Glycan-protein interactions control numerous biological events from cell-cell recognition and signaling to pathogen host cell attachment for infections. To infect cells, some viruses bind to immune cells thanks to DC-SIGN (dendritic cell [DC]-specific ICAM3-grabbing non-integrin) C-type lectin expressed on dendritic and macrophage cell membrane, via their envelope protein. Prevention of this infectious interaction is a serious therapeutic option. Here, we describe the synthesis of first water-soluble tetravalent fucocluster pseudopeptide-based thiacalixarene 1,3-alternate as viral antigen mimics designed for the inhibition of DC-SIGN, to prevent viral particle uptake. Their preparation exploits straightforward convergent strategies involving one pot Ugi four-component (Ugi-4CR) and azido-alkyne click chemistry reactions as key steps. Surface plasmon resonance showed strong inhibition of DC-SIGN interaction properties by tetravalent ligands designed with high relative potencies and β avidity factors. All ligands block DC-SIGN active sites at nanomolar IC 50 preventing cis-cell infection by Ebola viral particles pseudotyped with EBOV glycoprotein (Zaïre species of Ebola virus) on Jurkat cells that express DC-SIGN. In addition, we observed strong inhibition of DC-SIGN/human cytomegalovirus (HCMV)-gB recombinant glycoprotein interaction. This finding opens the way to the simple development of new models of water-soluble glycocluster-based thia-calixarene with wide-range antimicrobial activities.

Opportunistic Gram-negative Pseudomonas aeruginosa uses adhesins (e.g., LecA and LecB lectins, type VI pili and flagella) and iron to invade host cells with the formation of a biofilm, a thick barrier that protects bacteria from drugs and host immune system. Hindering iron uptake and disrupting adhesins’ function could be a relevant antipseudomonal strategy. To test this hypothesis, we designed an iron-chelating glycocluster incorporating a tetrahydroxamic acid and α-l-fucose bearing linker to interfere with both iron uptake and the glycan recognition process involving the LecB lectin. Iron depletion led to increased production of the siderophore pyoverdine by P. aeruginosa to counteract the loss of iron uptake, and strong biofilm inhibition was observed not only with the α-l-fucocluster (72%), but also with its α-d-manno (84%), and α-d-gluco (92%) counterparts used as negative controls. This unprecedented finding suggests that both LecB and biofilm inhibition are closely related to the presence of hydroxamic acid groups.