by this one-pot multi-enzyme system in our study.

Hepatoprotective and antioxidant activity of N-Trisaccharide in different experimental rats.

OBJECTIVES: To investigate the hepatoprotective, antioxidant and antihyperlipidemic effect of N-Trisaccharide isolated from Cucumis prophetarum (L.) on different experimental rats. METHODS: N-Trisaccharide (25 and 50 mg/kg.b.w), silymarin (25 mg/kg) and glibenclamide (25 mg/kg) was orally administered once daily for 28 days and toxicity evaluation studies were carried out. Liver damage was assessed by determining DNA damage, serum enzyme activities and hepatic histopathology of carbon tetrachloride (CCl4) induced hepatic injury in rats. Enzymatic and non enzymatic antioxidant levels in liver and kidney were determined and biochemical parameters such as, serum lipid profile, renal function markers were estimated in type 2 diabetic rats. RESULTS: DNA fragmentation analysis revealed the protective effect of N-Trisaccharide on liver DNA damage. Histopathological studies indicated that CCl4-induced liver injury was less severe in N-Trisaccharide (25 and 50mg/kg) treated group. Given at the above doses conferred significant protection against the hepatotoxic actions of CCl4 in rats, reducing serum markers like SGOT, SGPT, ALP, creatinine and urea levels back to near normal (p<0.05) compared to untreated rats. In diabetic rats, N-Trisaccharide treatment significantly reversed abnormal status of enzymatic and non-enzymatic antioxidants levels to near normal. Also, serum lipids such as TG, TC, LDL-C and VLDL-C levels were significantly (p<0.05) reduced compared to diabetic untreated rats. CONCLUSION: Present study results confirm that N-Trisaccharide possesses significant antihyperlipidemic, antioxidant and hepatoprotective properties.

A heparin-like glycosaminoglycan from shrimp containing high levels of 3-O-sulfated D-glucosamine groups in an unusual trisaccharide sequence.

The detailed characterization of a novel heparin-like glycosaminoglycan purified from the viscera (heads) of the shrimp Litopenaeus vannamei is reported. Structural analysis performed by mono- and two-dimensional nuclear magnetic resonance (NMR) spectroscopy revealed it to be rich in both glucuronic acid and N,6-sulfated glucosamine residues. The key peculiarities were its high 3-O-sulfated glucosamine content compared to mammalian heparins; a residue which is usually associated with the antithrombin (AT) binding site, and the location of these residues within 2-O-sulfated iduronate and glucuronate-containing sequences (I2S-A(∗)-G), a situation not found in mammalian heparin. It also exhibited higher molecular weight (∼36kDa) than conventional heparin (∼16kDa) but, negligible anticoagulant activity (∼5IU/mg compared to heparin ∼190IU/mg) and stabilization of AT, which has been linked directly to anticoagulation activity. A high affinity fraction, eluting at a similar salt concentration (0.75-1.5M NaCl) from an antithrombin affinity column, to the high affinity fraction of heparin, also showed only weak thermal stabilization of AT (+∼2°C). These structural peculiarities may help elucidate more clearly the relationship between structure and function of sulfated polysaccharides, and provide useful model compounds with which to better understand interactions of biological significance.

Anti-diabetic effect of a novel N-Trisaccharide isolated from Cucumis prophetarum on streptozotocin-nicotinamide induced type 2 diabetic rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Cucumis prophetarum (L.) is used in traditional Indian medicine for the treatment of inflammation related problems. AIM OF THE STUDY: The present investigation was designed to study the effect of N-Trisaccharide (a new compound isolated from the fruit of C. prophetarum (L.)) on hyperglycemia in streptozotocin (STZ)-nicotinamide (NA) induced type 2 diabetic rats. MATERIALS AND METHODS: Different doses of N-Trisaccharide (25 and 50 mg/kgb.w.) were administered once daily for 28 days to STZ-NA induced diabetic rats. Plasma insulin and glycogen levels were measured. The activities of hexokinase, glucose-6-phosphatase, fructose-1,6-bisphosphatase, glucose-6-phosphate dehydrogenase, glycogen synthase and glycogen phosphorylase were measured. Further, histological studies on pancreas were also carried out. RESULTS: The active compound at doses of 25 and 50 mg/kgb.w. given orally for 14 days showed 47.7% and 69.3% antihyperglycemic activity, respectively. Treatment at the same doses for 28 days provided complete protection against STZ-NA challenge (65 and 230 mg/kgb.w., respectively), intraperitoneally. N-Trisaccharide significantly (p≤0.05) increased the plasma insulin and liver glycogen levels in diabetic rats. The altered enzyme activities of carbohydrate metabolism in the liver and kidney of the diabetic rats were significantly (p≤0.05) improved. Additionally, N-Trisaccharide increased glycogen synthase and decreased glycogen phosphorylase activity in diabetic rats. Histological studies confirmed an increase in insulin level is due to stimulation of injured pancreatic ß-cells. CONCLUSION: The results of the study suggested that N-Trisaccharide possesses propitious effect on STZ-NA induced type 2 diabetes, indicating its usefulness in diabetes management.

Synthesis and conformational analysis of phosphorylated ß-(1→2) linked mannosides.

Phosphorylated ß-(1→2)-oligomannosides are found on the cell surface of several Candida species, including Candida albicans (an opportunistic pathogen). These molecules are believed to take part in the invasion process of fungal infections, which in the case of C. albicans can lead to severe bloodstream infections and death, and can therefore be considered important from a biological standpoint. Understanding the mechanism of their action requires access to the corresponding oligosaccharide model compounds in pure form. In the present work, synthesis of the model core structures involved in the invasion process of C. albicans, consisting of phosphorylated ß-(1→2)-linked mannotriose and tetraose, is reported. In order to elucidate the nature of these molecules in more detail, an extensive NMR-spectroscopic study encompassing complete spectral characterization, conformational analysis and molecular modelling was performed. The obtained results were also compared to similar chemical entities devoid of the charged phosphate group.