ISOKOTANINS AC - NEW BICOUMARINS FROM THE SCLEROTIA OF ASPERGILLUS-ALLIACEUS

Three new bicoumarin metabolites, isokotanins A [1], B [2], and C [3], were isolated from the sclerotia of Aspergillus alliaceus. Isokotanin A is a regioisomer of the known bicoumarin kotanin [4]. The structure s and spectral assignments for 1-3 were determined on the basis of sel ective INEPT, HMQC, HMBC, and NOESY nmr data, as well as by chemical i nterconversions. Isokotanins B and C show activity against the corn ea rworm Helicoverpa zea and the dried fruit beetle Carpophilus hemipteru s. The known compounds kotanin [4], desmethylkotanin [5], nominine, an d paspaline were also isolated from extracts of A. alliaceus sclerotia .