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Carbohydrates play important roles in life science, but their synthesis is always hampered by their complicated chemical structures. Scientists have never stopped trying to solve the problem of glycan synthesis from various aspects. Here a brief overview of recent progress in glycan synthesis, including chemical approaches, chemoenzymatic approaches, and automated synthesis, will be discussed, focusing on the efficiency of new glycosylation methods, the stereoselectivity of coupled products, and their applications in the assembly of complex glycan chains. [ABSTRACT FROM AUTHOR]

• The flippase SLC47A1 is a repressor of ferroptosis. • PPARA transactivates SLC47A1 to suppress ferroptosis induction through lipid remodeling. • Knockdown of SLC47A1 sensitizes cells to ferroptosis in a ACSL4-SOAT1–axis dependent manner to generate polyunsaturated fatty acid containing (PUFA) cholesterol esters. • Net effect of acyl-PUFAs with various head groups promotes ferroptosis. Ferroptosis is an iron-dependent form of cell death triggered by dysregulation of biochemical processes that culminate in lethal lipid peroxidation. Lipid metabolism is fundamental for determining ferroptotic fate, however, the mechanisms that alter lipid components to shape ferroptosis susceptibility remains elusive. A recent article by Lin and colleagues in Nature Communications systematically analyzed phospholipid transporters (phospholipid scramblases, flippases, and floppases), and identified that the lipid flippase solute carrier family 47 member 1 (SLC47A1) functions as a regulator of lipid remodeling and promotes ferroptosis resistance. SLC47A1 is transactivated by peroxisome proliferator activated receptor alpha (PPARA). Upon ferroptosis induction, SLC47A1 upregulation inhibits DHA/DPA polyunsaturated fatty acid containing glycerophospholipids (PUFA-PLs) accumulation to block ferroptosis. Depletion of either PPARA or SLC47A1 sensitized cells to ferroptosis by favoring ACSL4-SOAT1–mediated production of polyunsaturated fatty acid containing (PUFA) cholesterol esters. Ferroptosis has been widely linked to degenerative processes and tumor suppression. These findings indicate that lipid transporters may provide yet another means by which PUFA-containing membrane lipids convey ferroptosis sensitivity. [ABSTRACT FROM AUTHOR]

A low-temperature sol-gel process associated with different surfactants in ethanol solvent was applied to prepare ultrafine MnO2 nanowires and nanorods. The surfactants used in the synthesis procedure are crucial for the structure of products. Highly dispersed MnO2 nanowires was formed by assistance of cetyltrimethyl ammonium bromide while hierarchical particles assembled with nanowires were synthesized by usage of pluronic P123 triblock copolymer or Polyvinyl pyrrolidone. The free-standing sheet like structure aggregated with nanorods was obtained by using sodium dodecyl sulfate as a surfactant. All samples were characterized by SEM, TEM, XRD and the results indicated these MnO2 ultrafine nanostructures could be expediently produced by this facile method. [ABSTRACT FROM AUTHOR]

Abstract: In this work, a facile and rapid microwave-assisted hydrothermal route has been developed to prepare Bi2GeO5 nanoflakes. Ag nanoparticles were subsequently deposited on the Bi2GeO5 nanoflakes by a photoreduction procedure. The phases and morphologies of the products were characterized by powder X-ray diffraction (XRD), X-ray photoelectron spectrum (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectroscopy. Photocatalytic experiments indicate that such Ag/Bi2GeO5 nanocomposite possesses higher photocatalytic activity for RhB degradation under UV light irradiation in comparison to pure Bi2GeO5. The amount of Ag in the nanocomposite affects the catalytic activity, and 3wt% Ag showed the highest photodegradation efficiency. Moreover, the catalyst remains active after four consecutive tests. The present study provides a new strategy to design composite materials with enhanced photocatalytic activity. [Copyright &y& Elsevier]

