John R. Goodell

Development of an Automated Microfluidic Reaction Platform for Multidimensional Screening: Reaction Discovery Employing Bicyclo[3.2.1]octanoid Scaffolds

An automated, silicon-based microreactor system has been developed for rapid, low-volume, multidimensional reaction screening. Use of the microfluidic platform to identify transformations of densely functionalized bicyclo[3.2.1]octanoid scaffolds will be described.

Synthesis and cancer cell cytotoxicity of substituted xanthenes

A series of substituted xanthenes was synthesized and screened for activity using DU-145, MCF-7, and HeLa cancer cell growth inhibition assays. The most potent compound, 9 g ([N,N-diethyl]-9-hydroxy-9-(3-methoxyphenyl)-9H-xanthene-3-carboxamide), was found to inhibit cancer cell growth with IC(50) values ranging from 36 to 50 microM across all three cancer cell lines. Structure-activity relationship (SAR) data is presented that indicates additional gains in potency may be realized through further derivatization of the compounds (e.g., the incorporation of a 7-fluoro substituent to 9 g). Results are also presented that suggest the compounds function through a unique mechanism of action as compared to that of related acridine and xanthone anticancer agents (which have been shown to intercalate into DNA and inhibit topoisomerase II activity). A structural comparison of these compounds suggests the differences in function may be due to the structure of the xanthene heterocycle which adopts a nonplanar conformation about the pyran ring.

Novel acridine-based compounds that exhibit an anti-pancreatic cancer activity are catalytic inhibitors of human topoisomerase II

We have identified a small library of novel substituted 9-aminoacridine derivatives that inhibit cell proliferation of pancreatic cancer cell lines by inducing apoptosis [Goodell, J.R. et al., 2008. J. Med. Chem. 51, 179-182.]. To further investigate their antiproliferative activities, we have assessed the antiproliferative activity of these acridine-based compounds against several pancreatic cancer cell lines. All four compounds used in this study inhibited the proliferation of pancreatic cancer cell lines in vitro. In addition, we have employed a xenograft tumor model and found that these compounds also inhibit the proliferation of pancreatic cancer in vivo. In light of the potential importance of the anticancer activity of these acridine-based compounds, we have conducted a series of biochemical assays to determine the effect of these compounds on human topoisomerase II. Unlike amsacrine, these compounds do not poison topoisomerase II. Similar to amsacrine, however, these compounds intercalate into DNA in a way that they would alter the apparent topology of the DNA substrate. Thus, inhibition of the relaxation activity of topoisomerase II by these compounds has been reexamined using a DNA strand passage assay. We have found that these compounds, indeed, inhibit the catalytic activity of topoisomerase II. Thus, these novel acridine-based compounds with anti-pancreatic cancer activity are catalytic inhibitors, not poisons, of human topoisomerase II.

Reaction Discovery Using Microfluidic-Based Multidimensional Screening of Polycyclic Iminium Ethers

Polycyclic iminium ethers are ambident electrophilic intermediates that react with a range of nucleophiles in a highly condition-dependent manner to afford densely functionalized lactams. In an effort to expand the scope of reactivity and assist in the generation of new chemotypes from these intermediates, several iminium ethers were subjected to reaction screening using an automated microfluidics reaction platform. Application of this approach led to the discovery of several interesting reaction pathways involving the iminium ether intermediates that will be described.

Multidimensional Reaction Screening for Photochemical Transformations as a Tool for Discovering New Chemotypes

We have developed an automated photochemical microfluidics platform that integrates a 1 kW high-pressure Hg vapor lamp and allows for analytical pulse flow or preparative continuous flow reactions. Herein, we will discuss the use of this platform toward the discovery of new chemotypes through multidimensional reaction screening. We will highlight the ability to discretely control wavelengths with optical filters, allowing for control of reaction outcomes.

Synthesis and Reactivity of Bicyclo[3.2.1]Octanoid- Derived Cyclopropanes

Photochemical oxa-di-π-methane rearrangement of bicyclo[3.2.1]octanoid scaffolds affords multifunctional, donor-acceptor cyclopropanes. A related photochemical reaction of an iminium ether substrate uncovered an unprecedented aza-di-π-methane rearrangement of a β,γ-unsaturated iminium. Donor-acceptor cyclopropanes have been evaluated as substrates for reactions generating several new chemotypes.

Synthesis and evaluation of N-alkyl-9-aminoacridines with antibacterial activity.

A series of 9-alkylaminoacridines were synthesized and evaluated for activity against two strains of methicillin-resistant and one strain of methicillin-sensitive Staphylococcus aureus. Results are presented that show a clear structure activity relationship between the N-alkyl chain length and antibacterial activity with peak MIC99 values of 2-3 μM for alkyl chains ranging from 10 to 14 carbons in length. Although prior work has linked the function of acridine-based compounds to intercalation and topoisomerase inhibition, the present results show that 9-alkylaminoacridines likely function as amphiphilic membrane-active disruptors potentially in a similar manner as quaternary ammonium antimicrobials.

Unique Reactivity of anti- and syn-Acetoxypyranones en Route to Oxidopyrylium Intermediates Leading to a Cascade Process

Unique reactivity of anti- and syn-acetoxypyranones was observed in oxidopyrylium-alkene [5 + 2] cycloadditions. The subtle interplay between the corresponding acetoxypyranone conformation and steric bulk of tertiary amine bases causes syn-acetoxypyranones to undergo [5 + 2] cycloaddition appreciably faster than anti-acetoxypyranones. Additionally, the efficiency of a cascade process that afforded a novel tetracyclic lactol was determined to be dependent on the relative stereochemistry of each diastereomer, the amine base utilized, and the addition of water.

Synthesis and in silico screening of a library of β-carboline-containing compounds

Summary The synthesis of a library of tetrahydro-β-carboline-containing compounds in milligram quantities is described. Among the unique heterocyclic frameworks are twelve tetrahydroindolizinoindoles, six tetrahydrocyclobutanindoloquinolizinones and three tetrahydrocyclopentenoneindolizinoindolones. These compounds were selected from a virtual combinatorial library of 11,478 compounds. Physical chemical properties were calculated and most of them are in accordance with Lipinski’s rules. Virtual docking and ligand-based target evaluations were performed for the β-carboline library compounds and selected synthetic intermediates to assess the therapeutic potential of these small organic molecules. These compounds have been deposited into the NIH Molecular Repository (MLSMR) and may target proteins such as histone deacetylase 4, endothelial nitric oxide synthase, 5-hydroxytryptamine receptor 6 and mitogen-activated protein kinase 1. These in silico screening results aim to add value to the β-carboline library of compounds for those interested in probes of these targets.

FURTHER INVESTIGATION OF PYRANONE ACTIVATION

I. General Methods II. General Procedures for Acid-Mediated Reactions (Tables 1 & 2) III. Characterization of Cycloadduct 2 and By-products 3 & 4 IV. Preparation and Characterization of Pyranone 1c V. General Procedure for Microwave-Assisted Reactions (Table 3) VI. General Procedure for Microwave-Assisted Reactions (Table 4) VII. Preparation and Characterization of Acetoxypyranones 1c-g VIII. Computational Methods and Experimental Parameters IX. Spectra of Acetoxypyranones 1c-g