Modulation of γ-secretase activity by a carborane-based flurbiprofen analogue

All over the world, societies are facing rapidly aging populations combined with a growing num-ber of patients suffering from Alzheimer’s disease (AD). One focus in pharmaceutical research to address this issue is on the reduction of the longer amyloid-β (Aβ) fragments in brain by modula-tion of γ-secretase, a membrane-bound protease. R-Flurbiprofen (tarenflurbil) was studied in this regard, but failed to show significant improvement in AD patients in a phase 3 clinical trial. This was mainly attributed to its low ability to cross the blood-brain barrier (BBB). We here present the synthesis and in vitro evaluation of a racemic meta-carborane analogue of flurbiprofen. By intro-ducing the carborane moiety, the hydrophobicity could be shifted into a more favourable range for the penetration of the blood-brain barrier, evident by a logD7.4 value of 2.0. Furthermore, our analogue retained γ-secretase modulator activity in comparison to racemic flurbiprofen in a cell-based assay. These findings demonstrate the potential of carboranes as phenyl mimetics also in AD research.