Abstract: Ganglioside GM3 and its derivatives have many important biological functions. Using diethyl phosphite protected sialic acid as glycosyl donor and 3,2′,3′,4′-unprotected lactose as glycosyl acceptor, the sialic acid-containing trisaccharide was assembled with excellent anomeric stereoselectivity. The trisaccharide was further coupled with ceramide precursor to yield sphingosine 1. Based on this key intermediate, two different series of N-modified GM3 analogues with modifications on either the nitrogen of sialic acid residue or the nitrogen of ceramide moiety and GM3 itself were synthesized smoothly. [Copyright &y& Elsevier]

Abstract: Wireless sensor network can eliminate the high cost of wired network. However, in wireless sensor networks, an important but critical problem is the energy consumption of sensor nodes greatly limits the working life. The paper combining the application of genetic algorithm for wireless sensor networks in multi-objective optimization, taking into account the needs of specific application, a sensor network in the open pit slope detection example is introduced. Fitness function is designed according to the application of open-pit mine slope detection system. In the same conditions, using serial genetic algorithm, parallel genetic algorithm and quantum genetic algorithm for network energy optimization. Simulation results show that: genetic algorithm optimize the energy consumption, achieve the longest life cycle of the network. By comparing these three kinds of genetic algorithms, the quantum genetic algorithm is much better than the other two genetic algorithms in optimizing the energy consumption. [Copyright &y& Elsevier]

Abstract: The repeating GalpNAc-α-(1→4)-GalpNAc unit is part of a series of essential structures that can be found in many important biomolecules such as the glycoproteins and the O-antigenic polysaccharides of clinically important bacterial strains. In this paper, we describe an exclusive α-selective glycosylation reaction, using a 4,6-di-O-tert-butyldimethylsilyl-N-acetyloxazolidinone-protected thioglycoside as the glycosyl donor, under pre-activation conditions, with only half amount of the promoter, providing the product GalpNAc-α-(1→4)-GalpNAc in high isolated yield. This reaction can be also applied to increasing the length of the repeating structure, which is of significant use in further synthesis of branched or linear oligosaccharides. [ABSTRACT FROM AUTHOR]

Abstract: A new sialyl donor, N,N-acetyl, benzoyl-O-perbenzoyl-protected p-toluenethiosialoside, was synthesized and its sialylation reaction was investigated. This reaction proceeded in dichloromethane and β anomeric selectivity was achieved when NIS–TfOH was used as promoter. This method may be employed to construct the unnatural β-linked sialosides. [Copyright &y& Elsevier]

We have investigated the effects of two heat shock proteins, Hsp10 and Hsp60, on insulin-like growth factot-1 receptor (IGF-1R) signaling in cardiac muscle cells. Neonatal cardiomyocytes were transduced with Hsp10 or Hsp60 via adenoviral vector. Compared with the cells transduced with a control vector, overexpression of Hsp10 or Hsp60 increased the abundance of IGF-1R and IGF-1-stimulated receptor autophosphorylation. Thus, Hsp10 and Hsp60 overexpression increased the number of functioning receptors and amplified activation of IGF-1R signaling. IGF-1 stimulation of MEK, Erk, p90Rsk, and Akt were accordingly augmented. Transducing cardiomyocytes with antisense Hsp60 oligonucleotides reduced Hsp60 expression, decreased the abundance of IGF-1R, attenuated IGF-1R autophosphorylation, and suppressed the pro-survival action of IGF-1 in cardiomyocytes. Using cycloheximide to inhibit protein synthesis did not alter the effect of Hsp60 on IGF-1R signaling, and IGF-1R mRNA levels were not up-regulated by Hsp10 or Hsp60. Additional experiments showed that Hsp10 and Hsp60 suppressed polyubiquitination of IGF-1 receptor. These data indicate that Hsp10 and Hsp60 can modulate IGF-1R signaling through post-translational modification. In animal models of diabetes, diabetic myocardium is associated with decreased abundance of Hsp60, increased ubiquitination of IGF-1R, and lower level of IGF-1R protein. Declined myocardial protection is a major feature of diabetic cardiomyopathy. These data suggest that decreased Hsp60 expression and subsequent decline of IGF-1R signaling may be a fundamental mechanism underlying the development of diabetic cardiomyopathy. [ABSTRACT FROM AUTHOR]

