The preparation and characterization of a series of selective glucocorticoid receptor modulators are described. The preliminary structure-activity relationship of nonaromatic C-5 substitution on the tetracyclic quinoline core showed a preference for small lipophilic side chains. Proper substitution at this position maintained the transcriptional repression of proinflammatory transcription factors while diminishing the transcriptional activation activity of the ligand/glucocorticoid receptor complex. The optimal compounds described in this study were the allyl analogue 18 and cyclopentyl analogue 32. These candidates showed slightly less potent, highly efficacious E-selectin repression with significantly reduced levels of glucocorticoid response element activation in reporter gene assays vs prednisolone. Allyl analogue 18 was evaluated in vivo. An oral dose of 18 showed an ED(50) = 1.7 mg/kg as compared to 1.2 mg/kg for prednisolone in the Sephadex-induced pulmonary eosinophilia model and an ED(50) = 15 mg/kg vs 4 mg/kg for prednisolone in the carrageenan-induced paw edema model.

The preparation and characterization of a series of C-10 substituted 5-allyl-2,5-dihydro-2,2,4-trimethyl-1H-[1]benzopyrano[3,4-f]quinolines as a novel class of selective ligands for the glucocorticoid receptor is described. Substitution at the C-10 position of the tetracyclic core with linear, two-atom appendages (OCH(3), OCF(2)H, NHMe, SMe, CH=CH(2), Ctbd1;CH, CH(2)OH) provided molecules of high affinity (K(i) = 2-8 nM) for the human glucocorticoid receptor (hGR) with limited cross-reactivity with other steroid receptors (PR, MR, AR, ER). Optimal analogues showed slightly less potent but highly efficacious E-selectin repression with reduced levels of GRE activation efficacy in reporter gene assays relative to prednisolone. Preliminary SAR of analogues containing substitution at the C-9 and C-10 positions identified the 9-OH, 10-OMe analogue 50 and the 9-OH, 10-Cl analogue 58 as compounds that demonstrated potent, GR-mediated inhibition in a conconavalin A stimulated T-cell proliferation assay in both rodent and human whole blood monocytes. When evaluated for their in vivo effects in carrageenan-induced paw edema in rats, 50, 58, and 10-OCF(2)H analogue 35 showed dose-dependent anti-inflammatory effects (50, ED(50) = 16 mg/kg; 58, ED(50) = 15 mg/kg; 35, ED(50) = 21 mg/kg vs ED(50) = 15 mg/kg for 18 and ED(50) = 4 mg/kg for prednisolone).

No abstract

Novel Boc-CCK-4 derivatives were communicated recently as having high potency and selectivity for the CCK-A receptor (Shiosaki et al. J. Med. Chem. 1990, 33, 2950-2952). While Boc-CCK-4 binds selectively to the CCK-B receptor, replacement of the methionine with an N epsilon-substituted lysine dramatically reversed receptor selectivity, leading to the development of this novel series of tetrapeptides. A detailed structure-activity analysis of a series of urea-substituted tetrapeptides, represented by the general structure Boc-Trp-Lys(N epsilon-CO-NHR)-Asp-Phe-NH2, revealed that a number of substituted phenyl, naphthyl, and aliphatic urea residues in the lysine side chain yielded potent and selective CCK-A ligands. These tetrapeptides elicit full agonist responses in stimulating pancreatic amylase release that are effectively blocked by a selective CCK-A receptor antagonist. Conversion of the urea to a thiourea significantly reduced CCK-A binding potency as did replacement of the lysine with the homologous ornithine or homolysine. Tetrapeptides that were partial agonists (less than 80% efficacy) in phosphoinositide (PI) hydrolysis relative to CCK-8 did not exhibit high-dose inhibition of amylase secretion in guinea pig acini.