Unusual Structures and Cytotoxicities of Chitonoidosides A, A1, B, C, D, and E, Six Triterpene Glycosides from the Far Eastern Sea Cucumber Psolus chitonoides

Six new triterpene tetra-, penta- and hexaosides, chitonoidosides A (1), A1 (2), B (3), C (4), D (5), and E (6), containing one or two sulfate groups, have been isolated from the Far-Eastern sea cucumber Psolus chitonoides, collected near Bering Island (Commander Islands) from the depth of 100–150 m. Three of the isolated compounds (1, 3 and 6) are characterized by the unusual aglycone of new type having 18(20)-ether bond and lacking a lactone in contrast with wide spread holostane derivatives. Another unexpected finding is 3-O-methylxylose residue as a terminal unit in the carbohydrate chains of chitonoidosides B (3), C (4), and E (6), which has never been found before in the glycosides from holothurians belonging to the Psolidae family. Moreover, this monosaccharide is sulfated in the compound 4 into unprecedented 3-O-methylxylose 4-O-sulfate residue. Chitonoidoside C (4) is characterized by tetrasaccharide moiety lacking a part of the bottom semi-chain, but having disaccharide fragment attached to C-4 of Xyl1. Such architecture is not common in sea cucumber glycosides. Cytotoxic activities of the compounds 1–5 against mouse and human erythrocytes and human cancer cell lines: adenocarcinoma HeLa, colorectal adenocarcinoma DLD-1, and leukemia promyeloblast HL-60 cells were studied. The cytotoxic effect of chitonoidoside d (5) was the most significant in this series due to the presence of pentasaccharide disulfated sugar chain in combination with holostane aglycone. Surprisingly, the glycosides 1 and 3, comprising the new aglycone without γ-lactone, demonstrated similar activity to the known compounds with holostane aglycones. Chitonoidoside C (4) was less cytotoxic due to the different architecture of the carbohydrate chain compared to the other glycosides and probably due to the presence of a sulfate group at C-4 in 3-O-MeXyl4.

Extraction and Characterization of Lipopolysaccharide from Salmonella typhi

There is no standard process available for high purity LPS isolation, and it may be appropriate to mix two purification steps. For Salmonella typhi LPS that were subjected to normal microbiological & biochemical screening protocols, updated phenol-water extraction protocol & non-phenolic extraction methods were also used in present research. Pellet of crude LPS obtained with wet weight was 2.0 gm. yield of LPS was more by hot phenol method 1.94 mg/ml as compared to non-phenolic method 0.40 mg/ml. relative purity of LPS obtained by hot phenol method was more as compared to non-phenolic method, as protein content was 23.60 mg/ml in LPS extracted from hot phenol method & 26.62 mg/ ml in LPS extracted from non-phenolic method. However, Nucleic acid contain was comparable in LPS extracted from both methods. Qualitative analysis showed ladder like bands of LPS extracted by hot phenol method as compared to single band obtained for LPS extracted by non-phenolic method. Findings of silver staining clearly revealed ladder pattern of multi-rung bands that are characteristics of smooth form of gram negative bacteria due to difference in length of carbohydrate chain of O-antigen component. In order to clarify diseased conditions & better work on LPS profiling, this research may be crucial to lead to more successful diagnosis and care.

Amphipathic 1,3-oxazolidines from N-alkyl glucamines and benzaldehydes: stereochemical and mechanistic studies

Chiral N,O-heterocycles appended to a non-reducing carbohydrate chain, which are valuable synthons, reveal further stereodynamic implications.

DESENVOLVIMENTO NOS MÉTODOS DE GLICOSILAÇÃO: UMA CHAVE PARA ACESSAR SUAS APLICAÇÕES NA SÍNTESE DE MOLÉCULAS BIOATIVAS

DEVELOPMENT IN GLYCOSYLATION METHODS: A KEY TO ACCESS ITS APPLICATIONS IN THE SYNTHESIS OF BIOACTIVE MOLECULES. Glycosylation reaction is an important class of reactions in organic chemistry, and the development of the method contributes to the synthesis of many biologically active compounds containing various glycoside bonds. Is arguably the most important, albeit challenging, reaction in the field of carbohydrate chemistry. Examples of the products of glycosylation reactions are glycoproteins, glycolipids, glycosaminoglycans, oligosaccharides, and polysaccharides. Glycosylation types are classified according to the identity of the atom which binds the carbohydrate chain, i.e. C-linked, N-linked, O-linked or S-linked. In this short review, recent reports of the main glycosylation methods, basic mechanisms, factors influencing the stereoselectivity and their applications in the synthesis of bioactive molecules are described.

Purification and Characterization of a New Lectin from Loach Skin Mucus

Lectin from loach skin mucus plays an important role in pathogen defense. However, hardly can any paper relevant to the character of lectin from loach skin mucus be found in recent years. In this study, a kind of new lectin (LML), with a high hemagglutination activity of 166.23 × 103 HU/mg, was successfully isolated and purified from loach skin mucus. LML was a kind of glycoprotein with a molecular weight of 245 kDa. Also, the monosaccharide composition suggested that its carbohydrate chain was composed of rhamnose, arabinose, xylose, mannose, glucose, and galactose with a molar ratio of 2.02 : 11.66 : 2.06 : 1.00 : 14.09 : 6.00. Besides, LML depended on Ca2+ to induce hemagglutination and was strongly inhibited by D-lactose. The lectin exhibited powerful resistance to alkali and kept about 30% hemagglutination activity at pH 14.0, whereas its capacity of acid resistance was weak. The maximum hemagglutination activity of LML maintained at a temperature range from 20°C to 50°C. Moreover, the structure of LML was preliminarily studied, indicating it contained abundant glutamic acid, histidine, and serine, and its secondary structure contained α-helix (4.97%), β-sheet (27.55%), turns structure (49.78%), and unordered structure (17.70%).

