Development of chiral fluorinated alkyl derivatives of emixustat as drug candidates for the treatment of retinal degenerative diseases

Abstract

The discovery of how a photon is converted into a chemical signal is one of the most important achievements in the field of vision. A key molecule in this process is the visual chromophore retinal. Several eye diseases are attributed to the abnormal metabolism of retinal in the retina and the retinal pigment epithelium. Also, the accumulation of two toxic retinal derivatives, Nretinylidene-N-retinylethanolamine and the retinal dimer, can damage the retina leading to blindness. RPE65 (Retinal pigment epithelium-specific 65 kDa protein) is one of the central enzymes that regulates the metabolism of retinal and the formation of its toxic metabolites. Its inhibition might decrease the rate of the retina's degeneration by limiting the amount of retinal and its toxic byproducts. Two RPE65 inhibitors, (R)-emixustat and (R)-MB001, were recently developed for this purpose.Here we describe eleven steps-synthesis of the chiral fluorinated alkyl derivatives of emixustat. Two final compounds (enantiomers) showed significant inhibition of RPE-65 at a 2-fold lower concentration compared with (R)-MB001, one of the developed compounds caused 100% cell protection under all-trans-retinal treatment and both molecules showed equal potency as racemic emixustat. Such molecules might be used as drug candidates for developing novel treatments against retinal degeneration.