Inhibition of chitin synthetase from Saccharomyces cerevisiae by a new UDP-GlcNAc analogue

Iminosugars as glycosyltransferase inhibitors

Iminosugars are naturally occurring carbohydrate analogues known since 1967. These natural compounds and hundreds of their synthetic derivatives prepared over five decades have been mainly exploited to inhibit the glycosidases, the enzymes catalysing the glycosidic bond cleavage, in order to find new drugs for the treatment of type 2 diabetes and other diseases. However, iminosugars are also inhibitors of glycosyltransferases, the enzymes responsible for the synthesis of oligosaccharides and glycoconjugates. The selective inhibition of specific glycosyltransferases involved in cancer or bacterial infections could lead to innovative therapeutic agents. The synthesis and biological properties of all the iminosugars assayed to date as glycosyltransferase inhibitors are reviewed in the present article.

Targeting the fungal cell wall: current therapies and implications for development of alternative antifungal agents

Fungal infections are a worldwide problem associated with high morbidity and mortality. There are relatively few antifungal agents, and resistance has emerged within these pathogens for the newest antifungal drugs. As the fungal cell wall is critical for growth and development, it is one of the most important targets for drug development. In this review, the currently available cell wall inhibitors and suitable drug candidates for the treatment of fungal infections are explored. Future studies of the fungal cell wall and compounds that have detrimental effects on this important outer structural layer could aid in antifungal drug discovery and lead to the development of alternative cell wall inhibitors to fill gaps in clinical therapies for difficult-to-treat fungal infections.

Specific enzyme functionalities of Fusarium oxysporum compared to host plants

The genus Fusarium contains some of the most studied and important species of plant pathogens that economically affect world agriculture and horticulture. Fusarium spp. are ubiquitous fungi widely distributed in soil, plants as well as in different organic substrates and are also considered as opportunistic human pathogens. The identification of specific enzymes essential to the metabolism of these fungi is expected to provide molecular targets to control the diseases they induce to their hosts. Through applications of traditional techniques of sequence homology comparison by similarity search and Markov modeling, this report describes the characterization of enzymatic functionalities associated to protein targets that could be considered for the control of root rots induced by Fusarium oxysporum. From the analysis of 318 F. graminearum enzymes, we retrieved 30 enzymes that are specific of F. oxysporum compared to 15 species of host plants. By comparing these 30 specific enzymes of F. oxysporum with the genome of Arabidopsis thaliana, Brassica rapa, Glycine max, Jatropha curcas and Ricinus communis, we found 7 key specific enzymes whose inhibition is expected to affect significantly the development of the fungus and 5 specific enzymes that were considered here to be secondary because they are inserted in pathways with alternative routes.

1,3,4-Oxadiazoline derivatives as novel potential inhibitors targeting chitin biosynthesis: design, synthesis and biological evaluation

Two series of 1,3,4-oxadiazoline heterocycle derivatives were designed, synthesized and identified. Bioactivity assays showed that all synthesized compounds inhibited chitin synthesis in yeast, suggesting they might be a novel class of potential inhibitors against chitin biosynthesis. The structure-activity relationships (SAR) of these compounds are discussed.

Potent inhibition of chitin synthase by an azasugar--investigation of synergistic effect with UDP

We identified 6-deoxy-homoDMDP as a potent inhibitor of chitin synthase (Ki = 38 microM), displaying an uncompetitive inhibition pattern. Dual inhibition was also performed with the enzymatic reaction product uridine 5'-diphosphate in order to evaluate the concurrent effect of both inhibitors. An interaction coefficient alpha of 0.9 was found, revealing synergistic inhibition.

Chemical synthesis of UDP-4-O-methyl-GlcNAc, a potential chain terminator of chitin synthesis

Chitin synthase converts uridine diphosphoryl-N-acetylglucosamine (UDP-GlcNAc) to chitin (poly-beta-(1-->4)-GlcNAc). During polymerization, elongation occurs at the 4-OH (nonreducing) terminus of the growing chitin chain. Blockage of the 4-OH via incorporation of UDP-N-acetyl-4-O-methylglucosamine (UDP-4-OMe-GlcNAc, 3) can potentially terminate chitin polymerization, and represents a novel strategy for chitin synthase inhibition. The chemical synthesis of 3 and preliminary evaluation of its possible incorporation by chitin synthase are reported herein.

Second-generation dimeric inhibitors of chitin synthase

Chitin synthase (CS) is essential for fungal cell wall biosynthesis and is an attractive medicinal target. Expanded results from our efforts to develop mechanism based inhibitors of CS are presented here. Specifically, we describe uridine dimers linked by tartrate amides as potential pyrophosphate mimics.

Design, synthesis and biological evaluation of hetaryl-nucleoside derivatives as inhibitors of chitin synthase

We report here the design, synthesis and biological evaluation of new models of sugar analogues for chitin synthase. These UDP-GlcNAc mimetics associate a sugar-mimicking hetaryl group and uridine, linked with different pyrophosphate bioisosteres. The compounds displayed weak inhibition activity on chitin synthase and their antifungal potencies have been assayed against a large variety of pathogenic fungi.