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Synthesis, biological evaluation, and molecular modeling of 1-benzyl-1H-imidazoles as selective inhibitors of aldosterone synthase (CYP11B2).

Reducing aldosterone action is beneficial in various major diseases such as heart failure. Currently, this is achieved with mineralocorticoid receptor antagonists, however, aldosterone synthase (CYP11B2) inhibitors may offer a promising alternative. In this study, we used three-dimensional modeling of CYP11B2 to model the binding modes of the natural substrate 18-hydroxycorticosterone and the recently published CYP11B2 inhibitor R-fadrozole as a rational guide to design 44 structurally simple and achiral 1-benzyl-1H-imidazoles. Their syntheses, in vitro inhibitor potencies, and in silico docking are described. Some promising CYP11B2 inhibitors were identified, with our novel lead MOERAS115 (4-((5-phenyl-1H-imidazol-1-yl)methyl)benzonitrile) displaying an IC(50) for CYP11B2 of 1.7 nM, and a CYP11B2 (versus CYP11B1) selectivity of 16.5, comparable to R-fadrozole (IC(50) for CYP11B2 6.0 nM, selectivity 19.8). Molecular docking of the inhibitors in the models enabled us to generate posthoc hypotheses on their binding modes, providing a valuable basis for future studies and further design of CYP11B2 inhibitors.

Org 214007-0: A Novel Non-Steroidal Selective Glucocorticoid Receptor Modulator with Full Anti-Inflammatory Properties and Improved Therapeutic Index

Glucocorticoids (GCs) such as prednisolone are potent immunosuppressive drugs but suffer from severe adverse effects, including the induction of insulin resistance. Therefore, development of so-called Selective Glucocorticoid Receptor Modulators (SGRM) is highly desirable. Here we describe a non-steroidal Glucocorticoid Receptor (GR)-selective compound (Org 214007-0) with a binding affinity to GR similar to that of prednisolone. Structural modelling of the GR-Org 214007-0 binding site shows disturbance of the loop between helix 11 and helix 12 of GR, confirmed by partial recruitment of the TIF2-3 peptide. Using various cell lines and primary human cells, we show here that Org 214007-0 acts as a partial GC agonist, since it repressed inflammatory genes and was less effective in induction of metabolic genes. More importantly, in vivo studies in mice indicated that Org 214007-0 retained full efficacy in acute inflammation models as well as in a chronic collagen-induced arthritis (CIA) model. Gene expression profiling of muscle tissue derived from arthritic mice showed a partial activity of Org 214007-0 at an equi-efficacious dosage of prednisolone, with an increased ratio in repression versus induction of genes. Finally, in mice Org 214007-0 did not induce elevated fasting glucose nor the shift in glucose/glycogen balance in the liver seen with an equi-efficacious dose of prednisolone. All together, our data demonstrate that Org 214007-0 is a novel SGRMs with an improved therapeutic index compared to prednisolone. This class of SGRMs can contribute to effective anti-inflammatory therapy with a lower risk for metabolic side effects.

Conversion of N-hydroxytryptophan into α-functionalised tryptophans. An approach to the sporidesmin series

Reaction of the N-hydroxytryptophan derivative (5a) with pyruvoyl chloride gives access to the N-hydroxypiperazines (6a) and (13). O-Alkylation of the latter compounds, followed by base treatment in the presence or absence of methanol, affords the dioxopiperazines (7a) and (20), respectively. Subsequent oxidative ring closure using singlet oxygen yields the corresponding tetracyclic compounds (8a) and (25)–(29). The compounds (25) and (8a) having the skeleton and stereochemistry of the spirodesmins (1a–c) can be separated from their stereoisomers (26) and (27), respectively, by column chromatography. They are potential precursors of the fungal metabolites. Until now, attempts to replace the C-11 a methoxy group of (25) and (8a) by a sulphur substituent have failed.Finally, the properly substituted N-hydroxytryptophan derivative (5b) has been prepared by cycloaddition of (2b) with the nitroso olefin (3), followed by aminolysis of the addition product and subsequent selective reduction of the oxime function.

Conversion of N-hydroxytryptophans into α,β-dehydrotryptophan. An approach to the neoechinulin series

Reaction of the N-hydroxytryptophan derivative (21b) with pyruvoyl chloride gives access to the N-hydroxydioxopiperazine (28b). O-Tosylation of the latter compound, followed by base treatment, affords the dioxopiperazine (30b), an N(1)-allyl derivative of the fungal metabolite neoechinulin B (6). The biogenetic relevance of this reaction sequence is discussed.

Application of a ligand‐based theoretical approach to derive conversion paths and ligand conformations in CYP11B2‐mediated aldosterone formation

The biosynthesis of the mineralocorticoid hormone aldosterone involves a multistep hydroxylation of 11‐deoxycorticosterone at the 11‐ and 18‐positions, resulting in the formation of corticosterone and 18‐hydroxycorticosterone, the final precursor of aldosterone. Two members of the cytochrome P450 11B family, CYP11B1 and CYP11B2, are known to catalyze these 11‐ and 18‐hydroxylations, however, only CYP11B2 can oxidize 18‐hydroxycorticosterone to aldosterone. It is unknown what sequence of hydroxylations leads to the formation of 18‐hydroxycorticosterone. In this study we have investigated which of the possible conversion paths towards formation of 18‐hydroxycorticosterone and aldosterone are most likely from the ligand perspective. Therefore, we combined quantum mechanical investigations on the steroid conformations of 11‐deoxycorticosterone and its ensuing reaction intermediates with Fukui indices calculations to predict the reactivity of their carbon atoms for an attack by the iron‐oxygen species. Both F− and F0 were calculated to account for different mechanisms of substrate conversion. We show which particular initial conformations of 11‐deoxycorticosterone and which conversion paths are likely to result in the successful synthesis of aldosterone, and thereby may be representative for the mechanism of aldosterone biosynthesis by CYP11B2. Moreover, we found that the most likely path for aldosterone synthesis coincides with the substrate conformation proposed in an earlier publication (Ref. 2 ). To summarize, we show that on a theoretical and strictly ligand‐directed basis only a limited number of reaction paths in the conversion of 11‐deoxycorticosterone to aldosterone is possible. Despite its theoretical nature, this knowledge may help to understand the catalytic function of CYP11B1 and CYP11B2.