Human Lectins, Their Carbohydrate Affinities and Where to Find Them

Lectins are a class of proteins responsible for several biological roles such as cell-cell interactions, signaling pathways, and several innate immune responses against pathogens. Since lectins are able to bind to carbohydrates, they can be a viable target for targeted drug delivery systems. In fact, several lectins were approved by Food and Drug Administration for that purpose. Information about specific carbohydrate recognition by lectin receptors was gathered herein, plus the specific organs where those lectins can be found within the human body.

An electrospray ionization mass spectrometry study of azidoacetic acid/transition metal complexes

RATIONALE

The complexation behavior of transition metals with organic azides by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) is not completely understood. In this study, fragmentation patterns of complex ions having azidoacetic acid coordinated to Ni/Co/Fe were elucidated. The role of transition metals in the mediation of ligand rearrangements in gas phase is experimentally supported.

METHODS

The complexation of some transition metals, nickel, cobalt and iron, by azidoacetic acid was studied by means of ESI and MS/MS. Fragmentation patterns were discerned via consecutive MS/MS experiments on an ion trap mass spectrometer and confirmed by high-resolution (HR) Fourier transform ion cyclotron resonance MS. Density functional theory (DFT) calculations were used to characterize the major ions observed in MS.

RESULTS

Only singly positively charged complex ions were detected presenting various stoichiometries. MS/MS and theoretical calculations allowed us to confirm assignments and coordination sites. Structural evidence suggested that the azidoacetic acid can behave as monodentate and/or bidentate and coordination through the oxygen and nitrogen atoms are both possible. Experimental evidence strongly points to a role of Ni/Co/Fe, in oxidative state (I), in mediating C-C bond activation in the gas phase.

CONCLUSIONS

MS/MS and HRMS experiments were able to elucidate azidoacetic acid complexation with Ni/Co/Fe and several gas-phase processes involving metal reduction and rearrangements. The definition of the coordination pattern dictated by the competition between the nitrogen and the oxygen atoms is also dependent on the metal centre in a very dynamic process. Copyright © 2017 John Wiley & Sons, Ltd.

Antimicrobial and cytotoxic activities of 1,2,3-triazole-sucrose derivatives

A library of 1-(1',2,3,3',4,4',6-hepta-O-acetyl-6'-deoxy-sucros-6'-yl)-1,2,3-triazoles have been investigated for their antibacterial, antifungal and cytotoxic activities. Most of the target compounds showed good inhibitory activity against a variety of clinically and food contaminant important microbial pathogens. In particular, 1-(1',2,3,3',4,4',6-hepta-O-acetyl-6'-deoxy-sucros-6'-yl)-4-(4-pentylphenyl)-1,2,3-triazole (5) was highly active against all the tested bacteria with minimal inhibitory concentrations (MICs) ranging between 1.1 and 4.4 µM and bactericidal concentrations (MBCs) from 2.2 and 8.4 µM. The compound 1-(1',2,3,3',4,4',6-hepta-O-acetyl-6'-deoxy-sucros-6'-yl)-4-(4-bromophenyl)-1,2,3-triazole (3) showed antifungal activity with MICs from 0.6 to 4.8 µM and minimal fungicidal concentrations (MFCs) ranging between 1.2 and 8.9 µM. Furthermore, some of the compounds possessed moderate cytotoxicity against human breast, lung, cervical and hepatocellular carcinoma cell lines, without showing toxicity for non-tumor liver cells. The above mentioned derivatives represent promising leads for the development of new generation of sugar-triazole antifungal agents.

Formation of spherical and core-shell polymeric microparticles from glycopolymers

6-O-methacryloyl-α-d-glucoside 2 and 4-bromophenyl-6-O-methacryloyl-d-glucothioside 7, obtained by enzyme-catalyzed synthesis, have been homo-polymerized and copolymerized with styrene by a free radical process, yielding polymer materials with sugar moieties, attached to the polymer backbone via ester linkages. The results demonstrated that modifying the structural features of the monomers greatly affected the thermal and rheological properties of the polymers. The polymer materials obtained have been characterized by NMR, MALDI-MS, DSC, AFM, and EWC (equilibrium water content). The AFM images indicated the formation of spherical and core-shell polymeric microparticles.