3-Butenyloxycarbonyl (Bloc) has been identified as a new hydroxyl protecting group, which can be introduced under mild conditions in high yields and selectively removed by OsO 4 /NaIO 4 /2,6-lutidine in CH 3 CN–H 2 O without affecting most commonly-used protecting groups. Moreover, this new protecting group is inert under glycosylation conditions. [ABSTRACT FROM AUTHOR]

Stereo-controllable glycosylation reactions of 2,3-oxazolidinone protected glucosamine thioglycoside donor with different phenol acceptors based on preactivation protocol, are described. It was found that BF 3 ·Et 2 O worked as α-directing additive, while TTBP acted as β-directing additive. Simply by altering additives, either α-aryl glycosides or β-aryl glycosides were achieved in a stereoselective manner. The additives were also applied to the stereoselective glycosylation reactions of 2,3-oxazolidinone protected galactosamine donor with phenol substrates. [ABSTRACT FROM AUTHOR]

The objective of present study was to assess the simultaneous removal of organics and nitrogen by four lab-scale vertical subsurface flow constructed wetlands (V-SFCWs). The emergent plants employed were Canna indica . Five-month experiments showed that the planted and aerated system largely reduced the COD by 95%, NH 4 by 88% and total inorganic nitrogen (TIN) by 83%. It outperformed the unplanted or simple aerated system and was much better than non-aerated system. The study provided a strong evidence to support widespread research and application of spray aeration as a low-cost and energy-efficient aeration technology in V-SFCWs. [ABSTRACT FROM AUTHOR]

This paper characterizes the spatial distribution of environmental parameters (dissolved oxygen, pH and oxidation-reduction potential) and nitrogenous pollutants (total nitrogen, ammonia and nitrate) in horizontal subsurface flow constructed wetland that has been used to treat artificial wastewater containing high concentration of ammonia and nitrate. With sufficient carbon source supplement, the nitrogen removal rates were found to be significantly related to the spatial distribution of oxygen content affected by the characters of the layer. Correlations among pH, oxidation-reduction potential and dissolved oxygen indicated that the nitrogen removal rates under study conditions mainly depended on the location of the layer and zone in the constructed wetland. [ABSTRACT FROM AUTHOR]

Highlights: [•] o-Methylphenylthioglycosides were used as blocks in preactivation protocol. [•] The aglycon transfer was avoided. [•] The efficiency of glycosyl coupling reactions was enhanced. [•] The thioglycosides were efficiently employed in one-pot oligosaccharide assembly. [ABSTRACT FROM AUTHOR]

Abstract: Presented by CD1d protein, KRN7000, a potent synthetic α-galactosylceramide, is known to stimulate the iNKT cells to produce different bioactive cytokines. Six new KRN7000 analogues, in which the amide bond in KRN7000 is replaced with O, NH, or ester groups incorporating variation of the acyl chain, or possessing an additional four-atom linker between the galactose and phytosphingosine moiety, were designed and synthesized. The synthetic compounds were evaluated for their ability to stimulate cytokine release and the preliminary structure–activity relationships were discussed. The synthetic strategy will benefit the construction of more KRN7000 derivatives, which may contribute to cytokine profile bias. [Copyright &y& Elsevier]

Abstract: A new sialyl donor, N,N-dibenzyl-protected p-toluenethiosialoside, was synthesized and its sialylation reaction was investigated. This reaction proceeded in a preactivation manner and preferred to provide β-anomeric coupling products. The β-selectivity was rationalized based on the assumption that N,N-dibenzylamino group could serve as an oriented group to activate the hydroxyl group of acceptor from β-face. [Copyright &y& Elsevier]

