The Chemical Entities of Biological Interest (ChEBI) ontology is downloaded weekly from EMBL-EBI at http://www.ebi.ac.uk/chebi/. The data is made available under the Creative Commons License (CC BY 3.0, http://creativecommons.org/licenses/by/3.0/). For more information see: Degtyarenko et al. (2008) ChEBI: a database and ontology for chemical entities of biological interest. Nucleic Acids Res. 36, D344–D350.
An acid degradation product of a penicillin, produced by cleavage of the 1,7 bond, forming penicilloic acid; and formation of a bond between the exocyclic carbonyl carbon and N-1 with the elimination of water from these two positions and the exocyclic NH.