Synthesis,antioxidant, and antimicrobial activity of 3-(1H-indole-3-carbonyl)-2H-chromen-2-ones

A simple and convenient method for the one-pot synthesis of 3-(1H-indole-3-carbonyl)-2H-chromen-2-one derivatives from the reaction of 3-cyanoacetyl indole and salicylaldehyde in the presence of Na₂CO₃ in water: methanol (1:1) is described. Wider substrate scope, high yields, operational simplicity, and simple purification process make the protocol highly applicable in the synthesis of 3-(1H-indole-3-carbonyl)-2H-chromen-2-ones. For the first time, in vitro antioxidant and antimicrobial activity was studied. Compounds 5e , 7a , and 7b exhibits good radical scavenging ability against DPPH free radical. Compounds 7b , 5f , and 5g possess lower EC₅₀ values than the Standards AA and BHA and thus proving their high reducing power. Compounds 5d and 5f show good antibacterial activity against gram-positive bacteria (MRSA) while compounds 5c , 7a , and 7b exhibits good antibacterial activity against Bacillus sp. Compounds 5b and 5e show good antibacterial activity against gram negative bacterial strains (Escherichia coli, Klebsiella pneumoniae) and compounds 5g and 5h exhibits good antifungal activity against Candida albicans.     

Rapid two-step synthesis of mitrin from heparosan: a replacement for heparin

We have engineered a two-step enzymatic synthesis of Mitrin which is a more potent and homogeneous anticoagulant than the current animal-derived heparin. This engineered heparin may have advantages of being free from animal-derived pathogens and may also have reduced side effects such as heparin induced thrombocytopenia. This approach can also be extended to tailor heparin-based drugs with improved therapeutic characteristics to treat other disorders or infections in which heparin-like molecules play a major role.     

An Extremely Simple and Effective Colony PCR Procedure for Bacteria, Yeasts, and Microalgae

An extremely simple and effective colony PCR procedure is established for both gram-negative and gram-positive bacteria, yeasts, and microalgae. Among the four lysis buffers examined, Y-PER is observed to be more effective than Tris/EDTA, 0.2 % SDS, and 10 mM EDTA in the extraction of PCR-quality genomic DNA from those microorganisms. Vortexing or pipetting agitation of the cells in Y-PER for 5–10 s was sufficient to release genomic DNA for all the test bacteria and yeasts, and most microalgae. Additional incubation at 98 °C for 5 min for further cell disruption was essential only for Chlorella vulgaris due to its notoriously rigid cell wall.     

Stereoselective synthesis of the alpha-glycoside of a KDO "C"-disaccharide

The reaction of tert-butyl (4,5,7, 8-tetra-O-acetyl-3-deoxy-alpha-D-manno-2-octulopyranosyl chloride)onate donor 7 with the 6-formylgalactopyranoside acceptor 4 in the presence of SmI(2) provided only the KDO alpha-C-disaccharide 8. The bulky tert-butyl ester in the donor was used to reverse the stereochemical outcome of C-glycosylation, stereoselectively forming the alpha-"C"-disaccharide of KDO.     

Analysis of heparan sulfate oligosaccharides with ion pair-reverse phase capillary high performance liquid chromatography-microelectrospray ionization time-of-flight mass spectrometry

Heparan sulfate, a cell surface bound glycosaminoglycan polysaccharide, has been implicated in numerous biological functions. Heparan sulfate molecules are highly complex and diverse, yet deceivingly look simple and similar, rendering structure--function correlation tedious. Current chromatographic and mass spectrometric techniques have limitations for analyzing glycosaminoglycan samples that are in low abundance and that are large in size, due to their highly acidic nature arising from a large number of sulfate and of carboxylate groups. A new methodology was developed using capillary ion-paired reverse-phase C18 HPLC directly coupled to ESI-TOF-MS to address the above issues. On the basis of HS disaccharide analysis, dibutylamine was found to be the best suited for HS analysis among many ion-pairing agents investigated. Next, analysis of oligosaccharides derived from heparosan, the precursor for heparan sulfate, was undertaken to demonstrate its greater applicability in a more complex structural analysis. The established chromatographic conditions enabled the characterization of heparosan oligosaccharides of sizes up to tetracontasaccharide with high resolution in a single run and were amenable to negative ion electrospray MS in which sodium adduction and fragmentation were avoided. To date, these are the largest nonsulfated HS precursor oligosaccharides to be characterized by LC/MS. Finally, the current methodology was applied to the characterization of the biologically important ATIII binding pentasaccharide and its precursors, which differ from each other by sulfation pattern and/or degree of sulfation. All of these pentasaccharides were well-resolved and characterized by the LC/MS system with (34)SO(4) as a mass spectral probe. This newly developed methodology facilitates the purification and rapid characterization of biologically significant HS oligosaccharides, and will thus expedite their synthesis. These findings should undoubtedly pave the way in deciphering multiple functional arrangements, ascribed to many biological activities, which are predictably embedded in a single large chaotic, yet well-organized HS polysaccharide chain. Development of newer techniques for HS oligosaccharide analysis is greatly needed in the postgenome era as attention shifts to the functional implications of proteins and carbohydrates in general and HS in particular.     

Applications of isotopes in advancing structural and functional heparanomics

Heparanomics is the study of all the biologically active oligosaccharide domain structures in the entire heparanome and the nature of the interactions among these domains and their protein ligands. Structural elucidation of heparan sulfate and heparin oligosaccharides is a major obstacle in advancing structure–function relationships and heparanomics. There are several factors that exacerbate the challenges involved in the structural elucidation of heparin and heparan sulfate; therefore, there is great interest in developing novel strategies and analytical tools to overcome the barriers in decoding the enigmatic heparanome. This review focuses on the applications of isotopes, both radioisotopes and stable isotopes, in the structural elucidation of the complex heparanome at the disaccharide or oligosaccharide level using liquid chromatography, nuclear magnetic resonance spectroscopy, and mass spectrometry. This review also outlines the utility of isotopes in determining the substrate specificity of biosynthetic enzymes that eventually dictate the emergence of biologically active oligosaccharides.