Dynamic Micelles of Mannoside Glycolipids are more Efficient than Polymers for Inhibiting HIV-1 trans -Infection

C-Glycosylcrotylboronates for the Synthesis of Glycomimetics

The stereoselective synthesis of E- and Z- isomers of a C- mannosyl crotylpinacolboronate via Ni-promoted reactions on an allylic acetate and a diene precursor, respectively, is described. The E- and Z- isomers reacted with 1,2-O-isopropylidene glyceraldehyde in the presence or absence of (R)- and (S)- TRIP catalysts, to give predominantly 3,4-anti and 3,4-syn crotylation products, respectively, with moderate to high facial selectivity. These products were transformed to biologically relevant C-manno-disaccharides.

sp2-Iminosugar glycolipids as inhibitors of lipopolysaccharide-mediated human dendritic cell activation in vitro and of acute inflammation in mice in vivo

Glycolipid mimetics consisting of a bicyclic polyhydroxypiperidine-cyclic carbamate core and a pseudoanomeric hydrophobic tail, termed sp²-iminosugar glycolipids (sp²-IGLs), target microglia during neuroinflammatory processes. Here we have synthesized and investigated new variants of sp²-IGLs for their ability to suppress the activation of human monocyte-derived dendritic cells (DCs) by lipopolysaccharide (LPS) signaling through Toll-like receptor 4. We report that the best lead was (1R)-1-dodecylsulfonyl-5N,6O-oxomethylidenenojirimycin (DSO₂-ONJ), able to inhibit LPS-induced TNFα production and maturation of DCs. Immunovisualization experiments, using a mannoside glycolipid conjugate (MGC) that also suppress LPS-mediated DC activation as control, evidenced a distinct mode of action for the sp²-IGLs: unlike MGCs, DSO₂-ONJ did not elicit internalization of the LPS co-receptor CD14 or induce its co-localization with the Toll-like receptor 4. In a mouse model of LPS-induced acute inflammation, DSO₂-ONJ demonstrated anti-inflammatory activity by inhibiting the production of the pro-inflammatory interleukin-6. The ensemble of the data highlights sp²-IGLs as a promising new class of molecules against inflammation by interfering in Toll-like receptor intracellular signaling.

Impact of Glycolipid Hydrophobic Chain Length and Headgroup Size on Self-Assembly and Hydrophobic Guest Release

Encapsulation of a hydrophobic guest molecule inside a micelle and its stimuli-sensitive release is a useful strategy for target-specific drug delivery. Herein, nine biobased glycolipids were derived from plant sources. The influence of headgroup on the stability and aggregation pattern in water with different alkyl chain lengths was investigated to deduce the structure-property relationship. External factors, such as temperature, pH, and NaCl and urea concentrations, were employed to explore stimuli response of glycolipid nanoassemblies. Furthermore, solvatochromic dyes, such as pyrene, N-phenyl-1-naphthylamine, and curcumin, were utilized to examine hydrophobe loading capacities of these glycolipid assemblies. A fluorescence study was performed to investigate the enzyme-sensitive hydrophobe release. Interestingly, the pH-sensitive hydrophobic guests showed pH-responsive release from dynamic micelles. Finally, the synthesized glycolipids revealed their nanoassemblies as smart carriers for hydrophobic cargo.

Inhibition of dengue virus infection by mannoside glycolipid conjugates

Dengue virus (DENV), a mosquito-borne flavivirus, causes severe and potentially fatal symptoms in millions of infected individuals each year. Although dengue fever represents a major global public health problem, the vaccines or antiviral drugs proposed so far have not shown sufficient efficacy and safety, calling for new antiviral developments. Here we have shown that a mannoside glycolipid conjugate (MGC) bearing a trimannose head with a saturated lipid chain inhibited DENV productive infection. It showed remarkable cell promiscuity, being active in human skin dendritic cells, hepatoma cell lines and Vero cells, and was active against all four DENV serotypes, with an IC₅₀ in the low micromolar range. Time-of-addition experiments and structure-activity analyses revealed the importance of the lipid chain to interfere with an early viral infection step. This, together with a correlation between antiviral activity and membrane polarization by the lipid moiety indicated that the inhibitor functions by blocking viral envelope fusion with the endosome membrane. These finding establish MGCs as a novel class of antivirals against the DENV.

Topological Defects in Hyperbranched Glycopolymers Enhance Binding to Lectins

Central scaffold topology and carbohydrate density are important features in determining the binding mechanism and potency of synthetic multivalent of poly- versus monodisperse carbohydrate systems against a model plant toxin (Ricinus communis agglutinin (RCA₁₂₀ )). Lower densities of protein receptors favour the use of heterogeneous, polydisperse glycoconjugate presentations, as determined by surface plasmon resonance and dynamic light scattering.