A new approach for the synthesis of phenolic glycosides via aromatic O-glycosylation of 1,2-anhydrosugar and aryl boronic acids was disclosed. This method is characterized by the use of aryl boronic acid as the aryl source and produces phenolic glycosides in a stereoselective manner. This reaction provides an alternative approach to the synthesis of phenolic glycosides. It also represents a new application of aryl boronic acids as versatile reagents in organic synthesis. [ABSTRACT FROM AUTHOR]

Summary: A rice proteinase inhibitor (PI) gene OsPI8-1 was identified. Belonging to the potato inhibitor I family, this gene contains a 201bp coding region with no introns and encodes a deduced protein of 66 amino acids which holds a PI domain. There are two uniform gene copies, OsPI8-1a and OsPI8-1b, with direct-repeat arrangement and an interval span of 13kb on rice chromosome 8, corresponding to the site of BAC clone P0528B09 (Accession No. AP004703). Reverse transcription polymerase chain reaction (RT-PCR) assays showed that both OsPI8-1a and OsPI8-1b can be expressed in wild-type ‘Zhonghua No.11’. To investigate the physiological functions of OsPI8-1 in plant development, we analyzed the expression patterns of the reporter gene β-glucuronidase (GUS) driven by OsPI8-1 promoter at different developmental stages and tissues. It was demonstrated that no GUS signals were detected in the roots. Despite that very high GUS expression was examined in the shoot apical meristem, no detectable GUS activity in the developmental domains of leaf primordium was observed. OsPI8-1 promoter showed an obvious wound-induced response in mature leaves. Little GUS activity was detected in young nodes and internodes at the seedling stage, but active GUS expression was observed near the nodes on mature culms. In the developing stage of the anther, GUS signal was specifically located in the middle layer and the endothecium between the epidermis and tapetum. In the germinating seed, GUS expression was gradually accumulated in the side of scutellar epithelium close to the embryo. These tissue-specific accumulations suggested that OsPI8-1 has multiple endogenous roles on developmental regulation. In this report, the inhibitor function of OsPI8-1 to proteolytic enzymes and the potential influence of their poise on plant development (such as seed germination, tapetum degeneration, programmed cell death, etc.) were discussed. [Copyright &y& Elsevier]

Abstract: Diverse 2,3-oxazolidinone protected 2-amino-2-deoxy-d-glucose thioglycosides were prepared and studied as glycosyl donors at low temperature by BSM/Tf2O pre-activation protocol before the addition of glycosyl acceptors. The stereochemistry outcomes of a series of glycosylations were investigated. Different stereoselectivities of the coupling reactions were obtained, arising from the different protecting groups in the oxazolidinone donors. 4,6-Di-O-benzyl-N-benzyl-oxazolidinone protected thioglycoside donor 1c underwent glycosylation with general β-anomeric selectivity and the stereoselectivity could be also affected by glycosylation conditions. [Copyright &y& Elsevier]

Abstract: The recognition capabilities of two molecular receptors 2,7-di(3′-pyridyl)-1,8-naphthyridine (DPN) and 2,7-di(3′-quinolyl)-1,8-naphthyridine (DQN) toward monosaccharides in chloroform were evaluated. Both DPN and DQN possess a naphthyridine core moiety, in which two pyridinic nitrogen atoms serve as the proton acceptors. Attached to the C2 and C7 positions of naphthyridine are two identical arms, each of which consists of pyridine (DPN) or quinoline (DQN) moiety that also acts as the proton acceptor. The arrangement of hydroxyl groups in monosaccharides offers the proton donors complementary to the proton acceptors of DPN (or DQN) to form a quadruply hydrogen bonds complex. The binding processes were studied by UV–vis, fluorescence and 1H NMR spectrophotometric titrations as well as electrospray ionization mass spectroscopy. The binding strength between DPN (or DQN) and examined monosaccharides was comparable to that for many other hydrogen-bonding host molecules previously reported. [Copyright &y& Elsevier]

