Statistics and Ontology of Published Small Molecule Ring Systems.

Diversity and properties of ring systems contained in small molecules are of high interest for applications such as drug discovery and materials science. In the present work, we extract, analyze, and classify ring systems found in small-molecule compounds of open-access databases such as PubChem, ChEMBL, DrugCentral, IUPHAR, and LOTUS. We also developed a classification taxonomy of frequently found ring systems using an Open Biomedical Ontologies (OBO)-format ontology. Open-access software was used to automate the classification of compounds into their respective ring system classes. As an example, the natural product compounds of the LOTUS database were classified and are available as an open-access ontology dataset.