The Phloroglucinols of Dryopteris aitoniana PICHI SERM. (Dryopteridaceae, Pteridophyta)

Abstract

The phenolic compounds of the fern Dryopteris aitoniana were analyzed by improved methods avoiding alcaline reagents and contact with unbuffered SiO₂, which can cause deterioration. We confirmed the presence of five of the formerly (1971) reported six compounds, while the sixth, formerly incorrectly assumed to be aspidin (based on a spot in TLC), has now been isolated as cristals (TR‐1579). It has the empirical formula C₂₇H₅₂O₂, but its structure is still unknown. Five other compounds were isolated in pure form, tetra‐albaspidin BBBB (25‐BBBB) a known but rare phloroglucinol, and four new compounds: penta‐albaspidin BBBBB (37‐BBBBB), hexa‐albaspidin BBBBBB (38‐BBBBBB), tetraflavaspidic acid BBBB (26‐BBBB) and hexaflavaspidic acid BBBBBB (39‐BBBBBB). The structures were established by degradation NMR and partly by field‐desorption and fast‐atom‐bombardment (FAB) mass spectra. The oligoflavaspidic acids are very unstable compounds, deteriorating during isolation procedures using the older ‘standard method’.