[Display omitted] • CWs with NO 3 –-N generally contributes to more N 2 O emission than that of NH 4 +-N. • Plant N form preference affect N absorption by plants and the generation of root exudates. • Different nitrogen forms induce the niche differentiation of microbial community in CWs. • Microbiota assembly patterns in CWs with NO 3 –-N were more complex than that of NH 4 +-N. • Microbial mechanisms of N 2 O emission in CWs at different COD/N ratios were elucidated. Nitrous oxide (N 2 O) emission during the sewage treatment process is a serious environmental issue that requires attention. However, the N 2 O emission in constructed wetlands (CWs) as affected by different nitrogen forms in influents remain largely unknown. This study investigated the N 2 O emission profiles driven by microorganisms in CWs when exposed to two typical nitrogen sources (NH 4 +-N or NO 3 –-N) along with different carbon source supply (COD/N ratios: 3, 6, and 9). The results showed that CWs receiving NO 3 –-N caused a slight increase in total nitrogen removal (by up to 11.8 %). This increase was accomplished by an enrichment of key bacteria groups, including denitrifiers, dissimilatory nitrate reducers, and assimilatory nitrate reducers, which enhanced the stability of microbial interaction. Additionally, it led to a greater abundance of denitrification genes (e.g., nirK , norB , norC , and nosZ) as inferred from the database. Consequently, this led to a gradual increase in N 2 O emission from 66.51 to 486.77 ug-N/(m2·h) as the COD/N ratio increased in CWs. Conversely, in CWs receiving NH 4 +-N, an increasing influent COD/N ratio had a negative impact on nitrogen biotransformation. This resulted in fluctuating trend of N 2 O emissions, which decreased initially, followed by an increase at later stage (with values of 122.87, 44.00, and 148.59 ug-N/(m2·h)). Furthermore, NH 4 +-N in the aquatic improved the nitrogen uptake by plants and promoted the production of more root exudates. As a result, it adjusted the nitrogen-transforming function, ultimately reducing N 2 O emissions in CWs. This study highlights the divergence in microbiota succession and nitrogen transformation in CWs induced by nitrogen form and COD/N ratio, contributing to a better understanding of the microbial mechanisms of N 2 O emission in CWs with NH 4 +-N or NO 3 –-N at different COD/N ratios. [ABSTRACT FROM AUTHOR]

Chemical O -glycosylation is a key step for the synthesis of sugar-containing molecules such as glycolipids. However, traditional carbohydrate chemistry is characterized by extensive use of protective groups, resulting in laborious manipulations and poor atom economy. Here, we present a protecting-group-free glycosylation strategy employing dibenzyloxy-1,3,5-triazin-2-yl glycosides (DBT-glycosides) as glycosyl donors. The DBT-glycosyl donors could be prepared directly through an alkaline nucleophilic substitution from unprotected sugars in aqueous media. The O -glycosylation of alcohols by using DBT-glycosyl donors has been carried out under mild hydrogenolytic conditions, affording the corresponding alkyl glycosides stereo-selectively in good yields. [Display omitted] • A protecting group-free and stereoselective O -glycosylation method was described. • Glycosyl donors were prepared directly from unprotected sugars under water media. • Glycosylation reaction was performed under mild hydrogenolysis conditions. • Various sugar types (e.g., Glc, Gal, Man, GlcN, GlcNAc, etc) were screened. [ABSTRACT FROM AUTHOR]

