Design and identification of brain-penetrant, potent, and selective 1,3-oxazole-based cholesterol 24-hydroxylase (CH24H) inhibitors

Azole-, pyridine-, and pyrimidine-based cytochrome P450 (CYP) inhibitors strongly bind to CYP enzymes through the coordination between the heme iron of CYP and the sp2-nitrogen atoms of heteroaromatic rings, providing potent pharmacological effects by inhibiting the initiation of the catalytic cycles of target CYP enzymes. Although imidazole-, 1,2,4-triazole-, pyridine-, and pyrimidine-based CYP inhibitors have been widely explored, 1,3-oxazole-based CYP inhibitors have received little attention. In this study, we designed and identified novel 1,3-oxazole-based inhibitors of cholesterol 24- hydroxylase (CH24H; CYP46A1), a brain-specific enzyme involved in cholesterol catabolism, to form 24S-hydroxycholesterol. Detailed insights into the CH24H-ligand interactions were provided by the crystal structures of 1,3-oxazole compounds, including high-throughput screening hit 2 and rationally designed inhibitor 3f. Optimization of 3f led to the identification of 1,3-oxazole derivative 4 l as a potent, selective, and brain-penetrable CH24H inhibitor that significantly reduced 24HC levels in the mouse brain. The design of 1,3-oxazole-based CYP inhibitors holds the potential for the discovery of novel inhibitors with significant potency against a broad spectrum of CYP enzymes.