Molecular Umbrellas

Molecular Umbrella

Design and Synthesis of Molecular Umbrellas

This paper describes the design and synthesis of a series of conjugates derived from cholic acid, spermidine, and 5-(dimethylamino)-1-naphthalenesulfonyl (dansyl), which effectively shield the dansyl moiety from water. Direct coupling of cholic acid to both terminal amino groups of spermidine, and attachment of the environmentally-sensitive dansyl moiety to the remaining secondary amine, yields a “molecular umbrella” (Ia) whose fluorescent properties (λmax and emission intensity) reflect a nonpolar microenvironment in water and one that is relatively polar in intermediate dimethoxyethane/water mixtures. Comparison of Ia with analogous “single-walled” (II) and “no-walled” (III) umbrellas further indicates that a minimum of two walls is necessary in order to have “umbrella-like” properties. Examination of the fluorescent properties of a related double-walled umbrella, bearing a flexible (2-hydroxyethyl)carbamate moiety at the C-3 position of the sterol (Ib), reveals that “umbrella-like” properties are present even when facial amphiphilicity is not rigorously maintained; however, the molecule's ability to shield the fluorophore, as judged by its relative emission intensity, is diminished. “Methyl-capping” of the (2-hydroxyethyl)carbamate (i.e., Ic) enhances the umbrella's ability to provide a hydrophobic shelter in water. A tetra-walled analogue of Ia, bearing four cholic acid units (i.e., IV), has been synthesized and its dansyl group found to have reduced exposure toward water. The potential utility of molecular umbrellas in the area of drug delivery is briefly discussed

Molecular Umbrellas

Molecular Umbrella

Wnt Inhibition Correlates with Human Embryonic Stem Cell Cardiomyogenesis: A Structure–Activity Relationship Study Based on Inhibitors for the Wnt Response

Human embryonic stem cell-based high-content screening of 550 known signal transduction modulators showed that one “lead” (<b>1</b>, a recently described inhibitor of the proteolytic degradation of Axin) stimulated cardiomyogenesis. Because Axin controls canonical Wnt signaling, we conducted an investigation to determine whether the cardiogenic activity of <b>1</b> is Wnt-dependent, and we developed a structure–activity relationship to optimize the cardiogenic properties of <b>1</b>. We prepared analogues with a range of potencies (low nanomolar to inactive) for Wnt/β-catenin inhibition and for cardiogenic induction. Both functional activities correlated positively (<i>r</i>² = 0.72). The optimal compounds induced cardiogenesis 1.5-fold greater than <b>1</b> at 30-fold lower concentrations. In contrast, no correlation was observed for cardiogenesis and modulation of transforming growth factor β (TGFβ)/Smad signaling that prominently influences cardiogenesis. Taken together, these data show that Wnt signaling inhibition is essential for cardiogenic activity and that the pathway can be targeted for the design of druglike cardiogenic molecules

Synthesis and SAR of <i>b</i>‑Annulated 1,4-Dihydropyridines Define Cardiomyogenic Compounds as Novel Inhibitors of TGFβ Signaling

A medium-throughput murine embryonic stem cell (mESC)-based high-content screening of 17000 small molecules for cardiogenesis led to the identification of a <i>b</i>-annulated 1,4-dihydropyridine (1,4-DHP) that inhibited transforming growth factor β (TGFβ)/Smad signaling by clearing the type II TGFβ receptor from the cell surface. Because this is an unprecedented mechanism of action, we explored the series’ structure–activity relationship (SAR) based on TGFβ inhibition, and evaluated SAR aspects for cell-surface clearance of TGFβ receptor II (TGFBR2) and for biological activity in mESCs. We determined a pharmacophore and generated 1,4-DHPs with IC₅₀s for TGFβ inhibition in the nanomolar range (e.g., compound <b>28</b>, 170 nM). Stereochemical consequences of a chiral center at the 4-position was evaluated, revealing 10- to 15-fold more potent TGFβ inhibition for the (+)- than the (−) enantiomer. This stereopreference was not observed for the low level inhibition against Activin A signaling and was reversed for effects on calcium handling in HL-1 cells

A Fragment-Based Approach to Identifying <i>S</i>‑Adenosyl‑l‑methionine -Competitive Inhibitors of Catechol <i>O</i>‑Methyl Transferase (COMT).

Catechol O-methyl transferase belongs to the diverse family of S-adenosyl-l-methionine transferases. It is a target involved in the treatment of Parkinson’s disease. Here we present a fragment-based screening approach to discover noncatechol derived COMT inhibitors which bind at the SAM binding pocket. We describe the identification and characterization of a series of highly ligand efficient SAM competitive bisaryl fragments (LE = 0.33–0.58). We also present the first SAM-competitive small-molecule COMT co-complex crystal structure

A Fragment-Based Approach to Identifying <i>S</i>‑Adenosyl‑l‑methionine -Competitive Inhibitors of Catechol <i>O</i>‑Methyl Transferase (COMT).

Catechol <i>O</i>-methyl transferase belongs to the diverse family of <i>S</i>-adenosyl-l-methionine transferases. It is a target involved in the treatment of Parkinson’s disease. Here we present a fragment-based screening approach to discover noncatechol derived COMT inhibitors which bind at the SAM binding pocket. We describe the identification and characterization of a series of highly ligand efficient SAM competitive bisaryl fragments (LE = 0.33–0.58). We also present the first SAM-competitive small-molecule COMT co-complex crystal structure

Design and Synthesis of Tricyclic Imidazo[4,5-<i>b</i>]pyridin-2-ones as Corticotropin-Releasing Factor-1 Antagonists

The synthesis and SAR studies of tricyclic imidazo[4,5-b]pyridin-2-ones as human corticotropin-releasing factor receptor (CRF1) antagonists are discussed herein. Compound 16g was identified as a functional antagonist that inhibited CRF-stimulated cyclic adenosine monophosphate production and CRF-induced adrenocorticotrophic hormone release. Pharmacokinetics studies in rats showed that 16g was orally bioavailable, had good brain penetration, and had a moderate half-life. In our effort to identify CRF1 antagonists with improved pharmacokinetics properties, 16g exhibited a favorably lower volume of distribution

Structure-Based Design of ASK1 Inhibitors as Potential Agents for Heart Failure

Apoptosis signal-regulating kinase 1 (ASK1/MAP3K) is a mitogen-activated protein kinase family member shown to contribute to acute ischemia/reperfusion injury. Using structure-based drug design, deconstruction, and reoptimization of a known ASK1 inhibitor, a lead compound was identified. This compound displayed robust MAP3K pathway inhibition and reduction of infarct size in an isolated perfused heart model of cardiac injury