Abstract: In this study, novel flower-like PbGeO3 microstructures were successfully synthesized at low-temperature via a facile and rapid microwave-assisted solution-phase approach. The phases and morphologies of the product have been characterized by powder X-ray diffraction (XRD), energy dispersive spectrometry (EDS), selected area electron diffraction (SAED), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Experimental results revealed that the entire structure of the architecture is composed of a large quantity of individual nanorods with 100–300nm in width and several micrometers in length. Optical test showed that the absorption edge of the PbGeO3 sample was 315nm, corresponding to a bandgap of ~3.94eV. [Copyright &y& Elsevier]

A general approach for the synthesis of lactones or cyclic ethers via Pd-catalyzed C(sp 3 ) H activation and intramolecular C O functionalization starting from carboxylic acids or alcohols using the bidentate directing group has been developed. Substrates with both primary and secondary hydroxyl groups can undergo this reaction to produce the corresponding cyclic ethers. Furthermore, isobenzofuran-1(3 H )-ones with either electron-rich or electron-deficient groups as well as aliphatic lactones can be prepared by employing this reaction. [ABSTRACT FROM AUTHOR]

Glucagon-like peptide-1 (GLP-1) is an endogenous insulinotropic hormone with wonderful glucose-lowering activity. However, its clinical use in type II diabetes is limited due to its rapid degradation at the N-terminus by dipeptidyl peptidase IV (DPP-IV). Among the N-terminal modifications of GLP-1, backbone-based modification was rarely reported. Herein, we employed two backbone-based strategies to modify the N-terminus of tGLP-1. Firstly, the amide N -methylated analogues 2 – 6 were designed and synthesized to make a full screening of the N-terminal amide bonds, and the loss of GLP-1 receptor (GLP-1R) activation indicated the importance of amide H-bonds. Secondly, with retaining the N-terminal amide H-bonds, the β-peptide replacement strategy was used and analogues 7 – 13 were synthesized. By two rounds of screening, analogue 10 was identified. Analogue 10 greatly improved the DPP-IV resistance with maintaining good GLP-1R activation in vitro, and showed approximately a 4-fold prolonged blood glucose-lowering activity in vivo in comparison with tGLP-1. This modification strategy will benefit the development of GLP-1-based anti-diabetic drugs. [ABSTRACT FROM AUTHOR]

Tumor-associated carbohydrate antigens (TACAs), which are aberrantly expressed on the surface of tumor cells, are important targets for anticancer vaccine development. Herein, several N -acyl modified Tn analogues were synthesized and conjugated with carrier protein CRM197. The immunological results of these glycoconjugates indicated that 6 –CRM197 elicited higher titers of antibodies which cross-reacted with native Tn antigen than the unmodified 2 –CRM197 did. The IFN-γ-producing frequency of lymphocytes in mice treated with 6 –CRM197 was obviously increased, compared to that of mice vaccinated with 2 –CRM197 ( p = 0.016), which was typically associated with the Th1 response. Moreover, the elicited antisera against antigen 6 –CRM197 reacted strongly with the Tn-positive tumor cells, implying the potential of this glycoconjugate as an anticancer vaccine. [ABSTRACT FROM AUTHOR]

A convenient approach to the synthesis of novel triazole- N -glycoside derivatives was developed via CuSCN-catalyzed click reaction and Ullmann-type coupling reaction for the first time. The SGLT2 inhibitory activities of these synthetic N -glycosides were evaluated, and some compounds showed moderate SGLT2 inhibition activities at 100 nM. The results could benefit the discovery of new SGLT2 inhibitors for the treatment of diabetes. [ABSTRACT FROM AUTHOR]

Several phenylethanoid glycoside derivatives were designed and synthesized. Most of the synthetic compounds showed significant neuroprotective effects, including antioxidative and anti-apoptotic properties. Specifically, target compounds displayed potent effects against various toxicities such as H 2 O 2 and 6-hydroxydopamine (6-OHDA) in PC12 cells. Among the synthetic derivatives, three compounds ( 5 , 6 , 8 ) exhibited much superior activities to the marketed drug Edaravone. The compounds were able to prevent the 6-OHDA-induced damage in PC12 cells in a dose-dependent manner. The anti-apoptotic effects could be observed via cell morphological changes. Moreover, the compounds significantly reduced the intracellular ROS increase resulting from 6-OHDA treatment. The preliminary structure–activity relationships were also explored. Compounds 5 , 6 , 8 may hold the potential as promising neuroprotective agents and new lead compounds for the treatment of neurodegenerative diseases or cerebral ischemia. [ABSTRACT FROM AUTHOR]

