The first 1-azaanthraquinone compound was
found in mycelium of Pyrenochaeta terrestris, the fungus
responsible for “pinkroot disease” of onions.13 In higher
plants, the 1-azaanthraquinones were reported only from
Annonaceous plants, such as cleistopholine from Cleistopholis
patens,14 Annona hayesii,15 and Meiogyne virgata;16
dielsiquinone from Gutteria dielsiana;17 and scorazanone
from G. scortechinii.2