Fagraldehyde, a Secoiridoid Isolated from Fagraea fragrans

A secoiridoid aglycone with an atypical skeleton, named fagraldehyde (1), together with several known secoiridoids (gentiopicroside (2), sweroside (3), and swertiamarin (4)) were isolated from the bark and leaves of Fagraea fragrans collected in Cambodia. The conformations of 1 were evaluated on the basis of molecular modeling and NOESY correlations. A hypothetical biogenesis of fagraldehyde was proposed to explain the unusual skeleton. Compound 1 was weakly active in vitro against Plasmodium falciparum.