2-Pyridyl glycosides have been identified to be powerful glycosyl donors for the preactivation-based oligosaccharide synthesis. By using stoichiometric amount of Tf 2 O, the 2-pyridyl glycosides were pre-activated, which subsequently underwent glycosylation reactions smoothly to produce the coupled products in high yields. Furthermore, the 2-pyridyl glycosides were applied to the efficient oligosaccharide assembly by the preactivation-based one-pot oligosaccharide synthesis protocol. [ABSTRACT FROM AUTHOR]

Two water-soluble polysaccharides (ACPS1 and ACPS2) were isolated from the roots of Actinidia Chinensis by DEAE-52 cellulose and Sephacryl S300 chromatography. Preliminary structural characterization was conducted by physicochemical property, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analysis. ACPS1, with an average molecular weight of 5.58 × 10 5 Da, was mainly composed of rhamnose, arabinose, xylose, mannose and galactose in an approximate molar ratio of 1.48:4.28:4.30:1.00:17.83. ACPS2, with a high average molecular weight of 1.23 × 10 6 Da, mainly contained rhamnose, arabinose and galactose in a molar ratio of approximately 1.00:2.33:6.61. Both ACPS1 and ACPS2 exhibited the remarkable antioxidant activity to scavenge the DPPH radical and significant protective effects on H 2 O 2 -induced HEK 293 cells death in a concentration-dependent manner. Meanwhile, in vitro immunomodulatory activities of the two polysaccharides were evaluated. The results showed that treatment with 50–300 μg/mL of the samples could increase NO production and phagocytic activity of macrophages in a dose-dependent manner. The present results suggested that the two polysaccharides from Actinidia Chinensis may be potential antioxidant and immunomodulatory agents for preparing functional foods and nutraceuticals applied in food and pharmaceutical industries. [ABSTRACT FROM AUTHOR]

A new approach for the synthesis of triazolyl-linked α-(2-9) oligosialic acids by iterative copper(I)-catalyzed alkyne–azide cycloaddition (CuAAC) and desilylation has been developed. By using propargyl α-sialoside 5 and trimethylsilylated-propargyl 9-azido-α-sialoside 3 as building blocks, triazolyl-linked α-(2-9) di- to octa-sialic acids were constructed in good to moderate yields. Finally, the pseudo-α-(2-9)-oligosialic acids were obtained very smoothly via O-deprotection. The oligosialic acids with a triazolyl-linkage represent a new type of pseudooligosialic acids. This protocol may find applications in the preparation of oligosialic acid analogues with biological importance. [ABSTRACT FROM AUTHOR]

Abstract: Iminosugars have gained a remarkable importance as new therapeutic agents since 1966. In this study, compounds A and B, two iminosugar analogs synthesized previously, showed an inhibition of the growth of K562 cells. They allowed cell cycle arrested at the G0/G1 phase, promoted apoptotic activities and also lowered the mitochondrial membrane potential. Further exploration of the apoptosis mechanism revealed that compound B significantly suppressed the expression of Hsp70, which is a major anti-apoptotic molecular chaperone. Significant decrease was also found in the expression of Akt, a serine/threonine-specific protein kinase with anti-apoptosis activities also known as protein kinase B (PKB). At mitochondria level in comparison with compound A, compound B brought a better promotion in the expression of pro-apoptotic protein Bad in Bcl-2 family. As a result of the promotion, the expression of anti-apoptotic protein Bcl-xL was down-regulated. Cytochrome c was released, activating the intrinsic signaling pathways of caspase and resulting in the occurrence of cascade reaction. In addition, compound B stimulated autophagy effectively by up-regulating Beclin 1, thus causing the conversion of LC3-I to LC3-II through Akt/mTOR signaling pathway. In summary, these results indicated that compounds A and B induced cell death through multiple pathways. The disclosed results not only provide an evidence of antitumor activity of iminosugars as a foundation for further studies, but also may find potential applications in chronic myeloid leukemia therapy as new heat shock protein inhibitors and autophagy inducer. [Copyright &y& Elsevier]

