Kotanin A is a biscoumarin first isolated from Aspergillus glaucus by Buchi and co-workers at Massechussets Institute of Technology when identifying the toxic principles from mould-infested rice in Thailand in 1971. Kotanin A analogues were found to be non-toxic to mammals and the toxic principles were later identified as aflatoxins. Kotanin A is a symmetric biscoumarin with S axis chirality. Kotanin A, with its characteristic UV spectrum, is a useful chemotaxonomic marker for the Aspergillus genus.