Concepts and technologies for tracking bioactive compounds in natural product extracts: generation of libraries, and hyphenation of analytical processes with bioassays.

Since the advent of high-throughput screening (HTS) in the early 1990s, a wealth of innovative technologies have been proposed and implemented for the effective localization and characterization of bioactive constituents in complex matrices. The latest developments in this field are reviewed under the perspective of their applicability to natural product-based drug discovery. The approaches discussed here include TLC-based bioautography, HPLC-based assays with on-line, at-line and off-line detection, as well as affinity-based methods, such as frontal affinity chromatography, pulsed ultrafiltration mass spectrometry, imprinted polymers, and affinity capillary electrophoresis. Selected practical examples are given to illustrate the strengths and limitations of these approaches in contemporary natural product lead discovery. In addition, compatibility issues of natural product extracts and HTS are addressed, and selected protocols for the generation of high quality libraries are presented.