Design and syntheses of mono and multivalent mannosyl-lipoconjugates for targeted liposomal drug delivery

Multivalent mannosyl-lipoconjugates may be of interest for glycosylation of liposomes and targeted drug delivery because the mannose specifically binds to C-type lectin receptors on the particular cells. In this paper syntheses of two types of novel O-mannosides are presented. Conjugates 1 and 2 with a COOH- and NH2-functionalized spacer and the connection to a lysine and FmocNH-PEG-COOH, are described. The coupling reactions of prepared intermediates 6 and 4 with a PEGylated-DSPE or palmitic acid, respectively, are presented. Compounds 5, mono-, 8, di- and 12, tetravalent mannosyl-lipoconjugates, were synthesized. The synthesized compounds were incorporated into liposomes and liposomal preparations featuring exposed mannose units were characterized. Carbohydrate liposomal quartz crystal microbalance based assay has been established for studying carbohydrate-lectin binding. It was demonstrated that liposomes with incorporated mannosyl-lipoconjugates were effectively recognized by Con A and have great potential to be used for targeted liposomal drug delivery systems.

Glycomaterials for immunomodulation, immunotherapy, and infection prophylaxis

Synthetic carbohydrate-modified materials that can engage the innate and adaptive immune systems are receiving increasing interest to confer protection against onset of future disease, such as pathogen infection, as well as to treat established diseases, such as autoimmunity and cancer.

Mannoside Glycolipid Conjugates Display Anti-inflammatory Activity by Inhibition of Toll-like Receptor-4 Mediated Cell Activation

Inhibition of excessive Toll-like receptor 4 (TLR4) signaling is a therapeutic approach pursued for many inflammatory diseases. We report that Mannoside Glycolipid Conjugates (MGCs) selectively blocked TLR4-mediated activation of human monocytes and monocyte-derived dendritic cells (DCs) by lipopolysaccharide (LPS). They potently suppressed pro-inflammatory cytokine secretion and maturation of DCs exposed to LPS, leading to impaired T cell stimulation. MGCs did not interfere with LPS and could act in a delayed manner, hours after LPS stimulation. Their inhibitory action required both the sugar heads and the lipid chain, although the nature of the sugar and the structure of the lipid tail could be modified. They blocked early signaling events at the cell membrane, enhanced internalization of CD14 receptors, and prevented colocalization of CD14 and TLR4, thereby abolishing NF-κB nuclear translocation. When the best lead conjugate was tested in a mouse model of LPS-induced acute lung inflammation, it displayed an anti-inflammatory action by suppressing the recruitment of neutrophils. Thus, MGCs could serve as promising leads for the development of selective TLR4 antagonistic agents for inflammatory diseases.

Surface plasmon resonance as a high throughput method to evaluate specific and non-specific binding of nanotherapeutics

Surface plasmon resonance (SPR) is a powerful analytical technique used to quantitatively examine the interactions between various biomolecules, such as proteins and nucleic acids. The technique has been particularly useful in screening and evaluating binding affinity of novel small molecule and biomolecule-derived therapeutics for various diseases and applications including lupus medications, thrombin inhibitors, HIV protease inhibitors, DNA gyrase inhibitors and many others. Recently, there has been increasing interest in nanotherapeutics (nanoRx), due to their unique properties and potential for controlled release of encapsulated drugs and structure-specific targeting to diseased tissues. NanoRx offer the potential to solve many drug delivery challenges by enabling, specific interactions between molecules on the surface of the nanoparticle and molecules in the diseased tissue, while minimizing off-target interactions toward non-diseased tissues. These properties are largely dependent upon careful control and balance of nanoRx interactions and binding properties with tissues in vivo. Given the great promise of nanoRx with regard to engineering specific molecular interactions, SPR can rapidly quantify small aliquots of nanoRx formulations for desired and undesired molecular interactions. Moving forward, we believe that utilization of SPR in the screening and design of nanoRx has the potential to greatly improve the development of targeted nanoRx formulations and eventually lead to improved therapeutic efficacy. In this review, we discuss (1) the fundamental principles of SPR and basic quantitative analysis of SPR data, (2) previous applications of SPR in the study of non-particulate therapeutics and nanoRx, and (3) future opportunities for the use of SPR in the evaluation of nanoRx.

Nanoarchitectonics of biomolecular assemblies for functional applications

The stringent processes of natural selection and evolution have enabled extraordinary structure-function properties of biomolecules. Specifically, the archetypal designs of biomolecules, such as amino acids, nucleobases, carbohydrates and lipids amongst others, encode unparalleled information, selectivity and specificity. The integration of biomolecules either with functional molecules or with an embodied functionality ensures an eclectic approach for novel and advanced nanotechnological applications ranging from electronics to biomedicine, besides bright prospects in systems chemistry and synthetic biology. Given this intriguing scenario, our feature article intends to shed light on the emerging field of functional biomolecular engineering.