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Fullerene hexakis-adducts bearing 12 peripheral carbohydrate moieties have been prepared by grafting sugar derivatives onto the fullerene core through the copper mediated Huisgen 1,3-dipolar cycloaddition of azides and alkynes.

Fullerene hexakis-adducts bearing 12 peripheral mannose moieties have been prepared by grafting sugar derivatives onto the fullerene core and assayed as inhibitors of FimH, a bacterial adhesin, using isothermal titration calorimetry, surface plasmon resonance and hemagglutination assays.

L,D-Heptosides (L-glycero-D-manno-heptopyranoses) are found in important bacterial glycolipids such as lipopolysaccharide (LPS), the biosynthesis of which is targeted for the development of novel antibacterial agents. This work describes the synthesis of a series of fullerene hexa-adducts bearing 12 copies of peripheral sugars displaying the mannopyranose core structure of bacterial L,D-heptoside. The multimers were assembled through an efficient copper-catalyzed alkyne-azide cycloaddition reaction as the final step. The final fullerene sugar balls were assayed as inhibitors of heptosyltransferase WaaC, the glycosyltransferase catalyzing the incorporation of the first L-heptose into LPS. Interestingly, the inhibition of the final molecules was found in the low micromolar range (IC(50) =7-45 μM), whereas the corresponding monomeric glycosides displayed high micromolar to low millimolar inhibition levels (IC(50) always above 400 μM). When evaluated on a "per-sugar" basis, these inhibition data showed that, in each case, the average affinity of a single glycoside of the fullerenes towards WaaC was significantly enhanced when displayed as a multimer, thus demonstrating an unexpected multivalent effect. To date, such a multivalent mode of inhibition had never been evidenced with glycosyltransferases.

The synthesis of pillar[5]arene-based glycoclusters has been readily achieved by CuAAC conjugations of azido- and alkyne-functionalized precursors. The lectin binding properties of the resulting glycosylated multivalent ligands have been studied by at least two complementary techniques to provide a good understanding. Three lectins were selected from bacterial pathogens based on their potential therapeutic applications as anti-adhesives, namely LecA and LecB from Pseudomonas aeruginosa and BambL from Burkholderia ambifaria. As a general trend, multivalency improved the binding to lectins and a higher affinity can be obtained by increasing to a certain limit the length of the spacer arm between the carbohydrate subunits and the central macrocyclic core.

A synthetic approach combining recent concepts for the preparation of multifunctional nanomolecules (click chemistry on multifunctional scaffolds) with supramolecular chemistry (self‐assembly to prepare rotaxanes) gave easy access to a large variety of sophisticated [2]rotaxane heteroglycoclusters. Specifically, compounds combining galactose and fucose have been prepared to target the two bacterial lectins (LecA and LecB) from the opportunistic pathogen Pseudomonas aeruginosa.

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A series of water-soluble glycofullerenes containing up to 24 fucose residues have been prepared. These compounds were tested against the two bacterial fucose-binding lectins LecB and RSL, and C 60 (E) 12 bearing 24 fucose residues appeared to be the best known inhibitor of both lectins to date. We have shown that increasing both the valency and the length of the spacer between the central core and the peripheral sugars can be beneficial for the affinity. † Electronic supplementary information (ESI) available. See