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 aryl sulfate that is 4-nitrocatechol in which the hydroxy group that is meta to the nitro group has been converted into the corresponding hydrogen sulfate. It is used (commonly as its dipotassium salt) as a chromogenic substrate for sulphatase.