Synthesis of 3,4-dihydroxy-1,8-naphthalimides with inbuilt catechol and crown ether functionalities.

Herein the synthesis of 1,8-naphthalimides functionalised as the 3,4-dihydroxy-1,8-naphthalimide (catechol, Nap-Cat) and the corresponding 15-crown-5 (Nap-Crown) is reported. These compounds represent the first examples where these two recognition groups are directly incorporated into the 1,8-naphthalimide ring system. Both Nap-Cat and Nap-Crown were evaluated for their capacity to respond to analytes such as H2O2 (a mimic for cellular oxidation) and metal ions (as elements of environmental and physiological interest). While slow oxidation was observed for Nap-Cat upon prolonged exposure to H2O2, no significant changes in photophysical properties were observed upon treatment of Nap-Crown with metal ions.

Nickel-Catalyzed C-N Cross-Coupling of 4-Chloro-1,8-naphthalimides and Bulky, Primary Alkylamines at Room Temperature.

4-Amino-1,8-naphthalimides, potentially useful fluorescent probes in biological applications, are prepared via Ni(cod)2/IPr-catalyzed cross-couplings between 4-chloro-1,8-naphthalimide electrophiles and α,α,α-trisubstituted, primary alkylamines at room temperature. This method represents the first synthesis of 4-amino-1,8-naphthalimides using Ni-catalyzed C-N cross-coupling and provides the first examples of 4-amino-1,8-naphthalimides incorporating such bulky primary alkylamines, thereby highlighting the utility of Ni-catalyzed processes in synthesizing naphthalimide scaffolds that were inaccessible using established methods (SNAr; Pd or Cu catalysis).

A fluorescent histone deacetylase (HDAC) inhibitor for cellular imaging.

Fluorescence microscopy studies using 4-morpholinoscriptaid (4MS) demonstrated rapid cellular uptake of this scriptaid analogue into the cytoplasm but no nuclear penetration. As 4MS and scriptaid have the same in vitro activity against HDACs and KASUMI-1 cells; 4MS exemplifies a rational approach to subtly modify 'profluorogenic' substrates for intracellular studies.

In silico identification of an aryl hydrocarbon receptor antagonist with biological activity in vitro and in vivo.

The aryl hydrocarbon receptor (AHR) is critically involved in several physiologic processes, including cancer progression and multiple immune system activities. We, and others, have hypothesized that AHR modulators represent an important new class of targeted therapeutics. Here, ligand shape-based virtual modeling techniques were used to identify novel AHR ligands on the basis of previously identified chemotypes. Four structurally unique compounds were identified. One lead compound, 2-((2-(5-bromofuran-2-yl)-4-oxo-4H-chromen-3-yl)oxy)acetamide (CB7993113), was further tested for its ability to block three AHR-dependent biologic activities: triple-negative breast cancer cell invasion or migration in vitro and AHR ligand-induced bone marrow toxicity in vivo. CB7993113 directly bound both murine and human AHR and inhibited polycyclic aromatic hydrocarbon (PAH)- and TCDD-induced reporter activity by 75% and 90% respectively. A novel homology model, comprehensive agonist and inhibitor titration experiments, and AHR localization studies were consistent with competitive antagonism and blockade of nuclear translocation as the primary mechanism of action. CB7993113 (IC50 3.3 × 10(-7) M) effectively reduced invasion of human breast cancer cells in three-dimensional cultures and blocked tumor cell migration in two-dimensional cultures without significantly affecting cell viability or proliferation. Finally, CB7993113 effectively inhibited the bone marrow ablative effects of 7,12-dimethylbenz[a]anthracene in vivo, demonstrating drug absorption and tissue distribution leading to pharmacological efficacy. These experiments suggest that AHR antagonists such as CB7993113 may represent a new class of targeted therapeutics for immunomodulation and/or cancer therapy.

Synthesis and characterization of novel 2-amino-3-benzoylthiophene derivatives as biased allosteric agonists and modulators of the adenosine A(1) receptor.

A series of novel 2-amino-3-benzoylthiophenes (2A3BTs) were screened using a functional assay of A(1)R mediated phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2) in intact CHO cells to identify potential agonistic effects as well as the ability to allosterically modulate the activity of the orthosteric agonist, R-PIA. Two derivatives, 8h and 8i, differing only in terms of the absence or presence of an electron-withdrawing group on the benzoyl moiety of the 2A3BT scaffold, were identified as biased allosteric agonists and positive allosteric modulators of agonist function at the adenosine A(1) receptor (A(1)R) in two different functional assays. Our findings indicate that subtle structural variations can promote functionally distinct receptor conformational states.

Identification and characterization of kava-derived compounds mediating TNF-alpha suppression.

There is a substantial unmet need for new classes of drugs that block TNF-alpha-mediated inflammation, and particularly for small molecule agents that can be taken orally. We have screened a library of natural products against an assay measuring TNF-alpha secretion in lipopolysaccharide-stimulated THP-1 cells, seeking compounds capable of interfering with the TNF-alpha-inducing transcription factor lipopolysaccharide-induced TNF-alpha factor. Among the active compounds were several produced by the kava plant (Piper mysticum), extracts of which have previously been linked to a range of therapeutic effects. When tested in vivo, a representative of these compounds, kavain, was found to render mice immune to lethal doses of lipopolysaccharide. Kavain displays promising pharmaceutical properties, including good solubility and high cell permeability, but pharmacokinetic experiments in mice showed relatively rapid clearance. A small set of kavain analogs was synthesized, resulting in compounds of similar or greater potency in vitro compared with kavain. Interestingly, a ring-opened analog of kavain inhibited TNF-alpha secretion in the cell-based assay and suppressed lipopolysaccharide-induced TNF-alpha factor expression in the same cells, whereas the other compounds inhibited TNF-alpha secretion without affecting lipopolysaccharide-induced TNF-alpha factor levels, indicating a potential divergence in mechanism of action.

An improved synthesis of 5'-fluoro-5'-deoxyadenosines.

Synthesis of 5'-fluoro-5'-deoxyadenosine (5'-FDA) and structurally similar compounds is generally a poor yielding process. This is attributed to the instability of the selected synthetic intermediates. Herein, we report a general synthesis of 5'-fluoro-5'-deoxy-N6-substituted adenosines including a high yielding access to 5'-FDA.