Aryl Pyrazole Glucocorticoid Receptor Agonists: Probing Structure Activity Relationships in the Expanded Ligand Binding Pocket

Glucocorticoids (GCs) are a mainstay in modern medicine and one of the most frequently prescribed medications worldwide. They are used in the management of autoimmune-mediated conditions, organ transplantation, and some cancers. The transcriptional actions mediated by GCs include transrepression, proposed to be responsible for the anti-inflammatory activity, and transactivation, suggested to cause the unwanted side effects. A glucocorticoid receptor agonist (GRA) capable of dissociating the beneficial transrepression actions from the undesired transactivation activity is a highly sought-after target. In the presented studies, unique GRAs were designed, synthesized, biologically screened in assays using a rat insulinoma cell line, and evaluated through molecular docking experiments to probe structure activity relationships. The first study presents a series of aryl pyrazole glucocorticoid receptor agonists (APGRAs) with two modification sites. Compounds with an electron deficient aryl pyrazole moiety showed desirable activity with dissociated properties. Additionally, compounds 11aa and 11ab displayed anti-inflammatory efficacy comparable to dexamethasone (Dex) at 10 nM, with minimal transactivation activity and no reduction of insulin secretion in cultured rat 832/13 beta-cells. To build upon the conclusions of the first study, a set of novel, stereochemically pure, APGRAs were examined to recognize the stereochemical impacts of this scaffold. This study included an additional step to perform chiral separations via supercritical fluid chromatography, after which the stereochemically pure APGRAs were identified using two-dimensional nuclear magnetic resonance techniques. The isomers with an upward OH moiety was found to be approximately 70 percent more active on average than that with a downward OH. Finally, to explore the large space of the expanded ligand binding pocket in the human glucocorticoid receptor, the hydrocortisone (HC) scaffold was modified in two areas. The set of APGRAs derived from HC displayed potent activity, displaying greater than 95 percent the anti-inflammatory activity of Dex. Two compounds, 5 and 6, displayed exceptionally potent activity with up to 90 percent anti-inflammatory response at 0.1 nM while Dex only produced a 30 percent response at this concentration. This work contributes to the understanding of the complex GC activities and reveals numerous compounds with potent anti-inflammatory effects and improved selectivity in vitro.