Abstract: The glmS riboswitch is a ribozyme found in numerous Gram-positive bacteria and responds to the cellular concentrations of glucosamine 6-phosphate (GlcN6P). Given the importance of GlcN6P for cell wall biosynthesis, the glmS riboswitch has become a new drug target for the development of antibiotics. Herein, we describe the efficient synthesis of three GlcN6P analogues and their evaluation on inducing self-cleavage of the glmS riboswitch from Bacillus subtilis. Our results provide valuable information for further elucidation of the structure–activity relationships and drug design for glmS riboswitch antibiotics. [Copyright &y& Elsevier]

Abstract: A new class of pseudoacarviosins with 2,3-anhydro or unsaturated sugar moieties were synthesized efficiently. The designed target disaccharides were constructed by the glycosylation reactions using 2,3-anhydromonosaccharides as glycosyl donors. The glycosylation reactions were carried out in a highly stereoselective manner in most cases, especially when the preactivation protocol was used. The anhydrosugar units of disaccharides were kept intact during the deprotection operations of protective groups. Furthermore, the disaccharides containing anhydrosugar moieties were smoothly converted to the unsaturated disaccharides via the base-promoted rearrangement of sugar epoxides. [Copyright &y& Elsevier]

Abstract: A convenient synthesis of polyoxygenated tetrahydrothiopyrans and thiepanes from various alditol derivatives with xylo, ribo, manno, gluco, galacto, and fuco configurations is described. The preparation started from the corresponding partially protected alditols and proceeded in a ‘one-pot’ manner to afford the final products in 80%–95% yield. Furthermore, thiosugar compounds 2b, 2d, and 2g were converted to the optically pure polyoxygenated cycloalkenes through Ramberg–Backlund reaction in moderate to good overall yield. The procedures can be used for the preparation of polyoxygenated thiosugars and cycloalkenes on a relatively large scale. [Copyright &y& Elsevier]

Abstract: Based on the structural information of biomacromolecule–aminoglycoside complexes, a series of kanamycin B analogues were rationally designed and synthesized. A convenient approach to the construction of kanamycin derivatives, in which the C4′-position on ring I of neamine moiety was modified, was developed. Most synthetic analogues exhibited good to excellent antibiotic activity against some typical drug-resistant bacteria. The disclosed results suggested that the C4′-position of aminoglycosides such as kanamycin may be an ideal site for modification to gain new modifying enzyme-resistant aminoglycoside antibiotics. [ABSTRACT FROM AUTHOR]

Abstract: Fifteen novel six-membered azanucleoside derivatives were prepared and evaluated for their anti-hepatitis B virus (HBV) activity and cytotoxicity in human hepatoblastoma-derived liver Hep-G2 cells. The most potent compound 16b with an IC50 value of 2.74μg/mL (lower than 3TC) and a SI value of 13.5 was disclosed. The key synthetic steps involved the rearrangement of lactones (which were readily obtained from monosaccharides) and the Lewis acid-catalyzed condensation of nucleobases with azasugar donors. Using the versatile acetylated azasugar donors, azanucleosides covering three types of azasugars and four types of natural nucleobases were successfully obtained. The experimental results showed that some six-membered azanucleosides may find applications in the discovery of new anti-viral agents. [ABSTRACT FROM AUTHOR]