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Sphingosine-1-phosphate (S1P) synthesized by sphingosine kinase (SPHK) is a signaling molecule, involved in cell proliferation, growth, differentiation, and survival. Indeed, a sharp increase of S1P was linked to the pathological outcome with inflammation, cancer metastasis or angiogenesis etc. In this regard, the SPHK/S1P axis regulation has been a specific issue in anticancer strategy to turn accumulated sphingosine (SPN) into cytotoxic ceramides (Cers). For these purposes, there have been numerous chemicals synthesized for SPHK inhibition. In this study, we investigated the comparative efficiency of dansylated PF-543 (DPF-543) on the Cers synthesis along with PF-543. DPF-543 deserved attention in strong cytotoxicity, due to the cytotoxic Cers accumulation by ceramide synthase (CerSs). DPF-543 exhibited dual actions on Cers synthesis by enhance the serine palmitoyltransferase (SPT) activity, and by inhibiting SPHKs which eventually induced an unusual environment of the high amount of 3-ketosphinganine and sphinganine (SPA). SPA in turn was consumed to synthesize Cers via de novo pathway. Interestingly, PF-543 increased only the SPN level, but not for SPA. In addition, DPF-543 mildly activates acid sphingomyelinase (aSMase) that contributes a partial increase on Cers. Collectively, a dansyl-modified DPF-543 relatively en-hanced Cers accumulation via de novo pathway which was not observed in PF-543. Our results demonstrated that the structural modification on SPHK inhibitors is still an attractive anticancer strategy by regulating sphingolipid metabolism.

Nonalcoholic fatty liver disease is the most common chronic disease affecting a wide range of the world’s population and associated with obesity-induced metabolic syndrome. It is possibly emerging as a leading cause of life-threatening liver diseases for which a drug with a specific therapeutic target has not been developed yet. Previously, there have been reports on the benefits of Cudrania tricuspidata (CT) for treating obesity and diabetes via regulation of metabolic processes, such as lipogenesis, lipolysis, and inflammation. In this study, we investigated the ameliorative effect of orally administered 0.25% and 0.5% (w/w) CT mixed with high-fat diet (HFD) to C57BL/6J mice for 7 weeks. It was found that body weight, fat mass, hepatic mass, serum glucose level, and liver cholesterol levels were significantly reduced after CT treatment. In CT-treated HFD-fed mice, the mRNA expression levels of hepatic lipogenic and inflammatory cytokine-related genes were markedly reduced, whereas the expression level of epididymal lipogenic genes was increased. The mRNA expression level of beta-oxidation and Nrf-2/HO-1 genes significantly increased in CT-treated obese mice livers. We propose that CT alleviates hepatic steatosis by reducing oxidative stress and inflammation.

Fingolimod has been evaluated for use as an anticancer agent. However, many steps are required to synthesize fingolimod because of its intricate structure. A fingolimod analogue, N-(4-(2-((4-methoxybenzyl)amino)ethyl)phenyl)heptanamide (MPH), also has anti-cancer effects and is easier to synthesize but is poorly soluble in water. To compensate for its poor water solubility, MPH-loaded polymeric micelles were prepared by thin film hydration method using various polymers and the physicochemical properties of the MPH-loaded micelles such as particle size, drug-loading (DL, %), and encapsulation efficiency (EE, %) were evaluated. A storage stability test was conducted to select the final formulation and the release profile of the MPH-loaded micelles was confirmed by in vitro release assay. MPH-loaded mPEG-b-PLA micelles were selected for further testing based on their stability and physicochemical properties; they were stable for stable for 14 days at 4 °C and 25 °C and for 7 days at 37 °C. They showed anti-cancer efficacy against both A549 and U87 cancer cells. Encapsulation of MPH in polymeric micelles did not decrease the in vitro cytotoxicity of MPH. The findings of this study lay the groundwork for future formulations that enable the effective and stable delivery of poorly water-soluble agents.

PF-543, the most potent sphingosine kinase (SK) inhibitor, does not demonstrate effective anticancer activity in some cancer cells, unlike other known SK1 inhibitors. PF-543 has a non-lipid structure with a unique toluene backbone, however, the importance of this structure remains unclear. Therefore, the purpose of this study was to investigate changes in SK inhibitory and anticancer activities and to explore the role of the tolyl group structure of PF-543 through various modifications. We transformed the methyl group of PF-543 into hydrogen, fluorine, and hydroxy. PF-543 derivatives in which the methyl group was substituted by hydrogen and fluorine (compound 5) demonstrated SK1 inhibitory and anticancer activities similar to PF-543. Moreover, we performed molecular modeling studies of PF-543 and compound 5. To assess the metabolic stability of PF-543 and compound 5, we determined their degree of degradation using the liver microsomes of four different animal species (human, dog, rat, and mouse). However, both PF-543 and compound 5 showed poor microsomal stability. Therefore, for the medical applications of PF-543, the structural modifications of its other parts may be necessary. Our results provide important information for the design of additional PF-543 analogs.