Crystal structure of sodium (1S)-D-mannit-1-ylsulfonate

The title salt, Na+·C6H13O9S− [systematic name: sodium (1S,2S,3S,4R,5R)-1,2,3,4,5,6-hexahydroxyhexane-1-sulfonate], is formed by reaction of D-mannose with sodium bisulfite (sodium hydrogen sulfite) in water. The anion has an open-chain structure with the S atom and the C atoms of the carbohydrate chain forming an essentially planar zigzag chain in which the absolute values of the torsion angles lie between 173.6 (2) and 179.9 (3)°. The sodium cations are penta-coordinated by O atoms, with one link to a carbohydrate O atom and four to O atoms of sulfonate residues in separate anions, thus creating a three-dimensional network. The carbohydrate anions are arranged in a head (–SO3 −) to head (–SO3 −) arrangement, thereby forming two parallel sheets linked through coordination to sodium ions, with each sheet containing intermolecular hydrogen bonds between the anionic residues. Unusually, the double sheets are not connected to neighbouring sets of double sheets, either by ion coordination or intermolecular hydrogen bonding.

1-Deoxy-1-(N-methyl-4-fluorophenylamino)-D-arabino-hexulose

The title compound, C13H18FNO5, consists of D-fructose with an aromatic amine. The carbohydrate chain is in the acyclic keto form and has the zigzag conformation, while the solid-state NMR data suggests a conformational dimorphism at the aromatic amine group. The carbohydrate portion is involved in extensive O—H...O hydrogen bonding, which forms a two-dimensional network parallel to (001) and organized into fused homodromic ring patterns. The Hirshfeld surface fingerprint plots reveal a major contribution of the non-polar H...H and C...H interactions to the crystal packing forces.

4. The Role of Glycosylation in Cardiac Arrhythmias

Long QT syndrome (LQTS) is a debilitating cardiac arrhythmia, and mutations or malfunctions in the human ether-a-go-go–related gene (hERG) are the most common cause of LQTS. hERG is responsible for the cardiac potassium current (IKr), which is important for cardiac repolarization. It has 6 transmembrane domains, ranging from S1 to S6, and a complex N-linked oligosaccharide chain resides on the extracellular S5 pore linker region. The role of this glycosylation chain in hERG function has not yet been well distinguished and in the current study we aim to investigate the relationship between hERG protease susceptibility and the presence of the glycosylation chain. Using molecular techniques, we demonstrate that de-glycosylated hERG channels are degraded by the serine protease Proteinase K at a much faster rate than their glycosylated counter parts. Additionally, through removal of the end-chain sialic acid residues using the enzyme neuraminidase, we conclude that it is likely the physical blockade of susceptible protease sites that grants wild type hERG this glycosylation-dependent protection as opposed to charge repulsion facilitated by specific sugars in the carbohydrate chain. Our data show that the glycosylation chain found on hERG plays a role in protecting the channel from protease degradation, and could provide valuable insight into the development of the cardiac arrhythmia Long QT Syndrome.

Triterpene Glycosides from the Sea Cucumber Eupentacta fraudatrix. Structure and Cytotoxic action of Cucumarioside D with a Terminal 3-O-Me-Glucose Residue Unique for this Species

New minor triterpene glycoside, cucumarioside D (1) identified earlier as a candidate to new glycoside using LC-ESI QTOF-MS has been isolated from the sea cucumber Eupentacta fraudatrix as individual substance. The structure of the glycoside was elucidated using 2D NMR spectroscopy and MS. The glycoside has non-sulfated pentasaccharide carbohydrate chain branched by the second sugar (quinovose) and having 3-O-methylglucose as a terminal monosacharide residue that is an unique structural feature of sea cucumber triterpene glycosides from this species. A moderate cytotoxic activity of the glycoside 1 against the ascyte form of Echlich carcinoma cells and hemolytic activity has been found.

Crystal structure of the acyclic form of 1-deoxy-1-[(4-methoxyphenyl)(methyl)amino]-D-fructose

The title compound, C14H21NO6, (I), crystallizes exclusively in the acyclic keto form. In solution of (I), the acyclic tautomer represents only 10% of the population in equilibrium, with the other 90% consisting of β-pyranose, β-furanose, α-pyranose, and α-furanose cyclic forms. The carbohydrate chain in (I) has a zigzag conformation and the aromatic amine group has a transitional sp 2/sp 3 geometry. Bond lengths and valence angles in the carbohydrate portion compare well with the average values for related acyclic polyol structures. All of the hydroxyl groups are involved in intermolecular hydrogen bonding and form a two-dimensional network of infinite chains, which are interlinked by intramolecular hydrogen bonds and organized into R 8 8(16) homodromic ring patterns. A comparative Hirshfeld surfaces analysis of (I) and four other 1-amino-1-deoxy-D-fructose derivatives suggests the balance of hydrophilic/hydrophobic interactions plays a role in the crystal packing, favoring the acyclic isomer.