Synthesis of C6''-modified α-C-GalCer analogues as mouse and human iNKT cell agonists.

α-GalCer analogues that combine known Th1 polarizing C6''-modifications with a C-glycosidic linkage were synthesized. We employed a protecting group strategy that allowed the preparation of both saturated and unsaturated derivatives with variable C6''-substituents. Selected analogues demonstrate promising activity in mice. Interestingly, the introduction of a 6''-O-pyridinylcarbamoyl substituent to α-C-GalCer restores its antigenicity in human iNKT cells.