Guillermo Corrales

Glycosyl phenyl sulfoxides as a source of glycosyl carbanions: Stereoselective synthesis of C-fucosides

Abstract Phenylsulfinyl-lithium exchange on glycosyl phenyl sulfoxides leads to configurationally stable anomeric carbanions which can react stereoselectively with electrophiles. Thus, the reaction of 3,4-O-isopropylidene-α- l -fucopyranosyl phenyl sulfoxide with tBuLi followed by treatment with isobutyraldehyde led to the α-configured C-glycoside; the β-anomer furnished the corresponding β-C-glycoside.

Improvement and Validation of d‐Xylose Determination in Urine and Serum as a New Tool for the Noninvasive Evaluation of Lactase Activity in Humans

The phloroglucinol assay is the current method for d‐xylose determination in urine/plasma/serum. However, its sensitivity is limited when low amounts of d‐xylose are to be measured, such as in the noninvasive evaluation of intestinal lactase with 4‐galactosylxylose (gaxilose). An improved assay was therefore needed.

A New Strategy for Liquid-Phase Synthesis of Disaccharides Based on the Use of Glycosidases

A new strategy for the glycosidase-catalyzed liquid-phase synthesis of oligosaccharides, which facilitates the purification of the products, is described. This strategy is based on the use of glycosidases in two key steps: (i) glycosidation of a sugar bound to a soluble-support, and (ii) specific removal of the unreacted monosaccharide acceptor. Glucose is attached to the MPEG support through a linker derived from valeric acid. The introduction of the linker moiety was performed by an O-anomeric alkylation reaction. The galactosylation of the glucose-bound to the soluble-support using β-galactosidase gave, after removal of by-products by precipitation and filtration of the support, galactosyl-glucose disaccharides bound to MPEG. Finally the alkylated disaccharides were released from the MPEG by ethanolysis. Unreacted glucose could be removed from the support by hydrolysis using glucosidases.

Hydroxyl versus permethylated glycopolymers as gene carriers

Graphical abstract Figure. No caption available. ABSTRACT The main parameters that contribute to non‐viral gene delivery are chemical structure and charge distribution. Indeed, saccharide units have been reported to have specific interactions with proteins located in the outer leaflet of the plasma cell membrane that facilitate the cellular internalization of plasmid‐DNA vector complexes. In this work, glycopolymers based on statistical copolymers were synthesized through radical copolymerization of a cationic unit, N‐ethyl pyrrolidine methacrylamide (EPA), with two styrenic monomers derived from the hydroxylated and permethylated forms of &agr;‐glucose. These copolymers were evaluated as possible non‐viral gene carriers, and their ability to complex DNA was evaluated. The transfection efficiency and cytocompatibility of the polyplexes, in both fibroblastic and tumoral murine cell lines, was evaluated. Systems derived from &agr;‐glucose (GLCSt), over a monomer concentration range of 5–70 mol%, exhibited high toxicity and low transfection efficiency, and were not able to significantly improve on results obtained from positive poly‐EPA (PEPA) and polyethyleneimine (PEI) controls. However, systems derived from the permethylated form of &agr;‐glucose (MGLCSt), formed stable complexes with DNA or polyplexes, which showed improved transfection efficiency and cytocompatibility in comparison to positive controls. The high transfection efficiency can be clearly attributed to their cytocompatibility, which was notably found to be different for Swiss fibroblasts and B16 melanoma cells, high for Swiss and low for B16. As such, we present permethylated MCLCSt copolymers as good candidates for the possible development of therapies against melanoma.