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 organic heteropentacyclic compound that is calcein in which all four carboxy group hydrogens have been substituted by (acetyloxy)methoxy groups and the hyrodgens of the two hydroxy groups have been substituted by acetyl groups. It is a a non-fluorescent probe cleaved to a fluorescent probe by non-specific intracellular esterases.