Comparison of the Libraries

The number of recovered hits in the screening libraries varies, and depends on a 

Second-generation targeted libraries are designed to explore the chemical space near the hits in more detail. This is achieved by selecting compounds from the cells containing hits. The hit rates in the new libraries represent the capabihties of the different descriptor sets to predict biochemical activity. 

In contrast, the library designed on the basis of substructure descriptors as well as the autocorrelation-based library show a significant increase of hit rates. These descriptor sets can be used for identification of pharmacophore patterns and are applicable for selection of active compounds from a virtual library. 

Library Number of compounds (of preferred) Number of matched clusters (of preferred) Number of hits Hit rate (%) 

The examples demonstrate opportunities of computer-assisted optimization in library design. The quality of combinatorial Hbraries can be improved by computing similarities of virtual compounds or by estimation of activities [9, 136]. However, high diversity and high hit rates are usually not attainable in one library, and must be addressed in different design steps. 

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