Abstract
In recent years the selective inhibition of FKBP51 has emerged as a possible treatment for chronic pain, obesity-induced diabetes, or depression. All currently known advanced FKBP51-selective inhibitors, including the widely used SAFit2, contain a cyclohexyl residue as a key motif for enabling selectivity over the closest homolog and anti-target FKBP52. During a structure-based SAR exploration we surprisingly discovered thiophenes as highly efficient cyclohexyl replacement moieties that retain the strong selectivity of SAFit-type inhibitors for FKBP51 over FKBP52. Cocrystal structures revealed that the thiophene-containing moieties enable selectivity by stabilizing a flipped-out conformation of Phe67 of FKBP51. Our best compound 19b potently binds to FKBP51 biochemically as well as in mammalian cells, desensitize TRPV1 in primary sensory neurons, and has an acceptable PK profile in mice, suggesting its use as novel tool compound for studying FKBP51 in animal models of neuropathic pain.
Supplementary materials
Title
Structure-based discovery of a new selectivity-enabling motif for the FK506-binding protein 51
Description
I. Determination of the absolute configuration of the bottom group
II. Refinement tables of the obtained co-crystal structures
III. Characterization of the pharmacokinetic parameters for compound 19b
IV. Experimental section
V. 1H NMR and 13C NMR and HPLC traces
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