High-Throughput Method for the Production and Analysis of Large Natural Product Libraries for Drug Discovery

Abstract

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.