PF-543 has been known as a substance that strongly inhibits SK1. However, it also exhibits antineoplastic activity that is lower than other inhibitors of SK1. In this study, we compared PF-543 and synthesized a newly designed derivative of PF-543 (compound 2) in which two aromatic structures were connected in para-form. The synthesized derivative showed inhibitory effect on SK1, similar to that of PF-543. However, it was more cytotoxic to HT29, AGS, and PC3 cells than PF-543. We also carried out a docking study for SK1 and demonstrated that the synthesized derivative showed interaction with SK1 similar to PF-543. Results obtained from this study suggest that the structure of compound 2 may be well substituted for the structure of PF-543 in terms of biological activity, providing us important structural information for the design of new derivatives of PF-543.

PF-543 is a non-sphingosine analogue with inhibitory effect against SK1, based on a Ki of 4.3 nM and 130-fold selectivity for SK1 over SK2. Since the development of PF-543, animal studies demonstrated its valuable role in multiple sclerosis, myocardial infarction, and colorectal cancer. We synthesized labeled PF-543 for biochemical studies involving SK1. Overall, the 8-step synthetic route used 3,5-dimethylphenol as the starting material. A docking study of SK1 and SK1 inhibitory activity confirmed the structural similarity between the synthetic dansyl-PF-543 and PF-543. We also provide fluorescence spectra of dansyl-PF-543.

Efficient synthetic routes for the preparation of secondary and tertiary 1,2,3-triazoloamide derivatives were developed. A secondary α-1,2,3-triazoloamide library was constructed and expanded by a previously developed solid-phase synthetic route and a tertiary 1,2,3-triazoloamide library was constructed by a parallel solution-phase synthetic route. The synthetic routes rely on amide formation with secondary amines and chloro-acid chlorides, SN2 reaction with sodium azide, and the selective [3 + 2] Hüisgen cycloaddition with appropriate terminal alkynes. The target secondary and tertiary 1,2,3-triazoloamide derivatives were obtained with three-diversity points in excellent overall yields and purities using the reported solid- and solution-phase synthetic routes, respectively.

An efficient protocol for the solid-phase synthesis of 2,4-disubstituted 5-carbamoyl-thiazole derivatives has been developed. After the reaction scopes were investigated in solution-phase, the polymer-supported synthesis route was progressed using a sulfide linker in a traceless manner. The solid-phase synthetic protocol started with the Thorpe-Ziegler type cyclization of 2-chloroacetamide and polymer-bound cyanocarboimidodithioate, which is derived from Merrifield resin. The resulting 5-carbamoyl-thiazole was introduced to one substitution by N-acylation. After the oxidation of sulfides to sulfones for subsequent cleavage, nucleophilic desulfonative substitution with amines and thiols gave the target 2,4-disubstituted 5-carbamoyl-thiazole derivatives in good purities and overall yields.

The interactions between cholesterol and other membrane molecules determine important membrane properties. It was shown that even small changes in the molecular structure of cholesterol have a crucial influence on these interactions. We recently reported that in addition to alterations in the tetracyclic ring structure, the iso-branched side chain of cholesterol also has a significant impact on membrane properties (Scheidt et al., 2013). Here we used synthetic cholesterol analogs to investigate the influence of an unbranched aliphatic side chain of different length. The (2)H NMR order parameter of the phospholipid chains and therefore the molecular packing of the phospholipid molecules shows a significant dependence on the sterol's alkyl side chain length, while, membrane permeation studied by a dithionite ion permeation assay and lateral diffusion measured by (1)H MAS pulsed field gradient NMR are less influenced. To achieve the same molecular packing effect similar to that of an iso-branched aliphatic side chain, a longer unbranched side chain (n-dodecyl instead of n-octyl) at C17 of cholesterol is required. Obviously, sterols having a branched iso-alkyl chain with two terminal methyl groups exhibit altered cholesterol-phospholipid interactions compared to analogous molecules with a straight unbranched chain.

CD1d molecules recognize glycolipid antigens with straight chain fatty acid moieties. Although most of the residues in the CD1d binding groove are hydrophobic, some of the amino acids can form hydrogen bonds. Consequently, we have designed ω-hydroxy fatty acid-containing glycolipid derivatives of the prototypical CD1d ligand α-GalCer. The potency of the ω-hydroxy analogues of the proper length is comparable to that of α-GalCer. We propose, based on the biological results and molecular modeling studies, that a hydrogen bonding interaction is involved between the ω-hydroxy group and a polar amino acid residue in the hydrophobic binding groove.

