Mannose glyco-oligoamide β-D-Man-Py-γ-Py-Ind (β-D-Man, 1) and two new glyco-oligoamides, β-L-Man-Py-γ-Py-Ind (β-L-Man, 2) and 6-deoxy-β-D-Man-Py-γ-Py-Ind (6-deoxy-β-D-Man, 3), have been designed and synthesized to investigate the role of hydrogen-bonding cooperative donor centres of carbohydrates in their recognition by DNA. The free- and bound-state geometries were studied, as were the affinities of the D and L enantiomers of the mannose glyco-oligoamides (1 and 2) for DNA polymers [ct-DNA and poly(dA-dT)2]. TR-NOESY and DF-STD experiments for the diastereomeric complexes formed with DNA allow the asymmetric centres of the sugar residue that are close to the inner and outer regions of the DNA minor grooves to be distinguished. A C→N hairpin folding in β-L-Man derivative 2 was observed, with the α face of the sugar close to the indole ring. The C-2 and C-3 centres are orientated towards the inner region of the DNA minor groove. The affinity data for poly(dA-dT)2 indicate that there is a chiral discrimination process, with β-L-Man derivative 2 being the best ligand. 6-Deoxy-β-D-Man derivative 3 forms the least stable complexes with DNA. Molecular dynamics simulations of β-L-Man derivative 2 in complex with a double-strand dodecamer d(AT)12 are in agreement with the experimental NMR spectroscopic data. Thus, the cooperative donor centre 2-OH in the L-mannose enantiomer is a key contributor to the stability of the 2·poly(dA-dT)2 complex. Structural and affinity data have been obtained for different mannose oligoamides when binding to DNA polymers. A β-L-Man ligand (2) binds to poly(dA-dT)2 with a more well-defined structure, consistent with a better affinity. Thus, the placement of cooperative hydrogen-bond donor centres towards the inner region of the minor groove increases the binding affinity for polyAT(dA-dT)2. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Two different approaches to highly symmetric macrocycles by reversible Nicholas reactions have been developed. The first sequence uses a bis[Co2(CO)6] complex derived from a double propargylic alcohol supporting two natural product moieties. The reactions with BF3·OEt2 and different benzene dimethanols yielded either (1:1) or (2:2) adducts, depending essentially on the nature of the tether joining both Co clusters. Alternatively, the Nicholas reactions of Co-complexed propargyl alcohol templates with one steroid and one monoterpene fragment as well as one aromatic terminus containing an alcohol moiety yielded the corresponding macrocycles derived from self-dimerization. Both routes to macrocycles are complementary and efficiently produce sophisticated natural-product-containing structures. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA.

Unsaturated carbohydrate derivatives are useful intermediates in synthetic transformations leading to a variety of compounds. The aim of this review is to highlight the rich chemistry of Δ-2,3 unsaturated pyranosides, emphasizing the variety of transformations that have been carried out in these substrates during the last decade. © 2015 by the authors; licensee MDPI.

This study describes CholesteroNitrone 2 as an antioxidant and neuroprotective agent against ischemic injury. Neuroprotection was assessed using in vitro and in vivo experimental ischemia models. The compound significantly increased cell viability, induced neuroprotection following ischemic reperfusion, and decreased neurological deficit scores in treated animals, supporting the next preclinical studies as a potential agent for the treatment of stroke. (Figure Presented). © 2015 American Chemical Society.

This review covers work published in the calendar year 2014. The synthesis and reactivity of four-membered heteroatom-containing cycles are reviewed. New chemistry of these strained heterocycles, especially oxa- and azaheterocycles, is covered. © 2015 Elsevier Ltd

Hg(ClO4)2·3H2O, a cheap, water-tolerant, and stable salt, catalyzes the cycloisomerization reaction or α-allenols to 2,5-dihydrofurans in an efficient and selective manner. The reaction is general and can be applied to differently functionalized substrates, including alkyl-substituted, aryl-substituted, enantiopure, and tertiary allenols. In addition, density functional theory (DFT) calculations were performed to obtain insight into various aspects of the controlled reactivity of α-allenols under mercury catalysis. They suggest a dual activation of the allenol by the Hg complex that drives the reaction to the chemoselective formation of 2,5-dihydrofurans. © 2015 American Chemical Society.

