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.
These xanthones are usually restricted to the plant species of the family Guttiferae. The major C5 unit of the substituents included the commonly found 3-methylbut-2-enyl or isoprenyl group as in isoemericellin and the less frequent 3-hydroxy-3-methylbutyl as in nigrolineaxanthone P and 1,1-dimethylprop-2-enyl as in globuxanthone, respectively.