Sphingosine-1-phosphate (S1P) regulates the proliferation of various cells and promotes the growth of cancer cells. Sphingosine kinase (SK), which transforms sphingosine into S1P, has two isotypes: SK1 and SK2. To date, both isotypes are known to be involved in the proliferation of cancer cells. PF-543, an SK1 inhibitor developed by Pfizer, strongly inhibits SK1. However, despite its strong SK1 inhibitory effect, PF-543 shows low anticancer activity in vitro. Therefore, additional biological evidence on the anticancer activity of SK1 inhibitor is required. The present study aimed to investigate the intracellular localization of PF-543 and identify its association with anticancer activity by introducing a fluoroprobe into PF-543. Boron&ndash, dipyrromethene (BODIPY)-introduced PF-543 has a similar SK1 inhibitory effect as PF-543. These results indicate that the introduction of BODIPY does not significantly affect the inhibitory effect of SK1. In confocal microscopy after BODIPY-PF-543 treatment, the compound was mainly located in the cytosol of the cells. This study demonstrated the possibility of introducing fluorescent material into an SK inhibitor and designing a synthesized compound that is permeable to cells while maintaining the SK inhibitory effect.

The composition and chemical structures of the membrane forming molecules determine all essential properties of nature’s most important interface. Cellular membranes are subject to a hierarchical domain organization on the mesoscopic length scale.[1] This is triggered by preferential interactions between the major constituents of the membrane, e.g. phospholipids, cholesterol (Chol), glycolipids, and membrane proteins.[2] In particular, the attractive interactions between Chol and sphingolipids or saturated phospholipids and/or membrane proteins have been identified as the driving force for membrane domain formation.[3] Key to the lipid phase separation phenomena is the preferential interaction of Chol with saturated lipid chains.[4] Numerous examples of the specific interaction between Chol and saturated phospholipids or sphingomyelin have been reported.[5] The interaction between Chol and saturated lipid chains is thought to originate by attractive van der Waals interactions between Chol’s planar and rigid ring system (particularly the smooth α-face) and the saturated phospholipid chains.[6] This leads to a stiffening of the lipid chains, as indicated by an order increase, which is referred to as area condensation.[7] This increased packing density decreases membrane permeability.[8] Surprisingly, the influence of the aliphatic Chol side chain on lipid condensation and membrane domain formation is still not fully understood. Therefore, we have systematically studied the influence of the methyl-branched (iso-series) side chain of Chol with 5 to 14 carbon atoms[9] (Figure 1A) on important membrane properties.

We describe the synthesis and bioactivity of analogues of α-galactosylceramide (1) bearing a long-chain alkyl group substituted at the meta or para position of an aryl group embedded within the amide chain. We compared the ability of these compounds and of 1 and C6Ph (2, which has a phenyl group at the amide chain terminus) to stimulate murine invariant Natural Killer T cells and to dock with human CD1d.

Cholesterol-23, 23, 24, 24, 25, 26, 26, 26, 27, 27, 27-d11 and nondeuterated long-chain analogs of cholesterol were prepared by alkylation of cyano-containing sterols with isopentyl-d11 4-methylbenzenesulfonate (1.0equiv.) or with isoalkyl bromides, followed by reductive decyanation with excess potassium metal and a crown ether in toluene. The products are potentially useful probes of the role of the side-chain of cholesterol in the sterol's interactions with membrane lipids and proteins.

A fully synthetic self-adjuvanting cancer vaccine candidate was constructed through covalent conjugation of invariant natural killer T (iNKT) cell ligand α-galactosylceramide (αGalCer) with sialyl Tn (STn), a representative tumor-associated carbohydrate antigen (TACA). This two-component vaccine STn-αGalCer is devoid of antigenic peptide, featuring the well-defined structure with high simplicity. STn-αGalCer showed remarkable efficacy in inducing antibody class switching from IgM to STn-specific IgG. Subtypes of IgG antibody were primarily IgG1 and IgG3.

The influence of the length of the cholesterol alkyl chain on essential membrane properties such as lipid ordering (condensation), lateral diffusion, membrane permeability, and membrane domain formation was studied using a series of synthetic cholesterol derivatives without a side chain or with an iso-branched chain bearing 5 to 14 carbons in length. We found that cholesterol's aliphatic side chain is crucial for all of the membrane properties investigated. First, we detected that the side chain is responsible for more than half of the phospholipid condensation in bilayers. Second, the length of the sterol side chain strongly determines membrane permeation, since a slightly longer or shorter side chain renders the bilayer significantly more permeable. Third, lateral lipid and sterol diffusion highly depends on the side chain length. Fourth, the length of the cholesterol side chain also determines the lateral organization of lipids in raft mixtures. While all tested sterols induce domain formation, the lipid distribution between the liquid disordered or raft phase is strongly dependent on side chain length. Fifth, the sterol side chain also influences the partitioning of a transmembrane peptide domain into liquid-ordered or liquid-disordered domains. Therefore, in addition to the flat tetracyclic ring system of cholesterol, the iso-branched side chain of cholesterol plays a key role in producing the relevant membrane properties of eukaryotic cells that result in an optimal interaction with phospholipids and presumably with membrane proteins. Sterols bearing an unbranched alkyl side chain of varying length also influence important properties of lipid membranes. However, the extent of this impact is lower compared with that measured for the respective branched iso-side chain sterols. Obviously, sterols having a branched iso-chains with two terminal methyl groups exhibit altered cholesterol-phospholipid-interactions compared to molecules with a straight unbranched chain.

