Gaining confidence in high-throughput screening

The search for novel organic molecules with biological activity on human, animal, and plant physiological systems has passed through many phases over the centuries. From first steps testing single molecules on whole living systems to fully automated high-throughput screening (HTS) testing tens or hundreds of thousands of molecules per day on purified protein targets, the search has become ever more complex (1, 2). However, the increase in success has not been proportional to the effort and expense entailed. In particular, when considering the screening of “small molecules” (molecular mass <1,000 Da), the results of contemporary HTS have been plagued with problems of false positives, false negatives (3), and the abnormal behavior of certain molecules resulting from their physicochemical properties rather than their biological activity (4). In PNAS, Miller et al. (5) describe a significant evolution of current HTS technology that increases the confidence in the detection of truly active molecules by an order of magnitude. High-potency, highly specific molecular ligands are of great importance to modern medicine and agriculture and can also be valuable research tools that significantly aid the elucidation of metabolic pathways and control mechanisms. In its infancy, searching—or “screening” as it is now called—for active molecules relied on the analysis of plant and animal extracts and was a laborious, slow, and time-consuming process. As technology progressed and more rational methods were elaborated in the 1980s, screening evolved to a “process” whereby series of novel synthetic molecules were tested systematically for activity on one or even several different “targets” or target systems. In the 1990s high-throughput robotic screening methods based on microtiter plates were developed that took advantage of industrial-scale automation and large-scale data processing. This has allowed modern-day drug screening laboratories to “process” several tens or even hundreds of thousands of molecules per day (1, …