Structures of meroterpenes produced by Penicillium sp, an endophytic fungus found associated with Melia azedarach

The fungus Penicillium sp was isolated from the root bark of Melia azedarach after surface sterilisation and cultivated for three weeks on sterilised rice. A new meroterpene, named austinoneol, and the known meroterpenes 7-b-acetoxy-dehydroaustin, neoaustin and dehydroaustin were isolated from the methanol extract of this rice culture. Their structures were identified after extensive spectroscopic studies, which also helped on the revision of ¹H and 13C chemical shift assignment for some of the known meroterpenes.