Efficient, stereochemically unambiguous, total syntheses of pachastrissamine and its 2- epi -congener from the readily available common precursor (1 R )-1-{(4 S ,5 S )-2-oxo-4-[(trityl­oxy)methyl]-1,3-oxazolidin-5-yl}pentadecyl methanesulfonate are reported. Syntheses of (3a S ,6 R ,6a R )- and (3a S ,6 S ,6a R )-6-tetradecylhexahydro-2 H -cyclopenta[ d ][1,3]oxazol-2-one by this route have unambiguously resolved a dispute over the structures of these products.

The practical and efficient synthesis of D-erythro-sphingosine from commercially available D-ribo-phytosphingosine is described. An important feature of this synthesis is the selective transformation of the 3,4-vicinal diol of phytosphingosine into the characteristic E-allylic alcohol of sphingosine via a cyclic sulfate intermediate that contains a non-nucleophilic trifluoroacetamide protecting group.

The selective synthesis of D-xylo- and D-lyxo-phytosphingosines from commercially available D-ribo-phytosphingosine is described. Thermolysis of the N-carbonyl protected cyclic sulfate led to an inversion of configuration of the proximal hydroxyl group to give the xylo-isomer, whereas the corresponding bis-sulfonate resulted in an inversion of configuration of the distal hydroxyl group to give the lyxo-isomer. This study allowed the comparison between a cyclic sulfate and a bis-sulfonate in an intramolecular substitution reaction involving a carbonyl oxygen nucleophile.

Traceless solid-phase synthesis of 1,3,7,8-tetrasubstituted xanthine (1,3,7,8-tetrasubstituted 1H-purine-2,6(3H,7H)-dione) derivatives has been developed. The solid-phase synthetic route began on a solid supported N'-cyano-N-substituted carbamimidothioate, which was prepared from cyanamide, isothiocyanate, and Merrifield resin. After N-alkylation of carbamimidothioate resin with ethyl 2-bromoacetate, an imidazole ring is introduced by Thorpe-Ziegler-type cyclization. The resulting imidazole resin is converted to 1,3,7-trisubstituted xanthine resin using sequential reactions, such as Lewis acid-catalyzed urea formation, pyrimidine ring cyclization, and N-alkylation. After oxidation of sulfides to sulfones, traceless cleavage with amine or thiol nucleophiles afforded the desired 1,3,7,8-tetrasubstituted xanthines in good purities and overall yields (eight-steps; 36 examples). This efficient solid-phase synthesis enables the incorporation of four diversity points into the preparation of the 1,3,7,8-tetrasubstituted xanthines.

KRN7000, or α-GalCer, is a potent agonist for natural killer T (NKT) cells. The 3-hydroxyl group of its phytosphingosine moiety is important for activating NKT cells, whereas its 4-hydroxyl group is perceived to be less crucial. To experimentally determine the role of the 4-hydroxyl group, we synthesized the 3-deoxy analogue of α-GalCer. It was found that 3-deoxy-α-GalCer induced potent cytokine responses from NKT cells, comparable to those of both α-GalCer and 4-deoxy-α-GalCer. This result and our docking studies suggest that the effects of an absence of the 3-hydroxyl group are compensated by the presence of a hydroxyl group at the C-4 position. Thus, we conclude that the 4-hydroxyl group of α-GalCer is as important to the mechanism of action as the 3-hydroxyl group and that the two hydroxyl groups could play individual and cooperative roles in orienting the glycolipid into the proper position in CD1d to be recognized by the T cell receptor of NKT cells.

These studies provide an efficient and stereoselective synthetic route to (+)-MK7607 and its C-1 epimer from a common intermediate in high overall yields. The synthetic methodologies mainly rely on the stereospecific 1,3-allylic transposition of the hindered tertiary alcohol group through a palladium-catalyzed allylic rearrangement as well as a PBr(3)-mediated allylic-transposed bromination.

Bioisosteric analogues of pachastrissamine that contain sulfur and selenium atoms replacing the oxygen in the ring system, were efficiently prepared from a cyclic sulfate intermediate by sequential intermolecular and intramolecular S(N)2 displacement reactions of the dianions. The analogues exhibited cytotoxicities comparable to that of pachastrissamine.