Balaram Mukhopadhyay

Phase selective carbohydrate gelator

A simple eco-friendly carbohydrate gelator for phase selective gelation of oils from oil–water mixtures at room temperature, dye removal for water purification and X-ray crystal structure in the monohydrate form.

Antibacterial activity of long-chain fatty alcohols against mycobacteria

Tuberculosis is caused by the bacterium Mycobacterium tuberculosis and results in innumerable deaths across the world. The emergence of multidrug-resistant and extremely drug-resistant tuberculosis strains and its coinfection with HIV has made tuberculosis more difficult to treat. Therefore, new antimycobacterial agent(s) for both therapy and disinfection are urgently required. In this context the present study describes the antibacterial property of long-chain fatty alcohols against mycobacteria. The antimycobacterial activities of alcohols with chain length ranging from C(5) to C(13) were examined against Mycobacterium smegmatis mc(2) 155 and M. tuberculosis H(37)R(v). The best activity was found with one with a C(10) chain length. This bactericidal activity can partly be attributed to its ability to damage the robust and complex cell envelope of Mycobacteria. Moreover, our study reveals the ability of decanol to attenuate biofilm formation by M. smegmatis. This knowledge can be used to develop new therapeutics and disinfectants against mycobacteria.

Concise synthesis of a tetra- and a trisaccharide related to the repeating unit of the O-antigen from Providencia rustigianii O34 in the form of their p-methoxyphenyl glycosides

Concise synthesis of a tetra- and a trisaccharide related to the repeating unit of the O-antigen from Providencia rustigianii O34 is reported. Synthesis of the target oligosaccharides was achieved by rational protecting group manipulations on the commercially available monosaccharides followed by stereoselective glycosylations, using H2SO4-silica for trichloroacetimidate activation and in conjunction with N-iodosuccinimide for thioglycoside activation.

Synthesis of a tetrasaccharide related to the O-antigen from Azospirillum lipoferum SR65

Concise synthesis of a tetrasaccharide repeating unit of the LPS isolated from Azospirillum lipoferum SR65 has been accomplished through suitable protecting group manipulations and stereoselective glycosylation starting from commercially available L-rhamnose and D-glucose. The target oligosaccharide in the form of its p-methoxyphenyl glycoside is suitable for further glycoconjugate formation via selective cleavage of the OMP glycoside. Plant growth-promoting bacteria (PGPB) of genus Azospirillum plays important roles in the growth and development of plants. The interaction between the roots of the plants and the microbes is governed by the cell surface carbohydrate polymers (CPS, LPS, etc.). The present synthetic-based study elucidates aspects of plant-microbe interaction and future biofertiliser design.

Chemical O-Glycosylations: An Overview

Abstract The development of glycobiology relies on the sources of particular oligosaccharides in their purest forms. As the isolation of the oligosaccharide structures from natural sources is not a reliable option for providing samples with homogeneity, chemical means become pertinent. The growing demand for diverse oligosaccharide structures has prompted the advancement of chemical strategies to stitch sugar molecules with precise stereo‐ and regioselectivity through the formation of glycosidic bonds. This Review will focus on the key developments towards chemical O‐glycosylations in the current century. Synthesis of novel glycosyl donors and acceptors and their unique activation for successful glycosylation are discussed. This Review concludes with a summary of recent developments and comments on future prospects.

Synthesis and evaluation of iminocoumaryl and coumaryl derivatized glycosides as galectin antagonists.

A collection of iminocoumarylmethyl glycoside derivatives have been prepared by copper-catalyzed multi-component reaction of carbohydrate propargyl derivatives, sulfonyl azides, and salicylaldehyde or o-hydroxy acetophenone. The method is simple, versatile to all three components, and exceptionally high yielding. The carbohydrate N-sulfonyl iminocoumarine hybrid molecules were evaluated for binding galectin-1, -2, -3, -4N, -4C, -7, -8N, -9N, and 9C using a competitive fluorescence polarization assay. Selective compounds were identified against galectin-3, 7, 8N, and 9N with up to 40-fold affinity enhancements relative to methyl α-d-galactopyranoside due to the coumarylmethyl moieties.

Concise synthesis of the trisaccharide repeating unit of the O-polysaccharide from Aeromonas hydrophila A19 (O:14).

Chemical synthesis of the trisaccharide repeating unit of the O-polysaccharide from Aeromonas hydrophila A19 (O:14) is reported in the form of its p-methoxyphenyl glycosides. Suitably protected monosaccharide synthons were prepared either by literature procedure or by strategies developed in house. Stereoselective glycosylations were accomplished by the activation of thioglycosides using N-iodosuccinimide in conjunction with H2SO4-silica in good to excellent yields.

Synthesis of a tetrasaccharide related to the repeating unit of the O-antigen from Escherichia coli K-12.

Synthesis of a tetrasaccharide related to the repeating unit of the O-antigen from Escherichia coli K-12 is reported in the form of its octyl glycoside. Syntheses of the 1,2-cis glycosidic linkages have been accomplished by using NIS in conjunction with H(2)SO(4)-silica, and it was found to be stereoselective and productive. The synthesized tetrasaccharide will be utilized as the substrate for galactofuranosyltransferase, WbbI.

Concise synthesis of two trisaccharides related to the cytotoxic triterpenoid saponin isolated from Pithecellobium lucidum

Convergent synthesis of two trisaccharides related to the cytotoxic triterpenoid saponin isolated from Pithecellobium lucidum is reported. The trisaccharides are synthesized in the form of their propargyl glycosides to leave the scope for further glycoconjugate formation through various multi-component reactions. A simple protecting group manipulation is followed using commercially available monosaccharides, D-glucose, D-xylose, D-fucose and L-rhamnose. H(2)SO(4) immobilized on silica is used as the Brönsted acid source for the N-iodosuccinimide-mediated thioglycoside activation for stereoselective glycosylations and proved to be a better choice over traditional Lewis acid catalysts such as TMSOTf and TfOH.

Chemical synthesis of the tetrasaccharide repeating unit of the O-antigenic polysaccharide from Plesiomonas shigelloides strain AM36565

Chemical synthesis of the tetrasaccharide repeating unit of the O-antigenic polysaccharide from Plesiomonas shigelloides strain AM36565 is reported. Glycosylations between suitably protected monosaccharide synthons were achieved by the activation of thioglycosides in the presence of H2SO4-silica in conjunction with N-iodosuccinimide. The glycosylations accomplished were highly stereoselective and afforded the desired products in good to excellent yields.