Polyvalent C-glycomimetics based on l-fucose or d-mannose as potent DC-SIGN antagonists†
The C-type lectin DC-SIGN expressed on immature dendritic cells is a promising target for antiviral drug development. Previously, we have demonstrated that mono- and divalent C-glycosides based on D-manno and L-fuco configurations are promising DC-SIGN ligands. Here, we described the convergent synthesis of C-glycoside dendrimers decorated with 4, 6, 9, and 12 α-L-fucopyranosyl units and with 9 and 12 α-D-mannopyranosyl units. Their affinity against DC-SIGN was assessed by surface plasmon resonance (SPR) assays. For comparison, parent O-glycosidic dendrimers were synthesized and tested, as well. A clear increase of both affinity and multivalency effect was observed for C-glycomimetics of both types (mannose and fucose). However, when dodecavalent C-glycosidic dendrimers were compared, there was no difference in affinity regarding the sugar unit (L-fuco, IC50 17 μM; D-manno, IC50 12 μM). For the rest of glycodendrimers with L-fucose or D-mannose attached by the O- or C-glycosidic linkage, C-glycosidic dendrimers were significantly more active. These results show that in addition to the expected physiological stability, the biological activity of C-glycoside mimetics is higher in comparison to the corresponding O-glycosides and therefore these glycomimetic multivalent systems represent potentially promising candidates for targeting DC-SIGN.