We report on spectroscopic and photodynamical behaviours of 5-amino-2-(2′-hydroxyphenyl)benzoxazole (5A-HBO) in different solutions. The dye undergoes an ultrafast ICT reaction (<50 fs) (comparable to that observed for its methylated derivative, 5A-MBO), in agreement with the results of TD-DFT theoretical calculations (gas phase). Depending on the used solvent, the ICT reaction can be followed by a reversible/irreversible excited-state intramolecular proton transfer (ESIPT) reaction or by breaking of the intramolecular hydrogen bond (IHB). 5A-HBO in n-heptane solution exhibits an irreversible and slow (20 ps) ESIPT reaction, while that of the parent compound, HBO, takes place in less than 150 fs. Compared to excited HBO behaviour, theoretical calculations on 5A-HBO suggest a higher energy barrier (∼4 kcal mol-1) between the relaxed enol and keto tautomers, in addition to a less stabilization of the latter, which is in agreement with experiments in n-heptane. On the other hand, in dichloromethane, after the ICT reaction a subsequent and reversible proton motion occurs in an extraordinary slower regime (ns-time scale). No isotopic effect (OH/OD exchange) was observed in this solvent reflecting that the reversible ESIPT reaction evolves along the IHB and solvent coordinates. Using tetrahydrofurane and acetonitrile, we observed a breaking of the IHB due to specific intermolecular interactions with solvent molecules. This leads to the formation of open-enol forms, which undergo an ICT reaction as it occurs in 5A-MBO. These results bring new findings in the coupled ICT and ESIPT reactions. The photobehaviour of this new dye remarkably changes with the solvent nature, opening up the window for further research and possible applications in sensing polarity or H-bonding of media similar to that of the biological ones. © 2015 the Owner Societies.

We report on the steady-state, picosecond and femtosecond time-resolved studies of a charge and proton transfer dye 6-amino-2-(2'-hydroxyphenyl)benzoxazole (6A-HBO) and its methylated derivative 6-amino-2-(2'-methoxyphenyl)benzoxazole (6A-MBO), in different solvents. With femtosecond resolution and comparison with the photobehaviour of 6A-MBO, we demonstrate for 6A-HBO in solution, the photoproduction of an intramolecular charge-transfer (ICT) process at S1 taking place in ∼140 fs or shorter, followed by solvent relaxation in the charge transferred species. The generated structure (syn-enol charge transfer conformer) experiences an excited-state intramolecular proton-transfer (ESIPT) reaction to produce a keto-type tautomer. This subsequent proton motion occurs in 1.2 ps (n-heptane), 14 ps (DCM) and 35 ps (MeOH). In MeOH, it is assisted by the solvent molecules and occurs through tunneling for which we got a large kinetic isotope effect (KIE) of about 13. For the 6A-DBO (deuterated sample in CD3OD) the global proton-transfer reaction takes place in 200 ps, showing a remarkable slow KIE regime. The slow ESIPT reaction in DCM (14 ps), not through tunnelling as it is not sensitive to OH/OD exchange, has however to overcome an energy barrier using intramolecular as well as solvent coordinates. The rich ESIPT dynamics of 6A-HBO in the used solutions is governed by an ICT reaction, triggered by the amino group, and it is solvent dependent. Thus, the charge injection to a 6A-HBO molecular frame makes the ICT species more stable, and the phenol group less acidic, slowing down the subsequent ESIPT reaction. Our findings bring new insights into the coupling between ICT and ESIPT reactions on the potential-energy surfaces of several barriers. This journal is © the Owner Societies.

