Phenylbenzoisoquinolindione alkaloids accumulate in stamens of Xiphidium caeruleum Aubl. flowers

Nine previously undescribed phenylbenzoisoquinolindione alkaloids with identical aza-phenylphenalenone core structure and with different amino acid-derived side chains at position 2 were identified. Phenylbenzoisoquinolindiones specifically occur in flower organs of the Haemodoraceae, subfamily Haemodoroideae.