Metabolism of cinnoline to N-oxidation products by Cunninghamella elegans and Aspergillus niger

Cultures of the fungi Cunninghamella elegans and Aspergillus niger were grown in fluid Sabouraud medium at 28°C for 3 days and then dosed with cinnoline (1,2-diazanaphthalene). After 3 more days, metabolites were extracted from the cultures with ethyl acetate, separated by high-performance liquid chromatography, and identified by mass spectrometry and proton nuclear magnetic resonance spectroscopy. Both fungi oxidized 2–10% of the added cinnoline to mixtures of cinnoline 2-oxide and cinnoline 1-oxide. Received 10 June 1998/ Accepted in revised form 25 September 1998