Synthesis of constrained ceramide analogs and their potent antileukemic activities

Constrained ceramide analogs were designed and synthesized by binding terminal alcohol and amine of ceramide with additional carbonyl functional group as 3-acetyl (3), 3-propionyl (4), 3-benzoyl (5), and 3-hexadecanoyl-4-(1-hydroxyhexadec-2-enyl)-oxazolidin-2-ones (6). Compounds 4 and 5 showed potent antileukemic activities against human leukemia HL-60 cells with good correlation between cell death and DNA fragmentation.

A direct organocatalytic entry to sphingoids: asymmetric synthesis of d-arabino- and l-ribo-phytosphingosine

The organocatalytic asymmetric synthesis of D-arabino- and L-ribo-phytosphingosine is described employing a diastereo- and enantioselective (S)-proline-catalyzed aldol reaction of 2,2-dimethyl-1,3-dioxan-5-one and pentadecanal as the key step.

An Efficient Synthesis of d-erythro- and d-threo-Sphingosine from d-Glucose: Olefin Cross-Metathesis Approach

[reaction: see text] The D-erythro- and D-threo-sphingosine were synthesized via E-selective olefin cross-metathesis using a D-glucose-derived building block and long-chain terminal alkene.

Development and application of diazirines in biological and synthetic macromolecular systems

Many different reagents and methodologies have been utilised for the modification of synthetic and biological macromolecular systems. In addition, an area of intense research at present is the construction of hybrid biosynthetic polymers, comprised of biologically active species immobilised or complexed with synthetic polymers. One of the most useful and widely applicable techniques available for functionalisation of macromolecular systems involves indiscriminate carbene insertion processes. The highly reactive and non-specific nature of carbenes has enabled a multitude of macromolecular structures to be functionalised without the need for specialised reagents or additives. The use of diazirines as stable carbene precursors has increased dramatically over the past twenty years and these reagents are fast becoming the most popular photophors for photoaffinity labelling and biological applications in which covalent modification of macromolecular structures is the basis to understanding structure-activity relationships. This review reports the synthesis and application of a diverse range of diazirines in macromolecular systems.

Molecular species of ceramides from the ascomycete truffle Tuber indicum

The ceramide fractions were isolated from the chloroform/methanolic extractable of the fruiting bodies of Tuber indicum and separated into three kinds of molecular species TI-1, TI-2, and TI-3 by normal and reverse phase silica gel-column chromatography. By means of (1)H NMR and (13)C NMR spectroscopy, fast atom bombardment mass spectrometry (FAB-MS), and chemical degradation experiment, their component sphingoid base for TI-1 and TI-2 was uniformly (2S,3S,4R)-2-amino-1,3,4-octadecantriol, while the sphingoid of TI-3 was d-erythro-sphingosine, and their structures have been determined unequivocally to be (2S,2'R,3S,4R)-2-(2'-d-hydroxyalkanoylamino) octadecane-1,3,4-triol, the fatty acid composition of which consists of 2-hydroxydocosanoic, 2-hydroxytetracosanoic, and 2-hydroxytricosanoic acids (from major to minor); (2S,3S,4R)-2-(alkanoylamino)octadecane-1,3,4-triol, the fatty acid composition of which is unusual and consists of docosanoic, hexadecanoic, tricosanoic, octadecanoic and nonadecanoic acids (from major to minor); and (2S,3R,4E)-2-(alkanoylamino)-4-octadecene-1,3-diol, the component fatty acids of which were hexadecanoic (predominant) and octadecanoic acids, respectively.

New aminocyclitols as modulators of glucosylceramide metabolism

A series of 13 aminocyclitol derivatives belonging to two different families is described. Their configuration is governed by the regio- and stereocontrolled epoxide opening of a suitably protected conduritol-B epoxide. Studies on several glycosyl processing enzymes indicate that some of them are good inhibitors of glucosylceramide hydrolase. A rationale to account for preliminary structure-activity relationships is provided.

One-step labelling of sphingolipids via a scrambling cross-metathesis reaction

The alkyl chain in the backbone of sphingosine derivatives can be exchanged with functionalised (labelled) side chains in a single step under cross-metathesis reaction conditions.

Synthesis of 7-Oxasphingosine and -ceramide Analogues and Their Evaluation in a Model for Apoptosis

The 7-oxasphingosine (1), 7-oxaceramide (2), the thio-oxaceramide 3, and N-methyloxaceramide 4 were synthesised from D-galactose via the building block 9. The apoptosis-inducing properties of 1-4 were compared to those of sphingosine (Sph) and ceramide (Cer) using a human neuroblastoma (SK-N-BE) and a murine-promyelocyte-derived (32d) cell line. There were no differences between 2-4 and Cer in terms of their effects on the viability of cells and their ability to trigger cell proliferation. However, in the presence of N,N-dimethylsphingosine, an inhibitor of sphingosine kinase (SPHK), Cer was more potent than thio-ceramide 3 in 32d cells, while thio-ceramide 3 was more potent and efficacious in SK-N-BE cells, where it showed an IC50 value of 3 nM compared to 100 nM for Cer. In both SK-N-BE and 32d cells, 7-oxasphingosine (1) and Sph were equally toxic, even in the presence of N,N-dimethylsphingosine.

Fluorescence-labeled sphingosines as substrates of sphingosine kinases 1 and 2

Fluorescently labeled d-erythro-sphingosines have been successfully synthesized in 9 and 12 steps starting from commercially available Garner aldehyde. Determining the influence of the nature, position and linkage of the label on the in vitro phosphorylation rate by sphingosine kinases 1 and 2 resulted in the identification of a pyrene- and a NBD-labeled sphingosine which are both phosphorylated with efficiency comparable to the natural substrate.

Crystal structures of O-acetylated 2-acylamino-2-deoxy-d-galactose derivatives

The X-ray structures of 1,3,4,6-tetra-O-acetyl-2-deoxy-alpha-D-galactopyranoside derivatives with four different 2-(acylamino) substituents have been determined with Mo K(alpha) radiation at 123 K. The structure of the 2-acetylamino derivative and of its acyl-homologs with a 2-(propanoylamino)-, 2-(butanoylamino)-, and 2-(2-methyl-propanoylamino)-group crystallized in the monoclinic space group C2. The pyranose unit of all compounds has the usual 4C(1) shape. The different orientations of the 6-O-acetyl-groups are discussed. Conformations of the acylamino-group are compared to those found in the crystal structure of N-acetyl-alpha-D-galactosamine.