Linkage-Editing of 6,6'-Diacyl Neotrehalose and Evaluation of Mincle Activation Ability

Trehalose dimycolates (TDMs), prominent glycolipid components of the mycobacterial cell wall, consist of an α,α-trehalose scaffold acylated at the O6 and O6' positions with long-chain mycolic acids. TDMs and related 6,6'-diacyl trehaloses are recognized by macrophage-inducible C-type lectin (Mincle) and exhibit strong immune-stimulating effects. Accordingly, 6,6'-diacyl trehaloses have attracted attention as potential vaccine adjuvants. In contrast, 6,6'-diacyl neotrehalose, which features an α,β-trehalose scaffold, is a less potent ligand of Mincle. Herein, we applied a linkage-editing strategy to 6,6'-diacyl neotrehalose to synthesize three types of C-glycoside analogs: (R)-CHF-, (S)-CHF-, and CH₂-linked 6,6'-diacyl neotrehaloses. Biological evaluation and conformational analysis revealed that the (R)-CHF-linked analog exhibited a tenfold increase in potency compared to O-linked 6,6'-diacyl neotrehalose, with the enhanced activity attributed to a distinct binding mode.