A Solid-Phase Microextraction method for the Gas Chromatography-Mass Spectrometry analysis of blackberry (Rubus sp.) volatiles has been fully optimized by means of a Box-Behnken experimental design. The optimized operating conditions (Carboxen/Polydimethylsiloxane fiber coating, 66 °C, 20 min equilibrium time and 16 min extraction time) have been applied to the characterization for the first time of the volatile composition of Rubus ulmifolius Schott blackberries collected in Italy and Spain. A total of 74 volatiles of different functionality were identified; esters and aliphatic alcohols were the predominant classes in both sample types. Methylbutanal (2.02-25.70\%), ethanol (9.84-68.21\%), 2,3-butanedione (2.31-14.71\%), trans-2-hexenal (0.49-17.49\%), 3-hydroxy-2-butanone (0.08-7.39\%), 1-hexanol (0.56-16.39\%), 1-octanol (0.49-10.86\%) and methylbutanoic acid (0.53-21.48\%) were the major compounds in most blackberries analyzed. Stepwise multiple regression analysis of semiquantitative data showed that only two variables (ethyl decanoate and ethyl acetate) were necessary for a successful differentiation of blackberries according to their harvest location. © 2015 Elsevier Ltd.

The divergent behavior of two homologue allenals, namely, 2-(buta-2,3-dienyloxy)- and 2-(propa-1,2-dienyloxy)benzaldehydes, as cyclization substrates is described. 2-(Buta-2,3-dienyloxy)benzaldehydes suffers a formal allenic carbocyclization reaction to afford chromenes, whereas 2-(propa-1,2-dienyloxy)benzaldehydes react to yield chromones. The formation of chromenes is strictly a formal hydroarylation process divided into two parts, namely, allenic Claisen-type rearrangement and oxycyclization. An unknown N-heterocyclic carbene (NHC)-catalyzed allenic hydroacylation reaction must be invoked to account for the preparation of chromones. ortho-Allenylbenzaldehydes bearing either electron-donating substituents or electron-withdrawing substituents worked well to afford both the hydroarylation and hydroacylation products. This unexpected difference in reactivity can be rationalized by means of density functional theory calculations. © 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abstract: The reaction of racemic 2-amino-4H-pyrans, such as 3-amino-1-aryl-1H-benzo[f]chromene-2-carbonitriles, with N-bromosuccinimide (NBS), in CH2 Cl2, at room temperature, is a very quick, regio, stereoselective, and high yielding process, affording major racemic (1S,2S)-2-bromo-3-imino-benzo[f]chromene or racemic (1S,2S)-2-bromo-3-(bromoimino)-benzo[f]chromene derivatives, when using 1.0 or 2.2 equivalents of NBS, respectively. This reaction, extended to isomeric 2-amino-4-aryl-4H-benzo[h]chromene-3-carbonitriles, showed an unexpected reactivity, affording racemic (3S,4S)-3-bromo-2-(bromoimino)-benzo[h]chromene-3-carbonitriles or 2-oxo-2H-benzo[h]chromene-3-carbonitriles, when using 2.2 or 1.0 equivalents of NBS, respectively. The reaction of alkyl 6-amino-5-cyano-2-methyl-4H-pyran-3-carboxylates has yielded unstable racemic (3S,4S)-alkyl 3-bromo-2-(bromoimino)-3-cyano-6-methyl-3,4-dihydro-2H-pyran-5-carboxylates. The mechanism of these reactions has been investigated by computational methods. © 2014, Springer International Publishing Switzerland.

The highly diastereoselective base-promoted intramolecular cyclization of a variety of enantiopure sulfinyl dienyl amines provides novel sulfinyl tetrahydropyridines that are readily converted to 3-hydroxy tetrahydropyridines via sigmatropic rearrangement. The influence of N- and C- substituents on the process has been studied. Procedures to shorten the sequence such as the tandem cyclization followed by [2,3]-sigmatropic rearrangement, as well as cyclization of the free amine, under Boc- or ArSO- deprotection conditions have been examined. Good to excellent levels of selectivity are generally observed for the reported transformations (dr: 75/25 to >98/2). A novel protocol to access substituted amino dienyl sulfoxides is also reported. © 2015 American Chemical Society.

