Parallel liquid-phase synthesis of N-substituted 6-aminosulfonyl-2-oxo-1,2-dihydroquinoline-4-carboxamide and 6-aminosulfonylquinoline-4-carboxamide derivatives.

Two efficient strategies for solution-phase parallel synthesis of libraries of quinoline derivatives are described. The first synthetic pathway features the Pfitzinger reaction of isatin with diethyl malonate and sulfochlorination of the resulting 2-oxo-1,2-dihydroquinoline-4-carboxylate followed by generation of sulfonamide library. The second strategy employs the unusual behavior of 5-sulfamoylisatins in Pfitzinger reactions, which results in formation of 6-sulfamoyl-4-carboxyquinolines instead of the anticipated 2-oxo-1,2-dihydroquinoline structures. The obtained carboxylates appeared to be convenient synthetic intermediates for the generation of the corresponding carboxamide libraries. Using these reagents, the parallel solution-phase synthesis of more than 500 substituted quinoline and 2-oxo-1,2-dihydroquinoline derivatives has been accomplished on the 50-100-mg scale. Simple manual techniques for parallel reactions using special CombiSyn synthesizers were coupled with easy purification procedures to give high-purity final products. The scope and limitations of the developed approaches are discussed.

Suaveolindole, a new mass-limited antibacterial indolosesquiterpene from Greenwayodendron suaveolens obtained via high-throughput natural products chemistry methods.

Utilizing high-throughput isolation, purification, and analysis methods applied to a natural products library, a new mass-limited antibacterial indolosesquiterpene, suaveolindole (1), was obtained from Greenwayodendron suaveolens. The miniaturization of the structure elucidation of 1 was performed primarily using the CapNMR probe. Compound 1 was found to possess significant in vitro antibacterial activity against the Gram-positive bacteria Bacillus subtilis (ATCC 43223), Staphylococcus aureus (ATTC 6538P), and methicillin-resistant Staphylococcus aureus (ATTC 33591), with MIC values of 4, 8, and 8 microg/mL, respectively.

Miniaturization of the structure elucidation of novel natural products--two trace antibacterial acylated caprylic alcohol glycosides from Arctostaphylos pumila.

High-throughput isolation, purification and analysis methods applied to natural products libraries from plants gave rise to the discovery of two novel acylated caprylic alcohol glycosides (1, 2) produced by Arctostaphylos pumila. The NMR spectra were acquired using the CapNMR probe and performed on mass-limited samples, which enabled us to elucidate the structures of 2,6-diacetyl-3,4-diisobutyl-1- O-octylglucopyranoside (1, 200 microg) and 2,6-diacetyl-3,4-dimethylbutyl-1- O-octylglucopyranosid (2, 70 microg). Compounds 1 and 2 exhibited antibacterial activity against Gram-positive methicillin-resistant Staphylococcus aureus with an MIC of 128 microg/mL and 64 microg/mL, respectively.

High-throughput method for the production and analysis of large natural product libraries for drug discovery.

High-throughput methods were applied to the production, analysis, and characterization of libraries of natural products in order to accelerate the drug discovery process for high-throughput screening in the pharmaceutical and biotechnology industries. Library production integrates automated flash chromatography, solid-phase extraction, filtration, and high-throughput parallel four-channel preparative high-performance liquid chromatography to obtain the libraries in 96- or 384-well plates. Libraries consist of purified fractions with approximately one to five compounds per well. Libraries are analyzed prior to biological screening by a high-throughput parallel eight-channel liquid chromatography-evaporative light scattering detection-mass spectrometry system to determine the molecular weight, number, and quantity of compounds in a fraction. After biological screening, active fractions are rapidly purified at the microgram level and individual compounds are rescreened for confirmation of activity. Structures of active compounds are elucidated by NMR spectroscopy and mass spectrometry. Utilization of a novel microcoil probe allows NMR data to be gathered on 50 microg. As a demonstration, a library was made from the stem bark of Taxus brevifolia. Biological screening in the National Cancer Institute's in vitro panel of three cancer cell lines demonstrates that the process enables the discovery of active anticancer compounds not detected in the flash fractions from which the library originates.