Surfactant-free polymeric nanoparticles composed of PEG, cholic acid and a sucrose moiety

New amphiphilic polymers synthesized from a sucrose-containing conjugate exhibited interesting self-assembly properties in water. Owing to their amphiphilic characteristics polymeric nanoparticles were prepared by a nanoprecipitation method without any surfactants. These nanoparticles formulated with biocompatible building blocks can be considered a potential candidate for drug delivery applications.

Azidoacetone as a complexing agent of transition metals Ni2+/Co2+ promoted dissociation of the C-C bond in azidoacetone

The relevance of metal interactions with azides has led us to the study of the complexation of some transition metals, nickel and cobalt, by azidoacetone by means of electrospray ionization mass spectrometry (ESI-MS). Complexes were obtained from solutions of NiCl(2) and CoCl(2) , in methanol/water. Nickel was electrosprayed with other counter ion, bromide (Br), as well as other solvent (ethanol/water). For nickel and cobalt, the complexes detected were single positively charged, with various stoichiometries, some resulted from the fragmentation of the ligand, the loss of N(2) being quite common. The most abundant species were [Ni(II)Az(2)X](+) where X = Cl, Br and Az = azidoacetone. Some of the complexes showed solvation with the solvent components. Metal reduction was observed in complexes where a radical was lost, resulting from the homolytic cleavage of a metal coordination bond. Collision-induced dissociation (CID) experiments followed by tandem mass spectrometry (MS-MS) analysis were not absolutely conclusive about the coordination site. However, terminal ions of the fragmentation routes were explained by a gas-phase mechanism proposed where a C-C bond was activated and the metal inserted subsequently. Density functional theory calculations provided structures for some complexes. In [Ni(II)Az(2)X](+) species, one azidoacetone ligand is monodentate and the dominant binding location is the alkylated nitrogen and not the carbonyl group. The other azidoacetone ligand is bidentate showing coordination through alkylated nitrogen and the carbonyl group. These are also the preferential binding sites for the most stable isomer of [Ni(II)AzX](+) species.

Allergic asthma in patients with common variable immunodeficiency

BACKGROUND

Many patients with common variable immunodeficiency (CVID) have a clinical history suggestive of allergic respiratory disease. However, in such individuals, the prevalence of asthma and the role of atopy have not been well established. The objective of this study was to evaluate pulmonary function and identify asthma in patients with CVID. We also investigated the role of IgE as a trigger of asthma in these patients.

METHODS

Sixty-two patients diagnosed with CVID underwent spirometry, as well as skin prick testing and in vitro determination of serum-specific IgE levels for aeroallergens, together with bronchial provocation with histamine and allergen.

RESULTS

The most common alteration identified through spirometry was obstructive lung disease, which was observed in 29 (47.5%) of the 62 patients evaluated. Eighteen (29.0%) of the 62 patients had a clinical history suggestive of allergic asthma. By the end of the study, asthma had been diagnosed in nine (14.5%) patients and atopy had been identified in six (9.7%). In addition, allergic asthma had been diagnosed in four patients (6.5% of the sample as a whole; 22.2% of the 18 patients with a clinical history suggestive of the diagnosis).

CONCLUSION

In this study, CVID patients testing negative for specific IgE antibodies and suspected of having allergic asthma presented a positive response to bronchial provocation tests with allergens. To our knowledge, this is the first such study. When CVID patients with a history suggestive of allergic asthma test negative on traditional tests, additional tests designed to identify allergic asthma might be conducted.