Aminoglycoside compounds represent a family of highly charged naturally occurring pseudooligosaccharides, which have been used for a long time as antibiotics that bind ribosomal RNA, but their use has been hindered by their inherent toxicity and the resistance that has emerged to these compounds. To circumvent this drawback during the last years several synthetic strategies for aminoglycoside preparation have been developed. The present review surveys the recent synthetic efforts that are focused on the preparation of heterocyclic aminoglycosides.

Tacking into account the great potential of hydrogels bearing thiol functionalities, in this work we report the synthesis of thiolated hydrogels by free radical polymerization of (i) a thermo-responsive monomer, 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA); (ii) a lower ratio of a monomer having protected thiol group, 2-(acetylthio)ethyl methacrylate (AcSEMA) and (iii) a small proportion of tetraethylene glycol dimethacrylate (TEGDMA) as crosslinker. Subsequently, deprotection of thioacetate groups, by incubating the samples in basic solutions, allows obtaining hydrogels with free thiol groups. After this treatment, the pH dependence of the thiol-thiolate equilibrium makes the thermal response of novel P(MEO2MA-co-SEMA) strongly modulated by the pH. © 2014 Elsevier Ltd. All rights reserved.

Purpose: After spinal cord injury (SCI) a glial scar is generated in the area affected that forms a barrier for axon growth and myelination, preventing functional recovery. Recently,we have described a synthetic glycolipid (IG20) that inhibited proliferation of human glioma cells.We show now that IG20 inhibited the proliferation of astrocytes and microglial cells, the principal cellular components of the glial scar, and promoting axonal outgrowth and myelin production in vitro. Methods: Glial cells were inhibited with IG20 (IC50=10M) and studied by RT-PCR,Western Blotting, immunoprecipitation and fluorescence microscopy. Axonal outgrowth in dorsal root ganglia (DRG) and myelin production by oligodendrocytes were analyzed by immunocytochemistry. Adult rats were assayed in spinal cord contusion model and the recovery of treated animals (n = 6) and controls (n = 6) was followed. Results: The IG20 was localized in the cytosol of glial cells, forming a complex with RhoGDI, a regulator of RhoGTPases. Treatment of astroglial cultures with IG20 increase the expression of BDNF receptor genes (TrkBT1, TrkB Full). IG20 reduced the astroglial marker GFAP, while increasing production of myelin basic protein in oligodendrocytes and promoted axonal outgrowth from DRG neurons. Local injection of IG20, near a spinal cord contusion, promoted the recovery of lesioned animals analyzed by BBB test (P < 0.05). Conclusions: We propose that inhibition of astrocytes and microglia by IG20 could be diminished the glial scar formation, inducing the re-growth and myelination of axons, these elements constitute a new approach for SCI therapy. © 2015 - IOS Press and the authors. All rights reserved.

Prebiotics are non-digestible food ingredients (oligosaccharides) that reach the colon and are used as substrate by microorganisms producing energy, metabolites and micronutrients used for the host; in addition they also stimulate the selective growth of certain beneficial species (mainly bifidobacteria and lactobacilli) in the intestinal microbiota. In this article, a multidisciplinary approach to understand the concept of prebiotic carbohydrates, their properties and beneficial effects in humans has been carried out. Definitions of prebiotics, reported by relevant international organizations and researchers, are described. A comprehensive description of accepted prebiotics having strong scientific evidence of their beneficial properties in humans (inulin-type fructans, FOS, GOS, lactulose and human milk oligosaccharides) is reported. Emerging prebiotics and those which are in the early stages of study have also included in this study. Taken into account that the chemical structure greatly influences carbohydrates prebiotic properties, the analytical techniques used for their analysis and characterization are discussed. In vitro and in vivo models used to evaluate the gastrointestinal digestion, absorption resistance and fermentability in the colon of prebiotics as well as major criteria to design robust intervention trials in humans are described. Finally, a comprehensive summary of the beneficial effects of prebiotics for health at systemic and intestinal levels is reported. The research effort on prebiotics has been intensive in last decades and has demonstrated that a multidisciplinary approach is necessary in order to claim their health benefits. © 2015, Grupo Aula Medica S.A. All rights reserved.

