Unprecedented Thiacalixarene Fucoclusters as Strong Inhibitors of Ebola cis-Cell Infection and HCMV-gB Glycoprotein/DC-SIGN C-type Lectin Interaction.

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 with the help of DC-SIGN (dendritic cell [DC]-specific ICAM3-grabbing nonintegrin) C-type lectin expressed on dendritic and macrophage cell membranes, via their envelope protein. Prevention of this infectious interaction is a serious therapeutic option. Here, we describe the synthesis of the first water-soluble tetravalent fucocluster pseudopeptide-based 1,3-alternate thiacalixarenes 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 ß avidity factors. All ligands block DC-SIGN active sites at nanomolar IC50 preventing cis-cell infection by Ebola viral particles pseudotyped with EBOV glycoprotein (Zaire 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-calixarenes with wide-ranging antimicrobial activities.

Low-Valent Calix[4]arene Glycoconjugates Based on Hydroxamic Acid Bearing Linkers as Potent Inhibitors in a Model of Ebola Virus Cis-Infection and HCMV-gB-Recombinant Glycoprotein Interaction with MDDC Cells by Blocking DC-SIGN.

In addition to a variety of viral-glycoprotein receptors (e.g., heparan sulfate, Niemann-Pick C1, etc.), dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), from the C-type lectin receptor family, plays one of the most important pathogenic functions for a wide range of viruses (e.g., Ebola, human cytomegalovirus (HCMV), HIV-1, severe acute respiratory syndrome coronavirus 2, etc.) that invade host cells before replication; thus, its inhibition represents a relevant extracellular antiviral therapy. We report two novel p-tBu-calixarene glycoclusters 1 and 2, bearing tetrahydroxamic acid groups, which exhibit micromolar inhibition of soluble DC-SIGN binding and provide nanomolar IC50 inhibition of both DC-SIGN-dependent Jurkat cis-cell infection by viral particle pseudotyped with Ebola virus glycoprotein and the HCMV-gB-recombinant glycoprotein interaction with monocyte-derived dendritic cells expressing DC-SIGN. A unique cooperative involvement of sugar, linker, and calixarene core is likely behind the strong avidity of DC-SIGN for these low-valent systems. We claim herein new promising candidates for the rational development of a large spectrum of antiviral therapeutics.

Glycocluster Tetrahydroxamic Acids Exhibiting Unprecedented Inhibition of Pseudomonas aeruginosa Biofilms.

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.