Study of doubly charged alkaline earth metal and 3-azidopropionitrile complexes by electrospray ionization mass spectrometry

The present work describes a study of the complexation of calcium and magnesium by 3-azidopropionitrile by means of electrospray ionization mass spectrometry (ESI-MS). Complexes were obtained from solutions of calcium and magnesium salts of the type CaX2 and MgX2 (where X = Cl or NO3) in water and methanol/water. The complexes detected were mainly double positively charged, with various stoichiometries not depending on the solvent, since water and 3-azidopropionitrile were always the main ligands. Solvation with methanol was not observed unlike in a previous study of complexation of nickel and cobalt by 3-azidopropionitrile. The complex ions [M(II)Az4(H2O)](2+), [M(II)Az5](2+) (where M = Ca and Mg) are the most abundant for both metals, and both counter ions. Tandem mass spectrometric (MS/MS) analysis showed that, under collision-induced dissociation (CID) conditions, the most important processes occurring were loss of neutral ligands and the replacement of 3-azidopropionitrile by water. A complex species containing reduced alkaline earth metal was due to radical loss, resulting from homolytic cleavage in the azide ligand. Some terminal ions, in the fragmentation sequences, point to the nitrile group as the coordination site in the 3-azidopropionitrile. Density functional theory (DFT) calculations confirmed this coordination site and proved that 3-azidopropionitrile behaves as a monodentate ligand in the systems under study. Moreover, the theoretical study proved that the presence of water ligand introduces stability through a hydrogen bond established between the water molecule and one nitrogen atom of the azido group. In addition, the strong dipole moment of 3-azidopropionitrile (4.76 D), which is mainly related to presence of the nitrile group, favors the stabilization of the metal-ligand complexes through charge-dipole interactions and the coordination of the metal to the nitrile group.

Complexation of transition metals by 3-azidopropionitrile. An electrospray ionization mass spectrometry study

Most complexes of azides and transition metals involve the N(3)(-) azide anion as a ligand other than an organic azide. Complexes of organic azides with metals are involved in biological applications and in the deposition of nitrenes on metal surfaces, producing nitride layers for semi-conductors preparation; this makes the study of these interactions an important issue. This work describes a study of the complexation of nickel and cobalt by 3-azidopropionitrile by means of electrospray ionization mass spectrometry (ESI-MS). Complexes were obtained from solutions of NiCl(2) and CoCl(2) in methanol/water. In the case of nickel, other NiX(2) salts were investigated (where X = Br or NO(3)) and other solvents were also studied (notably ethanol/water). All complexes detected were single positively charged, with various stoichiometries, some resulted from the fragmentation of the ligand, the loss of N(2), and HCN being quite common. The most abundant cations observed were [Ni(II)AzAzX](+), where X = Cl, Br, NO(3). Some of the complexes showed solvation with methanol/ethanol/water. Metal reduction was observed in complexes where a radical was lost, resulting from the homolytic cleavage of a metal-nitrogen bond. Collision induced dissociation (CID) experiments followed by tandem mass spectrometry (MS-MS) analysis were not absolutely conclusive about the coordination site. However, terminal ions observed from the fragmentation routes were explained by a proposed gas-phase mechanism. Density functional theory calculations were carried out and provided structures for some complexes, pointing to the possibility of 3-azidopropionitrile acting as a mono- or a bidentate ligand.

Cardosins: A new and efficient plant enzymatic tool to dissociate neuronal cells for the establishment of cell cultures

In the present work, we examined the feasibility of using cardosins, plant aspartic-proteinases from Cynara cardunculus L., to isolate cells from rat embryonic brain. Using morphological and functional assays, we compared cell cultures obtained with cardosins with those prepared with a well-established trypsin protocol. Cardosins and trypsin dissociation produced cells with similar yield, viability, and GABA release in response to a depolarizing stimulus. However, cardosins-dissociated cells appeared to recover faster in culture, as assessed by the MTT-test and by the number and length of neurtites, suggesting that cardosins are less aggressive to neurons than trypsin. This feature might be helpful for research and medical purposes requiring fast manipulations of cells.

