Synthesis of the Nucleoside Moiety of Liposidomycins: Elucidation of the Pharmacophore of this Family of MraY Inhibitors

Tunicamycins (TCMs) and liposidomycins (LPMs) are naturally occurring inhibitors of the bacterial translocase (MraY). Based on structure–activity relationship (SAR) studies, a molecular model has been proposed for their inhibitory mechanism. This study points out the importance of the nucleoside moiety of liposidomycins in the inhibition of MraY. A simplified molecule (I) based on the liposidomycin core structure has been synthesised and tested on MraY. The compound displayed a moderate inhibitory activity (IC50=50 μM). The validation of the molecular model was then performed by synthesising higher homologues of I, containing an additional stereocentre in the 5′ position (XIV and XV). In agreement with the prediction, only the (S) isomer XV showed significant activity against MraY (IC50= 5 μM).