Three new azaphilones, sassafrin E (1), sassafrin F (2), and sassafrinamine A (3), were isolated from the filamentous fungus Aspergillus neoglaber. The structures of the compounds were determined by nuclear magnetic resonance spectroscopy, and were found to be novel analogues of two already known compound classes; sassafrins and berkchaetoazaphilones. Sassafrin E and F were both oxygen containing, while sassafrinamine A additionally contained a nitrogen atom, originating from an aminoethanol moiety, as well as extensive conjugation resulting in an intense purple colour of the pure compound. The structure of sassafrin E was further confirmed using deuterium exchange experiments coupled with high-resolution tandem mass spectrometry.
Keywords: Aspergillus neoglaber; Azaphilones; Pigments; Structural elucidation; Tandem mass spectrometry.