Synthesis of new chiral amines with a cyclic 1,2-diacetal skeleton derived from (2R, 3R)-(+)-tartaric acid

The syntheses of new chiral cyclic 1,2-diacetals from (2R, 3R)-( )-tartaric acid are described. C(2)-symmetrical diamines were prepared via direct amidation of the tartrate or from the corresponding bismesylate via reaction with sodium azide. For C1-symmetrical compounds, the Appel reaction was used to form the key intermediate, a monochlorocarbinol, from the diol. Some of the new chiral compounds, produced in good to high yields, may be potentially useful as asymmetric organocatalysts or as nitrogen and sulfur chelating ligands for asymmetric metal catalyzed reactions. Thus, a bis-N-methyl-methanamine derivative, used in substoichiometric amounts, was found to catalyze the enantioselective addition of cyclohexanone to (E)-beta-nitrostyrene with high diastereoselectivity (syn / anti = 92:8), albeit giving moderate optical purity (syn: 30 %).

Contrasting Behavior in Azide Pyrolyses: An Investigation of the Thermal Decompositions of Methyl Azidoformate, Ethyl Azidoformate and 2-Azido-N,N-dimethylacetamide by Ultraviolet Photoelectron Spectroscopy and Matrix Isolation Infrared Spectroscopy

The thermal decompositions of methyl azidoformate (N3COOMe), ethyl azidoformate (N3COOEt) and 2-azido-N,N-dimethylacetamide (N3CH2CONMe2) have been studied by matrix isolation infrared spectroscopy and real-time ultraviolet photoelectron spectroscopy. N2 appears as an initial pyrolysis product in all systems, and the principal interest lies in the fate of the accompanying organic fragment. For methyl azidoformate, four accompanying products were observed: HNCO, H2CO, CH2NH and CO2, and these are believed to arise as a result of two competing decomposition routes of a four-membered cyclic intermediate. Ethyl azidoformate pyrolysis yields four corresponding products: HNCO, MeCHO, MeCHNH and CO2, together with the five-membered-ring compound 2-oxazolidone. In contrast, the initial pyrolysis of 2-azido-N,N-dimethyl acetamide, yields the novel imine intermediate Me2NCOCH=NH, which subsequently decomposes into dimethyl formamide (HCONMe2), CO, Me2NH and HCN. This intermediate was detected by matrix isolation IR spectroscopy, and its identity confirmed both by a molecular orbital calculation of its IR spectrum, and by the temperature dependence and distribution of products in the PES and IR studies. Mechanisms are proposed for the formation and decomposition of all the products observed in these three systems, based on the experimental evidence and the results of supporting molecular orbital calculations.

Highly Stereoselective Aldol Reaction for the Synthesis of γ-Lactones Starting from Tartaric Acid

A simple stereoselective process for the synthesis of highly substituted gamma-lactones was developed based on aldol reactions between the enolate of dioxanes derived from tartaric acid and aldehydes. A range of aromatic and aliphatic aldehydes were reacted, in most cases achieving good yields and stereoselectivity. The limitations of this reaction were identified and a transition state is proposed.

Aldol reactions of dioxanes derived from tartaric acid. A total synthesis of (+)-nephrosteranic acid

[reaction: see text]. A general enantioselective synthesis of the paraconic acids was developed. The key step was a highly stereoselective aldol reaction between a dioxane dithioester derived from l-tartaric acid and a suitable aldehyde.

Improved anomeric selectivity for the aroylation of sugars

By manipulating the solvent and using bulky TMEDA as a base, good yields and improved anomeric selectivities were obtained for the aroylation of D-glucose over similar esterifications using pyridine. The reaction has been extended to mannose and the beta-anomer of pergalloylated mannose was predominantly obtained in one step by direct aroylation of the parent sugar.

Aziridines as a Protecting and Directing Group. Stereoselective Synthesis of (+)-Bromoxone

[reaction: see text] The directing ability of an aziridine group for the epoxidation of adjacent double bonds is demonstrated. The aziridine group is also used to effectively protect a double bond in a cycloenone system for a short synthesis of the title compound.

Mass spectrometric study of aliphatic alpha-carbonyl azides

A series of derivatives of 2-azidoacetic acid and 2-azidoacetone were synthesized and their behaviour under electron ionization conditions was investigated. This paper reports the electron ionization fragmentation mechanisms for five aliphatic alpha-carbonyl azides, which were clarified by accurate mass measurements and B/E linked scans. The substituent influences the abundance and the nature of the ions resulting from the molecular ion fragmentation.