β-Galactosidases from Kluyveromyces lactis and Kluyveromyces marxianus isolated from artisanal ewes' milk cheeses, were used to transgalactosylate lactose from cheese whey permeate (WP). The content of galactooligosaccharides (GOS) obtained by transgalactosylation was comparable with that formed using pure lactose as substrate. In order to obtain a mixture with higher prebiotic oligosaccharide content, isomerisation of the transgalactosylated WP was carried out using sodium aluminate as catalyst. The transgalactosylated mixtures at 6 h of reaction contained amounts of prebiotic carbohydrates (tagatose, lactulose, GOS and oligosaccharides derived from lactulose, OsLu) close to 50 g/100 g of total carbohydrates for all the strains tested, corresponding to 322 g prebiotics/kg whey permeate. Thus, the suitability of this methodology to produce mixtures of dietary non-digestible carbohydrates with prebiotic properties from WP has been demonstrated, which is interesting for the food industry since it increases the value and the applicability of this by-product from cheese manufacture. © 2015 Proprietors of Journal of Dairy Research.

The studies of drugs that could constitute a palliative to spinal cord injury (SCI) are a continuous and increasing demand in biomedicine field from developed societies. Recently we described the chemical synthesis and antiglioma activity of synthetic glycosides. A synthetic sulfated glycolipid (here IG20) has shown chemical stability, solubility in polar solvents, and high inhibitory capacity over glioma growth. We have used mass spectrometry (MS) to monitor IG20 m / z = 550.3 in cells and tissues of the central nervous system (CNS) that are involved in SCI recovery. IG20 was detected by MS in serum and homogenates from CNS tissue of rats, though in the latter a previous deproteinization step was required. The pharmacokinetic parameters of serum clearance at 24 h and half-life at 4 h were determined for synthetic glycoside in the adult rat using MS. A local administration of the drug near of spinal lesion site is proposed. © 2015 María Sánchez-Sierra et al.

Electrostatic and charge-transfer contributions to CH-π complexes can be modulated by attaching electron-withdrawing substituents to the carbon atom. While clearly stabilizing in the gas phase, the outcome of this chemical modification in water is more difficult to predict. Herein we provide a definitive and quantitative answer to this question employing a simple strategy based on dynamic combinatorial chemistry. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

We designed and synthesized two anomeric oleyl glucosaminides as anti-cancer agents where the presence of a trifluoroacetyl group close to the anomeric center makes them resistant to hydrolysis by hexosaminidases. The oleyl glycosides share key structural features with synthetic and natural oleyl derivatives that have been reported to exhibit anti-cancer properties. While both glycosides showed antiproliferative activity on cancer cell lines, only the α-anomer caused endoplasmic reticulum (ER) stress and cell death on C6 glioma cells. Analysis of sphingolipids and glycosphingolipds in cells treated with the glycosides showed that the α-anomer caused a drastic accumulation of ceramide and glucosylceramide and reduction of lactosylceramide and GM3 ganglioside at concentrations above a threshold of 20 μM. In order to understand how ceramide levels increase in response to α-glycoside treatment, further investigations were done using specific inhibitors of sphingolipid metabolic pathways. The pretreatment with 3-O-methylsphingomyelin (a neutral sphingomyelinase inhibitor) restored sphingomyelin levels together with the lactosylceramide and GM3 ganglioside levels and prevented the ER stress and cell death caused by the α-glycoside. The results indicated that the activation of neutral sphingomyelinase is the main cause of the alterations in sphingolipids that eventually lead to cell death. The new oleyl glycoside targets a key enzyme in sphingolipid metabolism with potential applications in cancer therapy. © 2015 Elsevier Inc. All rights reserved.