Stereoselective radical reactions of some tartaric and glyceric acid derivatives

[reaction: see text] Free radicals generated by the decarboxylation of dimethoxydioxanecarboxylic acids derived from L-(+)-tartaric acid and L-glyceric acid added to some maleimides and acrylates with high stereoselectivity. This method provides easy access to some chiral building blocks.

The effect of diethylamine on Stille alkylations with tetraalkylstannanes

The addition of diethylamine to Stille alkylation reactions using stannanes improves yields by reducing beta-hydride elimination and reduction reactions, it also serves as a substitute for other additives such as Cu(I)I.

The first synthesis of (-)-asperpentyn and efficient syntheses of (+)-harveynone, (+)-epiepoformin and (-)-theobroxide

A generally applicable strategy for the synthesis of a range of polyoxygenated cyclohexane natural products has been developed. The enantioselective syntheses of (-)-theobroxide, a polyoxygenated cyclohexane natural compound with potent growth inducing properties in potato microtubers has been achieved via a 1,2 O-silyl migration between trans-hydroxyl groups and a remote hydroxyl directed epoxidation of an enone derived from quinic acid. A thus derived alpha-iodoenone was subjected to Stille coupling with tetramethylstannane to afford the first title compound. A similar strategy enabled a route to the complete asymmetric synthesis of the acetylenic phytotoxin (+)-harveynone. By selective reduction of (-)-theobroxide, (+)-epiepoformin was also prepared in enantiopure form and similarly, stereoselective reduction of (+)-harveynone completed the first enantioselective synthesis of (-)-asperpentyn, another natural compound with antimicrobial activity.

Preparation of sucrose heptaesters unsubstituted at the C-1 hydroxy group of the fructose moiety via selective O-desilylation

Selective O-desilylation of 6,1',6'-tri-O-tert-butyldiphenylsilyl-2,3,4,3',4'-penta-O-benzo ylsucrose with hydrofluoric acid in acetonitrile led to the 1'-O-tert-butyldiphenylsilyl derivative (96% yield), which was further perbenzoylated and deprotected at OH-1' with tetrabutylammonium fluoride (86%). An analogous sequence with the corresponding O-acetylated sucrose derivative and tetrabutylammonium fluoride as desilylating agent resulted in a lower yield of the C-1' hydroxy derivative.

Diarrhea and malabsorption in primary humoral immunodeficiency

Patients with Humoral immunodeficiency syndromes frequently present recurrent infections, mainly of the digestive and respiratory tracts. This study carried out a clinical and laboratorial evaluation in 15 humoral immunodeficiency patients presenting chronic gastrointestinal symptoms. Out results emphasize the relevance of immunodeficiency syndromes in the differential diagnosis of chronic diarrhea.

Nephrotic syndrome associated with hepatointestinal schistosomiasis

Schistosomal nephropathy has long been related to the hepatosplenic form of schistosomiasis. In the last few years, 24 patients with hepatointestinal schistosomiasis and the nephrotic syndrome were studied. Aiming at evaluating a possible etiologic participation of schistosomiasis in the development of the nephropathy, this group was comparatively studied with a group of 37 patients with idiopathic nephrotic syndrome. Both groups had a different distribution of the histologic lesions. In the group with schistosomiasis there was a statistically significant prevalence of proliferative mesangial glomerulonephritis (33.3%), whereas in the control group there was prevalence of membranous glomerulonephritis (32.4%). On immunofluorescence, IgM was positive in 94.4% of the patients with schistosomiasis versus 55.0% in the control group (P < 0.01). In the group with schistosomiasis, 8 patients evidenced mesangial proliferative glomerulonephritis and 5, membranoproliferative glomerulonephritis. In both histological types immunofluorescence showed IgM and C3 granular deposits in the glomeruli. The data in this study suggests that mesangial proliferative and membranoproliferative glomerulonephritis, with glomerular granular IgM and C3 deposits, represent the renal lesions of the schistosomiasis associated nephropathy.